Dynamic modelling of aquatic exposure and pelagic food chain transfer of cyclic volatile methyl siloxanes in the Inner Oslofjord

The marine fate and pelagic food chain transfer of three cyclic volatile methyl siloxanes (cVMS: D4, D5 and D6) was explored in the Inner Oslofjord, Norway, using two dynamic models (the Oslofjord POP Model and the aquatic component of ACC-HUMAN). Predicted concentrations of D4, D5, and D6 in the water column were all less than current analytical detection limits, as was the predicted concentration of D4 in sediment (in agreement with measured data). The concentrations predicted for D5 and D6 in sediment were also in broad agreement with measured concentrations from the Inner Oslofjord. Volatilisation was predicted to be the most important loss mechanism for D5 and D6, whereas hydrolysis was predicted to dominate for D4. Concentrations of all three compounds in sediment are controlled by burial below the active mixed sediment layer. The marine food web model in ACC-HUMAN predicted “trophic dilution” of lipid-normalised cVMS concentrations between zooplankton and herring (Culpea harengus) and between herring and cod (Gadus morhua), principally due to a combination of in-fish metabolism and reduced gut absorption efficiency (as a consequence of high K_OW). Predicted D5 concentrations in herring and cod agree well with measured data from the inner fjord, particularly when measured concentrations in zooplankton were used to set the initial dissolved-phase aqueous concentrations. Predicted concentrations of D4 and D6 in fish were over- and under-estimated by the model – possibly due to extrapolation of the metabolism rate constant from D5.     

Determination of cyclic volatile methylsiloxanes in water,sediment, soil,biota, and biosolid using large-volume injection–gas chromatography–mass spectrometry

Several methods were developed to detect the cyclic volatile methylsiloxanes (cVMSs) including octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) in water, sediment, soil, biota, and biosolid samples. Analytical techniques employed to optimize measurement of this compound class in various matrices included membrane-assisted solvent extraction in water, liquid–solid extraction for sediment, soil, biota, and biosolid samples. A subsequent analysis of the extract was conducted by large-volume injection–gas chromatography−mass spectrometry (LVI−GC−MS). These methods employed no evaporative techniques to avoid potential losses and contamination of the volatile siloxanes. To compensate for the inability to improve detection limits by concentrating final sample extract volumes we used a LVI–GC–MS. Contamination during analysis was minimized by using a septumless GC configuration to avoid cVMS’s associated with septum bleed. These methods performed well achieving good linearity, low limits of detection, good precision, recovery, and a wide dynamic range. In addition, stability of cVMS in water and sediment was assessed under various storage conditions. D4 and D5 in Type-I (Milli-Q) water stored at 4 °C were stable within 29 d; however, significant depletion of D6 (60–70%) occurred only after 3 d. Whereas cVMS in sewage influent and effluent were stable at 4 °C within 21 d. cVMS in sediment sealed in amber glass jars at −20 °C and in pentane extracts in vials at −15 °C were stable during 1 month under both storage conditions.     

An examination of the physical properties,fate, ecotoxicity and potential environmental risks for a series of propylene glycol ethers

Propylene glycol ethers (PGEs) are comprised of mono-, di- and tri-PGEs and several of their acetate esters. The nature of the range of applications that use PGEs suggests that there is a potential for both intentional and unintentional entry of the materials into the environment. Selected physical/chemical properties, fate characteristics, aquatic toxicity data and calculated environmental concentrations were used to assess potential risks from the manufacture, handling, use, and disposal of PGEs. In general, the PGEs are low to moderately volatile, have high aqueous solubilities, low octanol-water partition coefficients (Kow), and bioconcentration factor values of <10, which indicate they are unlikely to accumulate in aquatic food chains. Both abiotic and biological degradation processes reduce environmental concentrations of PGEs. In air, vapor-phase PGEs react with photo-chemically produced hydroxyl radicals and have half-lives ranging from 5.5 to 34.4 h. A variety of ready and inherent biodegradation test methods, as well as tests that simulate biodegradation in wastewater treatment plants, surface water and soil have been conducted on PGEs. Significant aerobic biodegradation was generally observed, with a range of biodegradation half-lives on the order of 5-25 d. Acute aquatic toxicity studies with PGEs resulted in LC50 values ranging from approximately >100 to >20,000 mg/l for freshwater fish, the pelagic invertebrate Daphnia magna, green algae Selenastrum capricornutum (now called Pseudokirchneriella capricornutum) and bacteria. Level 3 multi-media modeling (EQC model of Mackay) was used to simulate regional-scale concentrations of PGEs in air, soil, water, and sediment. Toxicity thresholds were then compared with regional-scale water, soil and sediment concentrations to determine hazard quotients. Based upon this analysis, concentrations of PGEs are unlikely to pose adverse risks to the environment.     

