Toxicology Letters 140 /141 (2003) 323 /332
www.elsevier.com/locate/toxlet
Short communication
Accumulative heavy metal patterns in the sediment and biotic
compartments of the Tisza watershed
Ernö Fleit a,*, Gyula Lakatos b
a
Department of Sanitary and Environmental Engineering, Budapest University of Technology and Economics, H-1111 Budapest,
Műegyetem rakpart 3, Hungary
b
Department of Applied Ecology, University of Debrecen, H-4010 Debrecen, Egyetem tér 1, Hungary
Received 15 September 2002; accepted 12 December 2002
Abstract
The paper presents data on toxic heavy metals in sediments measured after two large chemical spills on the Tisza
watershed area. On the basis of the results, it is concluded that significant volume, high concentration heavy metals
reached the Upper Tisza and Szamos River sections. Based on the longitudinal distribution of the heavy metals in
sediments, the primary sedimentation zones and concentration increase compared with reference site was determined.
Results verified arrival of fresh spills of mining origin and superimposed pollution. Regarding to chronic
ecotoxicological effects, degradation and bioaccumulation rates of heavy metals priority problems are associated
with arsenic, lead, mercury and cadmium in the sediments of the Tisza and Szamos Rivers after the spills of Romanian
origin in 2000. Results indicate that the biological availability of the various heavy metals significantly differ along the
river, particularly upstream and downstream of the Tisza Lake. The recent investigation did not identify one single
sample in which muscular metal concentration of pike (Esox lucius L.) exceeded the present Hungarian consumer
guidelines. The investigated pike population on the Tisza River could be divided into characteristic subgroups based on
muscular tissue metal concentrations (Cd, Hg, Pb, Cu and As), depending on the bioavailability of the metalloids at the
different river sections. On the basis of the data evaluation, it is concluded that the present state of pollution on Tisza
River indicates the potential for deterioration and need for further biomonitoring.
# 2003 Elsevier Science Ireland Ltd. All rights reserved.
Keywords: Heavy metals; Bioaccumulation; Biomonitoring; Ecotoxicology
1. Introduction
Dam failure of the mine slurry of Baie Mare
(Romania) caused major environmental disaster in
* Corresponding author. Tel.: /36-1-463-4260; fax: /36-1463-3753.
E-mail address: fleit@vcst.bme.hu (E. Fleit).
Hungary and other downstream countries at the
end of January 2000. According to official estimates, the spill carried 100 tons of cyanide and
equal amounts of heavy metals (silver, copper,
zinc, cadmium, etc). The toxic plume reached the
Szamos River, then via the Tisza River, it entered
to the Danube on Yugoslavian territory. Measured cyanide concentrations were as high as 20 /
0378-4274/03/$ - see front matter # 2003 Elsevier Science Ireland Ltd. All rights reserved.
doi:10.1016/S0378-4274(03)00029-8
324
E. Fleit, G. Lakatos / Toxicology Letters 140 /141 (2003) 323 /332
30 mg/l on the Szamos River and 5 /10 mg/l on the
Hungarian section of the Tisza River, respectively.
Due to the prevailing hydrometeorological conditions and poor management, yet another dam
(Baia Borşa, Romania) was broken in only 2
weeks to the first environmental disaster. The
latter spill carried about 20 000 tons of heavy
metal rich mine slurry that eventually reached
Hungarian territory via another tributary of the
Tisza River. Acute toxic consequences of the first
spill (cyanide) were regional-scale damages in the
aquatic ecosystem of the Tisza River, mass kills of
several Vertebrata and Invertebrata taxa. The
second spill received less attention particularly in
terms of potentially occurring long-term, chronic
ecotoxicological effects.
The paper aims to provide preliminary assessment on the state of the sediment following the
two large spills and to initiate to build a comparative baseline data on the heavy metal contents of
some biotic compartments (pike muscular tissue)
on the exposed river sections. Preliminary data of
the environmental authorities and involved international agencies indicated that significant volume
of potentially hazardous heavy metal has been
accumulated in the Upper Tisza and Szamos
sediment. Consequently, future tasks are to be
focused on monitoring the chronic effects of the
sediment accumulated heavy metals for setting
priorities of rehabilitation actions.
