MT LEYSHON PROJECT ENVIRONMENTAL EVALUATION
STAT 620 (REF: 175040, TSV369)
PART 3: SOURCE, CAUSE AND EXTENT OF ALGAL GROWTH
IN PUDDLER AND CLARK CREEKS
A Report for Newmont Mining Services Pty Ltd
ACTFR Report No. 12/05
May 2012
MT LEYSHON PROJECT ENVIRONMENTAL EVALUATION
STAT 620 (REF: 175040, TSV369)
PART 3: SOURCE, CAUSE AND EXTENT OF ALGAL GROWTH
IN PUDDLER AND CLARK CREEKS
ACTFR Report No. 12/05
May 2012
Prepared for:
Newmont Mining Services Pty Ltd
Level 1, Colonnade Building
388 Hay St
Subiaco
WA6008
Prepared by Barry Butler
Australian Centre for Tropical Freshwater Research
James Cook University
Townsville Qld 4811
Phone: 07 47814262
Fax: 07 47815589
Email: actfr@jcu.edu.au
Web: www.jcu.edu/actfr
Australian Centre for Tropical Freshwater Research
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TABLE OF CONTENTS
1.
INTRODUCTION .............................................................................................................................. 3
2.
FACTORS THAT GOVERN ALGAL BIOMASS AND DIVERSITY ......................................... 4
3.
PREVIOUS STUDIES ....................................................................................................................... 8
4.
5.
3.1
DERM sampling in October2010.............................................................................................. 8
3.2
Historical Monitoring Data ....................................................................................................... 9
3.3
ACTFR Limnological Survey in August 2011 ....................................................................... 10
METHODS ........................................................................................................................................ 12
4.1
Sampling and Survey Activities .............................................................................................. 12
4.2
Site Locations ........................................................................................................................... 12
4.3
Sampling and Analysis Methods............................................................................................. 12
RESULTS AND DISCUSSION ....................................................................................................... 16
5.1
Results of the August 2011 Survey ......................................................................................... 16
5.1.1 General Water Quality ........................................................................................................ 16
5.1.2 Aqueous Nutrient Concentrations ..................................................................................... 17
5.1.3 Phytoplankton ...................................................................................................................... 18
5.1.4 Benthic Algae ....................................................................................................................... 19
5.2
Results of the 2012 Investigation ............................................................................................ 19
5.2.1 Nutrients ............................................................................................................................... 19
5.2.2 Phytoplankton ...................................................................................................................... 23
5.2.3 Benthic algae ........................................................................................................................ 28
6.
SUMMARY AND CONCLUSIONS ............................................................................................... 39
7.
REFERENCES ................................................................................................................................. 40
A.
APPENDIX........................................................................................................................................ 42
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1.
INTRODUCTION
Newmont Mining Services Pty Ltd (NMS) have commissioned the Australian Centre for Tropical
Freshwater Research (ACTFR) to carry out an environmental investigation at Mount Leyshon Mine in
order to address the algal growth related components of an Environmental Evaluation (EE) notice issued
by the Queensland Department of Environment and Resource Management (DERM) on 9th December
2011.
This is one of three separate reports prepared by NMS and their consultants, each addressing different
specific aspects of the EE notice (STAT 620). ACTFR were engaged to deal with the matters raised in the
following sections of the EE Notice:
6.
Identify the dominant genera/species of algae forming dense and prolific algal growth in Puddler and
Clark Creeks.
7.
Identify the source, cause and extent of algal genera and/or species forming dense and prolific algal
growth in Puddler and Clark Creeks. This investigation should include investigation of limiting
factors to algal growth, and determine if the algae is linked to inputs from the said premises.
8.
Assess the actual and potential impact of algal genera and/or species forming dense and prolific algal
growth on the receiving environment. The investigation must:
a.
See Below.
b.
Include assessment on the impacts on the environmental values identified for:
i.
Surface waters,
ii.
Sediment quality,
iii. Aesthetic values
iv. Riparian and aquatic flora and aquatic fauna.
c. Include a comparison and review of previous relevant studies undertaken.
d. Include relevant reference sites.
9.
Based upon the investigation undertaken as part of this environmental investigation determine and
report on all relevant options including costs and detailed remedial works required to address the
cause of the contamination and impacts on the receiving environment. Remediation options must
ensure protection of the environmental values of the receiving environment.
Section 8 a. of the EE Notice – “Identify and define the receiving environment including the relevant
environmental values of the receiving environment in accordance with ANZECC methodology” is
equally applicable to each component of the EE investigations and has therefore been addressed in an
overview report which collates and summarises the findings of each of the separate studies that have been
undertaken (NMS 2012)
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2.
FACTORS THAT GOVERN ALGAL BIOMASS AND DIVERSITY
Consistent with the established conventions in water quality science, this report employs the term “algae”
in reference to any photosynthetically active aquatic organisms that are not vascular plants, including for
example cyanobacteria and heteroautotrophic protista. Notably this is the same convention that was
followed in the DERM EE notice.
The vast majority of the scientific literature dealing with algal growth limiting factors in freshwater
ecosystems relates to perennial limnetic systems such as large lakes and rivers where primary
productivity principally occurs within the water column and in relative isolation from the benthos. Hence
much of the available information is not relevant to the predominately benthic ecosystems that occur
within small seasonally ephemeral streams in the semi-monsoonal dry tropics. The Queensland Water
Quality Guidelines (QWQG 2009) note the paucity of advice on how to deal with ephemeral waters and
draw attention to some ongoing/emerging research on that topic. However, that research has focussed
heavily on arid areas and on highly ephemeral waterways and lakes that are not recharged seasonally
(Smith et al 2004 provides an entry point into the literature on that topic), and to date very little specific
work has been done on the kinds of streams that are under investigation here.
ACTFR have been studying various aspects of the limnology and ecology of streams in the Burdekin
catchment for almost 25 years. Based on that experience we proposed a heuristic conceptual model to
help resource managers understand the likely links between water quality, productivity and biophysical
drivers in certain types of intermittent streams that commonly occur within the northern Burdekin
catchment (Burdekin Basin Water Resource Plan Current Condition Report, Butler 2005). The following
discussion draws on the principles and information sources outlined in that document, with appropriate
refinements to account for the fact that the streams under investigation here are somewhat smaller and
more ephemeral than the systems that are envisaged in that model.
Water Regime
The length of the periods during which water is absent from a stream is a fundamental determinant of
algal productivity and community structure in ephemeral waters. Since the streams in this study area dry
out almost every dry season, the algal species which become re-established each wet season must be
adapted to avoid and/or resist dessication, and that requirement eliminates many taxa which could inhabit
these streams if they did not dry out. Regeneration of dessication resistant algae generally occurs quite
rapidly upon rehydration; nevertheless, nutrients contained in first-flush stormwater runoff are not
typically assimilated as efficiently as they are in permanent waters which already contain an established
biomass of actively growing algae when the inflow occurs, and notably the minor phytoplankton blooms
which commonly occur in permanent waters in the immediate aftermath of stormwater inflows are rarely
observed in these ephemeral systems.
There are numerous streams throughout this region that retain enough water during most years to support
assemblages of aquatic macrophytes (i.e. vascular plants), principally reeds, bulrushes and/or submerged
species such as Ceratophyllum and Myriophyllum. These plants, and especially the submergent species,
very successfully compete with algae, and particularly phytoplankton, generally limiting their
proliferation. (For reasons that are not fully understood macrophytes appear to achieve dominance much
more readily in this region than they do in more temperate climatic regions).
No submergent macrophytes have been observed in either Clarke or Puddler Creeks, although there are a
few isolated places in both creeks where sparse stands of emergent macrophytes (Typha and Phragmites)
have taken a weak foothold in sands that are deep enough to retain moisture for most of the year. Given
that the past few years have been unusually wet and would have provided the best possible opportunity
for plants to colonise, the development of any assemblages extensive enough to influence algal
productivity is considered unlikely. This fact should be taken into consideration if comparing the algal
productivity of these creeks to other “reference” streams in the area.
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Frequency and Nature of Swiftflows
Drought frequencies in this region are quite high; however, rainfall is seasonal enough to ensure that there
is at least one hydrographic event each year that generates sufficient flow to flush out the streams and
scour the streambed. These flows wash away most of the algae and/or propagules that were present in the
stream prior to the event. They also remobilise sand and gravel, disrupting attached algae, potentially
burying benthic algae beds further downstream and washing away a lot of the nutrients that were
contained within the bottom sediments. The effects of these kinds of wet season sediment movements are
clearly evident in both Clarke and Puddler Creeks. Most of the reaches of Clarke Creek that are of interest
to this study host deep coarse sand substrates that appear to be highly mobile. For example, in August
2011 the site designated as Clarke 1 was a waterhole containing chest-deep water, but due to the
deposition of a sand slug during this year’s wet season, the standing water at that site is now only knee
deep. These kinds of major disturbances impose significant limits on the capacity for algae to colonise the
streambed.
Puddler Creek is a higher gradient stream containing much less well-sorted basal sediments. It has a
misfit low flow channel comprising sequences of rock, cobble and stone riffles interspersed by shallow
pools with coarse sand and gravel substrata. The rocky substrata provide more stable refuge for benthic
algae than sand, and although significant sloughing (i.e. breaking off of algae filaments) would be
expected to occur during high flow events, it is likely that the retained biomass would be sufficient to
allow rapid recovery. In most reaches of the creek the high flow parts of the channel contain significant
quantities of mobile sand (as evidenced by the paucity of established riparian plants). There is evidence
that slugs of this material have periodically been deposited within the low flow channel resulting in burial
of algal mats (discussed later in this report).
Persistency of baseflow
Baseflows (derived from surface discharges of groundwater) continuously replenish the supply of
aqueous nutrients; hence even if the nutrient concentrations in the water are quite low, the cumulative
load can be substantial. Some algal species have a preferred growing season and may senesce at various
times of the year, so if baseflows persist through winter the composition of the algal community will
usually fluctuate over time; nevertheless, in this region overall algal biomass generally continues to
increase during the dry season as long as flows persist.
The wet season rainfall totals that have been recorded in this study area over the past four years have been
above average (NMS 2012). Moreover, rainfall duration and frequency have also been unusually high
leading to greater soil infiltration and groundwater recharge, and consequently more prolonged baseflows
in surface streams. The effects that this has had on creek systems throughout the wider region have been
very obvious. Many creeks that have run dry each year for more than a decade have sustained flows for
the majority of the past four years, and as a consequence they have developed far more extensive algal
communities than they have previously. There is no doubt that the creeks in this study area, and especially
the less sandy higher gradient streams like Puddler Creek, have been influenced in the same way.
Standing Water Volume and Hyporheic Flow
The water levels in ephemeral streams constantly decline during the dry season until the streambed
eventually runs dry. Even if algal growth were to cease during that period, algal concentrations would
continue to increase simply due to the declining water volumes, and that factor must be taken into
consideration when assessing the densities of algal assemblages. In practice, because the surface of the
streambed is uneven, isolated pools and backwaters generally form as the water levels retract. Fragments
of the benthic algae growing within the flowing sections of the creek constantly break off and get carried
downstream (termed sloughing), and this tends to moderate the rate at which algae accumulates at a given
location. However, algae trapped in isolated pools and backwaters are not subject to such controls, hence
biomass can accumulate quite rapidly if the organisms continue to grow. If the algae are trapped in
perched pools growth rates may decline due to nutrient limitation (because there are no longer any
Australian Centre for Tropical Freshwater Research
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inflows to supply nutrients). However, many of the isolated pools still receive hyporheic (i.e. subsurface)
flow, even though surface connections to the main stream have been lost; hence rapid growth rates can be
still be maintained. The dense patches of dense algal growth that result from these processes are often the
most visible manifestation of algal productivity in ephemeral streams.
Light Availability
The ambient turbidity levels in many waterways in the Burdekin catchment are high enough to prevent
light from penetrating more than a few centimetres into the water column. This severely limits the amount
of light available to support photosynthesis and concomitantly imposes severe constraints on algal
productivity. However, all of the baseflow waters in this study area are clear and shallow enough to allow
sunlight to reach the streambed, so in this case turbidity is not a significant limiting factor for algae.
Nevertheless, shade from riparian trees and steep banks, internal shading of the benthos by leaf litter
deposited in the stream, and light attenuation caused by coloured organic substances (such as tannins)
released from decaying leaves, can all potentially limit the productivity of benthic algae in clear waters.
