苏州河底泥对上复水水质污染影响

研究了上海市苏州河底泥中有机物及营养盐释放对上复水水质的影响,分析了微生物与底栖生物底泥再悬浮对底泥释放过程的影响。研究表明,底泥中化学需氧量与水体中的化学需氧量成正比,底泥中生化需氧量与水体中的生化需氧量呈正比,再悬浮促进底泥中污染物向上复水体释放。底泥SOD与水体中DO成正比,底泥污染是影响苏州河水质的重要因素;对苏州河底泥进行疏浚工程可较好地提高水体中溶解氧的浓度、降低化学需氧量、生化需氧量及氨氮的浓度。     

Spatial and vertical distribution of polycyclic aromatic hydrocarbons in mangrove sediments

The distribution and historical changes of polycyclic aromatic hydrocarbons (PAHs) contamination in mangrove sediments in Hong Kong SAR were investigated. Surface sediments (2-3 cm) collected from four mangrove swamps exhibited significant spatial variations in concentrations of total PAH (with SigmaPAHs ranging from 56 to 3758 ng g(-1) dry wt), as well as the composition of 16 USEPA priority PAH compounds. Within a small swamp with an area of 0.68 ha, the total PAH concentrations also differed from sampling site to site, indicating that the PAH contamination is localized and confined to a very small area within the same swamp. Discharges from municipal and industrial wastewater, urban runoff, oil leakage from boats and ships, and accidental oil spill are possible sources of the PAH contamination. The sediment depth profiles reveal that the surface sediment layer (0-5 cm) had lower total PAH concentrations than that in the bottom layer (15-20 cm), and PAH composition also changed with the sediment layers. Based on the estimated annual sediment deposition rate in Hong Kong SAR of around 0.4-0.5 cm, the present findings suggest that the PAH contamination was most serious between 1958 and 1979 but started to decline thereafter. Such decline was probably due to changes in petroleum usage in urban areas and a better control of wastewater discharges from 1980 onwards in this region.     

Biomarker responses and PAH uptake in Mya truncata following exposure to oil-contaminated sediment in an Arctic fjord (Svalbard)

Expanding industrial activity (notably oil and gas exploration) in the Arctic requires assessment of the potential impact of chemicals on marine organisms living in seawater at low temperature. The bivalve Mya truncata is common in Svalbard fjord (Norway) where it experiences low temperature throughout the year. To measure the impact of polycyclic aromatic hydrocarbons (PAH) on M. truncata, the responses of three biomarkers [total oxyradical scavenging capacity-assay (TOSC), plasma membrane stability of haemocytes and respiration rates] were investigated from bivalves exposed to sediment contaminated with a PAH mixture (crude oil). After two weeks of exposure to the contaminated sediment, TOSC showed no change. The high TOSC value (4010+/-1339 unit mg(-1) protein) of Mya truncata (control group) is thought to protect biomolecules with a low turnover rate efficiently in a low food availability environment. In the exposed bivalves, the haemocyte cellular membranes were significantly destabilised compared with controls (P<0.05). Respiration rate of control and PAH-exposed individuals (0.055+/-0.020 mg O(2) dw(-1) h(-1)) was similar and relatively low as is typical for polar bivalves, reflecting a strategy to minimise energy expenditure to cope with 9 months of starvation. Bioaccumulation of PAH by M. truncata was also low, due probably to a combination of low metabolic rate and reduced solubility of the oil compounds at low temperature. Data indicated an uptake of mainly low molecular weight compounds (two and three ring molecules). A good correlation of logBAF(lipid) (bioaccumulation factor) and logK(ow) (octanol/water partitioning coefficient) was shown (r(2)=0.87). Tissue sensitivity and/or functional differences (digestive gland vs. haemocytes), PAH uptake route (dietary vs. gills), the low metabolic rate of M. truncata and the low environmental temperature (reducing the bioavailability of PAH) are factors that help explain these findings.     

Evaluation of dioxin contamination in sewage sludge discharges on coastal sediments from Catalonia, Spain.