Chemical fate,latitudinal distribution and long-range transport of cyclic volatile methylsiloxanes in the global environment: A modeling assessment

Cyclic volatile methylsiloxanes (cVMS) such as octamethycyclotetrasiloxane (D4), decamethycyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) are widely used as intermediates in the synthesis of high-molecular weight silicone polymers or as ingredients in the formulation of personal care products. The global environmental fate, latitudinal distribution, and long range transport of those cVMS were analyzed by two multimedia chemical fate models using the best available physicochemical properties as inputs and known persistent organic pollutants (POPs) and highly persistent volatile organic chemicals (“fliers”) as reference. The global transport and accumulation characteristics of cVMS differ from those of typical POPs in three significant ways. First, a large fraction of the released cVMS tends to become airborne and is removed from the global environment by degradation in air, whereas known POPs have a tendency to be distributed and persistent in all media. Secondly, although cVMS can travel a substantial distance in the atmosphere, they have little potential for deposition to surface media in remote regions. This contrasts with a deposition potential of known POPs that exceeds that of cVMS by 4–5 orders of magnitude. Thirdly, cVMS have short global residence times with the majority of the global mass removed within 3 months of the end of release. Global residence times of POPs on the other hand are in years. The persistent fliers resemble the cVMS with respect to the first two attributes, but their global residence times are more like those of the POPs.     

Cyclic volatile methylsiloxanes in fish from the Baltic Sea

Laboratory studies suggest that the cyclic volatile methylsiloxanes (cVMS) octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6) will persist in the aquatic environment and bioaccumulate in fish. Here these cVMS were measured in herring collected in the Swedish waters of the Baltic Sea and the North Sea and in grey seals from the Baltic Proper. D4, D5, and D6 were present in herring muscle at concentrations around 10, 200, and 40 ng g⁻¹ lipid weight, respectively. The ratio of these concentrations was similar to the relative magnitude of estimated emissions to water, suggesting that the efficiency of overall transfer through the environment and food web was similar (within a factor 2–3) for the three chemicals. The concentrations of D5 and D6 were similar in herring caught in the highly populated Baltic Proper and in the less populated Bothnian Sea and Bothnian Bay. The D4 concentrations were lower at the most remote northern station, suggesting that D4 is less persistent than D5 and D6. Herring from the North Sea had lower levels of all three chemicals. The concentrations of D4, D5 and D6 in grey seal blubber were lower than the lipid normalized concentrations in herring, indicating that they do not biomagnify in grey seals.     

Concentrations of cyclic volatile methylsiloxanes in biosolid amended soil,influent, effluent,receiving water,and sediment of wastewater treatment plants in Canada

A comprehensive surveillance program was conducted to determine the occurrence of three cyclic volatile methylsiloxanes (cVMS) octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) in environmental compartments impacted by wastewater effluent discharges. Eleven wastewater treatment plants (WWTPs), representative of those found in Southern Ontario and Southern Quebec, Canada, were investigated to determine levels of cVMS in their influents and effluents. In addition, receiving water and sediment impacted by WWTP effluents, and biosolid-amended soil from agricultural fields were also analyzed for a preliminary evaluation of the environmental exposure of cVMS in media impacted by wastewater effluent and solids. A newly-developed large volume injection (septumless head adapter and cooled injection system) gas chromatography – mass spectrometry method was used to avoid contamination originating from instrumental analysis. Concentrations of D4, D5, and D6 in influents to the 11 WWTPs were in the range 0.282–6.69 μg L⁻¹, 7.75–135 μg L⁻¹, and 1.53–26.9 μg L⁻¹, respectively. In general, wastewater treatment showed cVMS removal rates of greater than 92%, regardless of treatment type. The D4, D5, and D6 concentration ranges in effluent were <0.009–0.045 μg L⁻¹, <0.027–1.56 μg L⁻¹, and <0.022–0.093 μg L⁻¹, respectively. The concentrations in receiving water influenced by effluent, were lower compared to those in effluent in most cases, with the ranges <0.009–0.023 μg L⁻¹, <0.027–1.48 μg L⁻¹, and <0.022–0.151 μg L⁻¹ for D4, D5, and D6, respectively. Sediment concentrations ranged from <0.003–0.049 μg g⁻¹ dw, 0.011–5.84 μg g⁻¹ dw, and 0.004–0.371 μg g⁻¹ dw for D4, D5, and D6, respectively. The concentrations in biosolid-amended soil, having values of <0.008–0.017 μg g⁻¹ dw, <0.007–0.221 μg g⁻¹ dw, and <0.009–0.711 μg g⁻¹ dw for D4, D5, and D6, respectively, were lower than those in sediment impacted by wastewater effluent in most cases. In comparison with the no-observed-effected concentrations (NOEC) and IC50 (concentration that causes 50% inhibition of the response) values, the potential risks to aquatic, sediment-dwelling, and terrestrial organisms from these reported concentrations are low.     

