Dissolved and particulate trace metals in a Scottish sea loch: an example of a pristine environment?

In the near pristine environment of a silled fjord on the west coast of Scotland samples were taken for the determination of dissolved and particulate trace metals (Fe, Mn, Cu, Ni, Cd, Zn and Pb), together with nutrient and hydrographic data, during 19 surveys carried out over a year. An indication of the pristine nature of the environment are the low concentrations of dissolved silicon, phosphate and nitrate which are considerably lower than those of coastal waters which are subject to larger anthropogenic burdens. Distributions of dissolved Cu, Ni and Cd were found to broadly reflect conservative mixing of freshwater and seawater with both end members having similar concentrations. The concentration of dissolved Cu and Ni in seawater entering upper Loch Linnhe (Cu 0.28 μg l⁻¹; Ni 0.26 μg l⁻¹) was consistent with the 1:1 conservative mix of Irish Sea water and North Atlantic surface water predicted from radio-caesium tracer experiments (Mackay & Baxter, 1985). Atmospheric input of trace metals to upper Loch Linnhe appeared to be a relatively minor term in the mass balance relative to fluvial inputs. Values of distribution coefficients Kd were similar to those previously reported for the coastal environment. Iron showed the strongest affinity for the suspended sediments; with particulate percentages of the total load usually greater than 80%. Lead and Mn showed a similar strong affinity to the particle phase. For Cu, Ni and Zn the mass of the element in the dissolved phase was generally greater than that in the particulate fraction. Cadmium, was least associated with the particles, with typically greater than 90% existing in the dissolved phase.     

Effects of Animal Size on Concentrations of Metallothionein and Metals in Periwinkles Littorina littorea Collected from the Firth of Clyde, Scotland

Different sizes of Littorina littorea were collected from four areas in the Firth of Clyde, Scotland. Their metallothionein (MT) and heavy metal concentrations were analysed using the Silver Saturation Method and Atomic Absorption Spectrophotometry, respectively. Concentrations of MT, Cd and Zn (as μg g⁻¹ dry soft-body weight) generally decreased with an increase in size of L. littorea. MT concentrations were better correlated with Cd than with Zn or Cu concentrations. Nevertheless, MT and the metals in periwinkles (as μg individual⁻¹) increased significantly with increasing size. Concentrations of MT and the metals among the sampling areas were compared at a standardised soft-body weight (10 mg). The results from Discriminant Analysis based on all metal concentrations indicate that Largs is different from the other areas and characterised by high Fe concentrations in L. littorea. The problems and differences in using either soft-body weight or shell length as independent variable for size-standardisation are discussed.     

PAH contamination of western Irish Sea sediments

Concentrations of the sum of 15 PAHs in 22 surficial sediment samples from the western Irish Sea ranged from below 100 ng g⁻¹ in sandy sediments to a maximum of 1422 ng g⁻¹ in the centre of the mud basin. The concentrations are typical of coastal shelf sediments, but greater than those observed for aquatic sediments remote from known anthropogenic sources. Organic C and the % sediment <15 μm were positively correlated with ΣPAH. ΣPAH was normalised to organic C and particle size (i.e. expressed as ΣPAH/C^org and ΣPAH/%<15 μm) and significant relationships were still observed with organic C and %<15 μm. The results are discussed in the context of using organic C to normalise concentrations of PAHs to assess contamination levels in sediments.     