The fate of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in sewage sludges after discharge into the sea was investigated. Sediment samples were analysed at a sewage sludge disposal site as well as in the surrounding areas. Moreover, eight sediment samples from two rivers in Catalonia and three sediment samples from Catalonian Coast were analysed to determine the background levels of contamination. Total international toxicity equivalent (I-TEQ) values for these sediments ranged from 0.42 to 8.01 pg g, with a mean value of 4.15 pg/g and a median value of 3.69 pg/g. However, the I-TEQ values of sludge-treated areas were higher: 57.04 pg/g at the dumping site, and within a range of 13.42-47.76 pg/g near this site. Thus, European sediment quality objectives were exceeded. The higher concentrations coincided with changes in the ratio between PCDD and PCDF levels, suggesting the influence of the sewage sludge on coastal sediments.     

Modeling metal bioaccumulation in a deposit-feeding polychaete from labile sediment fractions and from pore water

Estuarine sediments are often highly enriched in particle-reactive metal contaminants and because aquatic animals have often been shown to acquire metals predominantly from their diet, benthic animals feeding on deposited or resuspended sediments may also accumulate metals through this uptake pathway. Laboratory experiments were performed in which the surface deposit-feeding polychaete, Nereis succinea, was exposed to As(+ 5), Cd, and Cr(+ 3) in pore water or in estuarine sediments with and without enrichment with algal debris. These experiments generated metal uptake parameters (assimilation efficiency of ingested metal [AE], uptake rate constant of dissolved metal, efflux rate constants following dietary or aqueous metal exposures) used in a kinetic model of metal bioaccumulation. The model showed that > 97% of the body burden of these metals is accumulated through ingested sediment. The kinetic model was further modified to consider the geochemical fractionation of the metals in the sediments because metals bound to some fractions were shown to be unavailable to these polychaetes. The modified model substituted the AE term for each metal by the percentage of metal extracted in neutral and weak acid exchangeable fractions (termed “carbonex” fraction) multiplied by the slope of the regression between the metal AE and its fractionation in carbonex. The modified model generated predictions of As, Cd, and Cr body burdens in polychaetes at three different estuarine sites that matched independent field observations at these sites (r² = 0.84 for sediments without organic enrichment, r² = 0.87 with organic enrichment). Model predictions that relied on total metal concentrations showed weaker relationships (r² = 0.11-0.50). This study adds to the evidence for the dominance of dietary uptake of metals in aquatic animals and identifies a key sedimentary fraction of metals that can account for bioavailability of sediment-bound metals.     

Estimation of heavy metal transformations in municipal solid waste

The behaviour of heavy metals bound to municipal solid waste (MSW) and exposed to 2 decades of anaerobic waste stabilization processes have been estimated. Heavy metal solid forms in a waste degradation residue have been compared with a reconstructed waste similar to that initially disposed of in 1973. The initial waste was composed of a mixture of shredded MSW (95% dry wt.) and anaerobic sewage sludge (5% dry wt.). A sequential chemical extraction method has been used to fractionate the heavy metals into five categories of available and reactive solid forms. The results imply that these forms can be ascribed to approximately 30% of the total content of the heavy metals in the degraded waste and the portion of heavy metals bound to oxidizable solid forms seems to be higher in the degraded than the fresh MSW. The bulk of the remaining heavy metals are assumed to be less available and bound into resistant lattice structures, such as metal and polymer items. A comparison between fractionation patterns of the waste in this study and of a few sediments collected from different environments imply similarities between the fresh MSW and an oxic sediment from one site and the sewage sludge and anoxic sediments from another site. Fractionation patterns of the degraded waste are found to be quite similar to those of the anoxic sediments, except for Pb, Ni and Cd which are more similar to fresh MSW.     

Phase association of polycyclic aromatic hydrocarbons in the Minjiang River Estuary, China

Persistent organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) are of great concern due to their persistence, bioaccumulation and toxic effects. In this work the levels of 16 priority PAHs were determined in water, pore water, sediment, soil and vegetable samples from Minjiang River Estuary, China. Total PAH concentrations varied from 9.9 to 474 microg/l in water, 82.1 to 239 microg/l in pore water, 112 to 877 ng/g dry wt. in surficial sediments, 128 to 465 ng/g dry wt. in soil and 8600 to 111,000 ng/g dry wt. in Chinese vegetables. Overall, the mean concentrations of PAHs were present in higher levels in pore water than that in surface water, due possibly to higher concentrations of dissolved organic carbon or colloids with which the hydrophobic pollutants were strongly associated. Such a concentration gradient implies a potential flux of pollutants from sediment pore water to overlying water. Contamination was dominated by high molecular mass PAH compounds in all samples, indicating combustion-derived sources (for example, pyrolysis at high temperature). The levels of PAHs in water and vegetable were relatively high in comparison to other studies, although PAHs in sediment and soil were comparable to those found in many other similar environments. The ratios of selected PAHs indicated again that PAHs in Minjiang River Estuary were mainly derived from incomplete combustion of fossil fuel.     

