Pesticide and Herbicide Residues in Sediments and Seagrasses from the Great Barrier Reef World Heritage Area and Queensland Coast

Pesticides and herbicides including organochlorine compounds have had extensive current and past application by Queensland's intensive coastal agriculture industry as well as for a wide range of domestic, public health and agricultural purposes in urban areas. The persistent nature of these types of compounds together with possible continued illegal use of banned organochlorine compounds raises the potential for continued long-term chronic exposure to plants and animals of the Great Barrier Reef. Sediment and seagrass samples were collected from 16 intertidal and 25 subtidal sampling sites between Torres Strait and Townsville, near Mackay and Gladstone, and in Hervey and Moreton Bays in 1997 and 1998 and analysed for pesticide and herbicide residues. Low levels of atrazine (0.1–0.3 μg kg⁻¹), diuron (0.2–10.1 μg kg⁻¹), lindane (0.08–0.19 μg kg⁻¹), dieldrin (0.05–0.37 μg kg⁻¹), DDT (0.05–0.26 μg kg⁻¹), and DDE (0.05–0.26 μg kg⁻¹) were detected in sediments and/or seagrasses. Contaminants were mainly detected in samples collected along the high rainfall, tropical coast between Townsville and Port Douglas and in Moreton Bay. Of the contaminants detected, the herbicide diuron is of most concern as the concentrations detected have some potential to impact local seagrass communities.     

Burial, crawling and drifting behaviour of the bivalve Macomona liliana in response to common sediment contaminants

To investigate the effect of sediment contamination on the tellinid bivalve Macomona liliana, juvenile shellfish (about 1.3 mm long) were exposed to copper- and zinc-dosed sand, and sediments collected from several contaminated sites. The behavioural responses measured included burial rate, crawling and drifting. In copper-dosed sediment, a significant reduction in the number of shellfish burying after 10 min occurred at 25 mg Cu kg⁻¹ (dry wt). After a 96-h exposure, shellfish crawled away from sediment with 10 mg Cu kg⁻¹ (dry wt), and when a weak current was provided they left this 10 mg Cu kg⁻¹ (dry wt) sediment by drifting. Zinc-dosed sediment slowed burial at 80 mg Zn kg⁻¹ (dry wt), and stimulated crawling and drifting at 40 mg Zn kg⁻¹ (dry wt). Some of the field-collected contaminated sediments slowed burial and stimulated drifting, but none affected crawling. It appears that juvenile drifting induced by sediment contamination could play a role in determining M. liliana distributions.     

Biochemical and Physiological Responses in Atlantic Salmon (Salmo salar) Following Dietary Exposure to Copper and Cadmium

Three experiments were conducted with Atlantic salmon (Salmo salar) to assess the effects of dietary exposure to copper and cadmium. The results presented here provide an overview, details of each experiment will be published in full elsewhere. In the first experiment, salmon parr exposed for four weeks to 35 and 700 mg Cu kg⁻¹ diet had significantly elevated intestinal copper concentrations, cell proliferation (PCNA) and apoptosis rates compared to control fish. No differences were observed in gill or plasma copper concentrations among the groups. In contrast to the controls, the Cu exposed groups did not grow significantly during the exposure period. The second experiment (three months exposure) was conducted to assess the effects of dietary copper (control, 35, 500, 700, 900 or 1750 mg Cu kg⁻¹ diet) on growth and feed utilization in salmon fingerlings. Growth was significantly reduced after three months exposure to dietary Cu concentrations above 500 mg kg⁻¹. Similarly, copper body burdens were significantly higher in fish exposed to elevated dietary copper concentrations (above 35 mg Cu kg⁻¹ diet). In the third experiment, salmon parr were exposed to one of six dietary cadmium concentrations (0, 0.5, 5, 25, 125 or 250 mg Cd kg⁻¹ diet) for four months. Cadmium accumulated in the liver>intestine>gills of exposed fish. Rates of apoptosis and cell proliferation in the intestine increased following exposure to dietary cadmium. Exposure to elevated concentrations of dietary cadmium had no effect on growth in salmon parr. Results from these studies indicate that cellular biomarkers have potential as early warning signs of negative effects on the overall fitness of an organism.     

