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1.
The impact and recovery from exposure to the herbicide diuron [DCMU; 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea] was assessed for three tropical seagrasses, maintained in outdoor aquaria over a 10-day period. Photosynthetic stress was detected using chlorophyll a fluorescence, measured with a Diving-PAM (pulse amplitude modulated fluorometer). Exposure to 10 and 100 μg l−1 diuron resulted in a decline in effective quantum yield (ΔF/Fm′) within 2 h of herbicide exposure in Cymodocea serrulata, Halophila ovalis and Zostera capricorni. Effective quantum yield also declined over the first 24 h of exposure in H. ovalis at even lower diuron concentrations (0.1 and 1.0 μg l−1). Effective quantum yield in H. ovalis and Z. capricorni was significantly depressed at all diuron concentrations (0.1–100 μg l−1) after 5 days exposure, whereas effective quantum yield in C. serrulata was only significantly lower in plants exposed to highest diuron concentrations (10 and 100 μg l−1). Effective quantum yield depression was present 5 days after plants exposed to 10 and 100 μg l−1 diuron were returned to fresh seawater. These results indicate that exposure to herbicide concentrations present in nearshore Queensland sediments present a potential risk to seagrass functioning.  相似文献   

2.
Variations in some physical, chemical, and nutrient conditions were investigated at Turkwel Gorge Reservoir and its inflowing river, Suam between 1994 and 1995. Seasonal changes in inflow volume had the greatest impact on the reservoir and river conditions investigated. A wide fluctuation in inflow volume combined with a regulated outflow independent of season resulted in a draw down of over 10 m in each year. Flood inflows during the wet season resulted in the lowest values of Secchi depth (range, 0.09–2.16 m), electrical conductivity (EC, range = 140–200 mS cm−1) and total alkalinity (TA, range = 75–111 mg l−1) while the highest values were measured during the dry season. A functional relation between EC and TA (TA = 0.529 mg l−1, EC: R2 = 0.876) suggests a predominance of carbonates among the anions. Vertical profiles of temperature and dissolved oxygen (DO) revealed that the reservoir is monomictic with a wide variation in the depth of the daily mixed layer. High values of pH (range = 6.7–8.9) and DO (range = 4.9–9.2 mg l−1) were associated with periods of peak phytoplankton photosynthesis while the lowest values followed reservoir mixing. Peak total nitrogen (TN, range = 119–526 μg l−1) and total phosphorus (TP, range = 8.9–71.6 μg l−1) levels during the wet season resulted from increased river loading. Values of dissolved reactive silica (DRS, range = 0.41–9.77 mg l−1) showed a wet season decline which was related to diatom depletion during the wet season. Annual reservoir areal loading rates of 27.38, 10.90 and 408.5 mg m−2 were computed for TN, TP and DRS respectively based on estimates of inflowing river loads in 1994.

At the inflowing river Suam, low levels of EC (range = 107–210 μS cm−1) and TA (range = 62–125 mg l−1) occurred during the wet season while the highest levels occurred shortly before the river dried up. The first flood water at the resumption of river inflow in March was characterized by very low levels of DO (range = 1.8–8.2 mg l−1) and high levels of TN (range = 205–3354 μg l−1) and TP (102–1259 μg l−1). River pII (6.9–7.7) and DRs (range = 9.01–19.93 mg l−1) varied irregularly throughout the year.  相似文献   


3.
S. V. Panno  W. R. Kelly   《Journal of Hydrology》2004,290(3-4):229-242
This investigation was designed to estimate the mass loading of nitrate (NO3−) and herbicides in spring water discharging from groundwater basins in an agriculturally dominated, mantled karst terrain. The loading was normalized to land use and NO3− and herbicide losses were compared to estimated losses in other agricultural areas of the Midwestern USA. Our study area consisted of two large karst springs that drain two adjoining groundwater basins (total area of 37.7 km2) in southwestern Illinois' sinkhole plain, USA. The springs and stream that they form were monitored for almost 2 years. Nitrate–nitrogen (NO3–N) concentrations at three monitoring sites were almost always above the background concentration (1.9 mg/l). NO3–N concentrations at the two springs ranged from 1.08 to 6.08 with a median concentration of 3.61 mg/l. Atrazine and alachlor concentrations ranged from <0.01 to 34 μg/l and <0.01 to 0.98 μg/l, respectively, with median concentrations of 0.48 and 0.12 μg/l, respectively. Approximately 100,000 kg/yr of NO3–N, 39 kg/yr of atrazine, and 2.8 kg/yr of alachlor were discharged from the two springs. Slightly more than half of the discharged NO3− came from background sources and most of the remainder probably came from fertilizer. This represents a 21–31% loss of fertilizer N from the groundwater basins. The pesticide losses were 3.8–5.8% of the applied atrazine, and 0.05–0.08% of the applied alachlor. The loss of atrazine adsorbed to the suspended solid fraction was about 2 kg/yr, only about 5% of the total mass of atrazine discharged from the springs.  相似文献   