A field studies and modeling approach to develop organochlorine pesticide and PCB total maximum daily load calculations: Case study for Echo Park Lake, Los Angeles, CA

Echo Park Lake is a small lake in Los Angeles, CA listed on the USA Clean Water Act Section 303(d) list of impaired water bodies for elevated levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in fish tissue. A lake water and sediment sampling program was completed to support the development of total maximum daily loads (TMDL) to address the lake impairment. The field data indicated quantifiable levels of OCPs and PCBs in the sediments, but lake water data were all below detection levels. The field sediment data obtained may explain the contaminant levels in fish tissue using appropriate sediment-water partitioning coefficients and bioaccumulation factors. A partition-equilibrium fugacity model of the whole lake system was used to interpret the field data and indicated that half of the total mass of the pollutants in the system are in the sediments and the other half is in soil; therefore, soil erosion could be a significant pollutant transport mode into the lake. Modeling also indicated that developing and quantifying the TMDL depends significantly on the analytical detection level for the pollutants in field samples and on the choice of octanol-water partitioning coefficient and bioaccumulation factors for the model.     

Source characterization using compound composition and stable carbon isotope ratio of PAHs in sediments from lakes, harbor, and shipping waterway

Molecular compositions and compound specific stable carbon isotope ratios of polycyclic aromatic hydrocarbons (PAH) isolated from sediments were used to characterize possible sources of contamination at an urban lake, a harbor, a shipping waterway, and a relatively undisturbed remote lake in the northwest United States. Total PAH concentrations in urban lake sediments ranged from 66.0 to 16,500 microg g(-1) dry wt. with an average of 2600 microg g(-1), which is approximately 50, 100, and 400 times higher on average than PAH in harbor (48 microg g(-1) on average), shipping waterway (26 microg g(-1)), and remote lake (7 microg g(-1)) sediments, respectively. The PAH distribution patterns, methyl phenanthrene/phenanthrene ratios, and a pyrogenic index at the sites suggest a pyrogenic origin for PAHs. Source characterization using principal component analysis and various molecular indices including C2-dibenzothiophenes/C2-phenanthrenes, C3-dibenzothiophenes/C3-phenanthrenes, and C2-chrysenes/C2-phenanthrenes ratios, was able to differentiate PAH deposited in sediments from the four sites. The uniqueness of the source of the sediment PAHs from urban lake was also illustrated by compound specific stable carbon isotope analysis. It was concluded that urban lake sediments are accumulating PAH from sources that are unique from contamination detected at nearby sites in the same watershed.     

Prediction of the bioaccumulation factors and body burden of natural and synthetic estrogens in aquatic organisms in the river systems

This study undertakes an initial prediction of the bioaccumulation factors and body burden of the steroid estrogens, estrone, estradiol, estriol and ethinylestradiol in a range of aquatic organisms (plankton, benthic and free-living invertebrates and fish) in river systems using a food-web model. These data are compared to that derived from less complex predictions based on octanol-water partition coefficient and molecular connectivity index. The model predicted that bioaccumulation of steroid estrogens occurred in all organisms, however, the values were small, and the maximum and minimum bioaccumulation factors in this study were found in the fish at the lowest trophic level with ethinylestradiol (332) and the fish at the highest trophic level with estriol (1.8), respectively. Moreover, the bioaccumulation factors were sensitive to the metabolic rates of the estrogens in the free living organisms, while the concentration of estrogens in sediment was a significant factor in determining these values in benthic invertebrates. Biomagnification contributed little to the overall bioaccumulation, but the importance increased in fish exposed to ethinylestradiol. The predicted bioaccumulation factors from the food web model were generally smaller than the calculated bioconcentration factors from the simpler octanol-water partition coefficient/molecular connectivity index based estimates. Compared to literature measured data, the predicted values for fish were approximately 1000 times less than the values observed in laboratory tests, while for invertebrates, the modeled values were less than two orders of magnitude below laboratory results. However, the model predicted a similar bioconcentration factor for plankton in relation to experimental data for Chlorella vulgaris for estrone and estriol.     

