Marine Pollution Bulletin 50 (2005) 1036–1049
www.elsevier.com/locate/marpolbul
Risks posed by trace organic contaminants in coastal sediments in
the Pearl River Delta, China
C.N. Fung a, G.J. Zheng a, D.W. Connell b, X. Zhang c, H.L. Wong
J.P. Giesy a,c, Z. Fang d, P.K.S. Lam a,*
a
a,c
,
Department of Biology and Chemistry, Center for Coastal Pollution and Conservation, City University of Hong Kong, 83 Tat Chee Avenue,
Kowloon, Hong Kong
b
School of Public Health, Griffith University, Logan Campus, University Drive, Meadowbrook, Qld. 4131, Australia
c
Department of Zoology, National Food Safety and Toxicology Center and Center for Integrative Toxicology, Michigan State University,
East Lansing, MI 48824-1311, USA
d
College of Life Sciences, South China Normal University, Guangzhou 510631, China
Abstract
Local marine environments in ChinaÕs Pearl River Delta (PRD), the most rapidly developing region in one of the worldÕs fastest
growing economies, have been experiencing significant environmental stress during the past decades. This investigation was conducted to determine the status and trends of persistence organic pollutants (POPs) such as polycyclic aromatic hydrocarbons
(PAHs), petroleum hydrocarbons (PHCs), polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides and dioxin-related
compounds in marine sediments collected from sixteen coastal stations in the Pearl River Delta (PRD) in March 2003. Elevated
concentrations of PAHs (94–4300 ng/g), PCBs (6.0–290 ng/g), PHCs (14–150 lg/g), and DDTs (1.4–600 ng/g) were detected in sediment samples. In addition, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-like activities in the sediment samples were estimated to
range from 0.3 to 440 pg TCDD-EQ/g. Sediments collected from Xiashan contained the greatest concentrations of trace organic
contaminations amongst all the sampling stations in the present study. The degree of trace organic contamination was, in general,
more severe at stations situated along the west shores of the PRD than their counterparts in the east. A preliminary assessment was
performed to examine the probable risks to the marine ecosystem due to POPs. The results showed that OC pesticide contamination
in the PRD was particularly serious and might pose a threat to the health of the marine inhabitants.
2005 Elsevier Ltd. All rights reserved.
Keywords: Environmental risks; Sediments; Polycyclic aromatic hydrocarbons; Petroleum hydrocarbons; Polychlorinated biphenyls; Organochlorine pesticides; Dioxin-related compounds
1. Introduction
Industries in China have undergone extremely rapid
development during the last two decades. Their intrinsic
advantages, such as relatively low labour and land costs,
have attracted huge amounts of foreign investment, and
many international enterprises have established their
*
Corresponding author. Tel.: +852 2788 7681; fax: +852 2788 7406.
E-mail address: bhpksl@cityu.edu.hk (P.K.S. Lam).
0025-326X/$ - see front matter 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.marpolbul.2005.02.040
manufacturing bases and headquarters in China. An
increasing number of factories have been built to cope
with the increasing economic development. Due to a
lack of effective urban planning, the rapid industrial
development has led to certain undesirable consequences. Many of the factories were built close to major
rivers or estuaries, where deliberate or accidental releases of domestic sewage and industrial effluents into
local waters have caused rapid deterioration in the environmental quality of coastal systems. Indeed, the Pearl
River Delta (PRD) in south China and the Yangtze
C.N. Fung et al. / Marine Pollution Bulletin 50 (2005) 1036–1049
River Delta (YRD) in central China, now recognized as
the ‘‘worldÕs factories’’, have been the focus of recent
environmental investigations. Many xenobiotic chemicals, especially metals and persistence organic pollutants
(POPs), tend to partition into various environmental
compartments, such as sediment, water and biota, once
they enter marine ecosystems. The accumulation of high
levels of these pollutants in any of these compartments
may exert adverse health effects on marine organisms
and humans. Identifying and monitoring the fate of
these pollutants in the marine environment is, therefore,
of critical importance in an attempt to protect ecological
and human health.
The PRD is located along the southern coastline of
China, and plays a pivotal role in the development of
ChinaÕs national economy. The PRD occupies an area
of approximately 41 000 km2 and has a population of
over 41 million. Industries in the PRD are mainly the
manufacturing of electronic products, garments, textile
products, plastic toys and other goods. Indeed, the
importance of agriculture in the PRD has been declining
over the past two decades, and over 95% of the gross
domestic product in the PRD is now contributed by
secondary (50%) and tertiary (45%) industries (http://
www.investhk.gov.hk/keystatistic1.aspx?id=522&code=
GPRDBKFACTSDEF).
The PRD is an open-ended V-shaped estuary system.
The Pearl River is the third largest river in China after
the Yangtze River and the Yellow River. The Pearl
River Delta has eight openings. Four outlets (Aimen,
Hutiaomen, Jitimen, and Modaomen) are located in
the west, while the other four outlets (Hengmen, Hongqimen, Jiaomen, and Humen) are located to the east and
drain into the Pearl River estuary. Hong Kong is located
1037
at the eastern side of this estuary, and Macau on the
western shore. The Pearl River flows into the South China
Sea with a discharge of over 3 · 1011 m3 and a sediment
load of around 8 · 106 ton annually (Richardson et al.,
2000). The six major cities located upstream, including
Guangzhou, Foshan, Zhongshan, Dongguan, Huizhou
and Jiangmen, have been intensively colonized by manufacturing industries. In the past decade, most of the
urban developments have been concentrated on the eastern side of the Pearl River, in order to be in close proximity to the cosmopolitan city of Hong Kong, which is
the main source of investment. The construction of a
bridge linking Zhuhai, Macau and Hong Kong, which
will be completed in 2006, is expected to significantly
enhance the development potential in areas along the
western side of the PRD in the future.
Since marine sediments can act as one of the most
important sinks for lipophilic contaminants, concentrations of these compounds in sediments have often been
used in monitoring programmes to indicate environmental quality. In recent years, concentrations of a range of
POPs have been measured in the PRD, and the results
are summarized in Table 1. For example, Yuan et al.
(2001) reported that the concentrations of PAHs, PCBs,
DDTs, and HCHs in sediments collected in the PRD
were, respectively, 740 ng/g, 2.5 ng/g, 29 ng/g and in
the range of 0.1–2.6 ng/g dry weight in 1996. Hong
et al. (1999) conducted another survey between 1996 and
1997, recording the levels of organochlorines (DDTs:
1.4–9.0 ng/g, HCHs: 0.3–1.2 ng/g, PCBs: 0.2–1.8 ng/g
dry weight) in the Pearl River Estuary, and concluded
that the probable sources of organochlorine contaminants were from major rivers entering into the PRD
estuary and Shenzhen Bay. In 1997, a number of
Table 1
Concentrations of trace organic contaminants (ng/g) in sediments collected in the Pearl River Delta in previous investigations
Contaminants
PAHs
PCBs
DDTs
HCHs
Year
1996
1997
1999
1999
1996
1996–97
1997
1999
1996
1996–97
1997
1997
1999
1997
1996–97
1997
1999
Range (ng/g)
References
Pearl River Estuary
Daya Bay
735.5
156.32–10 810.5
80–8415
–
2.49
0.18–1.82
10.2–486
–
28.57
1.36–8.99
2.6–1629
0.8–41.5
–
0.14–13.08
0.28–1.23
0.1–11.2
–
–
–
–
115–1134
–
–
–
0.85–27.37
–
–
–
–
0.14–20.27
–
–
–
0.32–4.16
All concentrations are expressed on a dry weight basis.