Pu, Cs and excess Pb in Russian Arctic sediments

The activity ratios of Pu and radiocesium isotopes have been used to delineate the major sources (such as global and close-in (debris) fallout, nuclear fuel reprocessing and fabrication plant effluents) in the environment. We have measured ²³⁸Pu, ^239,240Pu, ¹³⁷Cs, and excess ²¹⁰Pb concentrations in 107 surficial sediments as well as in 5 sediment cores collected in the summer months of 1993 and 1994 from the Ob and Yenisey Rivers (Russia) and the Kara sea. A comparison of the sediment core inventories of ^239,240Pu and ¹³⁷Cs, along with the ²³⁸Pu/^239,240Pu activity ratios, with those expected from global fallout allows us to estimate the relative amounts, if any, of reactor-derived ²³⁸Pu and ^239,240Pu from the dumped reactor sites in the study area.

In surficial sediment samples collected in 1993 and 1994, the ^239,240Pu concentrations varied between 4.2 and 856 mBq kg⁻¹, with a mean of 239 mBq kg⁻¹. In samples with a measurable ²³⁸Pu, the ²³⁸Pu/^239,240Pu activity ratios varied between 0.010 and 0.069, with an average value of 0.035 ± 0.014. This range can be compared to the average ²³⁸Pu/^239,240Pu activity ratio of 0.030 for the year 1993 from nuclear weapons testing and SNAP fallout obtained from soil studies, indicating very little (≤ 5%) additional sources of ²³⁸Pu to the sediments in the study area. The inventories of Pu in the 5 sediment cores from the study area varied between 2.67 ± 0.67 and 24.5 ± 2.2 Bq m⁻² with a mean value of 8.83 Bq m⁻². The ¹³⁷Cs concentrations in the upper 3 cm of the sediments varied between below detection limit to 71.4 Bq kg⁻¹, with a mean of 14.9 Bq kg⁻¹. The ¹³⁷Cs inventories in the 5 sediment cores varied between 156.7 ± 28.3 and 1600 ± 153.3 Bq m⁻², with a mean value of 583.3 Bq m⁻². The mean ratio of inventories of Pu to that of ¹³⁷Cs, 0.015, is comparable to the values in other places in the Arctic region. There is a significant correlation between total organic carbon and concentrations of ¹³⁷Cs, ^239,240Pu and ²¹⁰Pb, suggesting that organic matter-enriched fine particles are a likely carrier phase for these nuclides. The ratio of ¹³⁷Cs/^239,240Pu also suggests that most of these nuclides are derived from global fallout.     

Iodine-129 concentrations in marginal seas of the north Pacific and Pacific-influenced waters of the Arctic Ocean

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.     

The S pole distribution on magnetic grains in pyroxenite determined by magnetotactic bacteria

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.     

Polychlorinated biphenyls in the Brisbane River estuary, Australia

The concentrations of PCBs in water, sediments, fish (6 species), crustacea (3 species), molluscs (1 species), polychaetes (mixed species) and birds (1 species) from the Brisbane River estuary were determined. Levels were comparable to other similar situations elsewhere. No relationship was found between trophic class and PCB concentration although pelicans at the highest trophic level examined exhibited the highest muscle tissue concentration (i.e., 15.7 mg kg⁻¹ on a wet weight basis). The pattern of distribution of PCBs within body tissues of fish was closely related to lipid content.     

Pesticides in Sediments From Queensland Irrigation Channels and Drains

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.     

Tissue distribution of mercury in normal and abnormal young Common Terns

Sixteen young Common Terns (Sterna hirundo) from colonies on the south shore of Long Island, New York, had fairly consistent levels and tissue distribution patterns of total mercury in blood, liver, kidney, muscle, brain and feathers. Levels were highest in liver, blood and feathers, and were lower in muscle and brain. The latter two tissues showed low variability across birds, suggesting that they are more static repositories for mercurial compounds. Only slight, non-significant increases were detected in chicks 10–30 days old compared with 1–9 day olds. Four chicks with abnormal feather loss had significantly higher mercury levels than 12 normal chicks. The average intercorrelation among tissues was highest for liver (mean r² = 0.40) and blood (mean r² = 0.38). Liver is probably the single best tissue to serve as a surrogate for all others, due to high correlation with other tissues, large size, and ready availability. Use of a single tissue allows one to focus a study in greater detail and at lower cost than if several tissues were assayed.     