The potential role of mucus in the depuration of copper from the mussels Perna viridis (L.) and Septifer virgatus (Wiegmann)

Experiments were conducted to measure the mucus secretion rate in two common mussels in Hong Kong, Perna viridis (L.) and Septifer virgatus (Wiegmann), when chronically exposed to Cu (50 μg l⁻¹). After a 3-month exposure period, the mucus production rate of P. viridis at 25°C in the metal treatment was 2.65 times that of the control (10.7 vs 4.0 mg g⁻¹ dry wt h⁻¹), while S. virgatus showed a 1.85 times difference (4.41 vs 2.38 mg g⁻¹ dry wt h⁻¹). Mucus secretion by P. viridis under acute Cu exposure (0.5 mg l⁻¹) was significantly higher in the metal treatment than the control (13.43 vs 9.16 mg g⁻¹ dry flesh wt). Metal contents of the mucus secreted was about 18 times those in the control and 6 times in the soft tissues. Therefore, mucus appears to be an effective agent for Cu depuration in the mussel. The significance of these results to the local distribution and abundance of the mussels is discussed.     

Concentrations of Cd, Pb, Zn and Cu in contaminated wetlands of the Russian Arctic

The spatial distribution of the concentrations of heavy metals Cd, Pb, Zn and Cu were studied for contaminated wetlands located by industrial centres and villages influenced by anthropogenic contamination in the Russian Arctic. For comparison, non-contaminated wetlands were also studied in neighbouring areas. Samples were collected during the period 1977–1994 and included: (a) water, (b) particulate matter, (c) bottom sediments, (d) hydric soils and (e) hummock bog peat and polygonal bog peat. For impacted wetlands, the observed ranges for the concentrations of Cd, Pb, Zn, and Cu in water were 0.12–0.8, 0.9–2.5, 2.4–15 and 16–34 μg l⁻¹, respectively. For (b)- (e) the corresponding values were [1.2–5.4; 24–37; 120–320; 80–116]; [6.4–17; 34–59; 240–570; 115–280]; [10–32; 57–78; 315–480; 87–350] and [5.1–53; 51–150; 125–520; 80–440] mg/kg, dry wt, respectively. The metal concentrations were up to 1000 times higher than background levels determined for non-contaminated wetlands in the Russian Arctic. The contaminants appear to be a direct result of localized anthropogenic activity, arising primarily from geoprospecting, the oil and coal industry, and domestic waste.     

Tin and organotin in water, sediments, and benthic organisms of Poole Harbour

Tributyltin (TBT) concentrations in waters of Poole Harbour ranged between 2–139 ng l⁻¹ (as Sn) and increased to 234–646 ng l⁻¹ within marinas. Seasonal trends in contamination coincided with boat usage patterns and peaked during summer months. A combination of poor tidal flushing and removal of TBT to particulates restricts high levels of contamination to areas closest to marinas and moorings; TBT concentrations in benthic sediments decreased from 0.52 μg g⁻¹ near such sites to 0.02 μg g⁻¹ at the harbour mouth. Organotin accumulations in several benthic invertebrates including polychaetes (Nereis diversicolor), snails (Littorina littorea) and clams (Scrobicularia plana, Mya arenaria) reflect the distribution of contamination in the environment, though concentration factors (relative to water) vary considerably between species and were highest in sediment dwelling clams, notably Mya (1.3×10⁵). Compared to organotins, biological availability of inorganic tin is low.

Levels of TBT in parts of Poole Harbour exceed Environmental Quality Targets designed to protect marine life and may be responsible for poor recruitment, particularly in bivalves, at heavily contaminated sites.     

Cadmium content, accumulation and toxicity in dog whelks collected around the Welsh coastline

The concentration of cadmium in sexually mature Nucella lapillus was investigated around the coast of Wales. Higher concentrations of cadmium were found in whelks located in the Bristol Channel compared with Cardigan Bay Nucella. Accumulation and toxicity of cadmium were investigated at 50–600 μg Cd l⁻¹ over a period of 21 days. At the lower concentrations of 50–100 μg Cd l⁻¹ all Nucella survived the 21 days of experimentation. The rate of cadmium uptake after exposure to cadmium was inconsistent and not related to the degree of site contamination. At all sites the concentration of cadmium in Nucella, after treatment with 50–600 μg Cd l⁻¹ for 21 days, was significantly different from controls, but after 7 days it varied with the site and cadmium concentration. Only samples collected at Fishguard, Dale, and Swansea survived 21 days at 600 μg Cd l⁻¹. Tissue cadmium concentrations did not significantly effect the whole body concentration of zinc.     