There are a few narrow reaches of Puddler Creek where the riparian vegetation is dense enough to form a
relatively intact canopy. However, in most reaches of the creek the streambed is exposed to direct
sunlight for a significant proportion of the day and there are only a few localised areas where leaf litter
accumulates to the point where it could potentially inhibit algae. Some of the reaches of Clarke Creek that
lie within this study area support quite dense riparian vegetation, but in most places the creek is too wide
to benefit significantly from the shade and leaf litter that this provides. Accordingly light limitation of
algal growth is unlikely to be a significant factor in this study area.
Herbivory
Most of the native fish species that inhabit freshwaters in this region are omnivorous, and if present in
high abundances, they have the potential to reduce benthic algae biomass. Native species do not generally
feed on phytoplankton but the streams in this study area support significant populations of Tilapia and
that species feeds on both planktonic and benthic forms of algae. It is likely that these fish play a role in
moderating algal biomass accumulation, especially in deeper pools that can still be utilised when flow
rates and water levels decline during the dry season. Absence of fish from isolated pools, and shallow
backwaters and riffles may contribute to the high algal densities that develop in those microhabitats.
Nutrients
Algae unequivocally require nutrients to grow. In this region nutrients such as potassium, calcium,
magnesium, iron, silica, copper and zinc naturally occur in sufficient excess to ensure that they are not
growth limiting factors, and (although for some species of green algae the pH dependent availability of
carbon in the form of carbon dioxide may also be an issue –discussed in a later section of this report) it is
the availability of nitrogen and phosphorus which generally governs growth rates, and for the remainder
of this report the term nutrient will be used in reference to bioavailable compounds that are a source of
those two elements.
In streams where productivity principally occurs within the benthos (i.e. in close association with the
bottom sediments), the relationships between the nitrogen and phosphorus concentrations in the water
column and algal productivity are complex and not easily interpreted. That is partly because nutrient
concentrations within the bottom sediments (generally measured in mg/L) are generally orders of
magnitude higher than the levels in water column (measured in µg/L), and some species can access that
almost inexhaustible supply of nutrients and others cannot. (Diatoms, Euglena and cyanobacteria, for
example, are motile enough to enter the sediment interstices to take up nutrients during the night and
return to the surface to obtain light during the day). Unfortunately, because the capacity for algae to
utilise sedimentary nutrients varies substantially between species and circumstances, analysing the
nutrient content of bottom sediments rarely improves our capacity to interpret results.
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Moreover, in lotic systems such as these, flow rate and duration may be a more important indicator of
nutrient load and availability than concentration values – i.e. a prolonged constant flow of low nutrient
water can induce greater algal growth than a briefer pulse of nutrient-enriched water. The task of
assessing nutrient utilisation and internal loading in stream environments of this kind is therefore a
substantial research undertaking and generally requires the use of specialised techniques such as
radioactive labelling to asses uptake efficiencies.
When evaluating aqueous nutrient concentrations in benthic-dominated streams it is particularly
important to bear in mind that the potential significance of the reported values is often different to what it
would be if dealing with a limnetic system. Limnetic systems are dominated by microscopic planktonic
algae (i.e. phytoplankton) and these are captured in water samples, so even if they have assimilated most
of the available nutrients, water samples will still yield high total concentration values. Hence the
conventional view that low aqueous nutrient concentrations are diagnostic of low productivity (and vice
versa) holds true. In contrast benthic algae and the nutrients that they have assimilated are not captured in
water samples, and accordingly low aqueous nutrient results can sometimes be symptomatic of very high
algal productivity and conversely, high nutrient results may be indicative of unusually low algal biomass
(i.e. a lack of assimilation by algae).
Provided that these kinds of complications are taken into consideration it is still usually possible to make
some useful, albeit qualitative inferences regarding the significance of water quality results, and that has
been done in the results and discussion section of this report.
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3.
PREVIOUS STUDIES
3.1
DERM sampling in October2010
Relevant results obtained from samples collected by DERM in October 2010 are shown in Table 3.1. It is
difficult to gauge the significance of the algal cell counts provided without knowing precisely how and
where the samples were taken, and what they actually represented. Moreover, the algal identifications
given in the table are not suffiently precise to be able to infer what kinds of sampling methods would have
been needed in order to obtain representative samples. It is, however, noteworthy that the algal genera
that have since been recorded in these streams (in 2011 and 2012) all belong to the same broad groups
that were identified in 2010, and it seems likely that similar genera would have been present at that time.
If that is the case then most of the algae that was observed in 2010 would have comprised species that
exhibit a strong preference for benthic habitats, tending to accumulate on the streambed in any places
where flow rates are low enough for them to settle and/or where the substratum provides suitable surfaces
for attachment, often forming dense assemblages in microhabitats where conditions are particularly
favourable. Moreover, cyanobacteria (and other algal species attached to them) can periodically rise from
the bottom forming dense mats which can float on the water surface for prolonged periods before sinking
back to the bottom. Hence spatial distributions are so heterogeneous that it is virtually impossible to
collect discrete samples representative of the algal biomass within a particular section of stream.
However, most of the species in question can also live freely suspended within the water column, and if
the waterbody is reasonably well-mixed, conventional water samples may provide some useful
indications of biomass.
Table 3.1
Analytical results reported by DERM in October 2010.
Site
PCK1
PCC
SW47
STSF
Sump
SW108
Mt Hope
Ext Dam
Mt Hope
Drain
8.3
8.18
8.33
7.69
8.25
4.2
6.85
Key Surface Water Results
pH
SO4 (mg/L)
202
820
30
4,150
3,080
6,480
5,920
Total Dissolved Solids (mg/L)
1,240
2,400
980
6,760
6,030
9,950
9,200
Sulfide as S2- (mg/L)
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
Nitrate as N (mg/L)
0.05
<0.01
0.01
3.03
0.02
0.69
0.61
Kjeldahl Nitrogen as N (mg/L)
0.3
0.1
0.4
1.6
0.5
1.1
1.3
Total Nitrogen as N (mg/L)
0.4
0.1
0.4
4.6
0.5
1.8
1.9
<0.01
0.02
0.03
0.02
0.02
0.02
0.08
Blue green algae (cells/ml)
9,300
26,880
<1
<1
<1
Green algae (cells/ml)
5,280
3,500
3,630
4,000
93,000
Flagellates (cells/ml)
<1
<1
550
<1
<1
<1
<1
<1
<1
<1
4,200
910
40
3,000
203,000
Total Phosphorous as P (mg/L)
Key Algae Results
Golden algae (cells/ml)
Diatoms (cells/ml)
Accordingly if DERM targeted the benthos when collecting the algae samples in 2010, the magnitude of
the cell counts would largely be an artefact of the sampling process and the results would simply provide
an indication of the relative abundances of different taxa. However, if the counts were obtained from
standard water samples the results would suggest that phytoplankton levels were quite significant at the
time. The blue green algae (i.e. cyanobacteria) cell counts at PCK1 and PCC were within the 5000 to
50000 cells/ml range which is the amber alert level for management of Microcystis aerugenosa in waters
where human body contact is likely (Queensland Water Quality Guidelines 2009); however, there is no
means of knowing whether Microcystis or any other potential toxin-forming species were actually a
significant component of the cyanobacteria that were present in these samples. (Note that a yellow alert
would indicate the need to sample more extensively and conduct a risk assessment).
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The pH levels recorded at all three of the receiving water sites were only mildly alkaline and provide no
indication of anomalous photosynthetic activity levels. Algae consume carbon dioxide (i.e. carbonic acid)
when they photosynthesise, so in poorly aerated waters of the kind that are generally present in these
streams in the dry season, pH levels cyclically rise during the day and fall at night. In our experience,
when algae begin to bloom in moderately alkaline waters, daytime pH values almost always rise to levels
of at least 8.7. At that point there is no longer any free carbon dioxide left in the water and some algal
species must cease photosynthesising. However, cyanobacteria and some other species can obtain carbon
dioxide by enzymatically cleaving bicarbonate – a process that generates hydroxyl ions leading to
substantial additional pH increases during daylight hours, even in waters that have quite high alkaline pH
buffering capacity (i.e. high alkalinity). When algal blooms are developing it is common to encounter
daily maximum pH values as high as 9 to 11, and if the bloom progresses, values tend to fall a little less
each night until pH eventually stabilises at high levels. Hence the relatively moderate pH values reported
here tend to suggest that algal productivity was also moderate.
The DERM nutrient analysis results indicate that nitrate, and therefore total nitrogen, concentrations in
the sump and dam samples were higher than would be expected in natural surface waters. However, the
levels reported at the three receiving water sites were well within natural expectations for streams of this
kind (discussed in later sections).
3.2
Historical Monitoring Data
There are no records of algal sampling having been conducted at Mt Leyshon at any time prior to the
DERM sampling exercise in October 2010. Limited nutrient sampling was conducted on behalf of NMS
at some selected surface water monitoring sites between 2008 and 2009, but none of those sites were
located within the Puddler or Clarke Creek drainage systems; hence the data are not directly relevant to
the current study.
The NMS groundwater quality database contains 20 nitrate values for monitoring bore samples, mostly
collected in 2009. Bores that were distant from the mine site generally reported low nitrate values (less
than 0.01 mg N/L). However, four elevated nitrate results ranging from 1.6 to 9.9 mg N/L (i.e. 1600 to
9900 µg N/L) were reported at inner array bores MLM19 and MLM21. These bores, which are close to
the mine facilities and immediately upgradient of surface monitoring sites SW103 and SW107, also
reported high sulphate concentrations (see detailed discussion in SWS 2012).
Given that the nitrate enrichment was only observed in close proximity to the mine infrastructure and that
the reported concentrations are correlated to sulphate levels, there seems little doubt that some aquifers in
the headwaters of Puddler Creek have been affected by accession of nitrate from the dams and/or drains
on the mine site. Some of this nitrate could possibly be explosives residue, but it is more likely to be a
product of cyanide oxidation.
Groundwaters and especially those situated within the kinds of mineral formations that occur near ore
bodies, do sometimes naturally contain elevated background levels. Several authors have attempted to
provide estimates of the natural limits for background nitrate levels in groundwaters. Keating et al
(1996) used a value of 3000 µg N/L as being indicative of anthropogenic influences based on values
reported for United States groundwaters by Hallberg (1989). Baskaran et al (2002) suggested that
2000 µg N/L would be a more realistic estimate of the maximum background concentration based on
more recent overseas data. However, examination of existing Queensland data shows that even in some
anthropogenically affected areas a significant proportion of groundwaters contain nitrate levels well
below 100 µg N/L so it is obvious that the average concentrations in undisturbed groundwaters are
substantially lower than the estimated “maximum likely” value. (For example in 1994, in the LoganAlbert catchment, where agricultural development is not intensive, and complex soil and aquifer
formations protect most groundwaters from direct recharge effects, more than 66% of bores contained
nitrate concentrations below 100 µg N/L and the maximum value reported was 2300 µg N/L).
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Therefore, values above 2000 to 3000 µg N/L appear to be a reasonably definitive indication of
anthropogenic enrichment, although concentrations below that level are by no means a reliable indicator
of an absence of anthropogenic contamination.
3.3
ACTFR Limnological Survey in August 2011
A limnological survey carried out by ACTFR during the last week of August 2011 is the only source of
data indicative of the status of algal communities in receiving streams in the Mt Leyshon study area prior
to the commencement of the current EE investigation. That survey, which was carried out as part of the
NMS closure and environment program, aimed to assess the general ecological health of receiving waters
in the immediate vicinity of the mine site. At the time NMS were unable to obtain permission to enter the
adjoining property so ACTFR could not survey some of the sites that are of key interest to the current
study, including PCK1 and some of the upstream control sites. Visual surveys were conducted by walking
the length of the accessible sections of Puddler and Clarke Creeks to assess benthic algae assemblages,
collect algal samples for identification and find suitable locations to establish fish and invertebrate
monitoring sites, such as deeper pools where habitat conditions are best suited to the establishment of
healthy diverse aquatic biological communities. Hence the site locations chosen for that survey, shown in
Figure 3.1, did not always coincide with previously established water quality monitoring sites.
Relevant components of the dry season survey included analysis of water samples for chlorophyll-a to
assess phytoplankton biomass, visual assessment of benthic algae coverage to determine the extent and
nature of algal communities, targeted sampling of dense patches of benthic algae to identify dominant
genera and analysis of water samples for nutrients to gain some insight into the trophic status of the water.