4.
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.  相似文献   

5.
Shrimp larvae (Penaeus vannamei) collected from an uncontaminated area were challenged with sublethal concentrations of organochlorine pesticides. The effects of treatment with lindane, lorsban, chlordane and DDT, were a 5, −12, 13 and 21% increase in the larval respiratory rate, respectively. Glycogen synthesis decreased from the 0.471 μg g−1 h−1 of the control, to 0.455, 0.415, 0.400 and 0.365 μg g−1 h−1, for larvae submitted to DDT, chlordane, lindane and lorsban. In addition, we measured decreases in nucleic acid content, from 20.4 and 34.9% in larvae challenged by chlordane and lorsban, respectively, and values close to 25% for two other pesticides tested. These results indicate drastic metabolic changes, which may impinge on the commercial fishery and culture of this organisms.  相似文献   

6.
Organochlorines in Hong Kong Fish   总被引：6，自引：0，他引：6  
Muscle samples from 15 species of fish (n=1) purchased from markets in Hong Kong and 10 liver samples of tilapia (Tilapia mossambica) collected from the Shing Mun River were analysed for organochlorines (polychlorinated biphenyls, ΣDDTs, hexachlorobenzene, hexachlorocyclohexanes, chlordanes, mirex and dieldrin). Polychlorinated biphenyls (PCBs) were detected in 15 market fish samples but the levels were very low (around 1 ng g−1). PCB levels in tilapia livers collected from Tai Wai (29.3–65.1 ng g−1) were higher than those from Fo Tan (3.5–23.2 ng g−1) suggesting that there may be some local point soucres. ΣDDTs were detected in all samples, ranging from 3.3 to 75.6 ng g−1 in the market fish and from 7.1 to 88.8 ng g−1 in tilapia. The DDE/DDT ratios in the market fish (0.12–0.75) showed higher variability than those of tilapia (0.30–0.46), suggesting that some of the market fish may have been collected from areas where DDT was recently used. Results of this preliminary study show that organochlorine levels in Hong Kong market fish are low and do not cause any concern for human consumption. An on-going monitoring program, however, is recommended.  相似文献   

7.
This study examined the effect of copper on the settlement success of planula larvae of the reef-building coral Acropora tenuis during 1994 and 1996 at Magnetic Island, Great Barrier Reef. Copper concentrations of 2, 10, 20 μg l−1 did not inhibit larval settlement after 48-h exposure. However, copper concentrations of 42 μg l−1 and 81 μg l−1 significantly reduced settlement success of A. tenuis larvae after 48-h exposure compared with controls using normal seawater. At 200 μg l−1 copper, all larvae died. EC50 values for the effect of copper on A. tenuis larval settlement were calculated from the 1996 results using measured copper concentrations. The 48-h EC50 was 35 μg l−1 with an upper and lower 95% confidence limit of 37 μg l−1 and 32 μg l−1, respectively. The 48-h NOEC value for both experiments was 20 μg l−1 copper. These experiments provide some of the first data on sub-lethal effects of trace metals on tropical marine organisms, and demonstrate that relatively low copper concentrations impair or inhibit settlement of coral larvae.  相似文献   

8.
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 ipC25:2, and Southern Ocean seawater particulate matter samples were distinguished from near shore samples by the presence of nC21:6. 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.  相似文献   

9.
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.  相似文献   

10.
Pesticide concentration in sediment from irrigation areas can provide information required to assess exposure and fate of these chemicals in freshwater ecosystems and their likely impacts to the marine environment. In this study, 103 sediment samples collected from irrigation channels and drains in 11 agricultural areas of Queensland were analysed for a series of past and presently used pesticides including various organochlorines, synthetic pyrethroids, benzoyl ureas, triazines and organophosphates. The most often detected compounds were endosulphans (, β and/or endosulphan sulphate) which were detectable in 78 of the 103 samples and levels ranged from below the limit of quantification (0.1 ng g−1 dw) up to 840 ng g−1 dw. DDT and its metabolites were the second most often detected pesticide investigated (74 of the 103 samples) with concentrations up to 240 ng g−1 dw of ∑DDTs. Mean ∑endosulphan and ∑DDT concentrations were 1–2 orders of magnitude higher in sediments from the irrigation areas which are dominated by cotton cultivation compared to those which are dominated by sugarcane cultivation. In contrast to these insecticides, the herbicides diuron, atrazine and ametryn were the compounds which were most often detected in sediments from irrigation drains in sugarcane areas with maximum concentrations in areas of 120, 70 and 130 ng g−1 dw, respectively. In particular during flood events, when light is limiting, transport of these photosynthesis inhibiting herbicides from the sugarcane cultivation areas to the marine environment may result in additional stress of marine plants.  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   


13.
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.  相似文献   


14.
North-seeking bacteria (NSB) with 1 μm diameters migrate to the S pole only. They were applied to identify the S pole determination on a polished surface of magnetite-rich pyroxenite whose natural remanent magnetization (NRM) intensity was 5.64 × 10−3 Am2 kg−1. The microscopic observations were performed under dark-field illumination in a controlled magnetic field to 10 μT. The NSB formed clusters on limited areas of magnetite grains and scattered over the whole magnetite grains.