An environmental fate, exposure and risk assessment of ethylene oxide from diffuse emissions

Ethylene oxide (EO) is mainly used as a chemical intermediate and as a fumigant and sterilizing agent. Through its manufacturing and intended uses, EO may be released into the environment. Therefore, an assessment of the environmental significance of those potential emissions was conducted. Data were collected describing pertinent physical properties, degradation and other loss mechanisms that control the fate of EO in the environment. Available aquatic and terrestrial ecotoxicity data were assembled and used as the basis of calculating critical toxicity values to characterize hazard. Environmental compartment concentrations of EO were calculated using Level III fugacity-based modeling. Six scenarios were developed to account for different climatic conditions in various portions of the US. Finally, potential regional-scale risks to aquatic and terrestrial wildlife were determined. In the conceptual model that was developed in this assessment, EO diffuses into air, partitions between environmental compartments, is transported out of the different compartments via advection, and undergoes abiotic and biological degradation within each compartment. All known emissions within the continental USA were assumed to enter a modeled region roughly the size of the State of Ohio. Organisms (receptors) were assumed to dwell in both terrestrial and aquatic compartments. Receptors were assumed to include small mammals, soil invertebrates, water column (pelagic) organisms, and sediment benthos. The goal of this assessment was to characterize any potential adverse risks to terrestrial and aquatic wildlife populations. Hazard Quotients (HQ) were calculated by dividing predicted concentrations of EO in air, water, sediment, and soil by their critical toxicity values. Maximum calculated HQ values in air were 1.52x10(-7), in water were 1.17x10(-5), in sediment were 2.25x10(-4), and in soil were 1.37x10(-5). The results of this assessment suggest that EO as currently manufactured and used does not pose adverse risks to aquatic or terrestrial wildlife. In all cases, the HQ values were much less than the maximum desired HQ value of 1.0 (4,400-6,600,000 times), indicating that the potential for diffuse emissions of EO to pose adverse environmental risks is quite low.     

Positive vs. false detection: A comparison of analytical methods and performance for analysis of cyclic volatile methylsiloxanes (cVMS) in environmental samples from remote regions

Contamination and analytical variation can significantly hinder trace analysis of cyclic methyl volatile siloxanes (cVMS); potentially resulting in the report of false positives at concentrations approaching detection limits. To assess detection and variation associated with trace cVMS analysis in environmental matrices, a co-operative laboratory comparison for the analysis of octametylcyclotetrasiloxane (D4), decamethylcylcopentasiloxane (D5), and dodecametylcyclohexasiloxane (D6) in sediment and biota from the Svalbard Archipelago was conducted. Two definitions of detection limits were evaluated in this study; method detection limits (MDL, matrix defined) and limits of detection (LOD, solvent defined). D5 was the only cVMS detected above both LOD (0.08–0.81 ng g⁻¹ ww) and MDL (0.47–2.36 ng g⁻¹ ww) within sediment by all laboratories where concentrations ranged from 0.55 to 3.91 ng g⁻¹ ww. The percentage of positive detects for D5 decreased by 80% when MDL was defined as the detection limit. D5 was also detected at the highest frequency among all laboratories in fish liver with concentrations ranging from 0.72 to 345 ng g⁻¹ ww. Similar to sediment, percentage of positive detects for D5 decreased by 60% across all laboratories for fish livers when using MDL (0.68–3.49 ng g⁻¹ ww). Similar observations were seen with both D4 and D6, indicating that sample matrix significantly contributes to analytical response variation. Despite differences in analytical methods used between laboratories, good agreement was obtained when using MDL to define detection limits. This study shows the importance of incorporating variation introduced by sample matrices into detection limit calculations to insure data accuracy of cVMS at low concentrations.     