The European Environmental Agency set 12
environmental priorities in 1995, as it was issued in
the Dobris Report. One priority related to the
large-scale, regional industrial spills. Regionalscale spills of transboundary character, having
long-term ecotoxicological consequences occurred
on the Tisza River limiting vital water uses (i.e.
drinking water supply) in 2000. The high volume
of the transported heavy metals in the mine slurry
underlines the need to focus on the non-aqueous
phases (i.e. sediment and suspended solids) when
assessing and predicting the future state of the
exposed aquatic ecosystems.
The Water Framework Directive of the European Union (Water Framework Directive, 2000)
sets priorities in maintaining and preserving the
natural conditions of freshwater ecosystems and
when it is necessary, the rehabilitation. Rehabilita-
tion actions have to be based on the evaluation of
the state of the various environmental compartments (aqueous phase, sediment and biotic elements). Assessment of the bioavailability of the
sediment accumulated heavy metals is a major
element in setting rehabilitation priorities.
The paper discusses two data groups:
. Distribution of heavy metals in the sediment of
Szamos and Tisza Rivers in the follow-up
period of the two large spills.
. Heavy metal contents in pike tissues (Esox
lucius L.) on the Tisza River after about 8
months exposure time.
Complex physical, biochemical and microbiological processes occurring in and between the solid
phase, interstitial water and the water body
regulate distribution dynamics of the metals and
metalloids (Hansen et al., 1996). Ultimately, these
mechanisms determine the environmental fate and
hence the biological availability of the heavy
metals accumulated in sediment.
Envisaged scenarios on the Tisza watershed
implicate multiple and dynamically changing discharges of various chemicals, fractionated sedimentation
patterns,
varying
adsorption /
desorption mechanisms depending on the transportation processes of suspended solids. These
processes have not yet described. Consequently
the results of the sediment survey presented here
are considered as a momentary picture on the
primary sedimentation zones (hot-spots), a changing scene with largely unknown regulatory mechanisms that will determine future water quality
and long-term state of the aquatic ecosystem.
2. Materials and methods
2.1. Sediment survey
Two sampling campaigns were launched, one is
after the cyanide spill and yet another after the
heavy metal discharge. Fig. 1 shows the Tisza
watershed and the watercourses carrying the spills.
Sediment samples were collected at 11 sites
following the cyanide spill from which three were
E. Fleit, G. Lakatos / Toxicology Letters 140 /141 (2003) 323 /332
325
2.2. Fish tissue sampling
Three fish populations were investigated. Two
control groups were selected for comparison, one
is within and one is outside the Tisza watershed.
On the Tisza River, the ‘exposed population’ was
sampled in the period of October /November
2000. This allowed us to investigate heavy metals
patterns in fish tissues following 8 months exposure time.
Captured fish were deep-frozen and dissected to
various tissues (muscle, gonads, scales, etc.).
Altogether, 117 fish sample were collected on the
Tisza from which the results of the 25 pike
specimen are discussed herein. Presented results
are referring to fish muscle samples on the Tisza
section between Tiszaadony (668 rkm) and SzegedTápé (180 rkm). Average body mass was 239.2 g
with the average (standard) body length of 327.5
mm. Standard deviation of body mass was 135.9
and 58.3 regarding to standard body length.
2.3. Analytical methods
Fig. 1. The watershed of the Tisza and the watercourses
carrying the spills.
on the Szamos and eight on the Tisza River. One
sampling site on the Tisza River served as reference site, located upstream of the confluence point
of the Szamos River carrying the cyanide spill.
Following the second spill (heavy metal loaded
mine-tailing slurry) eight sampling sites were
selected. At three locations, stratified sediment
sampling was conducted to reveal differences
between recent and historical heavy metal concentrations. One particular location (near to Tivadar,
at 705 river km (rkm), that served as reference site
in case of the cyanide pollution) was used as
comparative background to detect differences for
it was sampled before and after the heavy metal
spill as well. Another reference point was also
added from the vicinity of this location that has
been isolated from the river on the flood-protected
area to measure natural background levels of
geochemical origin.
Quantitative and qualitative chemical analyses
were conducted at the internationally accredited
laboratory of the Bálint Analitika Ltd., Budapest.
Each measurement was made in two parallels.