Yuan et al. (2001)
Fu et al. (2001); Mai et al. (2001)
Mai et al. (2003)
Zhou and Maskaoui (2003)
Yuan et al. (2001)
Hong et al. (1999)
Kang et al. (2000); Fu et al. (2001); Mai et al. (2002)
Zhou et al. (2001)
Yuan et al. (2001)
Hong et al. (1999)
Fu et al. (2001); Mai et al. (2002)
Zhang et al. (2002)
Zhou et al. (2001)
Fu et al. (2001)
Hong et al. (1999)
Zhang et al. (2002)
Zhou et al. (2001)
1038
C.N. Fung et al. / Marine Pollution Bulletin 50 (2005) 1036–1049
researchers undertook an investigation to quantify the
concentrations of PAHs (160–11 000 ng/g dry weight),
PCBs (10–490 ng/g), DDTs (2.6–1600 ng/g), and HCHs
(0.1–13 ng/g) in the PRD sediment (e.g., Kang et al.,
2000; Fu et al., 2001; Mai et al., 2002). The concentrations of DDTs and HCHs in the sediments were 0.8–
42 and 0.1–11 ng/g, respectively (Zhang et al., 2002).
The contamination status of POPs in sediments collected from the Daya Bay to the east of Hong Kong,
not under the direct influence of the Pearl River, has
been studied by Zhou et al. (2001), who reported that
the concentrations for PCBs, DDTs and HCHs were
in the range of 0.9–27, 0.1–20 and 0.3–4.2 ng/g, respectively. In another study, Zhou and Maskaoui (2003)
found that PAH concentrations in the sediment ranged
from 120 to 1100 ng/g.
Despite the availability of data on the concentrations
of common POPs in the PRD, few attempts have been
made to assess the potential risks of these contaminants
on the marine environment and its inhabitants. One
objective of the present investigation was to establish a
comprehensive dataset on the concentrations of POPs
(PAHs, PCBs, PHCs, OC pesticides and dioxin-related
compounds) in coastal sediments in the Pearl River
Estuary. This was achieved through collating existing/
published data, and analyzing environmental samples
collected from a total of 16 stations along the full shore
length of the PRD. Additionally, sediment samples were
analyzed for dioxin-like compounds because information on this class of compounds in the PRD was lacking.
Based on these results, a preliminary assessment of risks
to the coastal system of the PRD due to these contaminants was undertaken.
2. Materials and methods
2.1. Sample collection and preparation
Surface marine sediments were collected with a Van
Veen grab from two sites in Daya Bay and fourteen
coastal sites fringing the Pearl River estuary in March
2003 (Fig. 1). The sediment samples were transferred
to polyethylene bags, kept in an icebox, and immediately
stored in a 20 C freezer upon return to the laboratory.
Prior to chemical analysis, frozen sediment samples were
thawed, thoroughly mixed, and then transferred to individual 50 ml polyethylene centrifuge tubes. Samples
were freeze-dried, and then homogenized in a solvent
pre-cleaned blender. The resulting powdered samples
were stored in pre-cleaned centrifuge tubes, and were
maintained in a desiccator before analysis.
2.2. Chemical analysis
All glassware was cleaned and rinsed sequentially
with water, acetone and hexane. All solvents used had
been purified by distillation. In general, the analytical
procedures followed those outlined in Zheng et al.
(2000). Three internal standards [C22, m-terphenyl and
decachlorobiphenyl (DCB)] were added to dried sediment samples, each of approximately 15 g, prior to solvent extraction. Each sediment sample was transferred
to a 250 ml round bottom flask and heated to approximately 80 C, refluxed for 2 h with 120 ml of methanol,
and then allowed to cool to room temperature. The cool
mixture was filtered through a glass filter paper, and the
filtrate was put into a separation funnel, and extracted
Fig. 1. The Pearl River Delta showing the sediment sampling locations.
C.N. Fung et al. / Marine Pollution Bulletin 50 (2005) 1036–1049
with 30 ml hexane for three times. The hexane extracts
were combined and the extract solution was reduced in
volume to 1 ml by rotary evaporation prior to column
chromatography. A chromatography column, packed
with glass wool at the bottom, followed by 8 g of preactivated silica gel and 2 g of activated copper, was
washed in sequence with 15 ml of methylene chloride
and 30 ml of hexane. The extracted hexane aliquot
(1 ml) was then added on the column for chromatographic separation. The column was eluted with 15 ml
of hexane, and then 20 ml of methylene chloride and
hexane (20:80) mixture to obtain Fraction 1 (containing
PHCs), and Fraction 2 (containing PAHs, PCBs and
OC pesticides), respectively. The volume of each fraction was further reduced to 100 ll by nitrogen blowdown for quantitation by gas chromatography.
As part of the analytical procedure, reagent blanks
were run in every extraction set to check for potential
contamination caused by the reagents and/or the glassware. Standard Reference Materials (SRM: HS-6 and
HS-2; National Research Council of Canada, Halifax,
Canada) were analyzed as above to validate the analytical methods used in this study. Concentrations of trace
organic contaminants reported in the present study were
not corrected for recoveries (see below). All results were
expressed on a dry weight basis.
2.3. PAHs and PHCs
Concentrations of PHCs [n-alkane and unresolved
complex mixture (UCM)] were determined by a Hewlett
Packard 6890 series gas chromatograph equipped with a
flame ionization detector (GC-FID) using a 30 m Ultra2-fused silica capillary column (0.2 mm diameter and
0.33 lm thickness film; 95% dimethyl-5% polysiloxane)
with the aid of an autosampler (Hewlett Packard 7683
series). The column head pressure was kept at 12 psi.
Temperatures in the injector and detector were maintained at 210 and 280 C, respectively. A programme
was set to maintain the initial oven temperature at
90 C for 2 min, and then increase to 280 C at a rate
of 10 C/min for 20 min. Total amounts of n-alkanes
and UCM were counted as total PHCs. The detection
limit for total PHCs was 50 ng/g. Recoveries of fuel oil
and kerosene were approximately 69% and 57%
respectively.
The 15 typical PAHs [naphthalene, acenaphthylene,
acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, benzo(b)fluoranthene, benzo
(k)fluoranthene, benzo(a)pyrene, indeno(1,2,3-cd)pyrene, dibenzo(1,2,5,6)perylene, and benzo(g,h,i)perylene]
were determined by a Hewlett Packard 6890 series gas
chromatograph coupled with a mass selective detector
(GC-MSD). Individual PAHs were identified using their
respective standards, and quantified based on peak areas
with reference to the internal standard m-terphenyl.
1039
Concentrations of total PAHs were determined by summing the concentrations of all the 15 PAHs. The detection limits for individual PAHs were 0.5 ng/g, with
recoveries ranging from 83% to 85%.
2.4. PCBs and OC pesticides
The quantification of PCBs and OC pesticides was
performed using a Hewlett-Packard 6890 gas chromatography equipped with an electron capture detector
(GC-ECD) using a 30 m HP-5 fused silica capillary column (0.2 mm diameter and 0.33 lm thickness film; 95%
dimethyl-5% polysiloxane). The oven temperature was
set at 100 C (hold 2 min), and then increased to
270 C at rate of 8 C/min (hold 20 min). Identification
of individual PCB congeners and OC pesticides were
based on the retention times of their respective standards. The PCB standard (SRM 2262) used for quantification was a mixture with known composition and
content, containing 28 congeners (PCB 1, 8, 18, 28, 29,
44, 50, 52, 66, 77, 87, 101, 104, 105, 118, 126, 128,
138, 153, 154, 170, 180, 187, 188, 194, 195, 200, 206).
The concentrations of individual PCBs and OC pesticides were quantified based on peak areas with reference
to the internal standard (DCB). The temperatures for
both the injector and detector were at 280 C. Detection
limits were 0.05 ng/g for individual OCs and PCBs.
Recoveries of OC pesticides and PCBs were, on average,
93% and 99%, respectively.
2.5. Dioxin-related compounds
The analytical protocol was based on those described
in Hilscherova et al. (2001, 2002). Dry sediments (20 g)
were homogenized with sodium sulfate (100 g), and
were Soxhlet extracted for 20 h with 400 ml dichloromethane (high purity DCM, Burdick & Jackson, Muskegon, MI, USA). Extracts were concentrated to
around 10 ml using a rotary evaporator at 39 C.