Assessment of bioavailability and effects of chemicals due to remediation actions with caging mussels (Anodonta anatina) at a creosote-contaminated lake sediment site

A study was conducted at Lake J?ms?nvesi in Central Finland, to identify the potential ecotoxicological risks of the remediation operation of a creosote-/PAH-contaminated lake sediment, made by capping during the years 1998-1999. Mussels (Anodonta anatina) were deployed to the lake at the same time as the remediation operation was started in November 1998. The contaminated area (0.5 ha) was covered by a filter geotextile (polypropylene), gravel and sand (1-1.5m) which were spread out on the ice and let to sink onto the bottom of the lake when the ice melted in May 1999. The possible impacts of capping to the adjacent environment were assessed from mussels exposed and particulate material settled (SPM) to collectors placed on the lake bottom. Mussel tissue, SPM, the water inside the collector were analyzed for polycyclic aromatic compounds (PAH)-compounds. Biological endpoints included body condition, glycogen and protein contents of adductor muscle. Mussels and SPM exposed downstream to the contaminated site (Site 3) contained the highest total PAH concentrations. Biota-sediment accumulation factors of acenaphthene, phenanthrene, anthracene, fluoranthene, pyrene and benzo(a)anthracene of mussels varied from 0.79 to 1.45. The glycogen and protein concentrations were lowest in adductor muscle from mussels exposed to conditions at Site 3. Concentrations of some PAH-compounds were found distinctly increased adjacent to the remediated area, possibly due to the agitation of contaminated sediment due to the capping. It is also possible that resuspension of sediment around remediated area (containing some PAHs) spread the deposited PAH-compounds.     

Occurrence of phthalates and bisphenol A and F in the environment

Certain xenoestrogens, namely bisphenol A (BPA), bisphenol F (BPF), butylbenzyl phthalate (BBP), dibutyl phthalate (DBP), and di(2-ethylhexyl)phthalate (DEHP), were measured in various compartments (surface water, sediments, sewage treatment plant effluents, sewage sludge, dump water, liquid manure) in order to contribute to a better understanding of exposure to these compounds in different environments. Hundred and sixteen surface-water samples and 35 sediments from rivers, lakes and channels, 39 sewage effluents, and 38 sewage sludges were collected in Germany. Furthermore, ten liquid manure, two waste-dump and two compost-runoff water samples were also analysed. BPA measurements showed low concentrations from 0.0005 to 0.41 microg L(-1) in surface water, in sewage effluents from 0.018 to 0.702 microg L(-1), in sediments from 0.01 to 0.19 mgkg(-1) and in sewage sludge from 0.004 to 1.363mgkg(-1) dw. Measured concentrations of BPF were clearly lower than BPA in all environmental media. DEHP dominated the phthalate concentrations, which ranged from 0.33 to 97.8 microg L(-1) (surface water), 1.74 to 182 microg L(-1) (sewage effluents), 27.9 to 154 mgkg(-1) dw (sewage sludge) and 0.21 to 8.44 mgkg(-1) (sediment). DBP was found only in minor concentrations and BBP, only in a few samples in low amounts. Very high concentrations of BPA and phthalates were confirmed in waste dump water and compost water samples as well as in the liquid manure samples.     

Assessment of two-compartment models as predictive tools for the bioaccumulation of trace metals in the amphipod Gammarus oceanicus Segerstråle, 1947 from Grunnfjord (Northern Norway)

The objective of the present study is to evaluate the suitability of the eulittoral gammaridean amphipod Gammarus oceanicus Segerstr?le, 1947 from Grunnfjord (Northern Norway) as a biomonitor for trace metals Cd, Cr, Pb, Cu, Ni and Zn and to analyse whether the two-compartment model could be used as a predictive tool to assess environmental quality. The focus here is on the adjustment of this model to situations where a linear extrapolation of accumulated metals to increasing external metal exposures is not applicable. The amphipods tested accumulated metals upon exposure and it was possible to estimate significant model parameters of two-compartment models, with the sole exception of Zn. These could be used to predict accumulation of Cd, Cr and Pb in a concentration-dependent uptake study, for Cr directly and regarding simultaneous parameter estimation, for Cd and Pb after adjustment taking into account a non-linear relationship between bioconcentration factors (BCFs) and external metal exposures. The elements Cu and Ni need further evaluation, since linear predictions from the two-compartment models were not applicable, whilst a relationship between kinetic parameters and metal exposures could not be established. Kinetic BCFs at theoretical equilibrium were 80-202 for Cd, 80-112 for Cr, 306 for Cu, 251-520 for Pb and 23 for Ni. A tentative estimation showed the following sequence of sensitivity of G. oceanicus to an increase of soluble metal exposure: 0.6 microg Cdl(-1), 0.8 microg Pbl(-1), 2.5-2.9 microg Crl(-1), 8.5 microg Cul(-1) and 11 microg Nil(-1). Available information can be used to quantify a measure of agreement or disagreement between bioaccumulation in different amphipods. This can be regarded as an important step in the calibration of biomonitors, which is necessary to assess the potential for bioaccumulation on a large geographical scale.     