Data presented are based on the arithmetic
average of two measurements. Metal determination was made according to Hungarian Standard
21470-50:1998 (corresponding to US EPA 6020
method) using ICP-MS instrumentation (MSZ,
1998; US EPA, 1990).
Metal analysis from fish used 2.50 g tissue
sample measured to a Teflon bomb with 0.1 mg
accuracy. Two cm3 65% nitric acid (Merck,
Suprapur) and 6 cm3 30% hydrochloric acid was
added to the sample followed by destruction in
microwave oven at low power. Following full
evaporation the same volume of acid and 25 ml
50 mg/l Sc, Rh, Lu inner standard-solution was
added to the bomb. Upon full destruction, the
sample was washed to 25 ml flasks. Analysis of the
metals was made by inductively coupled plasma
mass spectrometer (ICP-MS method). Tissue results are expressed in wet weight units. Sediment
results are referring to dry material contents.
E. Fleit, G. Lakatos / Toxicology Letters 140 /141 (2003) 323 /332
326
Assessment of data was based on applicable
Hungarian environmental standards in force. For
sediments, the authority limits for polluted soils
were used as given in Table 1 (Hungarian Ministry
for Environment, 2000). Intervention values are
indicating concentration levels when clean up is
obligatorily ordered by the environmental authorities. For fish allowed concentrations are set
(Hungarian Ministry of Health, 1999) by a ministerial order (As 1.0, Hg 0.3, Pb 0.5 and Cd 0.1 mg/
kg). It is noted that neither ecological sediment
quality criteria nor fish consumption guidelines for
sport fish are in force in Hungary at present.
3. Results
3.1. Longitudinal sediment characteristic
Chronic ecological effects of the pollutants
reaching surface water bodies are profoundly
affected by sediment-water body interactions often
showing site-specific character.
Based on the results, the following observations
were made on the heavy metal contents of the river
sediments after the first (cyanide) spill in 2000:
. The Hungarian intervention limit value for soils
was reached in the sediment of the Szamos at
the national border by the following elements:
arsenic (71.4 mg/kg), zinc (660 mg/kg), cadmium (4.8 mg/kg) and copper (345 mg/kg).
Values in bracket are the means of two parallel
measurements.
. Concentration of four toxic heavy metals (As,
Zn, Cd and Cu) was above the polluted level on
the Szamos River sediment at all three sampling
sites.
. In the sediment of Tisza River, the cadmium
reached the Hungarian intervention limit value
at three sampling locations, the arsenic at two
locations and the zinc at one sampling site.
Results of the sediment survey after the second
(heavy metal) spill originated indicated the following:
. The primary sedimentation zones on the Upper
Tisza section were at the Milota and Tivadar
regions on the basis of measured concentration
ranges (zinc, cadmium, lead and copper). Extremely high values were measured on the river
section upstream of Vásárosnamény (between
733/705 rkms) indicating the primary sedimentation zones of heavy metals.
. Concentrations of cadmium, copper, lead and
mercury were elevated significantly at the
reference site (Tivadar, 705 rkm) indicating
superimposed sediment pollution: cadmium
0.33 0/1.89, copper 23 0/147, lead 14.7 0/212,
mercury 0.05 0/0.16 mg/kg.
Fig. 2 shows the longitudinal profile of lead
concentrations on the Upper Tisza section, indicating the locations of metal accumulation in
surface sediment layer.
3.2. Vertical sediment profiles
Elevated heavy metal concentrations were measured in surface sediment samples at the national
border (Tiszabecs, 742 rkm). Concentration values
Table 1
Hungarian authority standards for soil (values in mg/kg unit, expressed in dry weight)
Element
A value (natural background)
B value (polluted)
C value (intervention)
Cd
Pb
Hg
As
Ni
Zn
0.5
25
0.15
10
25
100
1.0
100
0.5
15
40
200
2.0
150
1.0
20
150
500
E. Fleit, G. Lakatos / Toxicology Letters 140 /141 (2003) 323 /332
327
Fig. 2. Longitudinal distribution of lead concentrations on the Upper Tisza sediment (from Tiszabecs 742 rkm to Tuzsér 617 rkm).
in the surface sediment layer compared with the
lower laying sediment layer (in depth of 10 cm)
revealed an increase of about a magnitude of order
in many heavy metal (lead, silver, bismuth, cadmium, copper and zinc) concentrations indicating
newly arrived pollution of mining origin. Sampling
sites near to national border (Milota, 733 rkm and
Tivadar, 705 rkm) revealed the presence of hot
spots (heavy metal accumulation sites) due to the
hydromorphology of the river. Copper, cadmium,
lead and zinc concentrations were close to or
above the intervention limit (See Table 1).