Acid-treated copper granules were added to the extracts
to remove sulfur. The extracts were then concentrated
into 1000 ll by rotary evaporation.
Details of the in vitro HII4E-Luc bioassay used in
this investigation had been described in Hilscherova
et al. (2000). In brief, 250 ll of cell suspension (8 ·
104 cells/ml) was seeded into each of the 60 interior wells
of a 96-well culture View Plate (Packard Instruments,
Meriden, CT, USA). The 36 exterior wells of each plate
were filled with 250 ll culture media. Test and control
wells were dosed with 2.5 ll of the extract or solvent
as appropriate following 24 h incubation. Blank wells
received no dose. For the dose-response characterization, a dilution series, consisting of six concentrations
that had been prepared by 3-fold or 5-fold serial dilution
were tested (three replicate wells per concentration). A
luciferase assay was conducted after 72 h of incubation.
1040
C.N. Fung et al. / Marine Pollution Bulletin 50 (2005) 1036–1049
Briefly, culture media were removed and the cells were
rinsed with phosphate-buffered saline (PBS). Cells were
lysed, and luciferase assay reagents were added to the
wells. Plates were incubated at 30 C for 10 min, and
were then scanned with an ML3000 microplate reading
luminometer (Dynatech laboratories, Chantilly, VA,
USA). The relative potency (REP) of a sample was
calculated based on the dose-response relationship of
sample serial dilutions and 2,3,7,8-tetrachlorodibenzop-dioxin (TCDD) standard serial dilutions. TCDD
equivalent could be reported as REP-20%, REP-50%,
and REP-80% depending on the degree of deviation
from parallelism between the sample and standard
curves (Villeneuve et al., 2000). In the cases where the
observed maximum response for the sample was less
than 20%, the maximum response was used to calculate
the TCDD equivalent.
2.6. Risk assessment
Comparisons between the concentrations of specific
pollutants detected in the sediments and their corresponding sediment quality values (i.e. concentrations
below which adverse effects in the marine ecosystem
were unlikely) were performed in the present investigation. The levels of risks posed by certain chemicals in
the sediments were characterized by risk quotients,
which were calculated (Eq. (1)).
Risk quotientðRQÞ
Concentration of chemical X in sediment
¼
Sediment quality value
ð1Þ
In most cases, sediment quality values are not single
numbers, but are often represented in ranges of values,
which have lower and upper limits. These two values
could be used to calculate risk quotients under the
best-case (RQbcs) and worst-case (RQwcs) scenarios
(Eqs. (2) and (3)).
RQbcs
Lowest measured concentration of chemical X in sediment
¼
Upper limit of sediment quality value
ð2Þ
RQwcs
Highest measured concentration of chemical X in sediment
¼
Lower limit of sediment quality value
ð3Þ
The calculation of RQbcs and RQwcs provides a simple way to distinguish chemicals, which may or may not
require further analysis. In principle, RQbcs > 1 would
indicate that the chemical in question would require
attention, and probably some control measure or remedial action is needed. In contrast, if RQwcs < 1, the
chemical is probably of little concern, and thus should
be accorded a lower priority in terms of management actions. In situations where RQbcs < 1 or RQwcs > 1, a
more refined risk assessment should be undertaken to
ascertain the risks due to the specific chemicals. Here,
a precautionary approach may be needed as the sediment quality values used may not be specific or directly
applicable to the system under investigation (in this case,
the PRD).
3. Results
3.1. Petroleum hydrocarbons
Concentrations of total PHCs in the PRD sediment
ranged from 14 to 150 lg/g (Table 2). The greatest average concentration of PHCs was detected in the samples
collected in S13 (140 lg/g), followed by samples collected in S10 (130 lg/g), S12 (110 lg/g), and S15
(99 lg/g). Sediment from S16 contained the least concentration PHCs (15 lg/g) amongst all the sampling
stations. Comparatively small concentrations of PHCs
(14–63 lg/g) in sediments were recorded in S1 through
to S9, as well as S14 and S16. Ratios of UCM/n-alkane
ranged between 0.9 and 3.9 for most stations, indicating
that the sources of PHCs were generally not petrogenic
(Mazurek and Simoneit, 1984). Ratios of UCM/n-alkane
in S10 and S13 ranged between 4.1 and 5.8, suggesting
petrogenic sources for the PHCs at these two sites.
3.2. Polycyclic aromatic hydrocarbons
Concentrations of total PAHs in the sediment samples
are summarized (Table 3). The concentrations of total
PAHs (based on 15 individual PAHs) were in the range
of 94–4300 ng/g. The greatest concentration was detected
in the sediment samples collected in S15 which was
approximately twice the second and the third greatest
concentrations detected in S7 and S2, respectively. Relatively great concentrations of PAHs (510–820 ng/g) were
recorded in samples from S6, S8, S10, S12 and S13. All
the remaining stations exhibited similar (relatively small)
concentrations of PAHs and the least concentration was
recorded in S3. Proportions of low molecular weight (53
benzene rings) to high molecular weight PAHs (>3 benzene rings) varied amongst stations. Most stations contained similar concentrations of low molecular weight
and high molecular weight PAHs (combustion PAHs/
R PAHs: 50%). Comparatively greater concentrations
of high molecular weight relative to low molecular
weight PAHs (combustion PAHs/R PAHs: >60%) were
detected in sediments from S2, S13 and S15, suggesting
the importance of combustion as a source of PAHs. Sediments collected in S1, S3 and S5 had phenanthrene/
anthracene ratios > 15, indicating that the sources of
PAHs at these sites were petrogenic in origin.
C.N. Fung et al. / Marine Pollution Bulletin 50 (2005) 1036–1049
1041
6.2
3.7
9.9
9.1
2
1
4.3
3.9
8.3
8.3
7.6
15.8
14.7
0.93
0.92
2
1
7.0
6.5
13.6
21.6
75.3
96.9
98.8
3.15
3.49
2
2
1
S14
24.2
76.4
100.7
1
S15
43.2
1.26
2
1
28.5
117.4
145.9
24.3
81.6
105.9
108.3
2.93
3.36
2
1
28.2
82.5
110.7
S13
S12
24.1
115.3
139.4
142.6
4.12
4.79
2.56
41.0
2.53
3.24
61.3
3.59
1.09
30.0
18.4
62.4
80.7
2
1
2
18.5
106.6
125.1
127.9
5.36
5.76
1
20.5
110.2
130.7
S11
S10
Site
16.2
63.6
79.8
80.3
3.40
3.93
1.09
2.23
45.2
2.28
2.30
25.1
3.66
n-alkanes
UCM
Total PHCs
Average
Ratio UCM/n-alkane
5.9
21.4
27.3
8.9
15.4
24.4
24.0
1.59
1.73
40.4
1.48
1.17
1
16.4
24.3
40.7
19.5
22.8
42.2
2
1
19.5
24.6
44.1
12.0
30.8
42.9
2
1
11.1
28.0
39.1
14.7
47.7
62.5
2
1
13.1
47.0
60.1
13.5
14.7
28.2
2
1
15.2
16.6
31.8
15.5
34.4
49.9
2
1
12.3
28.2
40.5
7.0
16.0
23.0
2
1
9.1
14.5
23.6
S16
57.4
3.74
1.15
12.5
46.8
59.3
1
2
18.6
21.4
40.0
S8
S7
S6
S5
S4
S3
S2
S1
Site
Table 2
Concentrations (lg/g dry weight) of petroleum hydrocarbons, and UCM to n-alkane ratios in sediment samples collected from the Pearl River Delta
n-alkanes
UCM
Total PHCs
Average
Ratio UCM/n-alkane
2
Blank
3.88
13.4
28.9
42.3
1
2
11.4
44.2
55.6
S9
12.4
34.4
46.7
44.5
2.16
2.78
3.3. Organochlorines
Concentrations of various organochlorines are summarized in Table 4. Concentrations of total HCHs were
in the range of 12–350 ng/g, and the two extreme values
were recorded in S2 and S10, respectively. Sediment
samples collected from S1, S3 and S6 were comparatively less contaminated by HCHs (<30 ng/g). All the
remaining stations, except for S14 and S16, showed relatively great concentrations of HCHs (120–260 ng/g).