Geochemical survey and metal bioaccumulation of three bivalve species (Crassostrea gigas, Cerastoderma edule and Ruditapes philippinarum) in the Nord Medoc salt marshes (Gironde estuary, France)

A 15-month experiment combining a geochemical survey of Cd, Cu, Zn and Hg with a bioaccumulation study for three filter-feeding bivalve species (oysters, Crassostrea gigas; cockles, Cerastoderma edule; and clams, Ruditapes philippinarum) was conducted in a breeding basin of the Nord Medoc salt marshes connected to the Gironde estuary, which is affected by historic polymetallic pollution. Regular manual surface measurements of temperature, salinity, pH and dissolved O(2) concentration and hourly multiprobe in situ measurements throughout several periods for 6-8 weeks were performed. The geochemical behavior of metals in water, suspended particulate matter and sediment and their ecotoxicological impact on the three bivalve species were evaluated by in situ exposure of juvenile oysters (water column) and adult cockles and clams (sediment surface). The physico-chemical parameters reflected seasonal variations and basin management. A distinct daily periodicity (except salinity) indicated intense photosynthesis and respiration. In summer, low dissolved O(2) saturations ( approximately 40-50%) occurred in the early morning at 30 cm above the sediment, whereas in depressions, the water column near the sediment surface was suboxic. Cadmium, Zn and Cu concentrations in suspended particulate matter exceeded typical estuarine values and were much higher than the homogeneously distributed concentrations in different depth ranges of the basin sediment. Particles collected in sediment traps showed intermediate metal concentrations close to sediment values. These results suggest trace metal recycling due to reductive dissolution under suboxic conditions at the sediment surface resulting in trace metal release to the water column and adsorption onto suspended particles. Dissolved Cd, Zn and Hg concentrations (e.g. 13-136 ng l(-1); 0.3-25.1 microg l(-1) and 0.5-2.0 ng l(-1), respectively) in the basin corresponded to the concentration range typically observed in the Gironde estuary, except for some maximum values attributed to metal recycling. In contrast, dissolved Cu concentrations (1.08-6.08 microg l(-1)) were mostly higher than typical estuarine values, probably due to recycled Cu complexation by dissolved organic matter. Growth, bioaccumulation rates and kinetics in the whole soft body of the bivalves were analyzed every 40 days. Although Cd bioaccumulation of oysters was lower in the basin than in the estuary during the same period (27,000 ng g(-1), dry weight and 40,000 ng g(-1), respectively) these values are largely above the new human consumption safety level (5000 ng g(-1), dw; European Community, 2002). For cockles and clams, Cd bioaccumulation was lower, reaching 1400 ng g(-1) and 950 ng g(-1), respectively. Similar results were obtained for Zn and Cu suggesting physiological differences between the species and/or differences in the exposure of the organisms due to physico-chemical conditions and metal distribution between dissolved and particulate phases. In contrast, Hg bioaccumulation was highest for cockles reaching bioconcentration factors of approximately 200,000, which even exceeded that of Cd in oysters (50,000) for the same exposition period. Nevertheless, Hg concentrations remained relatively low in the three bivalve species.     

