Tiered aquatic ecological risk assessment of organochlorine pesticides and their mixture in Jiangsu reach of Huaihe River, China

Global occurrence of pyrethroid insecticides in sediment and the associated toxicological effects on benthic invertebrates: An overview

Pyrethroids are the third most applied group of insecticides worldwide and are extensively used in agricultural and non-agricultural applications. Pyrethroids exhibit low toxicity to mammals, but have extremely high toxicity to fish and non-target invertebrates. Their high hydrophobicity, along with pseudo-persistence due to continuous input, indicates that pyrethroids will accumulate in sediment, pose long-term exposure concerns to benthic invertebrates and ultimately cause significant risk to benthic communities and aquatic ecosystems. The current review synthesizes the reported sediment concentrations of pyrethroids and associated toxicity to benthic invertebrates on a global scale. Geographically, the most studied area was North America, followed by Asia, Europe, Australia and Africa. Pyrethroids were frequently detected in both agricultural and urban sediments, and bifenthrin and cypermethrin were identified as the main contributors to toxicity in benthic invertebrates. Simulated hazard quotients (HQ) for sediment-associated pyrethroids to benthic organisms ranged from 10.5±31.1 (bifenthrin) to 41.7±204 (cypermethrin), suggesting significant risk. The current study has provided evidence that pyrethroids are not only commonly detected in the aquatic environment, but also can cause toxic effects to benthic invertebrates, and calls for better development of accurate sediment quality criteria and effective ecological risk assessment methods for this emerging class of insecticides.

pH-dependent ecological risk assessment of pentachlorophenol in Taihu Lake and Liaohe River

Pentachlorophenol (PCP) has been reported toxic to aquatic organisms, and it frequently occurs at relatively high concentrations in most Chinese waters due to the re-emergence of schistosomiasis since 2003. Several studies about Water Quality Criteria (WQC) for PCP had been performed to protect the aquatic ecosystem, but in most of these studies the toxicity data were not properly analyzed (e.g. screening and processing methods). Moreover, little study was carried out on the ecological risk assessment (ERA) based on environmental factors. In this study, through collecting published native toxicity data of PCP along with relationships between toxicity and pH, pH-dependent WQC was established using a standardized scientific statistical method in China. The Criterion Maximum Concentration (CMC) and Criterion Continuous Concentration (CCC) were expressed as a function of pH. These were (1) CMC = exp(1.361×pH-8.034) and (2) CCC = exp(1.361×pH-10.434). At pH 7.8, the derived CMC and CCC were 13.21 and 1.20μg/L, respectively. In addition, four tiers of the ERA were conducted based on pH for different waterbodies at different seasons. In tiered 1, 2, 3 and 4 ERA, PCP exposure concentrations were standardized to that at pH 7.8. Results showed that all levels of ERA method in the tiered framework were consistent with each other, and the risks of PCP in Liaohe river of wet season, Taihu lake and Liaohe river of dry season increased successively. The Hazard quotient (HQ) method indicated that small fluctuations in pH would lead to misleading hazard results. PCP concentrations of 8.66μg/L at pH 7.37 in one site posed more risk than PCP of 9.57μg/L at pH 7.93 in another site. The joint probability suggested that ecological risks may exist 11.84% in the dry season and 1.51% in the wet season in Liaohe River, and 4.98% in Taihu Lake, respectively while 5% thresholds (HC₅) were set up to protect aquatic organisms. We hope this work could provide more information to manage and control PCP pollution in Taihe Lake and Liaohe River.