The least concentration of HCB (1.1 ng/g) was measured in sediments collected from S16. In contrast, sediments collected in S15 were contaminated by the
greatest concentrations of HCB (55 ng/g), followed by
sediment samples from S10. Stations S1, S2, S3, S6, S7
and S14 exhibited relatively small concentrations of
HCBs in the sediment samples (<10 ng/g), while the
remaining stations showed no marked differences in
the concentrations of HCBs (10–30 ng/g).
Concentrations of heptachlor and heptachlor epoxide
(HE) ranged from 0.04 to 17 ng/g and <0.05–5.6 ng/g,
respectively. The greatest concentrations of heptachlor
and HE were, respectively, recorded in samples from
S10 and S4, while the smallest concentrations of heptachlor were detected in samples from S16. Similar concentrations of HE were observed in samples from S2,
S3, S5, S6, S7, S8, S9 and S14, whereas concentrations
of HE were below detection limits in sediments from
all the remaining stations. Concentrations of heptachlor
were comparatively small (<6 ng/g) in sediments from
all stations, except S6, S10 and S12.
Concentrations of kepone were in the range of <0.05–
67 ng/g in the sediment samples. The maximum concentration (67 ng/g) was recorded in a sample from S10,
which was approximately two-fold greater than the second greatest concentration detected in samples from
S15. Small concentrations of kepone (<2 ng/g) were observed in samples from S1, S3, S6, S7, S14 and S16.
Concentrations of aldrin (<0.05–34 ng/g), dieldrin
(0.1–210 ng/g), and endrin (<0.05–40 ng/g) varied considerably among locations. The maximum concentrations of aldrin, dieldrin, and endrin were recorded in
samples from S13, S10, and S10, respectively. The concentrations of aldrin in the samples from S10 were comparable to those from S13. Sediments from S11, S12,
S13 and S15 contained greater concentrations of aldrin,
dieldrin, and endrin as compared to other sampling
sites.
The greatest concentration of total chlordanes
(CHLs) was detected in sediments from S5, while concentrations of CHLs in most other stations were below
detection limit, except for S2 (0.9 and 1.5 ng/g) and S4
(0.4 and 0.6 ng/g).
Concentrations of total DDTs were calculated based
on the combined concentrations of pp-DDE, pp-DDD
and pp-DDT. Concentrations of total DDTs ranged
1042
Table 3
Concentrations (ng/g dry weight) of 15 PAHs in sediment samples collected from the Pearl River Delta
Site
S1
S3
S4
S5
S6
S7
S8
S9
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
<0.5
1.1
0.7
0.8
44.2
1.2
19.9
17.5
10.0
8.8
3.5
8.2
0.5
0.6
1.1
118.1
37.3
42.6
<0.5
0.8
0.8
0.8
35.6
0.6
16.7
13.2
8.6
7.2
4.1
6.8
0.5
0.6
1.1
97.4
56.5
43.2
2.8
3.5
2.6
3.2
88.8
9.2
369.3
384.5
288.9
178.2
97.5
126.5
2.3
2.6
4.9
1564.9
9.7
69.4
5.8
2.1
1.4
2.2
84.5
8.7
366.8
378.0
280.9
172.0
94.7
120.3
2.0
2.4
4.2
1526.0
9.7
69.1
3.8
2.0
1.3
1.8
31.1
1.6
15.3
20.0
9.6
6.3
3.2
19.5
0.9
1.0
1.7
119.0
19.1
52.2
1.2
1.2
0.9
1.6
29.3
1.4
12.9
18.1
10.4
3.7
3.0
6.6
0.9
1.0
1.7
93.8
21.5
48.3
53.3
5.2
4.3
8.2
67.5
8.2
74.4
97.6
49.6
21.9
8.1
12.4
1.1
1.4
2.3
415.6
8.2
46.8
36.6
5.1
4.8
8.9
67.1
8.3
83.4
109.9
57.1
23.1
11.1
14.7
1.2
1.1
2.1
434.5
8.0
50.7
71.5
9.9
4.0
11.1
121.5
7.4
73.7
109.3
56.3
14.6
6.7
6.4
1.0
0.9
1.5
495.8
16.3
39.7
42.3
7.6
3.5
9.9
113.5
6.3
68.2
104.6
55.8
11.7
6.7
7.4
0.8
0.9
1.7
441.0
17.9
43.0
2.4
2.9
1.9
6.9
92.4
11.4
185.6
165.1
106.9
46.3
19.2
27.3
1.0
1.2
2.3
672.9
8.1
54.9
9.4
1.9
1.7
6.3
88.9
10.0
190.2
166.8
121.6
45.2
23.0
30.2
1.9
2.3
3.6
703.1
8.9
56.1
23.9
1.4
1.4
11.2
197.7
22.7
465.5
367.7
245.6
54.2
16.3
68.7
1.5
1.4
2.4
1481.6
8.7
51.2
36.0
1.3
1.3
12.9
224.5
29.0
505.7
398.5
251.4
104.8
51.1
66.3
1.6
1.6
2.4
1688.3
7.7
52.0
47.2
11.6
4.0
17.2
125.2
14.4
171.5
227.2
122.2
38.6
18.2
26.1
<0.5
<0.5
<0.5
823.4
8.7
52.5
51.1
8.8
4.2
15.6
120.4
12.2
149.1
207.3
114.9
34.6
19.3
20.0
0.8
1.0
1.6
760.9
9.9
52.5
19.3
10.6
5.6
16.7
93.4
8.0
86.4
130.8
59.4
11.2
6.8
6.9
0.7
0.9
1.5
458.2
11.7
47.6
13.3
9.7
4.6
13.4
89.7
7.7
84.6
124.8
54.4
11.5
4.9
5.9
0.6
0.7
1.1
426.9
11.7
47.7
Site
S10
1. Naphthalene
2. Acenaphthylene
3. Acenaphthene
4. Fluorene
5. Phenanthrene
6. Anthracene
7. Fluoranthene
8. Pyrene
9. Chrysene
10. Benzo(b)fluoranthene
11. Benzo(k)fluoranthene
12. Benzo(a)pyrene
13. Indeno(1,2,3-cd)pyrene
14. Dibenzo(1,2,5,6)perylene
15. Benzo(g,h,I)perylene
Total PAHs
Phenanthrene/anthracene
Combustion PAHs/total PAHs (%)
S11
S12
S13
S14
S15
S16
Blank
1
2
1
2
1
2
1
2
1
2
1
2
1
2
1
2
20.8
5.8
3.7
22.4
63.0
18.5
190.6
156.5
127.0
17.6
4.5
4.5
0.5
0.6
0.9
636.9
3.4
49.0
15.7
5.6
3.4
18.7
55.6
17.3
124.5
141.9
116.9
14.7
5.5
3.3
0.9
1.1
1.7
526.9
3.2
54.3
33.9
4.0
10.4
8.6
74.9
9.8
63.3
97.2
51.6
14.2
9.2
9.1
1.3
1.5
3.0
391.9
7.6
47.7
29.2
12.1
8.8
8.4
72.2
8.9
69.7
96.6
57.0
17.1
7.4
7.1
1.5
1.8
2.9
400.9
8.1
47.8
30.5
9.7
4.3
12.9
150.6
16.1
74.4
225.2
104.0
13.1
9.7
13.0
1.6
1.4
2.6
669.1
9.4
55.4
49.0
9.7
3.9
16.5
148.1
12.1
70.8
201.9
158.9
11.9
6.0
9.2
1.1
1.3
1.8
702.1
12.2
55.8
16.2
8.5
4.5
8.4