Seasonality of bioaccumulation of trace organics and lysosomal integrity in green-lipped mussel Perna viridis

Lysosomal integrity in mussels is widely used as a biomarker in coastal environments to demonstrate exposure to trace organic pollutants. However, few studies have determined the long-term influences of seasonal variations on the bioaccumulation of trace organics and subsequently altered response of lysosomal integrity in mussels. This study aimed to test three null hypotheses that (1) bioaccumulations of total polycyclic aromatic hydrocarbon (∑ PAH) and (2) total polychlorinated biphenyl (∑ PCB), and (3) lysosomal integrity as indicated by Neutral Red retention time (NRRT) in haemocytes, in the green-lipped mussel Perna viridis were not seasonally dependent. The tissue concentrations of ∑ PAH and ∑ PCB and haemocytic NRRT were determined in P. viridis in a metropolitan harbour, subtropical Hong Kong during the wet and dry seasons from 2004 to 2007. Additional information on temperature, salinity, dissolved oxygen and total ammonia nitrogen in seawater, and sediment levels of ∑ PAH and ∑ PCB, were extracted from published data and re-analyzed. Our results accepted all null hypotheses, based on the minimal seasonal influences of seawater temperature and salinity on all studied parameters, in which no significant differences between the wet and dry seasons were detected. The seasonal effect was likely outweighed by the greatly improved water quality and pollution abatement noted inside the harbour, with a gradual shift in mussel PAHs from a pyrolytic origin to a petrogenic origin. Spatially, the site east of the harbour was relatively unpolluted. The single use of NRRT in P. viridis explained 25% of the total variation of the integrated pollution patterns in seawater, sediments and mussels. The present study suggested that the dynamic change of trace organics could be reflected by the response on lysosomal integrity in P. viridis, which was recommended as a routine screening biomarker in monitoring of harbour water quality across seasons.     

Chemical and ecotoxicological assessment of polycyclic aromatic hydrocarbon--contaminated sediments of the Niger Delta, Southern Nigeria

The extent of environmental contamination and sources of polycyclic aromatic hydrocarbons (PAHs) compounds to sediments of the Niger Delta, Nigeria were assessed using combined chemical analysis and toxicity bioassay techniques. Concentrations of two- to six-ring PAHs of molecular mass 128-278 and toxicity to Vibrio fischeri and Lemna minor are considered in this investigation. Levels of the sum of the 16 USEPA priority pollutant PAHs varied from 20.7 to 72.1 ng/g dry weight. Sediment PAH levels were highest in samples collected from Delta Steel located at the outskirts of Warri, and Quality control centre, Ughelli West; with total PAH concentrations of 72.1 and 67.5 ng/g dry weight, respectively. The overall levels of PAHs in this study are low compared to other regions and reveal moderate PAHs pollution in the sediments of the Niger Delta. Two- and three-ring aromatic hydrocarbons predominated in almost all the sediments, which indicate a petrogenic origin. The sediment total PAH (PAHtot) concentration, normalized to organic carbon content (OC), ranged from 120.2 to 1.99 ng PAHtot/mg OC; and showed distinctively that the sedimentary organic matter of the sample from Delta Steel is highly contaminated with PAHs, and had a value of 120.2 ng PAHtot/mg OC. The toxicity bioassays indicated that the sample collected from Warri Refinery Area (SDWRR) was the most toxic to V. fischeri, with an EC50 value of 0.45 mg sediment equiv./mL test medium; and samples from Ogunu (SDOGN) and Warri Refinery area (SDWRR) showed high toxicity to L. minor, with percent inhibitions of 42.6% and 33.67%, respectively, after 7 days of exposure. The total PAH concentrations showed no correlation with toxicity bioassays, and thereby implied that chemical analysis of PAHs cannot be an indicator of sediment toxicity.     

Influence of acid volatile sulfides and simultaneously extracted metals on the bioavailability and toxicity of a mixture of sediment-associated Cd, Ni, and Zn to polychaetes Neanthes arenaceodentata

Laboratory microcosm experiments were conducted to investigate the influence of acid volatile sulfides (AVS) and simultaneously extracted metals (SEM) in sediments on the bioavailability and toxicity of Cd, Ni, and Zn in sediments to polychaete worms Neanthes arenaceodentata. Cohorts of juvenile N. arenaceodentata were exposed to sediments spiked with metal mixtures containing Cd, Ni, and Zn (0.5-15 micromol x g(-1) of total SEM) with Low- (approximately 1 micromol x g(-1)), Medium- (approximately 5 micromol x g(-1)), and High-AVS concentrations (approximately 10 micromol x g(-1)) for 20 days to determine mortality, growth rate, and metal bioaccumulation. Tissue Cd and Zn concentrations at the end of the exposure were significantly higher in sediments with the low-AVS concentration at a given SEM concentration due to the increased dissolved metal concentrations in overlying water (OW). However, tissue Ni concentrations were not related to dissolved Ni in the OW. AVS concentrations also influenced the toxicity of metals to the worms. Significant mortality was observed only at the highest SEM treatments at Low-AVS series. Most individuals survived at the highest SEM treatments at Medium- and High-AVS series. Similarly, the growth rates of worms were reduced in treatments having higher molar differences between SEM and AVS ([SEM-AVS]). Overall, the bioavailability and toxicity of metals in sediments was not well predicted by sediment metal concentrations only, but considering the influence of geochemical factors (AVS) on the metal bioavailability improved the prediction of toxicity. Also, the relationship between tissue metal concentration and toxicity was used to determine which contaminant was most responsible for the observed toxicity of the metal mixture.     