Fate, effects and potential environmental risks of ethylene glycol: a review

The fate, effects, and potential environmental risks of ethylene glycol (EG) in the environment were examined. EG undergoes rapid biodegradation in aerobic and anaerobic environments (approximately 100% removal of EG within 24 h to 28 days). In air, EG reacts with photo-chemically produced hydroxyl radicals with a resulting atmospheric half-life of 2 days. Acute toxicity values (LC(50)s and EC(50)s) were generally >10,000 mg/l for fish and aquatic invertebrates. The data collectively show that EG is not persistent in air, surface water, soil, or groundwater, is practically non-toxic to aquatic organisms, and does not bioaccumulate in aquatic organisms. Potential long-term, quasi-steady state regional concentrations of EG estimated with a multi-media model for air, water, soil, and sediment were all less than predicted no effect concentrations (PNECs).     

Bioaccumulation of decamethylcyclopentasiloxane in perch in Swedish lakes

Decamethylcyclopentasiloxane (D5), a high production volume chemical used in personal care products, enters the environment both via air and sewage treatment plant (STP) recipients. It has been found in fish, and there is concern that it may be a bioaccumulative substance. In this work D5 was analyzed in perch from six Swedish lakes that did not receive STP effluent, and in perch and sediment from six lakes that received STP effluent. In the lakes receiving the STP effluent, the D5 concentrations in sediment varied over three orders of magnitude and were correlated with the number of persons connected to the STP normalized to the surface area of the receiving body. In the lakes not receiving effluent, the D5 levels in perch were all below the LOQ, while D5 was above the LOQ in almost all perch from lakes that received effluent. The D5 concentrations in perch and sediment from the lakes receiving STP effluent were correlated. This shows that STP effluent is a much more important source of D5 to aquatic ecosystems than atmospheric deposition, and that the risk of adverse effects of D5 on aquatic life will be greatest in small recipients receiving large amounts of STP effluent. The bioaccumulation of D5 was compared to that of PCB 180 on the basis of multimedia bioaccumulation factors (mmBAFs), which describe the fraction of the contaminant present in the whole aquatic environment (i.e. water and surface sediment) that is transferred to the fish. In four of the six lakes the mmBAF of D5 was >0.3 of the mmBAF of PCB 180. Given that PCB 180 is a known highly bioaccumulative chemical, this indicates that the bioaccumulation of D5 in perch is considerable.     

Assessing inter-laboratory comparability and limits of determination for the analysis of cyclic volatile methyl siloxanes in whole Rainbow Trout (Oncorhynchus mykiss)

Cyclic volatile methyl siloxanes (cVMS) are high volume production chemicals used in a wide range of industrial and consumer products. Three cVMS compounds (D4, D5, and D6) have and are undergoing environmental risk evaluations in several countries and have been proposed for legal regulation in Canada. As interest in monitoring concentrations of these chemicals in the environment increase, there is a need to evaluate the analytical procedures for cVMS in biological matrices in order to assess the quality of data produced. The purpose of this study was to determine laboratory testing performance for measuring residues of D4, D5, and D6 in a standard set of fish homogenate samples and to estimate limits of determination for each substance. The samples sent to each laboratory consisted of homogenized whole body tissues of hatchery raised rainbow trout which were fed food fortified with D4, D5, and D6 (dosed) and trout that were fed standard food rations (control). The participants analyzed each sample using their analytical method of choice using their own standards and procedures for quantification and quality control. With a few exceptions, participating laboratories generated comparable results for D4, D5, and D6 in both the dosed and control samples having z-scores between 2 and −2. Method detection limits for the whole fish matrix were on average 2.4 ng g⁻¹ ww for D4, 2.3 ng g⁻¹ ww for D5, and 1.8 ng g⁻¹ ww for D6.     