HCHs and DDTs in Yellow River of Henan section-a typical agricultural area in China: levels, distributions and risks

The levels, potential sources and ecological risks of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in Yellow River of Henan section, a typical agricultural area in China, were investigated. Surface water samples and suspended particulate matters (SPMs) were collected from 23 sites during two seasons. In wet season, the residues of ∑HCHs (α-HCH, β-HCH, γ-HCH and δ-HCH) and ∑DDTs (p,p'-DDT, o,p'-DDT, p,p'-DDE, p,p'-DDD) ranged from 41.7 to 290 and 4.42 to 269 ng/L in surface water, while those varied from 0.86 to 157 and 1.79 to 96.1 ng/g dw in SPM, respectively. Moreover, in surface water, the levels of HCHs and DDTs in wet season were much higher than those in dry season. The reverse was true for residues of HCHs and DDTs in SPM. Compared with the large rivers in other regions, the levels of HCHs and DDTs in the studied area ranked at high levels and the residual concentrations might cause adverse biological risk, especially for ∑HCHs during wet season. Distributions of HCHs and DDTs delineated that the input of tributaries made a significant effect on the residue of HCHs and DDTs in the mainstream. ∑HCHs in surface water were consist of 26.7 % α-HCH, 30.0 % β-HCH, 37.9 % γ-HCH and 5.45 % δ-HCH and those in SPM contained 5.16 % α-HCH, 22.1 % β-HCH, 60.5 % γ-HCH and 12.2 % δ-HCH on average. Combined with ratios of α-HCH/γ-HCH in surface water (0.70) and in SPM (0.09), the results strongly indicated that lindane was recently used or discharged in the studied area. The mean percentage of DDTs' isomers were 28.7 % p,p'-DDT, 29.8 % o,p'-DDT, 28.1 % p,p'-DDE and 13.4 % p,p'-DDD in surface water, while those were 12.5 % p,p'-DDT, 31.8 % o,p'-DDT, 30.5 % p,p'-DDE and 25.1 % p,p'-DDD in SPM. The ratios of (DDE + DDD)/∑DDTs and o,p'-DDT/p,p'-DDT revealed that the DDTs in the studied area mainly derived from long-term weathering of technical DDTs residue and the input of dicofol.

Occurrence and ecological risks from fipronil in aquatic environments located within residential landscapes

This study investigated the occurrence of fipronil and its metabolites in aquatic environments in residentially-developed landscapes, including five canals and three retention ponds. Fipronil was detected at four of the sites, with concentrations of 0.5-207.3 ng L(-1). Fipronil sulfone and fipronil sulfide were detected at three sampling sites, with concentrations ranging from 0.46 to 57.75 and 0.40-26.92 ng L(-1), respectively. Multiple risk assessment methods were performed to characterize potential ecological risks, including deterministic screening and probabilistic risk assessment techniques. The deterministic method indicated no risk to certain biotic groups (i.e. aquatic plants, fish, molluscs, and algae-moss-fungi), but did indicate risks to larval insects and crustaceans. Results from the probabilistic risk assessment indicated significant ecological risks (acute and chronic) ranging from 0.75 to 58.9% and 3.9-35.0% when organisms were exposed to the maximum and median concentrations detected, respectively. The potentially affected fraction of species (PAF) likely to be acutely impacted ranged from 4.6 to 8.1% (fipronil), 0.2-1.6% (fipronil sulfone), and 1.9-3.1% (fipronil sulfide) in the ponds with frequent detectable concentrations. The PAF likely to be impacted at chronic toxicity levels ranged from 16.5 to 23.8% for fipronil. Joint probability curve analysis indicated that concentrations exceeded the LC50 of the most sensitive 5% of species 8.5-18.8% of the time at two of the sites with the most frequent detections. Using the more conservative NOEC/LOEC values, there was a 75-78% probability that concentrations were high enough to negatively affect the most sensitive 5% of species at the same two sites, indicating significant risks for chronic toxicity. JPCs indicated a ≤2.6% probability of fipronil sulfone exceeding the LC50 concentrations for the most sensitive 5% of species at the same two sites; and a 4.3-6.8% probability of fipronil sulfide exceeding the LC50 concentrations at the same sites. Results indicate that fipronil and its sulfone and sulfide degradation products may present significant risks to aquatic organisms in some residentially-developed areas.