The NRM decreased to 1.02 × 10−5 Am2 kg−1 by alternating field (AF) demagnetization to 60 mT but no clusters appeared, while small populations of the NSB scattered on each grain. These scattered bacteria may gather toward the S pole resulting from magnetic domain walls.

When the sample acquired saturation isothermal remanent magnetization (SIRM) to 1 T, the NSB formed dense clusters at the opposite side to the applied field direction on the many grains as expected. This evidence indicated that the NSB can be useful micro-organisms for the determination of fine magnetic structures. Some grains also had NSB clusters at the edge of the grains toward the field direction or did not exhibit any clusters. The complicated distribution of the clusters (the S poles) may be explained by shape anisotropy of the magnetic grains.  相似文献   


15.
Physiological Responses of Five Seagrass Species to Trace Metals   总被引：5，自引：0，他引：5  
Trace metal run-off associated with urban and industrial development poses potential threats to seagrasses in adjacent coastal ecosystems. Seagrass from the largest urban (Moreton Bay) and industrial (Port Curtis) coastal regions in Queensland, Australia were assessed for metal concentrations of iron (Fe), aluminium (Al), zinc (Zn), chromium (Cr) and copper (Cu). Trace metal concentrations in seagrass (Zostera capricorni) leaf and root-rhizome tissue had the following overall trend: [Fe] > [Al] > [Zn] > [Cr] > [Cu]. Rainfall events and anthropogenic disturbances appeared to influence metal concentrations in seagrasses with the exception of Al, which does not appear to bioaccumulate. In laboratory experiments, five seagrass species (Halophila ovalis, H. spinulosa, Halodule uninervis, Z. capricorni, Cymodocea serrulata) were incubated with iron (1 mg Fe l−1) and copper (1 mg Cu l−1) and responses assessed by changes in PSII photochemical efficiency (Fv/Fm), free amino acid content and leaf/root-rhizome metal accumulation. Iron addition experiments only affected Halophila spp, while copper additions affected other seagrass species as well. Trace metal contamination of seagrasses could have ramifications for associated trophic assemblages through metal transfer and seagrass loss. The use of photosystem II photochemical efficiency as well as amino acid concentrations and composition proved to be useful sublethal indicators of trace metal toxicity in seagrasses.  相似文献   

16.
Water sampling during the 1993 IV Russian–US Joint Expedition to the Bering and Chukchi Seas (BERPAC) indicates that Pacific Ocean burdens of the long-lived radionuclide 129I are relatively low in the Pacific-influenced Arctic, particularly compared to high latitude waters influenced by the North Atlantic. These low concentrations occur despite the presence of potential submerged anthropogenic sources in the East Sea (Sea of Japan), and in the northwest Pacific Ocean, east of the Kamchatka Peninsula. The concentration of 129I entering the Arctic Ocean through Bering Strait, 0.7×108 atoms kg−1, is only slightly higher than observed in deep Pacific waters. Similar concentrations (0.44–0.76×108 atoms kg−1) measured in Long Strait indicate no significant transfer of 129I eastward into the Chukchi Sea in the Siberian Coastal Current from the Siberian marginal seas to the west. However, the concentrations reported here are more than an order of magnitude higher than the Bering Strait input concentration estimated (1.0×106 atoms kg−1) from bomb fallout mass balances, which supports other existing evidence for a significant atmospheric deposition term for this radionuclide in surface ocean waters. Near-bottom water samples collected in productive waters of the Bering and Chukchi Seas also suggest that sediment regeneration may locally elevate 129I concentrations, and impact its utility as a water mass tracer. As part of this study, two deep 129I profiles were also measured in the East Sea in 1993–1994. The near-surface concentration of 129I ranged from 0.12 to 0.31×108 atoms kg−1. The 129I concentration showed a steady decrease with depth, although because of active deep water ventilation, the entire 3000 m water column exceeded natural concentrations of the radionuclide. Atom ratios of 129I/137Cs in the East Sea also suggest an excess of 129I above bomb fallout estimates, also possibly resulting from atmospheric deposition ultimately originating from nuclear facilities.  相似文献   