Human intake of PCDDs, PCDFs, and dioxin like PCBs in Japan, 2001 and 2002

PCDDs, PCDFs, and dioxin like PCBs (dioxin) surveillance results derived from regular environmental monitoring as well as other dioxin surveys by national and local governmental bodies in Japan were collected and analyzed. Several thousand data for air and soil in fiscal year 2001 (from 01/04/2001 to 31/03/2002) and 2002, water (from the sea, rivers and lakes), sediment (from the sea, rivers and lakes), ground water, aquatic organisms, purified water from water purification plants, raw water from water purification plants, human breast milk, and human blood in fiscal 2001, and total diet study (TDS) and various kinds of foodstuff in fiscal 1998-2002 were collected. Average human uptake of dioxin in Japan in fiscal 2001 was estimated at 1.68 pg-TEQ/kg-bw/day, while uptake in fiscal 2002 was estimated at 1.52 pg-TEQ/kg-bw/day. Diet accounted for more than 90% of the total intake. Contributions of inhalation and soil ingestion were relatively small. Age-group-specific contribution of various foodstuff to total dietary intake was also estimated. The estimates of intake through fish and shellfish accounted for approximately 45-70% of total dietary intake in each age group. Monte Carlo simulation was conducted, using the data of the air and soil concentrations in fiscal 2001 and the total diet study data in fiscal 1998-2001, in order to obtain information on the variability of dioxin intake; The estimated average, median, 5th percentile and 95th percentile of the intake distribution were 1.78, 1.69, 0.95 and 2.91 pg-TEQ/kg-bw/day, respectively. This study found that the average total intake estimates in Japan in both fiscal 2001 and 2002 were estimated to be below tolerable daily intake level (TDI) defined by the Ministry of Health, Labour and Welfare, Japan (i.e. 4 pg-TEQ/kg-bw/day). The 95th percentile of the dioxin intake distributions estimated with Monte Carlo simulation using the data of the air and soil concentrations in fiscal 2001 and TDS data in fiscal 1998-2001 was also below the Japanese TDI.     

Simulating the temporal changes of OCP pollution in Hangzhou, China

A dynamic fugacity model was applied to simulate the changes of contents and transfer fluxes of hexachlorocyclohexane (HCHs) and dichloro-diphenyl-trichloroethane (DDTs) from 1950s in the environment of Hangzhou, China. The receptors are composed of air, surface water, soils, sediment and biota compartments. The model provides a method to combine loadings of HCHs and DDTs from various sources with a series of physical-chemical processes to estimate concentrations and transport fluxes of HCHs and DDTs. Model results suggested that the calculated concentrations were in line with the observed ones. The highest contents of HCH and DDT in the environment of study area were 523 t and 471 t before 1983, among which about 80.7% HCHs and 93.2% DDTs remained in the soil compartment. From 1984 to now, contents of HCHs and DDTs had decreased to about 0.07% and 0.40% of their highest amount (before 1983), and only about 0.001% and 0.014% will expect to be left in 2020 in the study area according to the model prediction. Before 1983, the main transfer fluxes of HCHs were deposition from air to soil, runoff from soil to water and diffusion from soil to air, but for DDTs the main transfer fluxes were deposition from air to soil and water, and transfer from water to sediment. From 1984 to now, runoff from soil to water and transfer from water to sediment became the dominant processes. Although a large amount of HCHs and DDTs had been applied to the study area, their residue levels in the soils were much lower than those in North China (had lesser HCHs and DDTs application than in South China) at present time, and close to other locations of South China (had similar HCHs and DDTs application level). It can be attributed to the high precipitation and temperature that enhances the processes of wet deposition, evaporation and degradation of OCPs. Sensitivities of the input parameters to the calculated concentrations were evaluated using coefficient-of-variation normalized sensitivity coefficients. The model was also subjected to uncertainty analyses using a Monte Carlo simulation.     

杀虫剂十氯酮的多介质环境行为模拟

应用EQC模型模拟十氯酮在多介质环境中的归宿和迁移通量.结果表明:土壤是十氯酮最大的贮存库,在稳态平衡条件下,残留率达到95.0%;在稳态非平衡条件下,十氯酮单独排放到水体,有37.5%残留在于排放的水体中,其在大气的浓度水平和质量分布均很低,在沉积物中的质量则来自于水体向沉积物的沉降迁移;十氯酮主要通过水体的水平迁移和土壤的厌氧降解输出;十氯酮的主要界面迁移过程是大气向土壤的迁移,其次是水体向沉积物的沉降和大气向水体的迁移.     