A case study on fuel oil contamination in a mangrove swamp in Hong Kong

Mangroves commonly found along tropical and subtropical coastlines are susceptible to oil pollution. In December 2000, around 500 1 m tall Kandelia candel saplings at the age of 3–5 years old located at the foreshore region of Sheung Pak Nai swamp, Hong Kong SAR, were found to be damaged by oil pollution. More than 80% of the saplings were either dead or washed away and leaving less than 5% healthy saplings with dense green leaves. Elevated concentrations of light n-alkanes (ranging from n-C₁₄ to n-C₂₀), pristane and phytane were recorded in surface sediments collected in December 2000. The ratio between light and total n-alkanes was 0.4. The total petroleum hydrocarbons (60–80 μg g⁻¹ TPH) and unresolved complex mixtures (60–70 μg g⁻¹ UCM) were higher than the background values of other mangrove sediments in Hong Kong, which were 40 and 20 μg g⁻¹, respectively. In certain root zone sediments, TPH concentrations were above 1000 μg g⁻¹. These results suggest that surface sediments in Sheung Pak Nai were contaminated by petroleum oil, most likely by illegal discharge of fuel oil which occurred between 1998 and 2002. One year later, in December 2001, unhealthy saplings had recovered and re-grown. The concentrations of TPH and UCM in sediments declined to around 40 μg g⁻¹, pristane and phytane dropped by 80%, and the ratio of light to total n-alkanes was 0.15, suggesting that residual oil in sediments was weathered leading to a remarkable recovery of the unhealthy saplings.     

The toxicity of marine sediments in Victoria Harbour, Hong Kong

When the toxicity of marine sediment in Hong Kong was evaluated, it was found that the seven sediments collected within Victoria Harbour were severely contaminated with heavy metals, at concentrations many times higher than those in sediments collected from outside the harbour. The highest metal content was recorded in site VS14 (located near the airport runway and the industrialized area), with copper, zinc, lead and chromium values of 3789, 610, 138 and 601 mg kg⁻¹ dry wt, respectively. This site also had the greatest alkaline phosphatase activities (15 fluorescent intensity unit g⁻¹ wet wt), the largest number of total coliforms (910 CFU g⁻¹ wet wt) and sulphate-reducing bacteria (8.5 × 10⁴ cells g⁻¹ wet wt), implying that site VS14 was also contaminated with organic matter and nutrients. Sediment bioassays, Microtox and algal tests, demonstrated that sediment elutriates obtained from site VS14 were of greatest toxicity. The EC₁₀ value in Microtox tests was 17% elutriate, and the 96-h IC₅₀ values using Skeletonema costatum and Dunaliella tertiolecta were 40 and 79% elutriate, respectively. No toxic effects were found in sediment samples collected from the control site outside Victoria Harbour. Significant correlations were found between the results of the algal toxicity test (using S. costatum) and the coliform count and metal content of the sediments. The Microtox test was less sensitive than the algal bioassay, and no sediment elutriate, even from the site mostly contaminated by heavy metals, caused more than 50% inhibition of the light-emitting activity of the bacteria. In this study, S. costatum (the diatom) provided a more sensitive and reliable test species than D. tertiolecta (the flagellate) in differentiating the toxicity of marine sediments.     

Accumulation of butyltins in muscle tissue of chinook salmon reared in sea pens treated with tri-n-butyltin

Muscle tissue of chinook salmon, Oncorhyncus tshawytscha, reared for 3 to 19 months in sea pens treated with an antifouling biocide, tri-n-butyltin (TBT), contained organotin concentrations of 0.28–0.90 μg g⁻¹ (as TBT). Organotins are present in some pen-reared salmon sold in the United States: eleven of 15 salmon advertised as aquaculture products and purchased from public markets contained organotin concentrations of 0.081–0.20 μg g⁻¹. Most common cooking practices do not effectively destroy or remove butyltins from salmon muscle tissue. We believe this is the first evidence of entry of organotins into the human diet in the United States.     