At one sampling point at Tiszakórod (728 rkm),
the lead concentration was so high that we
repeated the measurements (see also Fig. 2). The
results indicated lead concentrations of 1810 mg/
kg dry material sediment. This sample originated
from an inundated riverbank that became dry
during the cessation of the flood that carried the
spill. Stratified samples taken at Jánd (688 rkm)
proved that in spite of the high metal concentrations measured at the surface, no significant heavy
metal accumulation occurred in deeper laying
sediment layers of the downstream situated river
section at the period of sampling (March 2000).
Further downstream at Aranyosapáti (670 rkm)
concentrations were still high, around the Hungarian intervention value (zinc, arsenic, cadmium,
etc.). Downstream of the confluence point of the
Szamos River that carried the cyanide plume no
particular stratification could have been observed
in sediment values. Sediment of the Tisza River
downstream to the confluence point of the Szamos
River showed significant pollution in the investigated vertical sediment strata (0 /10 cm) due to
mixing, bioturbation during the past years.
Fig. 3 shows the vertical distribution of heavy
metals in sediments as measured at the national
border (Tiszabecs, 742 rkm).
3.3. Heavy metals in muscular tissue of pikes of the
Tisza River
3.3.1. Arsenic
Measured arsenic concentrations in pikes are
depicted on Fig. 4. Results indicate that the pike
population of the Tisza River can be divided into
two separate groups. Pikes downstream of the
Tisza Lake (Kisköre Reservoir) contain elevated
arsenic levels in their tissues, compared with those
that were captured upstream of the reservoir.
328
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Fig. 3. Vertical distribution of heavy metals in the sediment at the national border (Tiszabecs).
Fig. 4. Changes of arsenic concentration in pike muscle on the
Tisza River.
Fig. 5. Changes of cadmium concentration in pike muscle on
the Tisza River.
Higher arsenic concentrations in muscle might be
the results of higher geochemical background and/
or anthropogenic loads. Several arsenic compounds are accumulating in fish tissues but arsenic
is not toxic to fish (ATSDR, 1999).
The range of the measured cadmium concentrations is far below the human consumption guideline values (Hungarian Ministry of Health, 1999).
3.3.2. Cadmium
Fig. 5 shows the measured cadmium concentrations in pike muscle. As opposed to the concentration pattern revealed in arsenic distribution, the
cadmium contents of pike muscle shows different
layout. Higher cadmium exposure level was observed in middle and upper river sections. It is also
noted that the measured (ppb) of cadmium levels
are in the low to moderate concentration range.
3.3.3. Copper
Fig. 6 shows copper concentrations in pike
muscle on the Tisza River. Copper contents in
pike revealed linearly decreasing tendency towards
to downstream sections. Value of the linear
regression coefficient is r /0.79. The only elements
that showed linearly decreasing tendency in pike
tissues along the longitude of the river was the
copper. This would make us to hypothesize that
the copper was mainly present in soluble and
complexated form and the discharge was literally
washed out to the downstream river sections.
E. Fleit, G. Lakatos / Toxicology Letters 140 /141 (2003) 323 /332
329
Table 3
Heavy metal concentrations in pike muscle downstream of the
Tisza Lake
Fig. 6. Changes of copper concentration in pike muscle on the
Tisza River.
Relatively high concentrations in pike muscle
were measured in case of four other components
but only on the upstream river section: palladium,
tellurium, thulium and thorium (Pd, Te, Tm, Th).
The concentrations of these elements were elevated
by factors of 10/80 regarding to the control
populations within and outside of the watershed.
No physiological function is described so far on
these elements except the tellurium that is toxic.
Elevated concentrations of these rare earth elements are attributed to the hydrogeological background as well as past discharges of mining and
industrial origin.