Uncertainty analysis using a fugacity-based multimedia mass-balance model: Application of the updated EQC model to decamethylcyclopentasiloxane (D5)

The EQuilibrium Criterion (EQC) model developed and published in 1996 was recently revised to include improved treatment of input partitioning and reactivity data, temperature dependence and an easier sensitivity and uncertainty analysis. This New EQC model was used to evaluate the multimedia, fugacity-based fate of decamethylcyclopentasiloxane (D5; CAS No. 541-02-6) in the environment over a temperature range of 1–25 °C. In addition, Monte Carlo uncertainty analysis was used to quantitatively determine the influence of temperature and input partitioning and reactivity data on the behavior of D5 under various emission scenarios. Results indicated that emission mode was the most influential factor determining the fate and distribution of D5 in the model environment. When emitted to air and soil, D5 partitioned to and remained in the air compartment where rates of removal from degradation and advection processes were relatively rapid. In contrast, D5 emitted to water resulted in a substantial mass fraction of D5 being accumulated in the sediment compartment, where rates of removal from degradation and advection processes were slow. The mass distributions and fate of D5 in the model environment were strongly influenced by multiple input parameters, including temperature, the mode of emission (especially emission rate to water), K_OC and half-life in air. As temperature decreased from 25 °C to 1 °C, K_OC and half-life in air became increasingly more influential such that the mass distribution of D5 increased in air and decreased in sediment, resulting in decreased overall persistence.     

Concentrations,atmospheric partitioning,and air–water/soil surface exchange of polychlorinated dibenzo-p-dioxin and dibenzofuran along the upper reaches of the Haihe River basin,North China

Polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/PCDF) were overall measured and compared in ambient air, water, soils, and sediments along the upper reaches of the Haihe River of North China, so as to evaluate their concentrations, profiles, and to understand the processes of gas–particle partitioning and air–water/soil exchange. The following results were obtained: (1) The average concentrations (toxic equivalents, TEQs) of 2,3,7,8-PCDD/PCDF in air, water, sediment, and soil samples were 4,855 fg/m³, 9.5 pg/L, 99.2 pg/g dry weight (dw), and 56.4 pg/g (203 fg TEQ/m³, 0.46 pg TEQ/L, 2.2 pg TEQ/g dw, and 1.3 pg TEQ/g, respectively), respectively. (2) Although OCDF, 1,2,3,4,6,7,8-HpCDF, OCDD, and 1,2,3,4,6,7,8-HpCDD were the dominant congeners among four environmental sinks, obvious discrepancies of these congener and homologue patterns of PCDD/PCDF were observed still. (3) Significant linear correlations for PCDD/PCDF were observed between the gas–particle partition coefficient (K _p) and the subcooled liquid vapor pressure (P _L ⁰) and octanol–air partition coefficient (K _oa). (4) Fugacity fraction values of air–water exchange indicated that most of PCDD/PCDF homologues were dominated by net volatilization from water into air. The low-chlorinated PCDD/PCDF (tetra- to hexa-) presented a strong net volatilization from the soil into air, while high-chlorinated PCDD/PCDF (hepta- to octa-) were mainly close to equilibrium for air–soil exchange.     

Arsenic and mercury concentrations in major landscape components of an intensively cultivated watershed

To provide an understanding of arsenic (As) and mercury (Hg) concentrations in soil, sediment, water, and fish tissues, samples were collected from a Mississippi River alluvial floodplain located in northwest Mississippi. As concentrations increased approximately an order of magnitude from water (5.12 micrograms/l) to fish tissues (36.99 micrograms/kg) and an additional two orders of magnitude in soils, lake sediments, and wetland sediments (5728, 5614, and 6746 micrograms/kg), respectively. Average Hg concentrations in water, soils, lake sediments, and fish were 2.16 micrograms/l, 55.1, 14.5 and 125 micrograms/kg, respectively. As and Hg concentrations were within published ranges for uncontaminated soil, water, and sediments. As concentrations represented a low risk. Hg concentrations were also low but showed a greater tendency to concentrate in fish tissue. The dominant mode of entry of these materials into aquatic systems is through storm-generated runoff. Since both metals accompany sediments, agricultural conservation practices such as reduced tillage, buffer riparian strips, and bordering sediment ponds or drainage wetlands will minimize watershed input to aquatic systems.     