17.
A case study on fuel oil contamination in a mangrove swamp in Hong Kong   总被引：5，自引：0，他引：5  
Tam NF  Wong TW  Wong YS 《Marine pollution bulletin》2005,51(8-12):1092-1100
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.  相似文献   

18.
Input and distribution of linear alkylbenzenesulphonates (LAS) in the highly stratified Krka River estuary were studied during 1990–1991. Determinations of individual LAS homologues in wastewater and estuarine waters were performed using reversed-phase high-performance liquid chromatography (HPLC) with spectrofluorimetric detection. The investigated municipal wastewaters contained LAS homologues with alkyl-chain lengths from C10 to C13 at total concentrations in the range of 285–1041 μg l−1. Total LAS input via wastewaters into ibenik Harbour, the most polluted part of the estuary, was estimated at 12.6 kg day−1. A relatively large fraction of total LAS, depending on the wastewater particle load, was found in particulate form (11–59%). Distributions of the individual homologues in dissolved and particulate fractions were rather different, the latter being significantly enriched in higher homologues (C12, C13). The LAS concentration in the estuary was quite low (0.2–23.9 μg l−1) which was caused chiefly by a strong and fast dilution process. However, characteristic vertical distribution of LAS in the estuarine water column indicated that the wastewater plume spreads almost exclusively in the upper (brackish) layer. The concentration maxima were observed in the surface microlayer and at the brackish water/seawater boundary.  相似文献   

19.
The main aim of this study was to assess the hydrogen peroxide (HP) production rates (HPPR) related to anthropogenic pollution in coastal waters by laboratory and field experiments. HPPR's were assessed by simultaneous measurements of HP concentrations, cumulative solar UV irradiation and dissolved organic matter (DOM) fluorescence in the seawater samples at clean and polluted sites in the Mediterranean, Red and the Baltic Seas. The natural HP concentrations at all sites (8–100 nM) fall within the normal range recorded elsewhere, and follows a diurnal pattern. The polluted stations in the Mediterranean and Baltic Seas showed higher HPPR (3.2–16.6 nM m2 W−1 h−1) than the clean stations, while in the Red Sea no significant differences were found because the station that was considered a priori polluted was actually rather clean (2–3 nM m2 W−1 h−1). Laboratory experiments demonstrated that HPPR was positively linearly correlated to DOM fluorescence, however, this relationship was not found in the natural seawater samples examined in the field. The lack of relationship between HPPR and DOM in the field was attributed to enzymatic breakdown of HP as observed in dark decay experiments. HP dark decay rates were highest in polluted stations, probably due to larger bacterioplankton populations in these samples. Moreover, the HP dark decay rates were much lower in filtered than in non-filtered samples. Sun incubation of filtered (0.2 μm) seawater samples were performed to assess whether elimination of particles would yield higher HPPRs than in non-filtered samples. In the Baltic Sea (low UV irradiation) HPPR was higher in the filtered samples, while at sites with relatively high UV irradiation (Mediterranean and Red Seas), filtration of seawater did not stimulate HPPRs, probably due to UV-damage to planktonic microorganisms.  相似文献   

20.
Edible fish species were collected from 13 locations throughout San Francisco Bay, during the spring of 1994, for determination of contaminant levels in muscle tissue. Species collected included white croaker, surfperch, leopard and brown smoothhound sharks, striped bass, white sturgeon and halibut. 66 composite tissue samples were analysed for the presence of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (P0CBs), pesticides, trace elements and dioxin/furans. The US EPA approach to assessing chemical contaminant data for fish tissue consumption was used for identifying the primary chemicals of concern. Six chemicals or chemical groups were found to exceed screening values (SVs) established using the US EPA approach. PCBs (as total Aroclors) exceeded the screening level of 3 ng g−1 in all 66 muscle tissue samples, with the greatest concentrations (638 ng g−1) found near San Francisco's industrial areas. Mercury was elevated (> 0.14 μg g−1) in 40 of 66 samples with the greatest concentrations (1.26 μg g−1) occurring in shark muscle tissues. Concentrations of the organochlorine pesticides dieldrin, total chlordane and total dichlorodiphenyltri-chloroethane (DDT) exceeded screening levels in a number of samples. Dioxin/furans (as toxic equivalent concentrations (TEQ's)) were elevated (> 0.15 pg g−1) in 16 of the 19 samples analysed. Fish with high lipid content (croaker and surfperch) in their muscle tissue generally exhibited higher organic contaminant levels while fish with low lipid levels (halibut and shark) exhibited lower organic contaminant levels. Tissue samples taken from North Bay stations most often exhibited high levels of chemical contamination. The California Office of Health Hazard Assessment is currently evaluating the results of this study and has issued an interim Health Advisory concerning the human consumption of fish tissue from San Francisco Bay.  相似文献   

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