Mathematical modeling of PCB bioaccumulation in Perna viridis

In the present work, we built a mathematical model of polychlorinated biphenyl (PCB) bioaccumulation in Perna viridis, namely, a one-compartment model with a time dependent incorporation rate R (μg g⁻¹ lipid per ppb water per day), with positive substrate cooperativity as the underlying physical mechanism. The temporal change of the PCB concentration Q (μg g⁻¹ lipid) in the soft tissues of the mussel depends on the competition of the input rate RW and the output rate kQ, where W is the concentration of PCB in water (ppb water) and k is the elimination rate (per day). From our experimental data, k=0.181±0.017 d⁻¹. The critical concentration in water W_c for positive substrate cooperativity was found to be 2.4 ppb. Below W_c, R is a constant. For a water concentration of 0.5 ppb Aroclor 1254, R=24.0±2.4 μg g⁻¹ lipid ppb⁻¹ d⁻¹. Above W_c, positive substrate cooperativity comes into effect and R becomes a function of time and dependent on the concentration Q in a form R=γQ/(Q+δ). This is the case for a water concentration of 5 ppb Aroclor 1254, where γ=15.1 μg g⁻¹ lipid ppb⁻¹ d¹ and δ≈200 μg g⁻¹ lipid. From this model, the uptake is exponentially increasing when the PCB concentration in the mussel is small compared to 200 μg g⁻¹ lipid, and hyperbolically increasing when the concentration is large compared to 200 μg g⁻¹ lipid, which are consistent with the experimental data. The model is useful for understanding the true processes taking place during the bioaccumulation and for risk assessment with higher confidence. Future experimental data which challenge the present model are anticipated and in fact desirable for improvement and perfection of the model.     

Trace metal distributions in Saint John Harbour sediments

The concentration and areal distribution of selected trace metals (Cu, Zn, Pb, Cd, Mo, Ni, Mn and Hg) in surficial sediments of Saint John Harbour, New Brunswick, Canada, were studied to determine the extent of anthropogenic input and to estimate the effects of dumping dredged material in the outer harbour. Hg and Cd are of especial concern, since the disposal of dredge material containing these two elements is regulated under the Ocean Dumping Control Act.The concentrations of all metals are low: Cu 16, Zn 53, Pb 24, Cd 0.16, Mo 3, Ni 16, Mn 296 and Hg 0.04 μg g^?1. Hg and Cd levels in sediments are well below the permissible limits of 0.75 and 0.6 μg g^?1, respectively, set by the Ocean Dumping Control Act.The mean concentrations of trace elements are similar to the low mean values in the unpolluted Bay of Fundy. There is an overall decline in concentrations of metals in the sediments from the inner to the outer harbour. Comparison of the metal levels in the sediments from different areas within the harbour indicate that there is a detectable anthropogenic input in the Courtenay Bay area. Trace metal levels at the dumpsite are significantly lower than in the Courtenay Bay area, where the bulk of the dredged material originates.     

Effects of copper exposure on the scope for growth of the clam Ruditapes decussatus from southern Portugal