52.5
13.4
104.8
168.5
89.2
25.3
6.8
10.9
1.2
1.4
2.3
513.9
3.9
59.5
8.4
4.0
3.6
7.3
56.3
11.8
112.1
179.0
104.4
31.7
19.3
18.7
1.2
1.5
2.2
561.5
4.8
63.8
30.0
4.6
2.7
8.5
57.5
4.3
55.0
66.4
30.6
8.4
6.1
5.9
0.6
0.7
1.3
282.6
13.3
42.5
9.7
3.1
1.8
8.7
53.4
5.3
60.5
75.9
47.2
18.9
8.3
15.3
0.7
0.8
1.7
311.4
10.0
54.2
60.3
10.0
7.3
35.0
377.3
43.2
934.1
887.6
705.0
379.9
220.9
127.0
12.6
9.1
11.4
3820.7
8.7
61.6
48.7
14.0
6.3
42.6
409.5
43.3
994.4
933.2
825.6
508.6
279.7
161.3
15.1
10.7
14.1
4307.0
9.5
63.8
13.7
1.6
1.4
3.5
29.0
2.0
28.4
21.8
12.5
5.4
3.5
4.9
<0.5
<0.5
0.8
128.5
14.3
38.1
10.5
1.1
1.2
2.4
25.6
1.7
28.0
31.4
19.7
11.1
2.7
8.8
<0.5
<0.5
0.7
145.0
14.7
51.4
0.7
<0.5
<0.5
<0.5
0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
0.9
<0.5
<0.5
<0.5
2.1
0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
<0.5
0.6
<0.5
<0.5
<0.5
1.1
C.N. Fung et al. / Marine Pollution Bulletin 50 (2005) 1036–1049
1. Naphthalene
2. Acenaphthylene
3. Acenaphthene
4. Fluorene
5. Phenanthrene
6. Anthracene
7. Fluoranthene
8. Pyrene
9. Chrysene
10. Benzo(b)fluoranthene
11. Benzo(k)fluoranthene
12. Benzo(a)pyrene
13. Indeno(1,2,3-cd)pyrene
14. Dibenzo(1,2,5,6)perylene
15. Benzo(g,h,I)perylene
Total PAHs
Phenanthrene/anthracene
Combustion PAHs/total PAHs (%)
S2
1
C.N. Fung et al. / Marine Pollution Bulletin 50 (2005) 1036–1049
1043
Table 4
Concentrations (ng/g dry weight) of organochlorines in sediment samples collected from the Pearl River Delta
Site
S1
1
S2
2
1
S3
2
1
S4
2
S5
S6
1
2
1
2
S7
1
2
1
2
a-HCH
b-HCH
c-HCH
d-HCH
Total HCHs
1.81
12.82
5.60
1.17
21.40
2.33
10.07
3.30
1.72
17.43
2.45
11.04
4.57
0.29
18.36
1.91
8.51
0.42
1.11
11.95
1.24
24.47
2.71
0.45
28.86
2.03
19.90
3.81
1.29
27.03
17.19
95.93
42.16
9.66
164.94
19.91
83.32
57.40
15.05
175.68
17.29
78.24
17.18
6.57
119.28
13.32
98.12
8.65
4.53
124.62
6.25
13.67
4.30
2.59
26.81
5.80
6.52
7.44
3.89
23.65
2.23
109.21
5.21
1.07
117.73
7.55
115.72
3.80
2.77
129.84
HCB
Heptachlor
HE
Aldrin
Dieldrin
Endrin
Kepone
CHLs
5.67
4.47
<0.05
1.56
0.84
<0.05
<0.05
<0.05
2.70
1.21
<0.05
2.56
0.30
<0.05
<0.05
<0.05
4.39
4.92
2.95
2.46
44.43
3.34
6.04
1.47
2.09
3.79
2.26
1.95
35.50
2.05
3.13
0.87
3.07
0.08
1.55
0.68
0.22
0.21
0.64
<0.05
5.01
0.13
2.29
1.37
1.19
1.65
1.34
<0.05
12.11
0.40
4.83
6.92
7.33
5.36
3.62
0.64
18.52
2.94
5.60
7.00
9.58
4.17
2.10
0.35
19.45
5.13
5.31
4.55
10.40
6.50
4.04
4.04
30.38
3.14
3.09
2.80
0.14
2.21
1.65
3.29
7.80
11.96
3.26
3.35
3.41
1.22
1.15
<0.05
8.71
9.54
1.84
6.10
2.50
0.76
1.38
<0.05
6.43
0.07
1.63
6.51
3.52
3.15
1.30
<0.05
6.67
0.13
2.07
4.15
2.74
0.13
1.04
<0.05
pp-DDE
pp-DDD
pp-DDT
Total DDTs
0.84
1.31
0.11
2.26
0.30
0.76
0.31
1.37
71.76
33.22
16.51
121.48
64.50
27.57
5.57
97.64
0.45
0.37
0.58
1.40
1.19
0.97
1.53
3.68
7.33
9.40
9.98
26.71
12.58
5.35
9.10
27.03
5.40
5.81
6.06
17.28
2.12
3.04
3.29
8.46
3.41
2.04
1.38
6.83
2.50
1.12
0.92
4.54
3.19
1.70
5.21
10.10
2.74
1.13
5.19
9.05
Total PCBs
pp-DDT/DDTs
a-HCH/c-HCH
6.54
0.05
0.32
6.01
0.23
0.71
13.48
0.14
0.54
10.56
0.06
4.58
11.06
0.42
0.46
13.97
0.41
0.53
63.14
0.37
0.41
68.30
0.34
0.35
39.76
0.35
1.01
32.80
0.39
1.54
18.13
0.20
1.46
16.64
0.20
0.78
14.31
0.52
0.43
11.88
0.57
1.99
Site
S8
S9
S10
S11
S12
S13
S14
1
2
1
2
1
2
1
2
1
2
1
2
1
2
a-HCH
b-HCH
c-HCH
d-HCH
Total HCHs
22.24
104.44
37.78
21.96
186.41
19.56
84.67
25.50
16.20
145.93
19.38
109.29
5.32
12.11
146.10
11.84
118.56
12.93
13.17
156.49
55.78
191.25
33.68
43.53
324.23
73.46
177.19
45.16
56.81
352.62
27.60
94.46
18.32
20.40
160.78
28.98
114.73
18.15
21.26
183.12
19.95
149.92
12.45
12.88
195.21
18.86
174.99
22.36
20.64
236.85
54.96
139.98
28.32
21.83
245.09
33.40
182.66
19.76
25.22
261.05
2.33
62.35
3.85
4.70
73.23
2.00
43.61
1.77
0.66
48.04
HCB
Heptachlor
HE
Aldrin
Dieldrin
Endrin
Kepone
CHLs
15.28
2.70
3.11
3.11
8.62
5.67
6.22
<0.05
17.17
2.94
3.85
3.50
10.48
2.42
10.85
<0.05
25.69
2.51
2.05
1.23
5.42
1.99
3.07
<0.05
28.73
2.02
2.36
2.36
5.75
5.06
4.20
<0.05
45.04
16.89
<0.05
27.85
173.31
24.91
66.84
<0.05
37.72
14.45
<0.05
33.68
214.65
39.50
23.94
<0.05
13.16
3.24
<0.05
15.21
15.88
6.18
12.79
<0.05
20.04
2.55
<0.05
15.76
21.58
10.33
9.07
<0.05
18.25
11.89
<0.05
16.36
26.34
7.68
17.61
<0.05
14.41
10.45
<0.05
25.80
16.48
9.24
15.82
<0.05
21.15
3.57
<0.05
21.24
31.76
4.42
13.57
<0.05
26.19
3.04
<0.05
33.97
20.90
10.24
7.21
<0.05
4.02
2.22
1.88
1.28
2.28
1.49
1.15
<0.05
3.47
1.07
0.97
0.44
1.05
0.25
1.32
<0.05
pp-DDE
pp-DDD
pp-DDT
Total DDTs
8.62
6.90
7.78
23.30
10.48
10.95
10.85
32.28
5.42
9.16
2.87
17.45
5.75
6.54
6.47
18.75
247.61
187.39
145.57
580.57
229.17
239.17
131.45
599.78
18.88
28.88
13.95
61.71
21.06
19.08
7.78
47.92
26.34
9.62
14.05
50.01
16.48
10.75
11.67
38.91
31.76
13.32
18.53
63.60
20.90
10.04
15.44
46.38
2.28
1.88
1.54
5.70
0.61
1.07
1.77
3.45
Total PCBs
pp- DDT/DDTs
a-HCH/c-HCH
64.21
0.33
0.59
68.39
0.34
0.77
57.22
0.16
3.64
59.18
0.34
0.92
254.41
0.25
1.66
273.24
0.22
1.63
121.15
0.23
1.51
155.03
0.16
1.60
287.67
0.28
1.60
268.89
0.30
0.84
139.46
0.29
1.94
121.80
0.33
1.69
16.09
0.27
0.61
18.91