The data obtained from these sampling activities are presented and discussed in the results section of this
report. Note that this is the only available source of information indicative of late dry season conditions,
because the EE Notice did not allow sufficient time to conduct a dry season survey during the course of
the EE investigation.
During the September 2011 survey, water levels had retracted to the point where much of the streambed
was exposed making it easy to visually examine sediment layering within the streambed. At most sites the
substratum was found to comprise relatively well-sorted sandy sediment layers, however, at two sites in
the section of Puddler Creek that lies within the mining lease, a 3 to 5cm thick layer of black peaty
material with the appearance of decomposed algae was encountered at a depth of 2 to 8 cm in patches
below the sand surface. The existence of such layers supports the earlier contention that pre-existing algal
mats are sometimes buried by sand slugs mobilised during wet season swiftflow events.
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Figure 3.1
Sampling sites used during the August 2011 limnological survey.
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4.
METHODS
4.1
Sampling and Survey Activities
Large scale flow events wash away much of the algal biomass that has accumulated in the creeks during
the dry season and they also often mobilise and deposit fresh sand slugs which can bury much of the
benthic algae that remains. Hence the ecosystem is effectively reset at some stage each wet season and
once flows recede it can take a number of months for algal communities to fully re-establish. Maximum
biomass is generally achieved later in the dry season when the creek is beginning to dry out, and that
would be the optimum time of the year to assess the “prolific” algae growth cited in the EE Notice.
However, the reporting deadlines stipulated in the EE Notice precluded the possibility of sampling in the
dry season and in fact it was necessary to carry out the main sampling survey for this project during the
wet season in order to ensure that the report was completed on schedule.
January was relatively dry by wet season standards so the field trip was scheduled for February 6th and 7th
2012. Unfortunately 76 mm of rainfall was registered during the weekend prior to the sampling trip, so by
the time field personnel arrived on site the streams had effectively been flushed out. Nevertheless
significant lengths of Clarke and Puddler Creeks were visually surveyed for evidence of residual algal
biomass and water samples were collected for analysis of chlorophyll-a and nutrients. Additionally, in
order to gain a better understanding of the trophic status of the local streams, NMS incorporated
chlorophyll and nutrient sampling into their routine bimonthly water quality sampling program. The
results obtained from the February and April 2012 sampling runs are presented and discussed in
Section 5. A second visual survey to assess the re-establishment of benthic algae was conducted on April
30th 2012, two weeks after the completion of the April water sampling run. On that occasion there was
insufficient time to examine algae samples in the laboratory; however, it was visually evident that the
algal communities that were present in April 2012 were dominated by the same genera that had been
present in August 2011.
4.2
Site Locations
The locations of all of the surface water monitoring sites sampled by CMLR, ACTFR and/or NMS during
the course of this 2012 study are shown in Figure 4.1, and sites situated within or immediately
downstream of the Mt Leyshon Mining Lease are shown at higher resolution in Figure 4.2.
4.3
Sampling and Analysis Methods
Several personnel from different organisations (ACTFR, NMS and CMLR) were involved in the water
sampling activities associated with this study. Detailed sampling protocols were documented to ensure
that consistency was maintained between groups, and a copy of these is presented in the Appendix. The
following is just a brief summary of the sampling methods employed.
Open water samples representative of the general conditions at each site were collected at a mid-channel
position and at a depth of approximately 20 to 30cm at each site. Sampling methodology, sample bottles
and preservation techniques and analytical methodology met or exceeded standard method requirements
(i.e. DERM 2009, APHA 2005, and Standards Australia 1998).
CMLR staff also collected shallow “backwater” samples at some sites to check for localised variations in
the quality of water contained within small microhabitats where conditions conducive to sulphate
reduction could potentially develop.
Chlorophyll samples were stored on ice in eskies until transported back to the laboratory for further
processing within 24 hours of collection. The samples were filtered through Whatman GF-B glass
microfibre filters and the phytoplankton retained on the filter discs were preserved with magnesium
carbonate and immediately frozen.
Australian Centre for Tropical Freshwater Research
Page 12
Australian Centre for Tropical Freshwater Research
Page 13
Australian Centre for Tropical Freshwater Research
Page 14
Samples for dissolved nutrient analyses were pressure filtered on site by using disposable plastic syringes
to pass the sample through 0.45 µm Minisart filters. All nutrient samples were collected in clean unused
gamma-sterilised plastic tubes. These were initially kept on ice and were transferred to a freezer within a
few hours of collection.
The parameters that were analysed and the analytical methods that were employed are listed in Table 4.3.
Analysis methods and detection limits are also summarised in that table.
Table 4.3
WQ analyses performed in connection with the algae component of the EE investigation
Reporting
Parameter
APHA Method No.
Limit
Total Nitrogen and Phosphorus Simultaneous 4500-NO3- F and 4500-P F analyses
25 µg N/L
(TNTP)
after alkaline persulphate digestion
5 µg P/L
Nitrate
4500-NO3- F
1 µg N/L
Ammonia
4500- NH3 G
1 mg N/L
Filterable Reactive Phosphorus (FRP) 4500-P F
1 µg P/L
Chlorophyll a and phaeophytin
10200-H
0.1 µg/L
In August 2011 water samples were collected for identification and enumeration of phytoplankton but in
practice abundances proved to be too low to enumerate. Spot samples of benthic algae were also collected
in localised areas where dense assemblages had developed. These were subjected to microscopic
examination in order to identify the dominant genera present, but since the samples were not
representative of the communities that occupied most of the streambed, no attempt was made to
enumerate cell concentrations. Similar samples would have been collected again in February 2012, but on
that occasion algal biomass was simply too low for that to be feasible.
Australian Centre for Tropical Freshwater Research
Page 15
5.
RESULTS AND DISCUSSION
5.1
Results of the August 2011 Survey
5.1.1
General Water Quality
The results of general water quality analyses carried out on samples collected in August 2011 are shown
in Table 5.1.1. The key features of these results are as follows:

pH levels were only moderately alkaline and provided no indication of strong influences from
photosynthetic uptake of carbon dioxide or bicarbonate utilisation (discussed in Section 3).
Puddler Ck was still flowing slightly at the time, but not strongly enough to suggest that aeration
rates would have been sufficient to prevent carbon dioxide depletion (and consequent pH rises) if
algal productivity rates had been high.

Total alkalinity concentrations in Puddler Creek were very high, indicating that the water would
be prone to stabilising at high pH values should algal consumption rates reach the point where
carbon dioxide is depleted and algae begin consuming bicarbonate and producing hydroxyl ions.

Suspended particulate matter (SPM) concentrations were quite low indicating that light
attenuation due to turbidity would have been low. Note that the water would not have needed to
be particularly clear in order for sunlight to reach the bottom, because all of these sites other than
Clarke 1, were significantly less than 50 cm deep. In practice it was possible to see the bottom at
all of the sites that were surveyed, and this generally indicates that there was sufficient light
penetration to meet the photosynthetic needs of any benthic algae species.

Conductivity and hardness concentrations were high enough to potentially inhibit the growth of
some algal species, especially phytoplankton, but conversely there are some algal species that
prefer these kinds of conditions. Hence the existing salt concentrations would almost certainly
have played a role in determining the algal community composition and diversity. It is less
certain whether or not the high salinity levels would have inhibited the growth rates of the species
that were present, but that is a possibility that cannot be disregarded.
Total Organic
Carbon (mg/L)
Total Hardness
(mg CaCO3/L)
Total Alkalinity
(mgCO3/L)
Total Dissolved
Solids (mg/L)
Suspended
Particulate
Matter (mg/L)
Electrical
Conductivity
(µS/cm)
pH
Subcatchment
and Site
Table 5.1.1 Results of general water quality analyses carried out on samples collected in August 2011.
Puddler Ck
SW47
Puddler3
SW108
PCC
Puddler1
Puddler2
Clarke Ck
Clarke1
UC1
Clarke3
UC2
8.54
7.82
8.18
8.22
8.16
7.86
2540
2430
5640
2710
2850
2430
1.3
2.2
5.8
1.9
2.3
1.6
1500
1500
5100
1800
1900
1600
901
1070
698
725
680
630
349
382
2114
606
714
662
5
3
7
4
15
7
7.95
8.15
8.21
8.28
2540
1043
2270
1190
2
1
0.8
1
1900
680
1600
720
492
541
476
546
811
305
674
279
3
1
11
9
Australian Centre for Tropical Freshwater Research
Page 16
5.1.2
Aqueous Nutrient Concentrations
Nutrient analysis results obtained from water samples collected in August 2011 are shown in Table 5.1.2.
The table also lists the Trigger Values (TVs) provided for central region lowland streams in the
Queensland Water Quality Guidelines 2009 (QWQGs), and results that exceed a TV are highlighted in
blue. It should be noted that the TVs are applicable to waters that are at baseflow and are not strictly
intended for use in situations where waters have stagnated. Moreover, the TVs are not designed to be
compared to individual spot results, but rather to median values obtained from repetitive sampling
conducted over a full season – i.e. a site complies with the guidelines unless more than fifty percent of the
spot samples that have been collected regularly at that site over time, exceed the TV. Nevertheless, the
TVs still provide a useful benchmark for assessing the potential significance of individual results.
DIN:DIP Molar
Ratio
3
3
7
5
3
3
5
22
12
37
37
17
8
25
19
42
40
20
30
105
90
55
59
71
28
58
73
50
43
33
13.0
4.6
6.6
9.0
6.9
5.0
0.9
1.0
1.0
2.3
2.4
1.9
279
148
220
153
500
27
13
9
2
20
5
1
1
4
21
25
21
12
26
26
22
16
60
140
183
140
166
50
58
112
79
105
20
4.4
1.8
3.5
2.0
2.0
0.8
0.9
0.4
Nitrogen
Oxides
(µg N/L)
Total
Phosphorus
(µg P/L)
Filterable
Reactive
Phosphorus
(µg P/L)
TN:TP Molar
Ratio
4
1
13
11
7
8
Nitrate
(µg N/L)
176
219
267
223
184
159
Nitrite
(µg N/L)
Ammonia
(µg N/L)
Puddler Ck
SW47
Puddler3
SW108
PCC
Puddler1
Puddler2
Clarke Ck
Clarke1
UC1
Clarke3
UC2
QWQG TVs
Nutrient analysis results obtained from water samples collected in August 2011.
Total Nitrogen
(µg N/L)
Subcatchment
and Site
Table 5.1.2
It can be seen that total nitrogen levels were all low, as were the results for each of the individual
dissolved inorganic nitrogen species (nitrite, nitrate and ammonia). One ammonia value was slightly
above the TV but that is of little potential consequence. Conversely phosphorus concentrations were
elevated at all sites. None of the individual values were particularly anomalous compared to the kinds of
values that are commonly reported in small sluggishly flowing or stagnant waterholes located in grazing
areas. However, the consistency of the values recorded across all sites is highly unusual and places the
results at the upper end of the ranges that are normally encountered in livestock affected waterholes.
For example a post-wet season survey of waterholes located within ephemeral streams in the grazing
areas between Home Hill and Bowen (carried out as part of the EIA for the Water for Bowen Project),
generated 34 samples which yielded a maximum total phosphorus concentration of 369 µg P/L and an
80th percentile value of 165 µg P/L. However, the median total phosphorus value was only 50 µg P/L and
the filterable reactive phosphorus (FRP) levels were mostly less than 20 µg P/L (although there were a
few high values up to a maximum of 108 µg P/L). Notably in that study there was clear visual evidence of
impacts from cattle and/or pigs at most of the sites which reported elevated values. In contrast there was
little or no evidence of disturbances by livestock at most of the sites that were surveyed in the current
study. This observation, linked with the low levels of between-site variability and the fact that an
unusually high proportion of the phosphorus occurred in soluble form, tends to implicate groundwater as
possible source, although more monitoring would be required to test that assertion. Notably the lack of
significant between-site variations implies the existence of a diffuse phosphorus source unrelated to the
mine.
Australian Centre for Tropical Freshwater Research
Page 17
Published literature on the topic of nutrient limitation (see for example ANZECC 1992) supports the
conclusion that at nitrogen to phosphorus ratios between 6 and 20, both nitrogen and phosphorus could
simultaneously be limiting to different species. At ratios below 6, nitrogen availability is likely to limit
the growth of most species, and at ratios above 20, phosphorus will generally be the limiting nutrient.
Hence the nitrogen to phosphorus ratios reported at most of the Mt Leyshon sites in August 2011 suggest
that nitrogen would have been the limiting nutrient at that time.