The clam Ruditapes decussatus L. was collected from Ria Formosa, Faro, southern Portugal, and exposed to a sublethal copper concentration of 0.01 mg l⁻¹ for 20 days. Physiological measurements, respiration rates, clearance rates and absorption efficiency, were undertaken initially and after 2, 5, 9, 14 and 20 days and used to calculate Scope for Growth. Copper accumulation rate was calculated through the analysis of copper in the tissues at the same sampling times. The experiment showed two phases. Initially, copper was rapidly accumulated (1.95 μg Cu g⁻¹ dw day⁻¹ in the first 48 h), clearance rates declined markedly (lowest value 13.5% of control) and respiration rates increased (116% of control), resulting in a rapid decline of Scope for Growth, which showed a negative value after 5 days. In the second phase, (from day 9 on), the rate of copper uptake declined to 0.55 μg Cu g⁻¹ day⁻¹ and physiological responses were more stable. After 20 days, copper concentration in the tissues was 38.4 μg Cu g⁻¹ dw (bioconcentration factor 3840). Clearance rates were 50% of control rates and respiration rates were still high, 145% of control rates. Therefore, Scope for Growth and performance of the clams was still greatly affected (ca. 23% of the control values), indicating that though animals partially recovered through detoxifying mechanisms, excess copper caused sustained impairment of physiological functions. This experiment confirms that the physiological energetics approach and the integrated Scope for Growth measurement is a sensitive methodology to detect deviations from normal performance and assess stress at environmental realistic copper concentrations.     

Concentration of 7 Heavy Metals in Sediments and Mangrove Root Samples from Mai Po, Hong Kong

Concentration of 7 heavy metals, Zn, Fe, Cu, Cr, Cd, Pb and Ni in mudflat sediments, mangrove root sediments and root tissues of Acanthus ilicifolius, Aegicerus corniculatum and Kandelia candel from the Mai Po Nature Reserve, Northwest Hong Kong, were measured. Metal concentrations in the upper 0–10 cm of the sediment cores from the mudflat were 4–25% higher than those found in the bottom 21–30 cm. Relative Topsoil Enrichment Index approximated 1.0 for all the metals. Mudflat sediment concentrations of Fe, Ni, Cr, Cd and Cu were greater than those found in the mangrove sediments. Except for Fe, concentrations of the other 6 heavy metals were more elevated in the mangrove root sediments than in the corresponding root samples. Higher concentration factors for Zn, Fe and Cu may indicate bioaccumulation. Mean metal concentrations in both mudflat and mangrove sediments decreased in the order Fe > Zn > Pb > Ni > Cu > Cr > Cd. Mangrove root tissues also showed the same pattern except that Pb > Cu > Ni     

Evaluation of sediment contamination in the Red Sea coastal area combining multiple pollution indices and multivariate statistical techniques

In the recent years,the Red Sea coast of Yemen has been severely affected by intensive anthropogenic activities.The current study constitutes a thorough inquiry to evaluate the extent of heavy metals pollution in Yemen's Red Sea coast sediment and identifies the possible sources of pollution.The concentrations of five metals(copper(Cu),zinc(Zn),cadmium(Cd),lead(Pb),and nickel(Ni))collected from nine sites along the Red Sea coast of Yemen were assessed using an atomic absorption spectrophotometer(ASS).Sediment quality indices,such as the sediment quality guidelines(SQGs),potential ecological risk(RI),contamination factor(CF),pollution load index(PLI),geoaccumulation index(Igeo),and modified degree of contamination(mCd)were computed.In addition,multivariate statistical techniques(principal component analysis(PCA),hierarchical cluster analysis,and Pearson's correlation analysis)were applied to identify the potential sources of metals.The mean concentrations of Cu,Zn,Cd,Pb,and Ni were 51.3,61.9,4.02,9.9,and 33.4 mg/kg dry wt,respectively.The spatial distribution revealed that the metals concentrations were high at the middle zone and low southward of Hodeida city.According to the SQGs,the adverse biological effects of metals were occasionally associated with Cu and Cd,frequently associated with Ni,and not expected to occur with Zn and Pb.The RI indicated that the sediment of the studied sites pose low(RI<50)to considerable(100≤RI<200)ecological risk.The mean effect range-median quotient(M-ERM-Q)indicated that the combination of the studied metals had the toxicity probability of 21%at all studied sites.Igeo and CF indicated that the metals concentrations were in the descending order of:Zn>Ni>Pb>Cd>Cu,whereas the PLI and mCd indicated that Ras Isa(Site 5)and Urj village(Site 6)were the most polluted sites.PCA,cluster analysis,and correlation analysis found that Cd,Pb,and Ni mostly originated from anthropogenic sources while Cu and Zn were mainly derived from natural sources.Thus,it is evident that the intensive anthropogenic activities had negative influence on metals accumulation in the sediment of the Red Sea coast of Yemen leading to detrimental effects to the whole ecosystem.These comprehensive findings provide valuable information and data for future monitoring studies regarding heavy metals pollution and sediment quality at the Red Sea coast of Yemen.     