0.51
1.13
Site
S15
a-HCH
b-HCH
c-HCH
d-HCH
Total HCHs
HCB
S16
Blank
1
2
1
2
1
2
26.51
122.01
29.08
17.07
194.67
19.44
132.30
16.82
9.32
177.87
0.54
37.65
0.78
1.30
40.26
0.71
39.70
0.78
0.09
41.28
0.14
0.18
<0.05
<0.05
0.32
0.09
0.06
<0.05
<0.05
0.15
47.05
55.46
1.08
1.83
0.21
0.15
(continued on next page)
1044
C.N. Fung et al. / Marine Pollution Bulletin 50 (2005) 1036–1049
Table 4 (continued)
Site
S15
S16
Blank
1
2
1
2
1
2
Heptachlor
HE
Aldrin
Dieldrin
Endrin
Kepone
CHLs
2.86
<0.05
12.55
171.03
20.02
31.93
<0.05
5.96
<0.05
10.25
155.06
23.61
12.11
<0.05
0.04
<0.05
0.39
2.74
0.65
1.73
<0.05
0.11
<0.05
0.24
0.22
0.12
0.78
<0.05
0.00
<0.05
<0.05
0.23
0.08
<0.05
<0.05
0.06
<0.05
<0.05
0.27
0.23
<0.05
<0.05
pp-DDE
pp-DDD
pp-DDT
Total DDTs
191.03
199.71
111.77
502.51
235.06
177.75
125.81
538.61
2.74
2.17
1.73
6.63
0.22
1.08
1.18
2.48
0.15
<0.05
<0.05
0.15
0.27
<0.05
<0.05
0.27
Total PCBs
pp-DDT/DDTs
a-HCH/c-HCH
189.36
0.22
0.91
169.84
0.23
1.16
13.19
0.26
0.69
12.92
0.47
0.91
1.31
0.99
with most extracts giving responses of 50 ± 30% in the
bioassay (Fig. 2). Samples with relatively high activities
were from S4 (94%), S12 (110%), and S15 (93%), while
samples collected from stations S2, S4, S7, S8, S10,
S12, and S15 induced over 50% TCDDmax relative to
the TCDD standard curve. Since acid treatment should
have destroyed most of the acid liable contaminants
(PAHs and phenolic compounds, cyclodienes, etc.), the
dioxin-like activities observed in the H4IIE-luc bioassay
could be attributed to dioxins and PCBs.
Estimation of TCDD-EQs was based on the calculation of the amount of sample needed to produce a
response equivalent to EC20 to EC80 of TCDD following the method described in Villeneuve et al. (2000).
Among the samples, S4, S10, S12, and S15 showed relatively high responses in the H4IIE-luc bioassay with an
efficacy similar to the TCDD standard curve, which were
shown to be equivalent to 48–440 pg TCDD-EQ/g of
from 1.4 to 600 ng/g, and the minimum and maximum
values were recorded in S3 and S10, respectively. Concentrations of DDD, DDE and DDT in the sediments
were similar across the sampling stations.
The greatest concentration of PCBs (290 ng/g) was
detected in sediments collected in S12, followed by samples from S10 (270 ng/g). Relatively high concentrations
of PCBs (>120 ng/g) were found in sediment samples
from S11, S13 and S15. All the other stations showed
relatively small concentrations of PCBs (<70 ng/g) and
the least concentration was detected in sediments taken
from S1.
3.4. Dioxin-like compounds
Acid treated extracts of sediment samples collected
from the Pearl River Estuary elicited a significant induction of luciferase responses in the H4IIE-luc bioassay,
140.0
%-TCDD-max
120.0
%-TCDD-max
100.0
80.0
60.0
40.0
20.0
0.0
S1
S2
S3
S4
S5
S6
S7
S8
S9 S10 S11 S12 S13 S14 S15 S16
Fig. 2. Luciferase induction in the H4IIE-luc cell bioassay elicited by acid treated extracts of sediment samples collected from the Pearl River
Estuary. Response magnitude presented as percentage of the maximum response observed for 125 pg 2,3,7,8-tetrachlorodibenzo-p-dioxin standard
(%-TCDDmax).
C.N. Fung et al. / Marine Pollution Bulletin 50 (2005) 1036–1049
1045
Table 5
TCDD-like activities (presented as 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TCDD-EQs)) of acid treated sediment samples as determined by
in vitro bioassay
Sample location
TCDD-EQ1a
S1
S2
S3
S4
S5
S6
S7
S8
S9
S10
S11
S12
S13
S14
S15
S16
6.2
29.1
20.1a
39.7
28.6
13.2
28.8
18.8
14.1
68.3
22.6
305.4
122.0
47.7
185.5
3.0
TCDD-EQ20-80
TCDD-EQ50
2.2–0.1
27.2–24.3
0.4
21.7
42.8–54.5
19.5–5.7
12.2–9.7
27.2–22.7
18.1–16.3
12.8–9.6
71.9–84.4
8.3–2.2
328.7–414.6
50.1–17.6
16.0–0.5
258.5–737.1
1.3–0.1
48.3
10.7
10.9
24.8
17.2
11.1
77.9
4.3
369.1
29.7
2.8
436.5
0.3
Extrapolated region
<0.1b
<23.5b
<11.6b
<11.2b
<24.7b
<16.9b
<11.6b
<9.9b
<28.3b
<17.4b
<0.73b
TCDD-EQs are determined by the response equivalency approach at the level of response equivalent to 50% median effective concentration (EC50)
of the maximal response produced by the standard TCDDmax. The ranges of TCDD-EQs (in parentheses) are calculated from responses equivalent to
20% (EC20) and 80% (EC80) of TCDDmax.
a
TCDD-EQ was applied to the sample with a maximal response lower than the 20%-TCDDmax.
b
Some uncertainties of relative potency estimates existed due to extrapolation beyond the maxima of the measured %TCDDmax.
sediment (Table 5). These concentrations were about 20fold less to half of the guideline values suggested by the
Canadian Sediment Quality Guideline (CSQG) for the
protection of aquatic life (850 pg TEQ/g). Highest activities were observed in S15. Due to a difference in the efficacy between sample extracts and the TCDD standard
curve, values calculated for S1, S2, S5, S6, S7, S8, S9,
S11, S13, S14, S16 could only be considered as semiquantitative. The least TCDD-like activities were
recorded in S3, which had maximum responses <20%
TCDDmax compared to the TCDD standard.