Distribution of linear alkylbenzenes (LABs) in riverine and coastal environments in South and Southeast Asia

This paper reports the result of sewage pollution monitoring conducted in South and Southeast Asia during 1998-2003 using linear alkylbenzenes (LABs) as molecular tracers of sewage contamination. Eighty-nine water samples collected from Malaysia, Vietnam, and Japan (Tokyo), and 161 surface sediment samples collected from Tokyo, Thailand, Malaysia, Philippines, Vietnam, Cambodia, Indonesia, and India were analyzed for alkylbenzenes. The concentration range of SigmaLABs in river water particles in Southeast Asia (<0.005-0.913 microg/L) was comparable to or higher than those found in Tokyo (<0.005-0.638 microg/L). I/E ratios (a ratio of internal to external isomers of LABs) in tropical Asian waters were close to the value of LABs in raw sewage ( approximately 1) and much lower than those in secondary effluents (3-5). This suggests that untreated or inadequately treated sewage is discharged into the water. SigmaLABs concentrations in sediments from South and Southeast Asia ranged from <0.002-42.6 microg/g-dry with the highest concentration occurring at several populous cities. Low I/E ratios of the sediments with high SigmaLABs concentrations suggest a heavy load of untreated sewage. Clearly in view of the current data and evidence of the implications of sewage pollution, this paper highlights the necessity of the continuation of water treatment system improvement in tropical Asia.     

Natural and anthropogenic inputs of hydrocarbons to the Strait of Georgia

Sediment cores from the Fraser estuary, Vancouver Harbour and Strait of Georgia, suspended sediment samples from the Fraser River and sediment grabs from Vancouver Harbour have been analyzed for alkanes and parent and alkyl PAHs (polycyclic aromatic hydrocarbons). Principal components analysis (PCA) clearly distinguishes mixed sources by separating parent PAHs according to molecular size, and separating alkyl substituted PAHs from higher plant PAHs. We find the Fraser River to be the predominant source for natural and anthropogenic hydrocarbons to the Strait of Georgia. The natural hydrocarbon burden from the Fraser River is augmented principally by petroleum hydrocarbons and combustion PAHs from Vancouver. Contaminated sediments from Vancouver Harbour very likely have also been transported to a major ocean disposal site off the Fraser estuary. Petroleum alkanes, which dominate Fraser River suspended sediment samples, are lost by processes such as dissolution or microbial degradation during transport and sedimentation, while PAHs from the river are delivered essentially unchanged to sediments in the strait. Hydrocarbon composition undergoes little change with depth at a reference location in the Strait of Georgia, indicating that PAH inputs have changed very little since the early part of this century. In Vancouver Harbour the low rate of sediment accumulation coupled with surface mixing has led to the retention of contaminant PAHs within the surface mixed layer, while the rapid delivery of sediments from the Fraser River has buried contaminant PAHs from historical ocean disposal in the Strait of Georgia.     

Polycyclic aromatic hydrocarbons in nearshore marine sediments of Australia.

The occurrence and fate of polycyclic aromatic hydrocarbons (PAH) in nearshore marine sediments of Australia is discussed. Available information indicates that PAH are accumulating in the sediments and organisms of estuaries and harbours with both highly urbanized/industrialized and non-urban catchments. PAH levels in polluted sediments are similar to those of grossly polluted areas of Japan, North America and Europe, however PAH sources cannot be identified from the information available. PAH appear to persist in reducing environments, while in relatively pristine environments that have been previously exposed to PAH, conditions are probably favourable for the aerobic degradation of PAH by microorganisms.