Screening of high phytotoxicity priority pollutants and their ecological risk assessment in China's surface waters

The protection of aquatic plants has received less attention in ecological risk assessment of pollutants compared with animals. Some pollutants like herbicide, however, are more toxic to aquatic plants than to animals. Aquatic toxicity data of 126 priority pollutants were screened and analyzed in this study. Through data analysis, five priority pollutants namely 1,1,1-trichloroethane (1,1,1-TCA), 4-nitrophenol (4-NP), butylbenzyl phthalate (BBP), di-n-butyl phthalate (DBP) and N-nitrosodimethylamine (NDMA) were identified to have high phytotoxicity effect. The most sensitive aquatic plants to these five pollutants are all alage, including Chlamydomonas reinhardtii, Pseudokirchneriella subcapitata, Gymnodinium breve. The water quality criteria concentration of the five pollutants were derived by the species sensitivity distribution method. The acute criteria concentration for the five pollutants were derived to be 1474, 2180, 54.41, 98.52 and 520.4 μg L(-1), and the chronic criteria concentration for them were 147.4, 218.0, 5.441, 9.852 and 52.04 μg L(-1), respectively. For China's freshwater bodies, the results of ecological risk assessment based on the derived criteria showed that, for the selected pollutants except DBP, there were basically no significant risk in most of the studied water bodies. DBP showed apparent ecological risks in all of the studied water bodies, particularly in the middle Yellow River, the Xuanwu Lake, the Yuehu Lake, etc. Field monitoring data of the Liao River and the Taihu Lake showed that DBP had moderate risks in some of the sampling sites of both the watersheds, while BBP posed moderate risks only on a few sites of the Liao River.

Probabilistic ecological risk assessment of copper in Chinese offshore marine environments from 2005 to 2012

The objective of the present study was to conduct a probabilistic assessment of risk posed by copper found in the coastal marine environment of China from 2005 to 2012. This was achieved by applying a tiered ecological risk assessment (ERA) approach for characterization of risks of concentrations of copper from nationwide marine water monitoring program. The results show that from 2005 to 2012 the overall trend of hazard quotients (HQs) in the coastal marine environment of China the proportion of locations that exceed a HQ of 1.0 decreased from 64% in 2005 to 31% in 2012. While this indicates an overall improvement of the environment, there still have potential ecological risks in the most of the area, especially for the major gulfs of Liaodong and Bohai Bays and Yellow River Estuary. In addition, probabilities of exceeding the toxicity threshold for 5% of species were 27.6%, 5.4%, 4.9%, 0.8%, 0.4%, 1.0%, 1.8% and 0.12% annually between 2005 and 2012, respectively.

Application of species sensitivity distribution in aquatic probabilistic ecological risk assessment of cypermethrin: a case study in an urban stream in South China

A tiered ecological risk assessment was applied to quantitatively refine the overall probabilistic risk of cypermethrin, a pyrethroid insecticide, to aquatic organisms. These results were then validated through the bioassays using field water from an urban stream, Chebei Creek in Guangzhou, South China. Seventeen water samples were collected along Chebei Creek for evaluation. In total, 71% of the field waters were acutely toxic to Hyallela azteca and 24% of the waters caused 100% mortality. Toxic unit evaluation suggested that cypermethrin was one of the main contributors to toxicity. The tiered ecological risk assessment approach (deterministic quotient method and probabilistic methods, including joint probability curve and Monte Carlo Simulation) suggested that cypermethrin posed significant threats to aquatic ecology in this stream. The overall probabilistic risk of cypermethrin to aquatic species in Chebei Creek reached 66% when acute-to-chronic ratios were set at 125. An exceedance probability of cypermethrin in Chebei Creek that affected H. azteca as modeled using the joint probability curve method was 88%, suggesting that most sites were at risk due to cypermethrin exposure. This value was similar to the results obtained from acute toxicity tests (71% of field water samples were acutely toxic to H. azteca), indicating the effectiveness of the tiered approach to assess risk of cypermethrin in urban waterways. To the authors' knowledge, the present study is the first to provide a focused probabilistic evaluation of ecological risk for cypermethrin in a complex urban waterway environment. Despite uncertainties existing in the ecological risk assessment procedure, this approach provides a comprehensive assessment of ecological risk of cypermethrin, and subsequently, a foundation for further risk diagnosis and management in urban waterways.