4. Discussion
The quantification of POPs in sediments provides
several benefits which measurements performed in biota
and water cannot provide. First, from an analytical
point of view, it is much more convenient to carry out
chemical measurements in sediments than in biota and
water samples. For biota samples, it is necessary to
determine and clean up the lipids. For water samples,
large volumes of water need to be sampled, since the
concentrations of POPs in the water column are usually
very low. In contrast, the concentrations of POPs in sediments are usually much greater compared to those in
water due to differential partitioning of POPs into
sediments. Thus, only a small amount of sediment is required for chemical extraction and analysis. Second, the
analytical protocols for determining POPs in sediments
are comparatively less complicated, particularly in re-
gard to clean-up procedures. Third, the measurement
of POPs in sediments could reflect the status and trends
of local contamination over a relatively longer period of
time. Notwithstanding, environmental assessment based
on concentrations of POPs in sediments has a number of
limitations, which could be, at least in part, overcome/
supplemented by measurements in biota. For example,
sediment-based measurements may not accurately reflect bioavailability. Furthermore, contamination profiles and levels in sediments may not provide direct
answers to questions such as the likely impact of the
contaminants on ecological systems and/or human
health.
Maximum concentrations of HCHs, DDTs and PCBs
were all recorded in sediments from S10 (Xiashan). In
addition, levels of OC pesticide contamination (sum of
concentrations of all pesticide contaminants in Table 2
except HCHs and DDTs) in S10 were the most severe
compared to all the other stations. Sediments from
S10 also had the second greatest PHC concentrations.
These results indicate that trace organic contamination
at S10 was the most serious amongst all the sampling
locations.
Apart from S10, three other stations also had severe
contamination by POPs. Relatively high concentrations
of PHCs and HCHs were recorded in sediments from
S13. Large amounts of HCHs and PCBs were detected
in sediment samples collected from S12. Contamination
by OC pesticides, PAHs and DDTs was also serious in
sediments from S15. These three sampling locations,
therefore, may be ranked as the second most contaminated areas by POPs in the PRD.
1046
C.N. Fung et al. / Marine Pollution Bulletin 50 (2005) 1036–1049
Sediment samples from S2 and S7 contained large
amounts of PAHs but not other contaminants such as
OC pesticides and petroleum-related contaminants. Ratios of phenanthrene/anthracene (<15) and comparable
proportions of high molecular weight relative to low
molecular weight PAHs in samples from S2, S7 and
S15 implied that the sources of PAHs in these three
areas were mainly pyrolytic in nature.
Sediments at S1, S3 and S16 were comparatively free
of persistent organic contaminants. Small concentrations of PAHs, HCHs, DDTs, PCBs, and OC pesticides
were recorded in sediments from S1. The smallest concentrations of PAHs and DDTs were detected in S3,
while minimum concentrations of DDTs and OC pesticides were measured in S16. In general, S1 was the station with the lowest level of POP contamination
amongst all the sampling locations.
b-HCH contributed 28–96% of total HCHs in the
sediment samples from all stations. One possible reason
for its dominance might be due to its resistance to
biodegradation. Industrial HCHs contained high
proportions of the a-congener (65–70%), followed by
c-congener (12–14%), d-congener (6%) and b-congener
(5–6%). On the other hand, lindane contains mainly
the c-congener (>99%). a-HCH/c-HCH ratios of 4.64–
5.83 and 0 suggest the presence of industrial HCHs
and lindane, respectively (Iwata et al., 1995; Zhang et
al., 2003). Profiles of HCH contamination observed in
the present study did not concur with the above two scenarios, suggesting the occurrence of a mixture of industrial HCHs and Lindane in the PRD.
The proportions of DDT metabolites (pp-DDE and
pp-DDD) relative to the levels of total DDTs indicate
the extent of degradation of DDTs in sediments. The
presence of greater concentrations of DDTs relative to
their metabolites in sediment samples suggest a fresh
input of DDTs into the local environment. In the present
study, pp-DDE and pp-DDD accounted for a majority
(43–95%) of the total DDTs recorded in most of the sediment samples, implying an absence of fresh inputs.
Concentrations of DDE were comparatively greater
than those of DDD in most sediment samples collected
in this study. This finding is similar to that reported by
Zhang et al. (2003).
Concentrations of POPs recorded in the present study
were in general greater than those reported in previous
investigations (Table 1). Notwithstanding, concentrations
of PAHs (11 000 and 8400 ng/g) reported by Fu et al.
(2001) and Mai et al. (2001, 2003) were about two times
greater than those recorded in the present study. These results suggest that the levels of PAH contamination may
have declined over the period from 1997 to 1999 to the
present time. This may be attributed to the changing profiles of human activities in the PRD, but a more focused
investigation is needed to clarify this point. Alternatively,
differences in sampling sites may play a significant role.
Concentrations of PCBs in the PRD reported in the
past were relatively low, with the exception of one study
reporting relatively high concentrations (490 ng/g) in
1997 (Kang et al., 2000). The maximum PCB concentration (290 ng/g) recorded in the present study was still
smaller than that reported by Kang et al. (2000). Relatively high concentrations of PCBs, in general, tend to
indicate intensive industrial activities. Relatively high
concentrations of PCBs were recorded in sediments
from S10, S12 and S15, but not found in S7 and S8, located near the outlets of major rivers. This finding suggests that the sources of PCBs were probably not from
the upstream (catchment) areas, but were more likely
to be of a local origin.
Concentrations of HCHs and DDTs (maximum concentrations: 350 and 600 ng/g, respectively) recorded in
sediments in the present study were all several-fold
greater than those reported previously, except that the
concentrations of DDTs were smaller than levels
(1600 ng/g) reported in Fu et al. (2001). Since HCHs
and DDTs have been banned from use for several decades, their occurrence in the environment might reflect
past usage and/or redistribution of these chemicals between water and sediment in the upstream sites, which
were previously dominated by agriculture.
To examine the spatial pattern of trace organic contamination, a comparison was made with regard to the
concentrations of POPs between the eastern and western
shores of the PRD. The results indicated that for PAHs,
PHCs, HCHs, DDTs and PCBs, the most polluted sites,
such as S10, S12, S13, and S15, were all located along
the western coast. In contrast, sites, particularly S3, in
the eastern part of the PRD were generally less contaminated by POPs. Stations in Daya Bay (S1 and, to a certain extent, S2) were also characterized by relatively
small concentrations of POPs. Similar spatial patterns
have also been reported by Li et al. (2000, 2001). The
reason for such a pattern may be the southwestward
estuarine flow governed by Coriolis forces brings discharged contaminants from the northeast to the southwest regions (Luo et al., 2002; Mai et al., 2003).