Pollution survey of polycyclic aromatic hydrocarbons in surface water of Hangzhou, China

The concentrations of 10 polycyclic aromatic hydrocarbons (PAHs) were simultaneously measured for five times (July and November 1999–2002) in four water bodies of Hangzhou, China. To investigate possible sources of PAH contamination, sediments, soils, runoff water and atmospheric particles of the region were also analyzed for their PAH contents. The maximum levels of PAHs in the water bodies (34.4–67.7 μg/l) were found in July, while significantly lower PAH concentrations (4.7–15.3 μg/l) were measured in November. The contamination is substantial and it may have resulted in acute toxic effects on aquatic organisms. The measured PAH concentrations in sediments and soils (224–4222 ng/g), runoff water (8.3 μg/l) and air particles (2.3 μg/m³) are discussed in relation to concentrations and patterns found in the surface water bodies. Comparison of PAH levels in sediments and soils led to the conclusion that the erosion of soil material does not contribute significantly to the contamination of sediments. The atmospheric PAH deposition to water bodies in the city area of Hangzhou was estimated to be 530 tons/a, while the contribution of surface runoff water was estimated to be 30.7 tons/a. The ratios of selected PAH were then used to illuminate the possible origin of PAHs in the examined samples (petrogenic, pyrogenic).     

Bioaccumulation, bioavailability and environmental fate of chlorophenol impurities, polychlorinated hydroxydiphenylethers and their methoxy analogues

The bioaccumulation potential and environmental fate of polychlorinated hydroxydiphenyl ethers (HO-PCDEs; polychlorinated phenoxyphenols, PCPP), the major impurities of chlorophenol formulations and their methoxy analogues (MeO-PCDEs; polychlorinated methoxyanisoles, PCPAs) were investigated. Oligochaete worms (Lumbriculus variegatus) exposed to sediment spiked with a model substance of one HO-hexaCDE (4'-HO-PCDE 161) or its methoxy analogue (4'-MeO-PCDE 161) clearly accumulated the test compounds revealing the potential for environmental risk of HO-PCDEs and MeO-PCDEs. The HO-PCDE tested has earlier been reported as an abundant component in a Finnish chlorophenol formulation (Ky-5) and its methoxy analogue is recognized as an abundant MeO-PCDE in sawmill soil contaminated by the formulation. The occurrence of 4'-HO-PCDE 161 and its methoxy analogue among other HO-PCDEs and MeO-PCDEs in lake mussels (Anodonta piscinalis) incubated in a river contaminated via the manufacture of Ky-5 showed that these compounds are bioavailable and transported in the aquatic environment. Mussel comparison with sediment data pointed to a higher accumulation potential for MeO-PCDEs than for HO-PCDEs. The finding of HO-PCDEs in groundwater samples collected from a groundwater reservoir, which had been contaminated by chlorophenols, points to potential of HO-PCDEs for transport with water in soil.     

Factors influencing organotin distribution in different marine environmental compartments, and their potential health risk

Tributyltin (TBT) and triphenyltin (TPT) in different marine environmental compartments such as seawater, sediments, and inshore fishes were investigated in 21 Taiwanese harbors between 2001 and 2004 in order to determine the major factors influencing their distribution. The existence of major input sources and the limited water exchange rate inside the harbors were indicated by higher TBT concentrations in seawater from inner harbor than from outer harbor areas. The levels of TBT in sediments were found to be mainly affected by their geographic distribution, water exchange rates and shipping activity. No significant correlations in TBT concentrations between water, sediment and fish suggested TBT accumulation by fish might not result from water and sediment, but from their food. TPT were detected in most fish samples, but found in few sediment samples and none in seawater, indicating fish could be as a target element for monitoring contaminated levels of TPT in the aquatic environment. Mean concentrations of TBT in fish muscle higher than tolerable average residue levels (TARLs), and mean hazard indices of TBT and TPT higher than 1 suggested consumption of fishes from Taiwanese harbor areas might have potential high risk to human health.