5.1.3
Phytoplankton
Phytoplankton analysis results comprising chlorophyll and phaeophytin concentrations and algal cell
counts obtained from water samples collected in August 2011 are presented in Table 5.1.3. Chlorophyll-a
concentrations are a widely accepted indicator of relative phytoplankton biomass. Phaeophytin is an
inactive form of the chlorophyll molecule which accumulates in algal cells if they are stressed or recently
deceased. Hence phaeophytin to chlorophyll-a ratios provide an indication of the relative health of the
phytoplankton community. The salient features of the tabulated results are as follows.

Phytoplankton concentrations were too low to enumerate at all sites. That is typically the case
unless the algae are beginning to bloom.

All but one of the chlorophyll values were well below the ANZECC TV. In fact overall
concentrations were surprisingly low for the time of year.

The value of 10.7 µg/L which was reported at site SW108 exceeded the TV, but compared to the
levels that are commonly observed at similar sites in grazing areas around this region, this result
is quite moderate. For example the median chlorophyll-a value obtained in the Water for Bowen
EIA surveys (referred to in the previous section) was 14 µg/L, the 80th percentile was 31 µg/L and
the maximum was 200 µg/L. The fact that the nutrient concentrations at those sites were similar
to the levels obtained in this study tends to imply that phytoplankton growth at the Mt Leyshon
sites was somewhat inhibited by comparison. However, these sites support more persistent
baseflow than most streams in the Bowen area, so the lower values may simply be a consequence
of lower water resident times (i.e. phytoplankton could not accumulate at the Mt Leyshon sites
because they were constantly being washed downstream). Notably the EC levels at Site SW108
(5640 µS/cm) were twice as high as any other Puddler Creek site, so salinity does not appear to
have been a significant algal growth limiting factor. In fact the high EC value suggests that
evapo-concentration rates had been high and that is indicative of increased water residence time.
1.8
0.8
11.6
2.4
1.7
0.6
0.28
0.29
0.08
0.35
0.46
0.52
<20
<20
<20
<20
<20
<20
0.6
0.9
0.6
0.3
5
0.2
0.8
0.5
0.7
0.8
1.7
1.0
1.0
0.29
0.46
0.43
0.71
<20
<20
<20
<20
Australian Centre for Tropical Freshwater Research
Total
Chlorophyll-a
(µg/L)
0.5
0.2
0.9
0.8
0.8
0.3
Phaeophytin
(µg/L)
1.3
0.6
10.7
1.6
0.9
0.3
Active
Chlorophyll-a
(µg/L)
Algal Cells/ml
Puddler Ck
SW47
Puddler3
SW108
PCC
Puddler1
Puddler2
Clarke Ck
Clarke1
UC1
Clarke3
UC2
QWQG TV
Pha:Chl Ratio
Phytoplankton analysis results obtained from water samples collected in August 2011.
Chlorophyll-a results that are above the QWQG TV are highlighted in blue.
Subcatchment
and Site
Table 5.1.3
Page 18
5.1.4
Benthic Algae
Benthic algae coverages were generally moderate although, as is normally the case in streams of this
kind, dense assemblages occurred in patches. Samples for microscopic examination to identify the
dominant algal genera were taken from selected patches and the results are presented in Table 5.1.4. The
key characteristics and potential significance of these taxa are discussed in Section 5.2.
Table 5.1.4
Identifications of the dominant genera contained in samples taken from benthic algae mats
in Puddler and Clarke Creeks in August 2011.
PCC-400
PCC-250
PCC-250 OP
PCC-150
CC2
Euglena
Cymbella
Fragilaria
Rhizoclonium
Oedogonium
Euglena
Traces of
Oscillatoria
Euglena
Rhizoclonium
Cymbella
Traces of
Oscillatoria
Rhizoclonium
Oedogonium
Cymbella
Rhizoclonium
Oedogonium
Euglena
5.2
Results of the 2012 Investigation
5.2.1
Nutrients
Nitrogenous nutrient analysis results for water samples collected in February and April 2012 are
presented in Table 5.2.1. All results are reported in µg N/L. Values that exceed the QWQG TVs are
highlighted in blue. Samples in the table have been grouped by site type, drainage line and antecedent
flow condition. Sites within each group are, as far as possible, arranged from upstream to downstream.
The site type codes used in the table are as follows:
OMC
UML
ML
DML
Outside of the Mine Catchment (i.e. external reference);
Upstream of the Mining Lease (i.e. control site);
On the Mining Lease;
Downstream of the Mining Lease.
The salient features of the tabulated nitrogen values are as follows:

Total nitrogen concentrations at control and reference sites (type UML and OMC) were generally
higher under wet season conditions in February than they were under lower flow conditions in
April. A few of the total nitrogen results reported in February exceeded the QWQG, as did the
nitrate value reported in the Burdekin River at that time of the year. However, the other results for
these sites were well below guidelines.

The results at some of the sites located within close proximity to dams and drains on the mining
lease exhibited the opposite temporal trend with the highest values being reported under low flow
conditions in April. This is presumably indicative of groundwater seepage from mine
infrastructure. The main sites in question SW103, SW107, SW107.5 and SW108, which are
situated on a branch of Puddler Creek that is situated on the mining lease and within about 1.5 km
of potential groundwater input sources associated with the mine, reported highly anomalous
results for total nitrogen, organic nitrogen, and nitrate and nitrite (i.e. nitrogen oxides). Despite
the high concentrations in that section of Puddler Creek, the values reported 2 km further
downstream at PCC (still inside the lease boundary) were consistently low; both before and after
rainfall in February, and under low flow conditions in April. The sites downstream of that point
also yielded low results and provided no indication of accession of nitrogen from the mine site.
Australian Centre for Tropical Freshwater Research
Page 19
Australian Centre for Tropical Freshwater Research
27
26
27
27
29
63
49
27
34
32
35
21
9
18
20
16
18
20
22
24
25
17
19
65
16
7
766
59
106
15
23
19
22
6
19
19
34
200
147
15
28
27
28
28
30
63
51
28
36
32
36
23
10
19
21
17
19
20
23
25
26
18
20
66
17
8
770
61
108
16
24
20
22
7
19
20
35
202
148
16
60
Dissolved
Inorganic Nitrogen
1
1
1
1
1
0
2
1
2
0
1
2
1
1
1
1
1
0
1
1
1
1
1
1
1
1
4
2
2
1
1
1
0
1
0
1
1
2
1
1
Nitrogen Oxides
7
6
8
6
5
7
7
5
6
7
7
4
7
5
7
9
11
6
5
6
7
8
14
15
7
11
7
8
6
7
7
8
6
5
5
7
13
10
10
18
20
Nitrate
170
220
141
131
195
223
188
269
219
173
174
218
251
329
373
233
205
157
224
244
194
235
321
454
313
313
632
379
211
399
265
132
311
183
374
261
108
269
137
292
420
Nitrite
205
253
177
165
230
293
246
302
261
212
217
245
268
353
401
259
235
183
252
275
227
261
355
535
337
332
1409
448
325
422
296
160
339
195
398
288
156
481
295
326
Ammonia
347
583
257
274
348
685
262
322
267
235
229
286
453
380
431
630
356
232
270
459
395
426
672
819
447
471
1676
666
538
651
328
195
391
251
557
325
294
1057
615
463
500
Dissolved Organic
Nitrogen
OMC
OMC
OMC
OMC
OMC
OMC
OMC
OMC
OMC
OMC
OMC
OMC
UML
UML
UML
UML
UML
UML
UML
UML
UML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
Total Filterable
Nitrogen
Puddler
Broughton
Broughton
Broughton
Broughton
Burdekin
Puddler
Broughton
Broughton
Broughton
Broughton
Burdekin
Clarke
Puddler
Puddler
Clarke
Clarke
Puddler
Clarke
Puddler
Puddler
Clarke
Clarke
Clarke
Clarke
Clarke
Puddler
Puddler
Puddler
Puddler
Puddler
Puddler
Two Mile
Two Mile
Two Mile
Two Mile
Clarke
Puddler
Puddler
Puddler
Total Nitrogen
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Pre-rain
Pre-rain
Pre-rain
Post-rain
Post-rain
Post-rain
Low flow
Low flow
Low flow
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Post-rain
Post-rain
Post-rain
Post-rain
Site Type
06 Feb
07 Feb
07 Feb
07 Feb
07 Feb
09 Feb
11 Apr
12 Apr
12 Apr
12 Apr
12 Apr
12 Apr
01 Feb
02 Feb
02 Feb
07 Feb
06 Feb
06 Feb
10 Apr
10 Apr
10 Apr
01 Feb
01 Feb
01 Feb
01 Feb
01 Feb
01 Feb
01 Feb
02 Feb
02 Feb
02 Feb
02 Feb
02 Feb
02 Feb
02 Feb
02 Feb
07 Feb
07 Feb
07 Feb
07 Feb
Drainage line
Antecedent
Conditions
SM1
BR0
BR1
BR2
BR3
BK1
SM1
BR0
BR1
BR2
BR3
BK1
SW112
SW111
SW47
Horse Ck
SW112
SW111
SW112
SW111
SW47
CC1
SW105
SW106
CC2
SW101
SW103
SW107
SW108
SW109
PCC
SW104
TMC600
TMC500
TMC400
TMC
CC2
SW107.5
SW108
PCC
QWQG
Sample Date
Site
Table 5.2.1 Nitrogen nutrient analysis results (µg N/L) for water samples collected in February and April
2012. Site type codes are as follows: OMC=Outside of Mine Catchment; UML=Upstream of
Mining Lease; ML=On the Mining lease; DML=Downstream of Mining Lease. Values
highlighted in blue exceed the QWQG TV (shown at the bottom of the table).
35
33
36
34
35
70
58
33
42
39
43
27
17
24
28
26
30
26
28
31
33
26
34
81
24
19
777
69
114
23
31
28
28
12
24
27
48
212
158
34
Page 20
Australian Centre for Tropical Freshwater Research
1
2
15
2
3
29
65
47
3
3
2
1
5
2
1
1
0
1
1
0
0
1
0
0
1
2
0
0
2
1
1
1
2
0
0
0
1
0
0
0
1
0
0
0
0
1
0
3
5
3
2
Dissolved Inorganic
Nitrogen
Nitrogen Oxides
5
12
51
4
5
3
6
22
5
13
7
4
4
4
6
6
5
4
7
8
6
6
7
7
7
7
6
6
5
6
5
5
5
4
8
4
5
6
4
4
6
6
7
7
8
4
7
3
2
6
2
20
Nitrate
257
289
333
220
212
2404
2063
927
455
325
199
155
178
224
162
249
300
187
213
150
248
320
392
207
243
211
124
326
257
235
240
278
207
195
237
222
266
184
247
254
238
242
227
215
230
201
241
195
231
240
197
420
Nitrite
284
316
509
241
248
5320
3791
1505
485
406
228
183
206
247
205
288
331
225
274
202
277
347
416
236
277
263
164
359
294
274
281
342
280
229
285
255
314
219
256
284
273
271
267
252
261
245
283
238
272
351
239
Ammonia
307
329
608
259
299
5415
1544
544
461
232
270
1407
375
342
624
503
374
320
285
428
450
606
347
338
393
321
572
444
326
607
428
647
261
368
282
326
320
333
297
344
384
267
272
297
299
280
275
372
304
500
Dissolved Organic
Nitrogen
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
Total Filterable
Nitrogen
Clarke
Clarke
Clarke
Clarke
Clarke
Puddler
Puddler
Puddler
Puddler
Puddler
Puddler
Two Mile
Two Mile
Two Mile
Clarke
Clarke
Clarke
Puddler
Puddler
Puddler
Two Mile
Two Mile
Two Mile
Two Mile
Two Mile
Seventy Mile
Seventy Mile
Seventy Mile
Broughton
Broughton
Broughton
Broughton
Burdekin
Clarke
Clarke
Clarke
Puddler
Puddler
Two Mile
Two Mile
Two Mile
Two Mile
Two Mile
Seventy Mile
Seventy Mile
Seventy Mile
Broughton
Broughton
Broughton
Broughton
Burdekin
Total Nitrogen
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Site Type
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
07 Feb
07 Feb
07 Feb
06 Feb
06 Feb
06 Feb
06 Feb
06 Feb
06 Feb
06 Feb
06 Feb
06 Feb
07 Feb
09 Feb
07 Feb
09 Feb
09 Feb
09 Feb
09 Feb
11 Apr
12 Apr
12 Apr
11 Apr
11 Apr
11 Apr
11 Apr
11 Apr
11 Apr
11 Apr
11 Apr
12 Apr
13 Apr
12 Apr
13 Apr
13 Apr
12 Apr
13 Apr
Drainage line
Antecedent
Conditions
CC1
SW105
SW106
CC2
SW101
SW103
SW107
SW108
SW109
PCC
SW104
TMC600
TMC400
TMC
CC3
CC4
CC5
PCK1
PC2
SM2
TMC11
TMC2
FC1
TMC12
FC2
SM3
SM4
SM5
BR4
BR5
BR6
BR7
BK2
CC3
CC4
CC5
PC2
SM2
TMC11
TMC2
FC1
TMC12
FC2
SM3
SM4
SM5
BR4
BR5
BR6
BR7
BK2
QWQG
Sample Date
Site
Table 5.2.1 (Cont)
21
22
13
15
110 125
15
17
28
31
2884 2913
1657 1722
509 556
22
25
65
68
20
22
23
24
19
24
17
19
36
37
32
33
26
26
33
34
53
54
44
44
23
23
20
21
17
17
22
22
26
27
43
45
34
34
27
27
30
32
32
33
35
36
58
59
66
68
30
30
40
40
29
29
42
43
29
29
5
5
26
26
28
29
23
23
33
33
30
30
23
23
39
40
35
35
37
40
34
39
102 105
38
40
60
27
27
176
21
36
2916
1728
578
30
81
29
28
28
23
43
39
31
38
61
52
29
27
24
29
34
52
40
33
37
39
41
64
73
34
48
33
48
35
9
30
35
29
40
37
31
44
42
43
41
111
42
Page 21

Nitrate can be toxic to aquatic life at very high concentrations, so the ANZECC 2000 Australian
Water Quality Guidelines (AWQGs) include TVs for the protection of ecosystems against direct
toxic effects (the QWQGs being designed to protect against non-lethal effects such as
eutrophication). The 95% TV provided in the AWQGs was 700 µg N/L, but that value was highly
erroneous and a corrected value of 7200 µg N/L has been calculated by NIWA (Hickey 2002).