Data of primary statistical analysis on measurement results are given in Tables 2 and 3.
Level of priority pollutants (As, Cd, Cu, Hg, Pb)
in muscular tissues were analyzed by using nonparametric statistical methods. Results achieved
by the Wilcoxon-test and the two-sided
Table 2
Heavy metal concentrations in pike muscle upstream of the
Tisza Lake
Parameter
Arithmetic mean
Median
S.D.
As (mg/kg)
Cd (mg/kg)
Cu (mg/kg)
Hg (mg/kg)
Pb (mg/kg)
Body mass (g)
Body length (mm)
417.55
16.97
697.70
149.94
31.28
205.22
311.78
210.00
17.00
676.00
146.50
30.50
179.00
295.00
694.00
1.93
93.90
49.40
4.06
114.44
53.72
Parameter
Arithmetic mean
Median
S.D.
As (mg/kg)
Cd (mg/kg)
Cu (mg/kg)
Hg (mg/kg)
Pb (mg/kg)
Body mass (g)
Body length (mm)
1448.75
1.45
359.50
303.19
18.02
258.25
336.38
1510.00
1.36
351.50
277.00
17.30
224.00
334.00
354.44
0.30
56.67
93.22
3.49
146.57
60.53
Kolmogorov/Smirnov test (Table 4) lead us to
the following conclusions.
Both statistical tests verified that for the five
elements (As, Cd, Cu, Hg and Pb), the nullhypothesis of homogeneity has to be rejected.
Measured heavy metal concentrations in the
muscular tissues of the Tisza River pikes upstream
and downstream of the Tisza Lake were originated
from different distributions.
Opposed to the above conclusion, it was justified that the body length and mass values of the
collected pikes were originated from a homogenous statistical population, and the difference
observed was no significant with respect to these
morphometric parameters.
Connecting these two conclusions, it is envisaged that the length and mass of the sampled pike
population (as related to age and predatory
strategy) played little or no role in establishing
characteristically different heavy metal patterns in
muscular tissues. Consequently, experienced differences are due to external factors, as results of
different exposure conditions indicating highly
different bioavailability of the metals along the
longitude of river. Regarding to the muscular
concentrations of As, Cd, Cu, Hg and Pb, the
region of the Tisza Lake divides the pike population into two, significantly different sub-populations, a division that cannot be explained by
differences of the body weight and length.
This result concludes us that there are significant differences in exposure conditions upstream
and downstream of the Tisza Lake. The biological
E. Fleit, G. Lakatos / Toxicology Letters 140 /141 (2003) 323 /332
330
Table 4
Results of the Wilcoxon and Kolmogorov /Smirnov non-parametric statistical analyses
Parameter
Wilcoxon-test (risk of rejecting the null-hypothesis in Kolmogorov /Smirnov test (risk of rejecting the null-hypothesis
[0. . .1] interval)
in [0. . .1] interval)
As
Cd
Cu
Hg
Pb
Body
length
Body mass
0.20
0.00
0.00
8.0/10 2
0.00
0.69
1.20 /10 4
1.23 /10 5
1.23 /10 5
4.81 /10 4
1.23 /10 5
0.29
0.57
0.15
availability of the sediment accumulated heavy
metals is different on the particular river sections
and/or the absolute load is also differing.
4. Discussion
Environmental effects of mine tailings on the
aquatic ecosystems are discussed in details in
United States Geological Survey (USGS) reviews.
Data indicate (Fey, 1999) that metal contents of
the slurry of secondary utilization mines can be as
high as 1 /8 % having relatively high bioavailability due to the particle size which is typically in the
colloid range (100 /500 mm). Applying the lower
estimate (1%), it is presumed that the released
20 000 tons of slurry might contribute to around
2 /1011 mg additional lead load (200 tons of lead)
on the watershed. Theoretically, this discharge
could pollute 2/109 dm3 sediment volume regarding to the Hungarian intervention value for
lead in soils (100 mg/kg). This assumption is based
on zero lead contents prior to the mine accidents.