Perfluoroalkyl substances and organochlorine pesticides in sediments from Huaihe watershed in China

Twelve perfluoroalkyl substances (PFASs) and nine organochlorine pesticides (OCPs) were quantified in surface sediments from the Huaihe River, China, along which there are intensive industrial and agricultural activities. Concentrations of PFASs ranged from 0.06 to 0.46ng/g dry weight (dw), and concentrations of OCPs ranged from 1.48 to 32.65ng/gdw. Compared with other areas in China, concentrations of PFASs were lesser than the national mean value, while concentrations of OCPs were moderate. Concentrations of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) ranged from n.d. (not detected) to 0.03 and n.d. to 0.10ng/gdw, respectively. Among the three groups of OCPs, mean concentrations of hexachlorocyclohexane and its isomers (HCHs), dichlorodiphenyltrichloroethane and its metabolites (DDTs) and hexachlorobenzene (HCB) were 5.62±4.35, 2.43±3.12 and 1.55±4.17ng/gdw, respectively. Concentrations of HCHs and DDTs decreased from upstream to downstream along the mainstream of the Huaihe River. When compared to sediment quality guidelines (SQGs), concentrations of HCHs, DDTs and HCB would pose adverse biological effects. In general, contamination by PFASs in the upstream of the Huaihe River was more severe than that in the downstream, which was mainly caused by interception from dams, locks and industrial emissions. And OCPs from tributaries, especially the Yinghe River and Wohe River, were higher than those from Huaihe mainstream, and primarily came from historical inputs.

A cross-omics toxicological evaluation of drinking water treated with different processes

Cross-omics profiling and phenotypic analysis were conducted to comprehensively assess the toxicities of source of drinking water (SDW), effluent of conventional treatment (ECT) and effluent of advanced treatment (EAT) in a water treatment plant. SDW feeding increased body weight, and relative liver and kidney weights of mice. Hepatic histopathological damages and serum biochemical alterations were observed in the mice fed with SDW and ECT, but EAT feeding showed no obvious effects. Transcriptomic analysis demonstrated that exposure to water samples caused differential expression of hundreds of genes in livers. Cluster analysis of the differentially expressed genes which generated by both microarrays and digital gene expression showed similar grouping patterns. Proteomic and metabolomics analyses indicated that drinking SDW, ECT and EAT generated 59, 145 and 41 significantly altered proteins in livers and 8, 2 and 0 altered metabolites in serum, respectively. SDW was found to affect several metabolic pathways including metabolism of xenobiotics by cytochrome P450 and fatty acid metabolism. SDW and ECT might induce molecular toxicities to mice, but the advanced treatment process can reduce the potential health risk by effectively removing toxic chemicals in drinking water.

Identification of thyroid receptor ant/agonists in water sources using mass balance analysis and monte carlo simulation

Some synthetic chemicals, which have been shown to disrupt thyroid hormone (TH) function, have been detected in surface waters and people have the potential to be exposed through water-drinking. Here, the presence of thyroid-active chemicals and their toxic potential in drinking water sources in Yangtze River Delta were investigated by use of instrumental analysis combined with cell-based reporter gene assay. A novel approach was developed to use Monte Carlo simulation, for evaluation of the potential risks of measured concentrations of TH agonists and antagonists and to determine the major contributors to observed thyroid receptor (TR) antagonist potency. None of the extracts exhibited TR agonist potency, while 12 of 14 water samples exhibited TR antagonistic potency. The most probable observed antagonist equivalents ranged from 1.4 to 5.6 µg di-n-butyl phthalate (DNBP)/L, which posed potential risk in water sources. Based on Monte Carlo simulation related mass balance analysis, DNBP accounted for 64.4% for the entire observed antagonist toxic unit in water sources, while diisobutyl phthalate (DIBP), di-n-octyl phthalate (DNOP) and di-2-ethylhexyl phthalate (DEHP) also contributed. The most probable observed equivalent and most probable relative potency (REP) derived from Monte Carlo simulation is useful for potency comparison and responsible chemicals screening.