Seasonal studies on cadmium concentration and toxicity, oxygen consumption, digestive gland glycogen, and lipid in dog whelks collected at Aberystwyth, Wales

The concentration of cadmium in Nucella was investigated at different times of the year at one site. There was no significant difference in tissue cadmium at the times of the year investigated but tissue zinc was more variable. Accumulation and toxicity of cadmium were studied using 50–600 μg Cd l⁻¹ for 21 days. There was no significant seasonal difference in the rate of cadmium uptake but mortality appeared to vary with the season. Nucella did not survive 21 days at 600 μg Cd l⁻¹, but at lower concentrations 50–100 μg Cd l⁻¹ all survived.

Although there was significant drop in oxygen consumption between 7 and 14 days it did not appear to be related to the cadmium exposure. Glycogen levels on the other hand showed a decrease after cadmium treatment, while lipid values remained unchanged. Results are discussed in relation to energy source, season, and adaptation to the environment.     

Concentrations of Cd, Pb, Zn and Cu in pristine wetlands of the Russian Arctic

Background concentrations of Cd, Pb, Zn and Cu were studied for wetlands from pristine regions of the Russian Arctic: Severnaya Zemlya Archipelago, Vrangel Island, Arctic deserts and tundra of the North Taimyr Peninsula, Byrranga Mountainous Area, tundra zone of Mid-Siberia, North-East Siberia, Far North-East, and Amguemo-Anadyr Mountainous Area. These wetland regions were known to be relatively remote and isolated, with little human population and no local industry. Samples were collected during the period 1976–1993 and included: (a) snow and thaw water, (b) particulate matter, (c) bottom sediments, (d) hydric organo-mineral deposits and hydric soils, (e) polygonal bog peat and sedge-moss peat. Observed ranges for the background concentrations of Cd, Pb, Zn, and Cu in water were 0.001–0.15, 0.02–0.36, 0.05–2.9 and 0.23–6.2 μg l⁻¹ respectively. For (b)–(e) the corresponding values were [0.04–0.46; 1.3–41; 8.6–190; 0.7–63]; [0.05 0.99; 1.5–49; 2.5–153; 2.4–55]; [0.05–0.96; 1.7–44; 2.2–154; 2.0–82] and [0.03–0.83; 1.3–31; 2.1–124; 1.7–68] mg kg⁻¹, dry wt, respectively. Although full assessment of the pristine nature of the wetlands was not possible due to the limited data available, the observed metal concentrations reflect natural geochemical background levels and influence from localized minor ore-deposits present for some regions. In general, there was no evidence of impact from remote industrial regions of the Russian Arctic.     

Hydrocarbon and coprostanol levels in seawater, sea-ice algae and sediments near Davis station in eastern Antarctica: A regional survey and preliminary results for a field fuel spill experiment