Concentrations of various POPs measured in sediments from major rivers/estuaries in other parts of
China are provided in Table 6. Concentrations of PAHs
detected in the present investigation were comparable to
those reported for Hong Kong waters by Zheng and
Richardson (1999), but less than those reported in
Hangzhou city (Chen et al., 2004). PHC contamination
in the PRD was the least severe compared to other studies. Indeed, the high volume of river discharge in the
PRD could effectively disperse and prevent accumulation of petroleum-related compounds in the estuary. In
contrast, pollution due to PCBs, DDTs, and HCHs in
the PRD appeared to be relatively great compared to
other parts of China (Table 6). Overall, concentrations
of POPs in sediments in the PRD were greater than
C.N. Fung et al. / Marine Pollution Bulletin 50 (2005) 1036–1049
1047
Table 6
Concentrations of trace organic contaminants (ng/g) in sediments collected from different parts of China in comparison to those recorded in the
present study
Contaminants
Location
Year
Range (ng/g)
Reference
PAHs
Yalujiang Estuary, Jilin
Mingjiang, Fujian
Hong Kong Waters, Guangdong
Jiulongjiang, Fujian
Mingjiang, Fujian
Hangzhou city, Zhejiang
Xiamen Harbour, Fujian
Tonghui River, Beijing
Pearl River Estuary, Guangdong
1994, 1996
1996
1997
1999
1999
2002
2002
2002
2003
69–1500
175–817
7.25–4420
425–1522
112–877
132.7–7343
98–309
127–928
93.8–4307
Wu et al. (2003)
Yuan et al. (2001)
Zheng and Richardson (1999)
Yuan et al. (2001)
Zhang et al. (2004)
Chen et al. (2004)
Ou et al. (2004)
Zhang et al. (2004)
Present investigation
PCBs
Mingjiang, Fujian
Hong Kong Waters, Guangdong
Jiulongjiang, Fujian
Mingjiang, Fujian
Yangtze Estuary, Shanghai
Tonghui River, Beijing
Pearl River Estuary, Guangdong
1996
1997–1998
1999
1999
2001
2002
2003
4.69–7.27
ND–97.9
1.69–14.29
15.14–57.93
ND–18.95
0.78–8.47
6.01–287.67
Yuan et al. (2001)
Richardson and Zheng (1999)
Yuan et al. (2001)
Zhang et al. (2003)
Liu et al. (2003)
Zhang et al. (2004)
Present investigation
DDTs
Mingjiang, Fujian
Hong Kong Waters, Guangdong
Jiulongjiang, Fujian
Mingjiang, Fujian
Yangtze Estuary, Shanghai
Tonghui River, Beijing
Pearl River Estuary, Guangdong
1996
1997–1998
1999
1999
2001
2002
2003
6.17–63.88
0.27–14.8
8.61–73.70
1.57–13.06
ND–0.57
0.11–3.78
1.37–599.78
Yuan et al. (2001)
Richardson and Zheng (1999)
Yuan et al. (2001)
Zhang et al. (2003)
Liu et al. (2003)
Zhang et al. (2004)
Present investigation
HCHs
Hong Kong Waters, Guangdong
Mingjiang, Fujian
Tonghui River, Beijing
Pearl River Estuary, Guangdong
1997–1998
1999
2002
2003
0.1–16.7
2.99–16.21
0.06–0.38
11.95–352.62
Richardson and Zheng (1999)
Zhang et al. (2003)
Zhang et al. (2004)
Present investigation
PHCs
Hong Kong Waters, Guangdong
Hong Kong Waters, Guangdong
Xiamen Harbour, Fujian
Pearl River Estuary, Guangdong
1993
1997
2002
2003
116–1272
4.5–1996
133–943
13.6–145.9
Hong et al. (1995)
Zheng and Richardson (1999)
Ou et al. (2004)
Present investigation
ND = not detected.
All concentrations are expressed on dry weight basis.
those reported in previous studies. In some cases, local
sources appeared to be important in accounting for particularly high levels of contamination, e.g., at sampling
stations S10, S12, S13, and S15.
An assessment of potential environmental risks associated with POPs measured in the present study was
conducted and the results are summarized in Table 7.
Sediment quality values used in the calculation of risk
quotients included the Hong Kong Interim Sediment
Quality Value (HK-ISQV) and CSQG. Sediment quality
values are not available for certain POPs in the HKISQV and, in those cases, effects range-low (ERL) and
effects range-median (ERM) guideline values from the
US National Oceanic and Atmospheric Administration
(NOAA) were used [(http://response.restoration.noaa.
gov/cpr/sediment/squirt/squirt.html); Burton, 2002].
Only contaminants of which sediment quality values
are available were assessed in this study. Concentrations
of contaminants recorded in the sediment samples are
taken as the measured environmental concentrations
(MECs).
Interestingly, all the RQbcs estimated were below 0.1
and this might suggest that the pollutants under investigation pose little hazard to the ecosystem. For RQwcs,
anthracene had RQwcs < 1, based on both HK-ISQV
and CSQG. Similarly, the risk quotients for PCDD were
all below unity, even under the worst-case scenario.
These results indicate that the concentrations of these
chemicals in the sediments posed few risks to the local
aquatic system. For other contaminants, such as naphthalene, acenaphthylene, acenaphthene and benzo[a]pyrene, RQwcs < 1 only for one of the sediment
quality criteria (Table 7). Compounds with 1 5
RQwcs < 10 for both sediment quality criteria included
fluorene, phenanthrene fluoranthene, pyrene, chrysene,
and chlordane.
The RQwcs for DDT (and its metabolites), dieldrin,
and endrin were above 10, suggesting that these contaminants may be of concern to the integrity of the
PRD marine ecosystem. However, it is noted that the
risk quotients for these contaminants were all below
unity under the best-case scenario, so the ‘‘actual’’
1048
C.N. Fung et al. / Marine Pollution Bulletin 50 (2005) 1036–1049
Table 7
Estimated risk quotientsa (RQs) based on the concentrations of trace organic contaminants measured in the sediment samples (MECs), Hong Kong
Interim Sediment Quality Value (HK-ISQV) and the Canadian Sediment Quality Guidelines (CSQG)
Pollutants
MEC
HK-ISQVs (in ng/g)
CSQG (in ng/g)
Lower limit
Threshold
Probable
34.6
5.87
6.71
21.2
86.7
46.9
113
153
108
88.8
391
245
88.9
144
544
128
1494
1398
846
763
Naphthalene
Acenaphthylene
Acenaphthene
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Chrysene
Benzo[a]pyrene
<0.5–71.5
0.8–14.0
0.7–10.4
0.8–42.6
5.3–409.5
0.6–43.3
12.9–994.4
13.2–933.2
8.6–825.6
3.3–161.3
160
44
16
19
240
85.3
600
665
384
430
Total PAHs
Total PCBs
Total DDT
p,p 0 -DDD
p,p 0 -DDE
p,p 0 -DDT
53.2–4333.9
6.01–287.67
1.37–599.78
0.37–239.17
0.22–247.61
0.11–145.57
4022
22.7
1.58
2b
2.2
1b
Chlordane
Dieldrin
Endrin
HE
PCDD/Fs
<0.05–4.04
0.14–214.65
<0.05–39.50
<0.05–5.60
0.0003–0.4365
0.5b
0.02b
0.02b
/
/
Upper limit
2100
640
500
540
1500
1100
5100
2600
2800
1600
0.1 < RQwcs < 1
1 < RQwcs < 10
•
•
•
•
•
RQwcs > 10
•
•
•
•
•
44792
180b
46.1b
20b
27b
7b
/
21.5
3.89
1.22
2.07
1.19
/
189
51.7
7.81
374
4.77
6b
8b
8b
/
/
2.26
0.71
2.67
0.6
0.85
4.79
4.3
62.4
2.74
21.5
•
•
•
•
•
•
•
•
•
•
Only worst-case RQs (RQwcs) are shown. All best-case RQs were < 0.1.
a
Risk quotients were calculated based mainly on two sediment quality criteria ( = HK-ISQV; • = CSQG).
b
Effects range-low (ERL) and effects range-median (ERM) guideline values from the US National Oceanic and Atmospheric Administration
(NOAA) [(http://response.restoration.noaa.gov/cpr/sediment/squirt/squirt.html); Burton, 2002] were used as the corresponding HK-ISQVs were not
available.
risks posed by these chemicals should be further
investigated.
It is noteworthy that the CSQG is, in general, more
stringent than the HK-ISQV. The question here is which
criteria should be adopted in China or, more specifically,
in the PRD. Indeed, it might be more desirable to derive
system-specific criteria for the region. In the absence of
criteria specific to the PRD, the approach adopted in
this study involved using both the CSQG and the HKISQV to assess risks under the best- and worst-case scenarios. This type of preliminary assessment provides a
simple and useful means of screening pollutants of concern, and assists in prioritizing management efforts. This
procedure also allows a more refined assessment to proceed when more information becomes available in the
future.
Acknowledgement
This study was supported by a Central Allocation
Grant (8730020) awarded by the Research Grants
Council, Hong Kong, and the Area of Excellence
Scheme under the University Grants Committee of the
Hong Kong Special Administration Region, China
(Project no. AoE/P-04/2004).
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