Probabilistic ecological risk assessment of polycyclic aromatic hydrocarbons in southwestern catchments of the Bohai Sea, China

A probability risk assessment was undertaken to study the individual and combined ecological risks induced by six polycyclic aromatic hydrocarbons (PAHs) both in surface water and sediment from southwestern catchments of the Bohai Sea, China. The actual measured PAH concentrations in water and sediment were compared with toxicity effect data (the 10th percentile of predicted no effect concentration) to calculate the risk quotients (RQs) for an individual PAH. The equilibrium partitioning method was applied to estimate toxicity data in sediment. A method based on the equivalent concentration concept was proposed and applied to assess the combined ecological risk of multiple PAHs. Monte Carlo simulation and bootstrap technique were utilized to calculate the distribution of RQs and associated uncertainties. The ecological safety level was defined by RQ ≤ 1. Results indicated that both in water and sediment, fluoranthene and pyrene posed the highest risks, whereas acenaphthene and fluorene posed negligible risks. Naphthalene and phenanthrene did not pose risks to the ecological community in surface water but had relatively higher risks in sediment. The median RQs of combined risk in surface water and sediment were 0.934 and 2.42, and the probabilities of RQ > 1 were up to 0.473 and 0.599, respectively, which were much higher than the individual compound acting alone. The risk level in sediment was quite higher than in surface water probably owing to the non-equilibrium distribution between two phases, which suggested that local authorities should focus more on sediment quality management.

Perfluorinated compounds and organochlorine pesticides in soils around Huaihe River: a heavily contaminated watershed in Central China

Perfluorinated compounds (PFCs) and organochlorine pesticides (OCPs) were analyzed in surface soils along the Huaihe River. Sixteen target PFCs and nine OCPs were quantified in soils from a region of intensive industrial and agricultural development. Concentrations of PFCs and OCPs ranged from less than the limit of detection (LOD) to 1.22 ng/g and 3.63 to 227 ng/g, respectively. Contamination by OCPs was more serious than that of PFCs, which was consistent with the fact that OCPs were widely used in agriculture of the district while there was no known production or application of PFCs in the study area. The predominant PFCs in soils were PFOA and PFOS with concentrations that ranged from <LOD to 0.20 ng/g and <LOD to 0.21 ng/g, respectively. Among the three groups of OCPs, average concentrations of HCHs, DDTs, and HCB were 4.7, 23.7, and 1.4 ng/g, respectively. Results of principal component analysis revealed relatively weak associations between concentrations of PFCs and those of OCPs, while concentrations of OCPs exhibited similar patterns of distributions. Among the mainstream and five tributaries, the highest concentrations of PFCs were observed along the Pihe River, while the highest concentrations of OCPs occurred along the Xifeihe River. In general, concentrations of PFCs were evenly distributed, while those of OCPs exhibited relatively greater spatial differences.

The pollution and ecological risk of endosulfan in soil of Huai'an city, China

Endosulfan, a persistent organic pollutant newly listed under the Stockholm Convention, is currently widely produced and used as a pesticide in China. Concentrations of endosulfans (including α-, β-isomers, and their metabolite endosulfan sulfate) were determined in surface soil collected from Huai'an city, where the largest endosulfan producer is located. The concentrations of Σendosulfan (sum of α-endosulfan, β-endosulfan, and endosulfan sulfate) at all sites ranged from 0.28 to 44.81 ng/g dry weight (dw), following a lognormal distribution. The geometric mean was 1.09 ng/g dw, and the geometric standard deviation was 3.02. The β-endosulfan levels were consistently greater than those of α-isomer. The concentration ratios of α-endosulfan to β-endosulfan ranged from 0.03 to 0.70, which were much lower than the commercial endosulfan mixture. This is because that α-endosulfan is more volatile and degrades faster than β-endosulfan in soil. The contour map of Σendosulfan levels in soil indicates that the factory was the point pollution source with the highest endosulfan level in its surrounding area, especially the southern area. However, the non-point agricultural sources are more important. Based on Monte Carlo simulation, the Σendosulfan inventory in soil in Huai'an is estimated to be 0.8-3.0 tons. In order to understand the potential ecological risk of endosulfan, the Monte Carlo-based hazard quotient distribution was estimated and showed that Σendosulfan posed a potentially high risk to soil organisms. To our knowledge, this study is the first that reports soil pollution and risk of endosulfan around the manufacturer in China. This study will help China's implementation of Stockholm Convention for the reduction and elimination of endosulfan in future.