None of the results obtained in this study approach that value, so it is highly unlikely that the
elevated nitrate presents any direct toxicological risks to the ecosystem. The values are also well
below any guidelines to protect human uses (such as potability and livestock watering).

Site SW106, located on the mine lease within a small tributary of Clarke Creek, also reported
slightly elevated nitrate and total nitrogen levels. However, there were no indications of effects
downstream of that point, and all of the sites situated on Clarke Creek itself were low in nitrogen.

A high total nitrogen result was obtained at TMC400 (on Two Mile Ck) in April, but that was due
to unusually high particulate nitrogen concentrations and is not directly related to the high
dissolved nitrogen levels that were observed at the other sites. The high value presumably
indicates that, at the time, turbidity levels were elevated at that site.

All samples from sites located downstream of the mining lease yielded nitrogen results that are
well within QWQG expectations (noting that since the guideline values are medians, up to 50%
of individual exceedances would be accepted). The dissolved nitrogen levels at downstream sites
close to the lease were particularly low, and provided no indication of effects from the mine.
By regional standards, the section of Puddler Creek that reported elevated nitrate levels sustains quite
prolonged baseflows for a creek of its size. These are derived from surface discharges of groundwater
from shallow aquifers in the headwaters of the creek. As noted in Section 3.2, the limited available
evidence suggests that some aquifers in close proximity to the mine are nitrate enriched, and the existing
concentrations are high enough to suggest that accession of nitrate from the dams and/or drains on the
mine site is a contributing factor. There are insufficient data to determine if some of the existing nitrate is
naturally occurring, but that possibility cannot be disregarded.
In the course of monitoring activities throughout north Queensland over the past 30 years this author has
encountered localised occurrences of nitrate concentrations up to a maximum of about 800 µg N/L in the
vicinity of springs situated within relatively undisturbed surface streams. For example regional baseline
studies carried out in connection with the EIA for Century Mine (Dames and Moore 1994) showed that
the natural limestone aquifers downstream of the proposed mine site contained nitrate levels in the order
of 750 µg N/L, and localised occurrences of similar concentrations were detected in most surface streams
within a few hundred metres of the points where they intersected these aquifers.
Nitrate levels in groundwaters at the Mt Leyshon site appear to be correlated to sulphate concentrations,
and it would be reasonable to assume that a similar correlation would be observed at those surface water
sites that are located in the immediate vicinity of groundwater discharge points. However, it is important
to recognise that the nitrate concentrations in question here (reported in µg/L) are orders of magnitude
lower than the sulphate levels (reported in mg/L) and are therefore much more readily diluted, especially
when swiftflows are present in the receiving streams. Moreover, under baseflow conditions natural stream
ecosystems assimilate and/or remove nitrate much more rapidly than sulphate, and accordingly the effects
of groundwater nitrate inputs on ambient water quality are far more localised in both time and space. In
fact to date elevated nitrate levels have only been recorded at surface water sites during the falling limb of
the hydrograph (i.e. when groundwater-driven baseflows are moderately strong but surface runoff is
absent) and then only at sites located quite close to the potential source.
The available data suggest either that normal wet season flow events provide adequate dilution to prevent
measurable increases in nitrate levels from occurring and/or that water levels in the receiving stream rise
sufficiently during events to prevent groundwater from entering. Conversely the low concentrations
observed on the tail of the hydrograph (i.e. when baseflow is very low) suggest either that there was
insufficient flow to transfer nitrate downstream or that groundwater levels had fallen to the point where
surface discharge could no longer occur.
Australian Centre for Tropical Freshwater Research
Page 22
Under baseflow conditions in 2012, elevated nitrate levels were reported at some sites located within
about 1.5 kilometres of potential sources on the mining lease, but none of the other monitoring sites
showed any signs of nitrogen enrichment that could potentially be attributable to the mine (although there
were some indications of effects from agricultural inputs at the most distant sites on the Broughton and
Burdekin Rivers). Notably low to moderate nitrogen values were obtained at all sites on the main trunk of
Clarke Creek and at all of the Puddler Creek sites downstream of SW108; hence all of the elevated nitrate
results potentially sourced from the mine were recorded at sites that are well within the boundaries of the
mining lease.
The rapid disappearance of nitrate from the receiving water column can almost always be partially
attributed to assimilation by algae and/or riparian vegetation, but in 2012 algal productivity was limited
by phosphorus availability (see below) and algal biomass was moderate enough to suggest that other
mechanisms were involved. For example microbial denitrification, a process which involves the
conversion of nitrate into non-bioavailable gaseous forms of nitrogen, occurs in any natural aquatic
microhabitats where low dissolved oxygen concentrations occur. Oxygen levels within the open water
column of flowing streams are generally too high to support denitrification; however, there are numerous
microhabitats where oxygen levels can be low enough. These include the pore waters trapped within
bottom sediments, the water lying within and beneath leaf litter packs, and the water underneath dense
patches of benthic algae. The latter microhabitat is particularly favourable for denitrification because
microbes require organic carbon, and algae are a rich source of readily bioavailable carbon.
Direct uptake by heterotrophic microbes such as fungi is a further source of nitrogen assimilation that is
often overlooked in the literature on this topic. For example Pearson and Connolly (2000) found that
artificial elevation of the nitrate concentrations in rainforest streams containing low phosphorus levels
stimulated microbial decomposition of coarse organic matter (leaf litter) leading to increased
macroinvertebrate growth rates and abundances; but no other effects were apparent.
Phosphorus nutrient analysis results (µg P/L) for water samples collected in February and April 2012 are
shown in Table 5.2.2. It is immediately obvious from these results that the relatively high FRP
concentrations that had been present in both Clarke and Puddler creeks in August 2011 were no longer in
evidence in 2012. In fact, other than the elevated total phosphorus value recorded at TMC in April (which
was due to high particulate levels in the water rather than dissolved phosphorus), all of the values
reported at sites upstream, within and immediately downstream of the mine lease were very low, and the
Burdekin River and lower Broughton were the only sites where any results exceeded the QWQGs. The
reason for the disappearance of the high phosphorus values between 2011 and 2012 is unclear and more
monitoring will be required to determine if this is a reproducible seasonal effect.
Not surprisingly, given how low the phosphorus results were, the nitrogen to phosphorus ratios suggest a
high likelihood that phosphorus would be the limiting nutrient for algal growth in the water column, and
hence low phytoplankton concentrations would be expected. Clearly under these conditions benthic algae
which are capable of extracting some phosphorus from the bottom sediments, and/or remaining in place
so that they can cumulatively extract phosphorus from flowing water, would be at a distinct advantage
and this was evidenced by the prevalence of benthic algae species at all sites (discussed in the next
section).
5.2.2
Phytoplankton
Phytoplankton analysis results for water samples collected in February and April 2012 are presented in
Table 5.2.3. As expected phytoplankton biomass was low and generally correlated to the phosphorus
concentrations. A single moderately elevated chlorophyll value of 20 µg /L was reported at SW106 under
low flow conditions in April 2012, but as discussed previously, values of that magnitude are quite
commonly encountered under low flow conditions throughout the grazing catchments of the dry tropics,
so that isolated result is no cause for potential concern. Note for example that the algal cell density was
still too low to enumerate at a detection limit of 20 cells/ml, and the lowest trigger for the management of
waters containing potentially toxic algae is 500 cells/ml.
Australian Centre for Tropical Freshwater Research
Page 23
Australian Centre for Tropical Freshwater Research
DIN:DIP Molar Ratio
Total Phosphorus
43
15
22
33
32
82
22
13
16
33
31
58
23
26
28
17
21
21
27
16
18
21
19
17
19
8
11
24
16
8
23
8
12
11
25
8
17
12
13
18
50
TN:TP Molar Ratio
OMC
OMC
OMC
OMC
OMC
OMC
OMC
OMC
OMC
OMC
OMC
OMC
UML
UML
UML
UML
UML
UML
UML
UML
UML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
Filterable Reactive
Phosphorus
Puddler
Broughton
Broughton
Broughton
Broughton
Burdekin
Puddler
Broughton
Broughton
Broughton
Broughton
Burdekin
Clarke
Puddler
Puddler
Clarke
Clarke
Puddler
Clarke
Puddler
Puddler
Clarke
Clarke
Clarke
Clarke
Clarke
Puddler
Puddler
Puddler
Puddler
Puddler
Puddler
Two Mile
Two Mile
Two Mile
Two Mile
Clarke
Puddler
Puddler
Puddler
Site Type
Drainage line
Antecedent
Conditions
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Pre-rain
Pre-rain
Pre-rain
Post-rain
Post-rain
Post-rain
Low flow
Low flow
Low flow
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Post-rain
Post-rain
Post-rain
Post-rain
Dissolved Organic
Phosphorus
06 Feb
07 Feb
07 Feb
07 Feb
07 Feb
09 Feb
11 Apr
12 Apr
12 Apr
12 Apr
12 Apr
12 Apr
01 Feb
02 Feb
02 Feb
07 Feb
06 Feb
06 Feb
10 Apr
10 Apr
10 Apr
01 Feb
01 Feb
01 Feb
01 Feb
01 Feb
01 Feb
01 Feb
02 Feb
02 Feb
02 Feb
02 Feb
02 Feb
02 Feb
02 Feb
02 Feb
07 Feb
07 Feb
07 Feb
07 Feb
Total
Filterable Phosphorus
SM1
BR0
BR1
BR2
BR3
BK1
SM1
BR0
BR1
BR2
BR3
BK1
SW112
SW111
SW47
Horse Ck
SW112
SW111
SW112
SW111
SW47
CC1
SW105
SW106
CC2
SW101
SW103
SW107
SW108
SW109
PCC
SW104
TMC600
TMC500
TMC400
TMC
CC2
SW107.5
SW108
PCC
QWQG TV
Sample Date
Site
Table 5.2.2 Phosphorus nutrient analysis results (µg P/L) for water samples collected in February and
April 2012. Site type codes are as follows: OMC=Outside of Mine Catchment;
UML=Upstream of Mining Lease; ML=ON the Mining lease; DML=Downstream of Mining
Lease. Results highlighted in blue exceed the QWQG TV shown at the bottom of the table.