Dispersion of naturally occurring ions in groundwater from various rock types in a portion of the San Pedro river basin, Arizona

The groundwater in an alluvial basin in southern Arizona was analyzed for concentrations of Ca⁺⁺, Mg⁺⁺, Na⁺, and Cl⁻, ions.

The variety of rock types in the area, plus the undisturbed state of the groundwater basin, make comparative rock mineralization-groundwater ionization interpretations possible. Ionic dispersion in groundwater eminating from source areas composed of differing rock types is plotted as isogram maps. These isolated areas of differing mineral composition each exhibit a unique ionic contribution to groundwater. The ion concentrations in groundwater were then used as naturally occurring tracers to determine source areas of recharge and to delineate subsurface barriers to the normal basin flow net. Ion dispersion plots reveal the carbonates of the Dragoon Mountains to be a major contributor of Ca⁺⁺ and Mg⁺⁺ to the deep alluvial portion of the basin. Cl⁻ dispersion patterns show the granitic intrusives of the Tombstone Hills produce a barrier effect in the normal flow pattern of the basin as well as being a contributor of Cl⁻ to groundwater.     

Distribution, source and evolution of nitrate in a glacial till of southern Alberta, Canada

This paper addresses the distribution, origin and controls upon nitrate in a 30-km² area of the Interior Great Plains Region of southern Alberta, Canada. High concentrations of nitrate (> 100 mg l⁻¹ NO⁻₃-N) occurred in several isolated enclaves below the water table in brown weathered till. Nitrate concentrations of over 300 mg l⁻¹-N were encountered in groundwater samples collected from these enclaves. Low nitrate concentrations (< 1.1 mg l⁻¹ NO⁻₃-N) were also encountered in the weathered till upgradient and downgradient of the nitrate enclaves. Groundwater samples collected from the underlying grey nonweathered till and bedrock had NO⁻₃-N concentrations of < 1.1 mg l⁻¹.

Through the application of geochemical (NO⁻₃-N and NH⁺₄-N) studies, environmental isotope studies (tritium), microbial analyses (nitrifiers) and laboratory experiments, it was shown that the high nitrates found in the weathered till are the result of the oxidation of ammonium present within the tills. It is postulated that this oxidation occurred during the Holocene epoch when water tables were much lower than present-day levels (5–18 m, and 2 m below ground, respectively).

Through the use of Eh measurements, the enumeration of denitrifying bacteria and laboratory experiments, the potential for denitrification was shown to exist below the present-day water table in the weathered till as well as in the nonweathered till and bedrock. Isotopic data showed that less denitrification may be occurring within the nitrate enclaves than in adjacent downgradient areas.     

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.     

Derived concentration factors for caesium-137 in edible species of North Sea fish

Concentration factor (CF=Bq kg⁻¹ fillet/Bq kg⁻¹ filtered sea water) values for ¹³⁷Cs in fillets of cod (Gadus morhua), haddock (Merlanogrammus aeglefinus), plaice (Pleuronectes platessa) and whiting (Merlangius merlangius), were derived from fish and filtered seawater concentrations. Samples were collected in twelve sampling boxes in the North Sea over an eight-year period—1978–1985. The range of results with species, between species, and between surveys are discussed. Mean CF values of 92, 58, 39, and 150 were found in cod, haddock, plaice, and whiting respectively. These support the IAEA recommended CF value of 100 for fish in generalised dose assessments.     

Organochlorines and other environmental contaminants in muscle tissues of sportfish collected from San Francisco Bay

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.     

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.     

Nitrate and herbicide loading in two groundwater basins of Illinois'' sinkhole plain

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.     

Toxic Effects of Cadmium on Fertilizing Capability of Spermatozoa, Dynamics of the First Cleavage and Pluteus Formation in the Sea Urchin Anthocidaris crassispina (Agassiz)