A tiered ecological risk assessment of three chlorophenols in Chinese surface waters

INTRODUCTION

The ecological risks posed by three chlorophenols (CPs), 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP), and pentachlorophenol (PCP) in Chinese surface waters were assessed.

MATERIALS AND METHODS

This was achieved by applying a tiered ecological risk assessment (ERA) approach ranging from deterministic methods to probabilistic options to measured concentrations of CPs in surface water of seven major watersheds and three drainage regions in China and the chronic toxicity data for indigenous Chinese species.

RESULTS AND DISCUSSION

The results show that the risks of three chlorophenols are ranked PCP>2,4-DCP≈2,4,6-TCP. PCP posed little ecological risk while 2,4-DCP and 2,4,6-TCP posed negligible or de minimis risk in Chinese surface water. However, the risks varied with different river basins, for example, PCP posed some ecological risk in the Yangtze, Huaihe, and Pearl Rivers. The magnitude of 2,4-DCP and 2,4,6-TCP pollution in North China was more serious than that in South China.

CONCLUSION

The probabilistic risk assessment approach, which can provide more information for risk managers and decision makers, was favored over the screening-level single-value estimate method. However, the results from all tiers of the ERA methods in the framework were consistent with each other.

Estimating chemical emissions from home and personal care products in China

China's economy has grown significantly and concomitantly so has the demand for home and personal care (HPC) products. The detection of chemicals used in HPC products is increasing in profile as China strives to improve its environmental management. China is developing robust exposure models for use in regulatory risk-based assessments of chemicals, including those chemicals used in HPC products. Accurate estimates of chemical emissions play an important role within this. A methodology is presented to derive spatially refined emissions from demographic and economic indicators with large variations in emissions calculated, showing product usage being higher in East and South China. The less affordable a product, the greater the influence per capita Gross Domestic Product has on the product distribution. Lastly, more spatially resolved input data highlights greater variation of product use. Linking product sales data with population density increased the observed variability in absolute usage distribution of HPC products at the county > province > regional > country scale.

Combined toxicity of three chlorophenols 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol to Daphnia magna

The toxicity of single and combined mixtures of 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP), and pentachlorophenol (PCP) to Daphnia magna was studied. The toxicity ranking of these three single chlorophenols (CPs) to Daphnia magna was PCP > 2,4-DCP > 2,4,6-TCP. The toxic units (TU) approach was used to estimate the combined effects in experiments, the median effective concentration (EC(50)) values were 0.87-1.21 and 0.46-0.59 for binary and ternary mixtures, respectively. Response surface models of General Linear Models (R(2) > 0.90, residual deviation < 3.25) were established for all three binary mixtures. The toxicity for ternary mixtures based on the EC(50)-value and 10% effective concentration (EC(10))-value fixed mixture ratio presented a synergism. The risk based on the single CP's toxicity test may be underestimated. In addition, four approaches (concentration addition, toxicity equivalency factors, effect summation, and independent action) were used for the calculation of combined effects of the mixture. The experimental results showed that concentration addition and toxicity equivalency factor approaches were effective methods for calculation of additive effects of mixtures from binary systems of CPs; while independent action and effect summation (low simulated tail) predicted lower toxicity than experimental results. Limitations of the traditional focus on the effects of single agents were highlighted; hazard assessments ignoring the possibility of joint action of CPs will almost certainly lead to significant underestimations of risk.