15
11
18
22
29
47
13
7
13
28
26
40
21
13
22
7
13
20
22
13
13
20
17
16
16
8
11
7
14
6
20
7
12
11
19
7
14
8
12
10
1
2
5
0
6
4
3
3
7
15
16
6
10
1
5
3
11
5
2
3
10
10
8
13
5
1
2
1
10
2
5
1
1
2
8
1
5
6
8
9
14
9
13
22
23
43
10
4
6
13
10
34
11
12
17
4
2
15
20
10
3
10
9
3
11
7
9
6
4
4
15
6
11
9
11
6
9
2
4
1
20
18
86
26
18
24
18
26
55
37
16
16
11
44
32
34
82
37
24
22
63
49
45
78
107
52
130
337
61
74
180
32
54
72
50
49
90
38
195
105
57
6
8
6
3
3
4
13
18
15
7
10
2
3
4
4
14
33
4
3
7
24
6
8
60
5
6
191
25
63
13
5
10
6
3
5
10
12
234
87
75
Page 24
Australian Centre for Tropical Freshwater Research
DIN:DIP Molar Ratio
Total Phosphorus
29
20
24
21
16
5
10
8
17
7
10
114
16
17
20
24
18
19
35
18
15
23
10
11
31
33
35
27
29
35
34
83
22
29
21
18
9
10
14
11
15
15
28
27
29
32
32
29
59
50
TN:TP Molar Ratio
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
Filterable Reactive
Phosphorus
Clarke
Clarke
Clarke
Clarke
Clarke
Puddler
Puddler
Puddler
Puddler
Puddler
Puddler
Two Mile
Two Mile
Two Mile
Clarke
Clarke
Clarke
Puddler
Puddler
Puddler
Two Mile
Two Mile
Two Mile
Two Mile
Two Mile
Seventy Mile
Seventy Mile
Seventy Mile
Broughton
Broughton
Broughton
Broughton
Burdekin
Clarke
Clarke
Clarke
Puddler
Puddler
Two Mile
Two Mile
Two Mile
Two Mile
Two Mile
Seventy Mile
Seventy Mile
Seventy Mile
Broughton
Broughton
Broughton
Broughton
Burdekin
Site Type
Drainage line
Antecedent
Conditions
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Dissolved Organic
Phosphorus
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
07 Feb
07 Feb
07 Feb
06 Feb
06 Feb
06 Feb
06 Feb
06 Feb
06 Feb
06 Feb
06 Feb
06 Feb
07 Feb
09 Feb
07 Feb
09 Feb
09 Feb
09 Feb
09 Feb
11 Apr
12 Apr
12 Apr
11 Apr
11 Apr
11 Apr
11 Apr
11 Apr
11 Apr
11 Apr
11 Apr
12 Apr
13 Apr
12 Apr
13 Apr
13 Apr
12 Apr
13 Apr
Total
Filterable Phosphorus
CC1
SW105
SW106
CC2
SW101
SW103
SW107
SW108
SW109
PCC
SW104
TMC600
TMC400
TMC
CC3
CC4
CC5
PCK1-500 m
PC2
SM2
TMC11
TMC2
FC1
TMC12
FC2
SM3
SM4
SM5
BR4
BR5
BR6
BR7
BK2
CC3
CC4
CC5
PC2
SM2
TMC11
TMC2
FC1
TMC12
FC2
SM3
SM4
SM5
BR4
BR5
BR6
BR7
BK2
QWQG TV
(Cont)
Sample Date
Site
Table 5.2.2
23
16
19
17
12
5
6
8
3
10
3
6
26
11
15
15
18
17
12
23
17
13
15
7
10
15
28
24
23
25
28
26
42
20
17
14
14
9
5
4
10
4
9
10
19
26
25
26
26
19
40
4
6
8
1
2
1
0
0
0
1
0
0
8
1
1
1
1
6
2
5
9
2
4
1
0
2
6
8
4
6
4
3
1
14
8
6
1
4
0
1
4
2
5
5
9
12
16
15
15
9
5
19
10
11
16
10
4
6
8
3
9
3
6
18
10
14
14
17
11
10
18
8
11
11
6
10
13
22
16
19
19
24
23
41
6
9
8
13
5
5
3
6
2
4
5
10
14
9
11
11
10
35
20
23
36
56
27
41
2395
341
150
60
73
60
27
52
44
69
46
46
37
18
53
66
58
77
68
28
22
36
36
25
38
28
17
26
28
30
40
79
74
47
69
57
39
21
24
23
19
19
28
11
3
6
35
3
8
1612
637
160
22
20
21
10
3
5
7
6
4
8
13
6
8
5
5
11
8
9
4
5
4
5
4
6
4
13
12
9
8
15
4
22
13
32
22
16
7
7
10
9
8
25
3
Page 25
Australian Centre for Tropical Freshwater Research
Pha:Chl Ratio
OMC
OMC
OMC
OMC
OMC
OMC
OMC
OMC
OMC
OMC
OMC
OMC
UML
UML
UML
UML
UML
UML
UML
UML
UML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
Total Chlorophyll-a
(µg/L)
Puddler
Broughton
Broughton
Broughton
Broughton
Burdekin
Puddler
Broughton
Broughton
Broughton
Broughton
Burdekin
Clarke
Puddler
Puddler
Clarke
Clarke
Puddler
Clarke
Puddler
Puddler
Clarke
Clarke
Clarke
Clarke
Clarke
Puddler
Puddler
Puddler
Puddler
Puddler
Puddler
Two Mile
Two Mile
Two Mile
Two Mile
Clarke
Puddler
Puddler
Puddler
Site Type
Drainage line
Antecedent Conditions
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Pre-rain
Pre-rain
Pre-rain
Post-rain
Post-rain
Post-rain
Low flow
Low flow
Low flow
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Pre-rain
Post-rain
Post-rain
Post-rain
Post-rain
Phaeophytin (µg/L)
06 Feb
07 Feb
07 Feb
07 Feb
07 Feb
09 Feb
11 Apr
12 Apr
12 Apr
12 Apr
12 Apr
12 Apr
01 Feb
02 Feb
02 Feb
07 Feb
06 Feb
06 Feb
10 Apr
10 Apr
10 Apr
01 Feb
01 Feb
01 Feb
01 Feb
01 Feb
01 Feb
01 Feb
02 Feb
02 Feb
02 Feb
02 Feb
02 Feb
02 Feb
02 Feb
02 Feb
07 Feb
07 Feb
07 Feb
07 Feb
Active Chlorophyll-a
(µg/L)
SM1
BR0
BR1
BR2
BR3
BK1
SM1
BR0
BR1
BR2
BR3
BK1
SW112
SW111
SW47
Horse Ck
SW112
SW111
SW112
SW111
SW47
CC1
SW105
SW106
CC2
SW101
SW103
SW107
SW108
SW109
PCC
SW104
TMC600
TMC500
TMC400
TMC
CC2
SW107.5
SW108
PCC
QWQG TV
Sample Date
Site
Table 5.2.3 Phytoplankton analysis results for water samples collected in February and April 2012. Site
type codes are as follows: OMC=Outside of Mine Catchment; UML=Upstream of Mining
Lease; ML=ON the Mining lease; DML=Downstream of Mining Lease. Results highlighted
in blue exceed the QWQG TV (shown at the bottom of the table).
0.5
1.7
0.5
0.5
0.8
1.9
0.5
0.5
0.3
0.5
1.6
2.9
0.5
0.3
0.3
0.2
0.3
0.3
0.3
0.5
0.3
1.1
1.5
3.7
0.5
0.5
3.2
0.9
1.3
0.5
0.8
0.3
0.3
0.3
1.6
0.2
0.7
0.7
1.3
0.8
5
0.2
0.3
0.2
0.2
0.2
0.4
1.0
0.4
<0.2
<0.2
<0.2
1.0
0.2
0.3
0.2
0.4
<0.2
0.3
0.5
0.6
<0.2
0.2
0.4
0.8
0.2
0.2
0.2
0.7
0.5
0.2
0.2
0.3
0.2
0.3
0.8
0.8
<0.2
<0.2
0.5
<0.2
0.7
2.0
0.7
0.7
1.0
2.2
1.5
0.9
0.3
0.5
1.6
3.9
0.7
0.6
0.5
0.6
0.4
0.6
0.8
1.1
0.3
1.3
1.9
4.5
0.7
0.7
3.4
1.6
1.9
0.7
1.0
0.6
0.5
0.6
2.4
1.0
0.8
0.8
1.9
0.9
0.3
0.1
0.3
0.3
0.2
0.2
0.6
0.4
0.4
0.2
0.1
0.3
0.3
0.5
0.4
0.7
0.3
0.5
0.6
0.5
0.4
0.2
0.2
0.2
0.3
0.3
0.1
0.4
0.3
0.3
0.2
0.5
0.4
0.5
0.3
0.8
0.1
0.1
0.3
0.1
Page 26
Australian Centre for Tropical Freshwater Research
Pha:Chl Ratio
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
ML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
DML
Total
Chlorophyll-a
(µg/L)
Clarke
Clarke
Clarke
Clarke
Clarke
Puddler
Puddler
Puddler
Puddler
Puddler
Puddler
Two Mile
Two Mile
Two Mile
Clarke
Clarke
Clarke
Puddler
Puddler
Puddler
Two Mile
Two Mile
Two Mile
Two Mile
Two Mile
Seventy Mile
Seventy Mile
Seventy Mile
Broughton
Broughton
Broughton
Broughton
Burdekin
Clarke
Clarke
Clarke
Puddler
Puddler
Two Mile
Two Mile
Two Mile
Two Mile
Two Mile
Seventy Mile
Seventy Mile
Seventy Mile
Broughton
Broughton
Broughton
Broughton
Burdekin
Site Type
Drainage line
Antecedent
Conditions
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Post-rain
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Low flow
Phaeophytin
(µg/L)
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
10 Apr
07 Feb
07 Feb
07 Feb
06 Feb
06 Feb
06 Feb
06 Feb
06 Feb
06 Feb
06 Feb
06 Feb
06 Feb
07 Feb
09 Feb
07 Feb
09 Feb
09 Feb
09 Feb
09 Feb
11 Apr
12 Apr
12 Apr
11 Apr
11 Apr
11 Apr
11 Apr
11 Apr
11 Apr
11 Apr
11 Apr
12 Apr
13 Apr
12 Apr
13 Apr
13 Apr
12 Apr
13 Apr
Active
Chlorophyll-a
(µg/L)
CC1
SW105
SW106
CC2
SW101
SW103
SW107
SW108
SW109
PCC
SW104
TMC600
TMC400
TMC
CC3
CC4
CC5
PCK1-500 m
PC2
SM2
TMC11
TMC2
FC1
TMC12
FC2
SM3
SM4
SM5
BR4
BR5
BR6
BR7
BK2
CC3
CC4
CC5
PC2
SM2
TMC11
TMC2
FC1
TMC12
FC2
SM3
SM4
SM5
BR4
BR5
BR6
BR7
BK2
QWQG TV
Sample Date
Site
Table 5.2.3 (Cont)
0.5
0.5
20.0
0.5
0.3
0.8
3.2
1.1
1.1
1.1
1.1
0.3
2.4
0.3
0.3
0.5
1.1
0.6
0.3
0.7
0.5
0.3
2.1
0.5
0.5
0.3
0.3
0.5
1.1
1.1
0.8
4.3
5.9
0.5
0.8
0.3
0.5
0.8
<0.2
0.5
0.8
1.6
0.5
1.1
1.6
0.8
1.1
1.1
1.3
1.9
2.4
5
0.2
0.6
3.7
0.4
0.5
<0.2
1.1
1.2
0.2
0.6
<0.2
<0.2
0.6
0.3
0.3
0.2
0.2
<0.2
0.2
0.4
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.6
0.2
0.2
0.2
1.0
0.2
0.4
<0.2
0.7
0.6
0.3
0.8
<0.2
0.3
0.6
0.4
0.2
<0.2
0.7
0.2
0.4
0.4
0.9
1.0
0.7
1.1
23.7
0.9
0.8
0.8
4.3
2.2
1.3
1.7
1.1
0.3
3.0
0.6
0.6
0.7
1.3
0.7
0.5
1.1
0.7
0.5
2.3
0.7
0.7
0.5
0.5
1.1
1.3
1.3
1.0
5.2
6.1
0.9
0.8
0.9
1.1
1.1
0.8
0.5
1.1
2.2
0.9
1.3
1.6
1.5
1.3
1.5
1.7
2.8
3.4
0.3
0.5
0.2
0.4
0.6
0.1
0.3
0.5
0.2
0.4
0.1
0.4
0.2
0.5
0.5
0.3
0.2
0.2
0.4
0.4
0.3
0.4
0.1
0.3
0.3
0.4
0.4
0.5
0.2
0.2
0.2
0.2
0.0
0.4
0.1
0.7
0.5
0.3
1.0
0.2
0.3
0.3
0.4
0.2
0.1
0.5
0.2
0.3
0.2
0.3
0.3
Page 27
5.2.3
Benthic algae
The swiftflow event which occurred immediately prior to the February 2012 field survey had scoured the
streambed and there was no visual evidence of any benthic algae at any of the sites that were visited. By
April 30 2012 benthic communities had re-established at all of the sites that were surveyed on both
Puddler and Clarke Creeks. These comprised the same dominant genera that had been recorded in August
2011; namely, Rhizoclonium, Oedogonium, Euglena and Cymbella. Fragilaria was also dominant in a
few places on Puddler Creek, mainly on the bottom of deeper pools where water current velocities tend to
be lower. Very small but dense assemblages of Oscillatoria were also visually evident in a few isolated
pools which were at an advanced stage of drying out.