Realistically, the exposed floodplain and riverbed
area might stretch to several hundred square
kilometers as internationally applied sediment
quality criteria are lower than intervention standards for soil, and the potential site of exposure
(grazing and feeding on the uppermost sediment
layer, bioturbation, etc.) is only a few centimeters
deep in the vertical profile of the sediment. This
indicates that expected long-term ecological effects
are on the regional scale. A particularly important
factor in relation to suspended solid bound metal
transport processes is the existence of two manmade reservoirs on the exposed river section
(Tiszalök and Kisköre, alias Tisza Lake). On these
reservoirs, the fractionated sedimentation of suspended solids of various particle sizes occurs and
the surface adsorbed metals are deposited in these
locations. Different exposure conditions are evidenced in the muscular tissues of predatory fish
population as it was described in this paper.
Comparison of sediment data from other Hungarian rivers showed that apart from nickel,
chromium and zinc, the concentration of other
toxic heavy metal concentrations in the Tisza
sediment were above of the Danube, Sajó and
the Soroksári /Danube branch values. Average
values of cadmium, lead and copper were about
twice (Cd), or 4-fold (Pb, Cu) compared with other
Hungarian reference sediment values. Considering
long-term ecological effects, the most hazardous
two elements (Cd and Pb) represent a long-term,
special problem on Tisza River.
It is of interest to compare our results with
historical data of other European rivers. In earlier
studies (Beurkens et al., 1994), measured time
trends of heavy metals in the sedimentation zone
of the Rhine. Historical data of the heavy metal
contents of Rhine sediment and the recent findings
on the Tisza River are compared in Table 5.
Comparison of the two data sets shows that on
average the present concentrations of two metals
(copper and lead) in the Tisza exceeded historical
levels measured in Rhine sediment in the middle
eighties. All the other measured metals were below
the Rhine pollution level. It is also noted that the
E. Fleit, G. Lakatos / Toxicology Letters 140 /141 (2003) 323 /332
331
Table 5
Historical average concentrations of River Rhine and of the Tisza River sediments in 2000
Heavy metals (mg/kg)
Rhine (1945)a
Rhine (1965)a
Rhine (1985)a
Tisza (2000)
Cd
Pb
Cu
Ni
Cr
Zn
As
Hg
4
170
80
35
110
1100
50
2
20
400
300
60
500
2500
140
11
11
170
100
40
200
1000
25
2
2.5
261
161
36
26
476
29
0.1
a
Beurkens et al. (1994).
results of the international water quality management program of the Rhine started to show up in
sediment quality during the middle eighties.
Fish survey revealed no heavy metal concentration in muscular tissues that was above the
applicable Hungarian fish consumption guidelines.
Hungarian regulation, however, is concerned on
commercial fish and not on fish from natural
water. Considering the US guideline values for
mercury (US EPA, 1997) for example, the measured average mercury concentrations in pike of
Tisza River (247 mg/kg mercury, wet weight) would
refer only to three pike meals per month (3 /227
g) not to exceed recommended mercury intake. It
is, therefore, strongly suggested to establish Hungarian consumption guidelines for fish considering
non-commercial fishing in natural aquatic environment. Based on the heavy metal concentrations
in fish tissues, the environmental authorities could
map and survey regularly the problems of ‘small
concentrations-chronic exposure’ water quality
problems that are still going unnoticed due to the
applied monitoring system (focused largely on
aqueous phase, with relatively low sampling frequency).
Regarding the Tisza and particularly the Szamos River, it cannot be concluded that the
ecological state and exposure levels of the two
rivers are solely attributable to the large-scale
Romanian mine accidents in 2000. One of the
main conclusion of the survey was that sediment as
well as fish in their tissues reflects the past
industrial and urban effects of national and
international origin. Measured data, therefore,
necessarily reflects to the integrated results of the
past and present pollutant loads of conservative
pollutants. In case of some heavy metals, the
effects of the Romanian discharges are already
detectable in the elevated heavy metal levels of
predatory fish population of the Upper Tisza
section and it is anticipated that the expression
of the ecotoxicological effects require decades to
develop. The future fate of the already accumulated metals in sediment is largely dependent on
the initiation of rehabilitation projects and introduction of environmentally sound management
practices on the entire watershed.
Acknowledgements
This project was partially supported by a grant
of the Hungarian Ministry of Environment. The
authors acknowledge the gratuitous assistance of
the laboratory of Bálint Analitikai Ltd., for ICPMS analyses.
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