China's water pollution by persistent organic pollutants

Available data were reviewed to assess the status of contamination by persistent organic pollutants (POPs), including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), in drinking water sources and coastal waters of China. The levels of POPs in China's waters were generally at the high end of the global range. A comparison of China's regulatory limits indicated that PCBs in rivers and coastal water may pose potential human health risk. Occurrence of DDTs in some rivers of China may also pose health risk to humans using the regulatory limits of DDTs recommended by the European Union. Future monitoring of POPs in China's waters should be directed towards analytes of concern (e.g. PCBs and PCDD/Fs) and to fill data gaps for analytes (e.g. PBDEs, PCDD/Fs, and chlordane) and in watersheds/regions (e.g. West China) where data are scarce.

Probabilistic ecological risk assessment for three chlorophenols in surface waters of China

Individual and combined assessment of risks of adverse effects to aquatic ecosystems of three chlorophenols (CPs), including 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP) and pentachlorophenol (PCP), were conducted. A probabilistic approach based on the concentrations of CPs in surface waters of China was used to determine the likelihood of adverse effects. The potential risk of CPs in surface waters of China was determined to be of concern, especially PCP and mixtures of CPs. The risks of adverse effects were examined as the joint probabilities of exposure and response. The joint probability for PCP was 0.271 in the worst case and 0.111 in the median case, respectively. Based on the cumulative probability, 5% of aquatic organisms included in the assessment would be affected 21.36% of the time in the worst case and 5.99% of the time in median case, respectively. For the mixtures of CPs, the joint probability were 0.171 in the worst case and 0.503 in median case, respectively and 5% of species would be affected 49.83% of the time for the worst case and 12.72% in the median case, respectively. Risks of effects of the individual CPs, 2,4-DCP and 2,4,6-TCP were deemed to be acceptable with a overlapping probability of < 0.1 with 5% of species being affected less than 4% of the time.

Residues of organochlorine pesticides (OCPs) in upper reach of the Huaihe River, East China

Residues of HCHs and DDTs in surface water and suspended particulate matter (SPM) from upper reach of the Huaihe River, East China, were investigated. Levels of total HCHs (∑HCH) and total DDTs (∑DDT) in water detected by GC-ECD ranged from 0.85 to 12.77 ng L⁻¹ and from 3.54 to 33.59 ng L⁻¹, respectively. According to European and America water quality guidelines, HCHs were within safe levels while DDT would pose adverse biological effects. Distribution of OCPs in water indicated that input of tributaries was important factor for the Huaihe River. For OCPs in SPM, concentrations varied from 1.01 to 25.22 ng g⁻¹ for ∑HCH and not detected to 4.74 ng g⁻¹ for ∑DDT. Compared with sediment quality guidelines, HCHs and DDTs might have an ecological risk. The main reason for OCPs residues in the Huaihe River was usage of lindane and technical DDT. Furthermore, composition of DDTs reflected fresh inputs of dicofol mixture in some sites.

Emission inventory for PFOS in China: review of past methodologies and suggestions

Perfluorooctane sulfonate (PFOS) is a persistent, bioaccumulative, and toxic chemical that has the potential for long-range transport in the environment. Its use in a wide variety of consumer products and industrial processes makes a detailed characterization of its emissions sources very challenging. These varied emissions sources all contribute to PFOS' existence within nearly all environmental media. Currently, China is the only country documented to still be producing PFOS, though there is no China PFOS emission inventory available. This study reviews the inventory methodologies for PFOS in other countries to suggest a China-specific methodology framework for a PFOS emission inventory. The suggested framework combines unknowns for PFOS-containing product penetration into the Chinese market with product lifecycle assumptions, centralizing these diverse sources into municipal sewage treatment plants. Releases from industrial sources can be quantified separately using another set of emission factors. Industrial sources likely to be relevant to the Chinese environment are identified.

Probabilistic risk assessment of common booster biocides in surface waters of the harbours of Gran Canaria (Spain)

The presence of booster biocides in the aquatic environment has been associated with a risk to non-target species due to their proven toxicity. The aim of the present study was to determine the spatial and temporal distribution of common booster biocides in different harbours of the island of Gran Canaria (Spain) and evaluate, by means of a probabilistic risk assessment (PRA), the ecological risk posed by these compounds. With these objectives, a monitoring campaign was conducted between January 2008 and May 2009, collecting a total of 182 seawater samples. Four common booster biocides (TCMTB, diuron, Irgarol 1051 and dichlofluanid) were monitored. Diuron levels ranged between 2.3 and 203 ng/L and Irgarol 1051 between 2.4 and 146.5 ng/L. The ecological risk associated with these levels was always low, however, with probabilities of exceeding the 10th percentile of autotroph toxicity below 3.5%.