Effects of cadmium on the fertilizing capability of spermatozoa, dynamics of the first cleavage and pluteus formation in the sea urchin, Anthocidaris crassispina, were investigated. Exposure to cadmium concentrations of 0.32, 0.56, 1.0, 1.8, 3.2, 5.6 and 10.0 mg l⁻¹ for 30 min caused a significant adverse effect on the fertilizing capability of spermatozoa (EC₅₀=1.7 mg l⁻¹). For the first cleavage kinetics assay, eggs were pre-exposed to 0, 0.18, 0.32, 0.56, 1.0, 1.8, 3.2 and 5.6 mg l⁻¹ of cadmium for 30 min. Fresh sperms of fixed concentrations were then added to the eggs and the percentage of divided zygotes estimated. Concentration-dependent toxic effects on the dynamics of the first cleavage in A. crassispina were observed between 0.18 and 5.6 mg l⁻¹ cadmium. Calculation of EC₅₀ values by probit analysis at different stages of the first cleavage revealed that EC₅₀ values increased gradually from 0.37 mg l⁻¹ at the beginning to 2.24 mg l⁻¹ at the end of the cleavage process. Different larval classes (normal, abnormal and retarded plutei, preplutei, dead embryos/larvae) of A. crassispina obtained from eggs pre-treated with cadmium for 30 min and then exposed to cadmium throughout embryogenesis were also examined. The percentage of abnormal plutei was significantly higher than that of the control at 0.56 mg l⁻¹ cadmium and higher. The 48 h EC₅₀ calculated for the number of normal plutei was 1.5 mg l⁻¹. A χ²-test revealed significant changes in the distribution of proportions of different larval classes only at cadmium concentrations 1.8 mg l⁻¹. At 5.6 mg l⁻¹ of cadmium, small malformed plutei, and oval embryos with rudimentary skeleton, poorly differentiated intestines and no mouth (pre-pluteus stage) were observed. The relative sensitivity of various end points to cadmium is also compared and discussed.     

Organochlorine micropollutants in the Jiulong River Estuary and Western Xiamen Sea, China

Organochlorine contaminants including 12 polychlorinated biphenyl (PCB) congeners and 18 insecticides were determined in water, pore water and sediments of the Jiulong River Estuary and Western Xiamen Sea, China. The results showed that the levels of the total PCBs ranged from non-detectable to 1500 ng l⁻¹ in water, from 209 to 3870 ng l⁻¹ in pore water, and from 2.78 to 14.8 ng g⁻¹ dry weight in sediments. Total organochlorine insecticide concentrations were from below the limit of detection to 2480 ng l⁻¹ in water, from 267 to 33400 ng l⁻¹ in pore water, and from 4.22 to 46.3 ng g⁻¹ dry weight in sediments. Concentrations of PCBs and insecticides in pore water were significantly higher than those in surface water, due to the high affinity of these hydrophobic compounds for sediment phase. The PCB congeners with the highest concentrations were CB153, CB180 and CB194, which together accounted for 68–87% of total PCBs in water, pore water and sediment. Among the hexachlorocyclohexane (HCH) compounds, beta-HCH was found to be a major isomer. Analysis of 1,1,1-trichloro-2,2-bis-chlorophenyl-ethane (DDT) and its metabolites showed that 1,1-dichloro-2[o-chlorophenyl]-2[p-chlorophenyl]-ethylene (DDE) was dominant in the group. In comparison to a 1998 study in the Western Xiamen Sea, levels of organochlorines were enhanced due probably to recent inputs and changes in sediments.     

Hydrocarbons in surface sediments from the Changjiang (Yangtze River) Estuary, East China Sea

Sedimentary aliphatic (AH) and polycyclic aromatic hydrocarbons (PAHs) were studied in the Changjiang Estuary and the adjacent East China Sea. Total AH ranged from 2.20 to 11.82 μg g⁻¹ and consisted of n-alkanes and a dominant petroleum-related unresolved complex mixture (UCM). Within the n-alkanes, terrestrial plant wax compounds prevailed at nearly all stations. Of the PAHs, biogenic perylene dominated at stations receiving riverine inputs. Anthropogenic PAHs originating from combustion/pyrolysis processes varied from 17 to 157 ng g⁻¹, while fossil PAH concentrations ranged from 42 to 187 ng g⁻¹. Both biogenic and anthropogenic hydrocarbons are primarily derived from riverine discharges and accumulate at shallow-water stations. Distinct phase associations lead, nevertheless, to different sedimentation patterns. Fossil PAHs are enhanced at offshore stations where they are introduced directly by shipping activities. Biomarker fingerprints ascribe their source to Chinese crude oils. The overall levels of anthropogenic hydrocarbons are low compared to relevant areas worldwide and reveal a low/moderate level of hydrocarbon pollution.     

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.