Rhizoclonium (Hair algae, Family Cladophoraceae) Image 1: Rhizoclonium
and Oedogonium (Family Oedogoniaceae) are
filamentous green algae (Chlorophytes) which are
commonly found in local streams. The basal cell of
each filament can act as a holdfast for attachment to
solid substrates, including other plants, but in quiet
backwaters the filaments often occur as a free-floating
mass. The cell walls of Oedogonium are very hard,
which makes them an ideal substratum for attachment
of other epiphytic algae, such as Cymbella (which is a
common associate). Chlorophyte assemblages are not
generally considered to be aesthetically pleasing, and
Rhizoclonium in particular is a common nuisance for
aquarists because it adversely affects the visual appeal
of fish tanks (see Image 1). However, from an
ecological perspective these are important species
which provide food and habitat for other aquatic
biota, and in poorly aerated waters they are also an
important source of oxygenation.
Euglena is not an alga, but rather a unicellular flagellated protistan which is customarily included in algal
surveys because it is capable of photosynthesis and is therefore functionally similar to algae. It is one of
the most ubiquitous “alga” that occurs in freshwater environments. Notably it is not an obligate autotroph;
it is a heteroautotroph which can grow in the dark, and/or in water with low nutrient concentrations, by
feeding on organic matter.
Cymbella is a unicellular diatom (a group generally referred to as Heterokonts, although the taxonomy is
currently unsettled). It can grow freely suspended in the water column but it generally prefers benthic
habitats and can attach itself to substrata by producing mucilaginous stalks. Cymbella commonly attaches
itself to Oedogonium and other filamentous algae, and the relationships between these species are
reportedly subject to substantial seasonal variations, the relative dominance of each taxa being prone to
shift abruptly in response to subtle cues (see for example Roos 1979).
Fragilaria (sometimes spelled Fragelaria, family Fragilariaceae) is a diatom that forms fragile
filamentous colonies. It can grow suspended in the water column or on the benthos. Oscillatoria is a
genus of filamentous cyanobacterium which reproduces by fragmentation. It is virtually ubiquitous
throughout this region and is commonly found in quite locations such as stock watering-troughs and
tanks. Some species of Oscillatoria can produce toxins including microcystins, anatoxins and potentially
aplysiatoxins, which can cause allergic dermal reactions in humans. However, despite its very wide
occurrence, especially in livestock drinking water, Oscillatoria toxicity has rarely been reported in this
region.
Algal communities significantly influence the appearance of the waterways that they occupy. The
periphyton mats which form on the bottom of pools when the water column is relatively still and calm are
often brownish in colour (see images 2 to 4). This can be partially attributed to the presence of silt and
fine particles of organic detritus that have been incorporated into the algal layer. However, Cymbella and
Australian Centre for Tropical Freshwater Research
Page 28
Fragilaria contain golden brown to brown chloroplasts, and most the brownish colouration evident in
images 2 to 4, is simply caused by a predominance of those genera.
Image 2:
Brown periphyton mat at Site SW107.5 30/04/12
Australian Centre for Tropical Freshwater Research
Page 29
Image 3:
Brown periphyton mat at Site SW108 30/04/12
Image 4:
Brown periphyton mat at Clarke1
Australian Centre for Tropical Freshwater Research
Page 30
Most of the sites surveyed in this study lacked the type of calm pools required to develop the sorts of
periphyton coverages shown in the preceding photos. Thin diatom biofilms were still present in places at
the more hydrodynamically active sites (see Image 5), but as can be seen in Images 6 to 16, filamentous
green algae was the dominant periphyton at all sites other than the three shown in the preceding images,
including the upstream control sites on Puddler Creek and Clarke Creek, and the external reference sites
located on unnamed tributaries of the Broughton.
Image 5: Close-up view of a mixed Rhizoclonium, Oedogonium and Euglena community at CC2
30/04/12 (green), surrounded by a thin layer of diatom biofilm (yellowish brown).
Image 6:
Distance view of the algae shown in Image 5 (CC2 30/04/12)
Australian Centre for Tropical Freshwater Research
Page 31
Image 7:
A reach of Clarke Creek located 1.28 km upstream of CC2 (looking upstream)
Image 8:
A reach of Clarke Creek located 1.28 km upstream of CC2 (looking downstream)
Australian Centre for Tropical Freshwater Research
Page 32
Image 9:
Filamentous green algae at site PCK (principally Rhizoclonium)
Image 10: Isolated patch of filamentous green algae in a backwater at site PCC
Australian Centre for Tropical Freshwater Research
Page 33
Image 11: Control Site SW112 on Clarke Ck
Image 12:
Control site SW111 on Puddler Creek
Australian Centre for Tropical Freshwater Research
Page 34
Image 13:
Upstream of control site SW111 on Puddler
Image 14:
Reference Site 1 – Unnamed Broughton River tributary
Australian Centre for Tropical Freshwater Research
Page 35
Image 15:
Image 16:
Reference Site 1 – Unnamed Broughton River tributary
Reference Site 2 – Unnamed Broughton tributary
Australian Centre for Tropical Freshwater Research
Page 36
It is evident from the preceding images that, in general, the algae assemblages at the control and reference
sites were more visually prominent than they were at the sites potentially influenced by the mine. The
mass per unit area of algae at those sites was in fact only moderately higher than the impact sites,
however, the differences were accentuated because the water levels at the control and reference sites had
retracted further, thus exposing a greater proportion of the algal beds to the air. When this happens, the
long filaments of Rhizoclonium and Oedogonium are no longer supported by water, so they collapse to
form tangled mats dense enough to shade the underlying water. Motile “algae” such as Euglena, diatoms
and cyanobacteria therefore attempt to migrate to the surface in order to obtain light, and as a result
surface algae densities can become very high.
In flowing sections of the creek these effects can develop relatively slowly because algal filaments and
associated epiphytes continually break off and get carried downstream (termed sloughing). However,
when algae get trapped in isolated pools, surface densities can increase quite rapidly. (Note that in
streams of this kind pools usually continue to receive subsurface throughflows for significant periods
after the surface connections have dried out. Hence there are usually sufficient inputs of aqueous nutrients
to support vigorous algal growth even though the pools appear to be stagnant).
As can be seen in Images 17 and 18, the visual effects of these natural drying out processes can be
unappealing to the human observer and could easily be misconstrued as being indicative of an unhealthy
ecosystem. It is in fact likely that conditions will become even more unsightly over the next few months
when the creek beds dry out and most of the algal biomass begins to decay. However, these processes are
a natural part of the annual cycle for ephemeral waters of this kind, and are by no means indicative of illhealth.
Image 17:
Emergent filamentous green algae at Control Site SW112 on Clarke Ck
Australian Centre for Tropical Freshwater Research
Page 37
Image 18:
Exposed filamentous green algae in an isolated pool near site PCC
Australian Centre for Tropical Freshwater Research
Page 38
6.
SUMMARY AND CONCLUSIONS
This report has found no evidence that algal growth within the sections of Puddler and Clarke Creeks
potentially affected by Mt Leyshon mine is any more dense or prolific than the algal growth that is
currently evident in other similar streams in the region. In fact the density and areal coverage of
periphyton mats at the upstream control sites on Puddler and Clarke Creek, and in other small tributary
streams that are free of influences from the mine, actually appear to be slightly higher, although that is
probably an artefact caused by minor differences in flow persistency and the rates at which each site dries
out.
The unusually high rainfall over the past four years has generated increased baseflow and as a result
streams throughout the region have flowed and retained water for longer periods during the dry season
than they have for a least the previous decade. Since benthic algae continue to grow whenever water is
present and growth rates can increase substantially if the water is flowing, the density of algal
communities has increased very noticeably during this wet period. ACTFR believe that this natural effect
was very likely the source of the algae-related issues raised in the EE Notice.
The algal genera that were present at the monitoring sites all commonly occur in streams throughout the
local region, and are essential sources of food and/or habitat for most of the freshwater organisms that
inhabit these seasonally ephemeral waters. The only potentially problematic genus recorded in this study
was the cyanobacterium Oscillatoria. However, that genus is virtually ubiquitous to fresh waters
throughout the region, and it was only detected in very small amounts at the Mt Leyshon sites during this
investigation.
Clarke and Puddler Creeks stop flowing each year at some stage during the dry season. In the process
algae are concentrated into residual pools which stagnate and gradually dry out. The exposed patches of
decomposing and/or desiccated algae can be visually unappealing to the human observer and could easily
be misconstrued as being indicative of an unhealthy ecosystem. However, these processes are a natural
part of the annual cycle for ephemeral waters of this kind, and are by no means indicative of ill-health.
Since there was no evidence of anomalously dense or prolific algal growth at any of the sites surveyed
during this study it was not possible to address all relevant sections of the EE Notice. Specifically,
although this report details the ways in which algae and other components of the aquatic environment
interact with one another, there was no means of assessing the impacts of a phenomenon that was not
observable over the course of the study, (as specified in Section 8b of the EE Notice), and no basis for
making the remedial recommendations called for in Section 9.
This study did, however, find evidence of nitrate accession in some the groundwaters and surface waters
situated on the mining lease. Under baseflow conditions in 2012 there was evidence of localised
occurrences of elevated nitrate concentrations at receiving stream sites situated within 1.5 km of water
storage structures associated with the mining operation. The reported nitrogen concentrations could
potentially have stimulated excessive algal growth, but at the time phosphorus levels were limiting, and as
a consequence the phytoplankton concentrations at all of the affected sites were very low. Under lower
flow conditions in August 2011 phosphorus concentrations were sufficiently high to potentially enhance
algal growth but at that time nitrogen concentrations were low enough to limit algal responses, and
phytoplankton levels were again quite low. The moderately elevated phosphorus levels were quite evenly
distributed throughout the local drainage system suggesting that they originated from a diffuse catchment
source unrelated to the mine.
Australian Centre for Tropical Freshwater Research
Page 39
7.
REFERENCES
ANZECC and ARMCANZ (2000) Australian Water Quality Guidelines for Fresh and Marine Waters.
Australia and New Zealand Environment Conservation Council and Agriculture and Resource
Management Council of Australia and New Zealand, Canberra.
ANZECC and ARMCANZ (2000b) Australian Guidelines for Water Quality Monitoring and Reporting.
Australia and New Zealand Environment Conservation Council and Agriculture and Resource
Management Council of Australia and New Zealand, Canberra. ISBN 09578245 1 3. !SSN 1038
7072.
APHA (1998) Standard Methods for the Examination of Water and Wastewater. 20th Edition. American
Public Health Association, American Water Works Association and Water Environment
Foundation. Washington, U.S.A.
Baskaran, S., K. L. Budd, R. M. Larsen and J. Bauld (2002). A groundwater quality assessment of the
Lower Pioneer Catchment, Qld. Bureau of Rural Sciences, Department of Agriculture, Fisheries
and Forestry - Australia, Canberra. 62.
Bauld, J., L. L. Leach and S. M. W. (1996). Impact of land use on groundwater quality in the Burdekin
River Delta and the Burdekin River Irrigation Area : Abstract. Downstream effects of land use. H.
Hunter, Eyles, AG and Rayment GE, Department of Natural Resources, Queensland: 195.
Butler, B. and D. Burrows (2007). Dissolved Oxygen Guidelines for Freshwater Habitats of Northern
Australia. Australian Centre for Tropical Freshwater Research, Townsville. ACTFR Report
07/32.