Determination and aquatic risk assessment of pesticide residues in riparian drainage canals in northeastern Greece

An approach combining monitoring and ecotoxicological data has been undertaken to assess pesticide loading in the drainage canals of two transboundary rivers of northeastern Greece near the Greek/Bulgarian/Turkish borders as well as the subsequent risk to non-target aquatic organisms. Aquatic risk assessment was based on the Risk Quotient (RQ=MEC/PNEC) regarding three trophic levels, algae, aquatic invertebrates and fish. Alachlor, atrazine, carbaryl, carbofuran, cypermethrin, DEA, DIA, diazinon, dimethoate, endosulfan, metolachlor, monilate, prometryn and trifluralin were the compounds detected at the highest concentrations on a regular basis. Extreme concentrations were observed just after high rainfall events during the month of pesticide application. Aquatic risk assessment revealed non-acceptable risk for 10 compounds when median concentrations were used as ΜEC values. However, should extreme concentrations be taken into account, 15 compounds were considered as likely to pose a threat to aquatic organisms. Conformity to EC environmental quality standards is also discussed.

Polycyclic aromatic hydrocarbons and ecotoxicological characterization of sediments from the Huaihe River, China

The distribution, source, ecological risk and ecotoxicity of polycyclic aromatic hydrocarbons (PAHs) of sediments from 7 sampling sites, named as Xinyang (XY), Huainan (HN), Bengbu (BB), Xuyi (XuY), Fuyang (FY), Mengcheng (MC) and Zhengzhou (ZZ), in the Huaihe River basin, China, have been investigated. The total concentrations of 16 USEPA priority PAHs ranged from 62.9 to 2232.4 ng g⁻¹ dry weight (d.w.) with a mean concentration of 1056.8 ng g⁻¹ d.w. Through the assessment of ecological risk, we found that the levels of PAHs in the Huaihe River should not exert adverse biological effects. The total benzo[a]pyrene toxicity equivalent (TEQ) values calculated for samples varied from 0.01 to 194.1 ng g⁻¹ d.w., with an average of 65.9 ng g⁻¹. The toxicity data were accordant with the chemical analysis results in this study. HN, BB and ZZ showed the greatest pollution extent both in the chemical analysis and the study of ecotoxicological effects.

Probabilistic ecological risk assessment of DDTs in the Bohai Bay based on a food web bioaccumulation model

The fugacity-based food web model was developed to simulate the bioaccumulation of dichloro-diphenyl-trichloroethanes (DDTs) in the aquatic ecosystem in the Bohai Bay. The internal exposure levels (IELs) of DDTs in various organism categories were calculated. Monte Carlo-based uncertainty analysis was performed to get the of IEL distributions of DDTs in organisms. Probabilistic ecological risk assessment (ERA) was performed based on IEL distributions and internal species sensitivity distributions (SSDs). The results show that fugacities and bioaccumulation factors (BAFs) generally increased with increasing trophic level in the food web. Octanol-water partition coefficient (K(ow)), DDT levels in water and the lipid contents had the greatest influences on IELs in the organism bodies. The ecological risks of DDTs were relatively high. The risk order was p,p'-DDT>p,p'-DDE>p,p'-DDD. At an internal hazard quotient (HQ(int)) criterion of 1/5, the risk probabilities were 0.10 (0.055-0.17), 0.079 (0.045-0.13) and 0.053 (0.028-0.092) for p,p'-DDT, p,p'-DDE and p,p'-DDD, respectively. The results from ERA based on the internal exposure approximated those based on external exposure. The food web model is a feasible method to predict the extent of bioaccumulation and IELs of hydrophobic organic pollutants in organisms as a step to evaluate their risk posed on aquatic ecosystems.