A survey of hydrocarbons and the sterol coprostanol, together with a hydrocarbon degradation experiment, was conducted in a coastal marine environment in East Antarctica. Aliphatic hydrocarbon levels in sea-ice algae were 1.9–12.5 mg m⁻² and in seawater particulate matter 0.07–0.17 μg l⁻¹. Sea-ice algae contained the diatom biomarker, the highly branched isoprenoid (ip) diene ipC_25:2, and Southern Ocean seawater particulate matter samples were distinguished from near shore samples by the presence of nC_21:6. Sea-ice algae and seawater particulate matter samples showed a predominance of even chain n-alkanes. Hydrocarbon levels in sediment samples from anoxic fjord basins were high (45–48 μg g⁻¹) compared to a sub-tidal marine sample (0.7 μg g⁻¹), and were predominantly of bacterial origin. Contaminants detected were linear alkyl benzenes in sewage effluent from Davis station, and polycyclic aromatic hydrocarbons (PAH) which were present in very low levels (parts per trillion) throughout the environment. High levels of 2,6-dimethylnaphthalene were found in anoxic sediment from Ellis Fjord and may arise from a novel bacterial source. Coprostanol concentrations in sediments ranged from 67 to 1280 ng g⁻¹. A dual origin is proposed from marine mammalian faeces and, at several sites, from conversion of algal-derived sterols by anaerobic bacteria. Future studies examining the impact of human sewage from scientific bases or other ventures should use care in interpreting results when such high baseline values, from marine mammalian input, may occur naturally around the Antarctic coast. The potential exists, however, for the technique to distinguish between human and mammalian inputs through measurement of the coprostanol to epicoprostanol ratio, particularly if undertaken with appropriate comparative sampling. Results for a hydrocarbon degradation experiment where a light fuel was applied to an Antarctic beach, showed loss of up to 99% of the fuel within 2 months, mainly by volatilization.     

Dissolved trace metal distributions in Port Jackson estuary (Sydney Harbour), Australia

Concentrations of dissolved metals (Cd, Cu, Ni, Mn and Zn) were determined for summer and winter, under low-flow conditions in Port Jackson, a microtidal, well-mixed estuary in south-east Australia. Mean concentrations of Cd (0.04+/-0.02 microg/l), Ni (0.86+/-0.40 microg/l), Mn (20.0+/-25 microg/l) and Zn (6.47+/-2.0 microg/l) were below water quality guidelines. Concentrations of Cu (1.68+/-0.37 microg/l), however, slightly exceeded recommended values. Dissolved Ni and Mn behaved mostly conservatively, whereas Cd, Cu and Zn showed mid-estuarine maxima. Peaks in Cd, Cu and Zn concentrations were located in the upper estuary, independent of the salinity and suspended particulate matter loading, and were consistent with anthropogenic inputs of metals in the estuary. Concentrations of dissolved Cu were highest in summer, whereas concentrations of Cd, Ni and Mn were significantly lower in summer than winter (P< or =0.05). The increase in temperature and biological activity during summer explained the seasonal variation. The sequence of log K(d) values (20-30 salinity) was Mn>Zn>Cu>Ni. These results give unique information concerning the contemporaneous distribution of dissolved trace metals in the Port Jackson estuary and they provide a data set against which the long-term contamination may be assessed.     

Residue levels of HCHs,DDTs and PCBs in shellfish from coastal areas of east Xiamen Island and Minjiang Estuary,China

Shellfish samples were collected from the coastal cultivating areas of east Xiamen Island and Minjing Estuary, China and analyzed for hexachlorocyclohexanes (HCHs), DDTs and polychlorinated biphenyls (PCBs) by GC. Concentration ranges of HCHs, DDTs and PCBs in the coastal area of east Xiamen Island were 0.18–345, 75.2–2143 and ND-23 ng g⁻¹ dry wt., respectively; those for Minjiang Estuary were ND-5.07, 21.5–2396 and ND-6.78 ng g⁻¹ dry wt., respectively. The results showed that the organochlorines were evidently accumulated in marine bivalve molluscs, particularly in oyster. The concentrations of organocholorine pollutants in shellfish samples varied with the sampling locations, the season of collection and organism species, but were generally higher than those in the sediments. The concentrations of DDTs in the shellfish were high as compared with HCHs and PCBs, so that DDTs can be considered as the typical organochlorines in the survey areas. The residue levels and compositions of HCHs, DDTs and PCBs are discussed.