Butler B. (2005) Water quality. In: Brizga S.O., Kapitzke R., Butler B., Cappo M., Connolly N., Lait R.,
Pearson R. G., Pusey B., Smithers S. and Werren G. L. (2005) Burdekin Basin Water Resource
Plan: Current Environmental Condition Report. Department of Natural Resources and Mines,
Queensland. Appendix E.
Dames and Moore. (1994) The Century Project. Draft Impact Assessment Study Report. Volumes 1-3.
Century Zinc. Commissioned by Century Zinc Limited through Kinhill Cameron and McNamara.
DERM (2009) Queensland Water Quality Guidelines, Version 3. Department of Environment and
Resource Management ISBN 978-0-9806986-0-2
DERM (2009) Monitoring and Sampling Manual 2009. Environmental Protection (Water) Policy 2009.
Version 1 September 2009. Queensland, Department of Environment and Resource Management.
Keating, B. A., Bauld, J., Hillier, J., Ellis, R., Weier, K. L., Sunners, F., and Connell, D. (1996).
Leaching of nutrients and pesticides to Queensland groundwaters. Downstream Effects of Land
Use. H. M. Hunter, Eyles, A. G., and Rayment, G. E. Brisbane, Department of Natural Resources.
Newmont Mining Services (NMS) (2012) Response to Notice to Conduct an Environmental Evaluation,
DERM Reference STAT620, for Environmental Authority MIN 100902009, May 2012.
Pearson, R. G. and N. M. Connolly (2000). Nutrient enhancement, food quality and community
dynamics in a tropical rainforest stream. Freshwater Biology 43: 31-42.
Roos, P. J. (1979) Architecture and development of periphyton on reed-stems in Lake Maarsseveen
Summaries and Papers of Scientific Meetings Organized by the Netherlands Hydrobiological
Society. Aquatic Ecology. Volume 13, Numbers 2-3 (1979), 117, DOI: 10.1007/BF02284745
Australian Centre for Tropical Freshwater Research
Page 40
Schlumberger Water Services (SWS) (2012) Mt Leyshon Project; Source, Cause and Extent of sulphate
in groundwater and surface water. Response to Environmental Evaluation Required under EA
MIN100902209.
Smith, R., Jeffree, R., John J. and Clayton P. (2004) Review of Methods for Water Quality Assessment
of Temporary Stream and Lake Systems. Australian Centre for Mining Environmental Research
(ACMER). Final Report. September 2004.
Standards Australia (1998) Water Quality – Sampling. Part 1: Guidance on the design of sampling
programs, sampling techniques and the preservation and handling of samples. AS/NZS
5667.1:1998. Standards Australia, Homebush.
Weier, K., (1999) The quality of groundwater beneath Australian sugarcane fields. CSIRO Tropical
Agriculture, St. Lucia, 1999.
Australian Centre for Tropical Freshwater Research
Page 41
A.
APPENDIX
ACTFR Sampling Protocols
Adherence to the sampling protocols outlined below will generally ensure that sample integrity is
maintained. Note, however, that it is not possible to anticipate all contingencies. Accordingly field
personnel must be alert to any situation-specific factors that could potentially impact on the quality or
reliability of samples, and it is ultimately their responsibility to take any additional precautions that might
be necessary.
The containers, syringes, filters and gloves provided by the laboratory are disposable items and they
should not be re-used. Do not hesitate to dispose of samples and re-sample using new containers and/or
equipment if there is any reason to suspect that the original sample has been compromised in some way
(for example if a container lid has been dropped on the ground or a drop of sweat has fallen onto your
gloves). The laboratory will provide surplus containers and equipment to cover such contingencies.
Nutrients
The nutrient analyses required for this project are as follows:






Total (unfiltered) nitrogen and phosphorus – TN and TP
Total dissolved (filterable) nitrogen and phosphorus – TDN and TDP
Nitrate – NO3
Nitrite – NO2
Ammonia – NH3
Filterable reactive phosphorus – FRP
Samples for these analyses are transferred to gamma-sterilised plastic tubes using a clean disposable
plastic syringe. The TN and TP sample is not filtered and is simply transferred via syringe to a 60 ml
tube. All other nutrient samples (TDN, TDP, NO3, NO2, NH3 and FRP) are filtered into 10 ml tubes (6
tubes per sample).
Nutrients are ubiquitous in the environment and the concentrations that occur in human sweat, sun
screens, soil, dust, smoke, ash and organic matter can be 1,000 to 1,000,000 times higher than the levels
found in natural surface waters. Accordingly, special precautions are required to avoid contaminating
samples. Tubes are provided in clip-seal plastic bags; they should be placed back in the bag immediately
after sampling
Notably the period during which tubes are uncapped should be kept as brief as possible. Hence tubes
should only be uncapped after the syringe is ready for sample delivery, and each tube should be re-capped
immediately before proceeding to the next. Tubes and caps should never be put down while they are
open. Instead both should be held in the gloved hand taking care to ensure that there is no contact with the
inside of the tube or the cap. (This is best done by holding the cap between the thumb and forefinger, and
cradling the tube in the other fingers of the same hand).
Sample bottles and vials for metals analyses have usually been washed with nitric acid, so they are a
major potential source of nitrogen contamination. The preservatives used for other analyses can also
cause similar problems. Accordingly nutrient samples should be taken and stored separately (in a
dedicated portable freezer or cooler) before any other sample bottles are touched. (Alternatively, if there
are two personnel involved, one person can do nutrient and chlorophyll samples, and the other can handle
the rest of the samples).
Australian Centre for Tropical Freshwater Research
Page 42
Sampling Procedure
At each site, immediately prior to sampling, put on a clean pair of disposable gloves and use a clean
plastic box or equivalent to create a clean work space where syringes, filter packets and sealed tubes can
be laid down. Remove tubes from their clip seal bag, label them and set them down on the clean
workspace. A new (unused) syringe should then be taken from its packet and rinsed three times with the
water to be sampled, taking care to avoid drawing in coarse suspended particulate materials if possible.
During all stages of the sampling procedure water should be drawn from a depth of 10 cm below the
water surface.
On the first rinse completely fill the syringe and expel all of the water to waste (resisting the temptation to
squirt by-standers). On each subsequent rinse fill the syringe to one-quarter capacity, retract the plunger
to its maximum extent (in order to create a large air space) and then shake the syringe vigorously before
immediately ejecting the water. This procedure is important to minimise the chances of particulate matter
adhering to the inside walls of the syringe. Inspect the syringe after the final rinse. Re-rinse if there is any
visible particulate matter adhering to the walls. If that does not effectively clean the syringe use a new one
and take greater care to avoid drawing in visible particulate matter.
To start collecting samples, draw water into the rinsed syringe from 10 cm below the water surface, uncap
the 60 ml TN and P sample tube, and fill it precisely to the calibration mark. Immediately replace the cap.
Refill the syringe (if using a 60 ml syringe it is best to slightly overfill it, because the first few mls of
sample will be used to wash the filter). Open the filter packet to expose the back of the filter housing,
insert the (filled) syringe into the connection orifice and remove the filter from its packet (i.e. connect the
filter to the syringe without touching the filter housing with your hands). Place the empty filter packet on
the clean workspace until sampling is completed.
The first few mls of filtered sample should be rejected. The remaining water in the syringe can then be
filtered directly into each of the six 10 ml tubes provided. Each tube should be uncapped, filled to the
calibration line molded into the neck and immediately recapped before proceeding to the next tube. It is
particularly important to avoid overfilling the tubes to ensure that they do not burst when frozen. If it is
necessary to refill the syringe, temporarily place the filter assembly back in its packet without touching it
with your hands. If the filter becomes blocked use another clean filter, remembering to again reject the
first few mls of filtrate. If it proves impossible to fill 3 tubes before the filter blocks, it would be advisable
to use one of the pre-filters provided. These fit in-line between the syringe and the main filter. Note that
the housing of the main filter is yellow and the pre-filter housing is clear, white or green.
Return the tubes to the plastic bag and seal it. Place samples in cold storage immediately and ensure that
they are frozen as soon as possible. Ensure that freezers, coolers and freezer blocks used for storage and
transport of nutrient samples are very clean.
Samples should ideally be placed in a portable freezer immediately after collection. Ice slurries are an
effective means of initially cooling samples in the field but, since some potable waters can contain high
nutrient concentrations, that option should only be employed if the ice has been made from laboratory
grade de-ionised water. Alternatively, for interim field storage purposes, the samples can be placed in a
cooler ensuring that the tubes are positioned such that they are in direct contact with clean freezer blocks.
Samples in field coolers should be transferred to a freezer as soon as possible, and ideally they should be
deep frozen before they are shipped to the laboratory.
Nutrient samples can be stored for months provided that they remain deep frozen. Hence there is time to
ensure that they are fully frozen before they are shipped to the laboratory. In fact it is feasible to
accumulate samples collected on different days and submit them to the laboratory later as a single batch.
Note that this option is not applicable for chlorophyll samples.
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Chlorophyll a and phaeophytin
Samples for chlorophyll a and phaeophytin analysis (indicative of the concentrations of planktonic algae,
termed phytoplankton) are collected in a one litre black plastic bottle. Provided that the water in the
stream to be sampled is deeper than 40 cm, the bottle should simply be filled by immersing to a depth of
25 cm below the water surface with the mouth of the bottle facing into the prevailing current. In waters 20
to 40 cm deep the sample should be collected at least 5 cm below the water surface and 15 cm above the
bottom, taking extreme care to ensure that bottom algae and/or detritus are not disturbed in the process,
and that surface water does not enter the bottle.
If the water is less than 20 cm deep it would be advisable to search a short distance upstream to find a
deeper location. (Moving downstream may also be an option if the site has not yet been disturbed by
sampling personnel). If there are no locations greater than or equal to 20 cm deep, sample at the deepest
point, record the sampling depth and note whether or not surface water entered the bottle.
The bottles provided are ready for use. They should not be rinsed prior to sampling (because algae can
potentially adhere to the insides of the bottle, in which case the rinsing process can actually increase the
concentrations in the sample).
Samples must be immediately chilled (below 4°C), but never frozen (freezing destroys algae by fracturing
cell walls). The samples must be filtered and preserved within 24 hours of collection so it is important to
ship them to the laboratory as soon as possible after collection, and confirm that the lab will be ready to
filter them as soon as they arrive. The lab does not normally work on weekends, so sampling should not
be done on a Friday, Saturday or Sunday, unless special arrangements have been made with the
laboratory manager.
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Nutrient Sampling Summary:
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Take any precautions necessary to protect samples from potential contamination
Collect nutrient samples and store them separately before collecting samples for other analyses
Wear a new pair of disposable gloves at each site
Use a clean plastic box or equivalent to create a clean work area where tubes and syringes can be laid
down without risking contamination
Remove tubes from the clip-seal plastic bag and label them
Open a new disposable syringe and rinse it at least three times with the water to be sampled, ensuring
that there is no visible particulate matter adhering to the insides
Draw sample into the syringe from a depth of 10 cm below the water surface
Use the syringe (without fitting a filter) to fill the 60 ml tube for TN and TP analyses
Fill the tube to the calibration mark; do not overfill
Re-fill the syringe (slightly over-fill if using a 60 ml syringe)
If the water is not excessively turbid attach a main filter (yellow housing) directly to the full syringe
without touching it with your hands; if the water is turbid attach a pre-filter (housing white, clear or
green) to the syringe and then attach the main filter to the pre-filter outlet
Discard the first few mls of water that is passed through the filter(s)
Filter sample into each of the six 10 ml tubes
Open, fill and recap each tube before opening the next, and minimise the time that each tube is open
Return the tubes to their clip-seal plastic bag and seal it
Freeze, or at least chill, the samples immediately
After sampling dispose of gloves, syringes, filters and associated packaging, responsibly
Ensure that samples are deep frozen as soon as possible, ideally before they are shipped to the
laboratory
Chlorophyll Sampling Summary:
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Confirm arrangements with freight carriers and laboratory staff to ensure that the samples will be
filtered within 24 hrs of collection
Use a one litre black plastic bottle for sample collection
Do not pre-rinse the bottle.
Fill by immersing the bottle with the opening facing into the prevailing current.
Sample bottle immersion depth:
water >40 cm deep;
25 cm below the water surface.
water 20-40 cm deep;
15 cm above the bottom.
water <20 cm deep;
avoid if possible; record details
Do not disturb bottom algae or detritus
If possible, do not allow surface water to enter the bottle
Chill the sample immediately
Ship the samples to the laboratory ASAP
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