Historical deposition behaviors of organochlorine pesticides (OCPs) in the sediments of a shallow eutrophic lake in Eastern China: Roles of the sources and sedimentological conditions

Organochlorine pesticides (OCPs) were quantified in sediments from Lake Chaohu, a shallow eutrophic lake in Eastern China, to investigate their historical deposition behaviors and to reconstruct their use history. The OCP concentrations ranged from 2.17 to 18.61 ng g⁻¹ in the surface sediments in the lake region and from .28 to 86.27 ng g⁻¹ in the inflowing river. The highest values of the aforementioned variables were attributed to urban-industrial pollution sources in the west lake region and decreased with distance from the river inlets. Historically, OCP contamination displayed three stages in Lake Chaohu: an initial increase before the 1930s, a sharp increase until the 1980s, and a decrease due the implementation of policies banning their use in the 1980s. During the second stage, the OCP concentrations increased rapidly from .69, .58, 1.95 and .02 ng g⁻¹ in the C4, C5, C6 and C10 samples in the 1930s to 8.68, 61.89, 24.14 and 3.53 ng g⁻¹, respectively, in the early 1980s. This temporal trend of OCP concentrations corresponded with historically intense anthropogenic activities, indicating that contamination by OCPs was accompanied by industrialization and civilization prior to their prohibition. In addition, dichlorodiphenyltrichloroethane (DDT) contamination was derived from the historical use of technical DDTs, whereas hexachlorocyclohexane (BHC) contamination was attributed to the historical use of technical BHCs with Lindane and new inputs of illegal DDTs. Strong positive relationships between the OCP concentrations and the total organic carbon (TOC) concentrations, sediment grain sizes (<4 μm), nutrient contents and heavy metal contents indicated that the sedimentary conditions and human activities affected the depositional characteristics of the OCPs. The DDT residues and their metabolites, particularly those in the inlet rivers, should be of concern because they result in an ecotoxicological risk in the catchment of Lake Chaohu.     

Organochlorine Pesticides in Sediments around Chaohu Lake: Concentration Levels and Vertical Distribution

Eighteen organochlorine pesticides (OCPs) were investigated in surface sediments from the Nanfei River and in four sediment cores from the primary estuaries of Chaohu Lake, Eastern China. The results indicate that the OCP concentrations in the surface and core sediments around Chaohu Lake were 3.48–121.08 (with a mean of 34.93) ng/g and 0.60–39.28 (7.07) ng/g, respectively. Significantly higher concentrations of ΣOCPs were observed in sediment samples from the Nanfei River and its estuary. The three important OCP contributors around Chaohu Lake were dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), and hexachlorobenzene (HCB), which originated primarily from the historical use of technical DDTs and HCHs. A principal component analysis (PCA) suggests that HCB and lindane may originate from the same sources, and DDTs were greatly influenced by organic carbon from the soil environment and the impact of urbanization processes.     

Organochlorine pesticides in Cyprinus carpio from Sidi Salem Dam,north-western Tunisia

Cyprinus carpio (Linnaeus, 1758) caught in Sidi Salem Dam in 2011 were analysed for the levels of organochlorine pesticides (OCPs), including hexachlorobenzene (HCB), aldrin, heptachlor, lindane, dieldrin, endrin, and pp′-DDT and its two main metabolites pp′-DDD and pp′-DDE, in order to evaluate the extent of contamination of the dam. Fish were sampled monthly within the dam during 2011. Muscle, liver and gill tissues were analysed by gas chromatography for the determination of OCPs. Samples had variable concentrations of OCPs, ranging from 2.26 to 17.93 ng g?1, 0.59 to 42.67 ng g?1 and 3.30 to 84.27 ng g?1, which were isolated from gills, muscle and liver, respectively. The organochlorine pesticide levels found posed no threat to human health. The highest OCP levels were found in the liver tissues. The pp′-DDE concentrations and their ratios to ΣDDTs indicate aged DDT pollution and suggests that there has been no recent input of technical DDT from the agricultural areas into Sidi Salem Dam.     

巢湖表层水体中有机氯农药的分布及其组成

以固相萃取-气相色谱法/电子捕获检测器(SPE-GC/ECD)作为检测手段,对巢湖表层水体中有机氯农药(OCPs)的分布及组成特征进行分析.结果表明:研究区13个采样点中共检出包括六六六(HCHs)、滴滴涕(DDTs)、β-硫丹(β-Endosulfan)、艾氏剂(Aldrin)、六氯苯(hexachlorobenzene)和七氯(Heptachlor)在内的16种有机氯农药,其总含量范围为0.54～64.01ng.L-1;16种有机氯农药中以HCHs和DDTs为主,其平均质量浓度分别为5.56ng.L-1和16.57ng.L-1,约占其总量的84.75%;研究区的有机氯农药污染除了主要源于历史上农田中有机氯农药的残留外,近期可能还有新的农药污染源进入水环境;研究区所检出的各类有机氯农药均未超过国家地表水环境质量标准,巢湖表层水体中有机氯农药含量及潜在风险均属于中等偏低水平.     

Characterization,ecological and health risks of DDTs and HCHs in water from a large shallow Chinese lake

The levels of dichloro diphenyl trichloroethanes (DDTs) and hexachlorocyolohexanes (HCHs) in water from Lake Chaohu were measured. The residues, possible sources and potential ecological and health risks of these compounds were analyzed. The results show that the contents of total DDTs and HCHs in the water varied from 1.52 to 21.79 and from 1.58 to 31.66 ng L^− 1, respectively, which were higher than those in other Chinese lakes. The main sources of HCHs and DDTs were lindane and technical DDT, respectively. The o,p′-DDT/p,p′-DDT ratios indicated the new illegal inputs of DDT in all studied inflow rivers and some lake areas. The MOS10 (margin of safety) values suggested that the Lake was facing a potential ecological risks from p,p′-DDT, whereas the risk of γ-HCH was small. Both carcinogenic and noncarcinogenic risks of DDTs and HCHs associated with the water use were very low.     

Occurrence,distribution and possible sources of organochlorine pesticides in peri-urban vegetable soils of Changchun,Northeast China

The characterizations of residue levels and sources of organochlorine pesticides (OCPs) in soils are necessary to evaluate the potential pollution and risks of OCPs to the ecosystems and human health. A total of 51 surface soil samples were collected from peri-urban vegetable fields of Changchun and 13 OCPs were analyzed to learn the composition, spatial distribution and sources. The concentrations were in the ranges of 0.94–107.8 ng g^?1 for DDTs, 0.89–98.3 ng g^?1 for HCHs, 0.22–18.20 ng g^?1 for Chlordanes, nd–4.49 ng g^?1 for aldrin and nd–9.66 ng g^?1 for dieldrin, respectively. The total OCPs concentrations ranged from 2.44 to 177.1 ng g^?1 and the higher residues were mainly distributed in northeast and southwest sites, as well as sites along the Yitong River. According to the concentrations and detection frequencies, DDTs and HCHs were the most dominant compounds. Compositional analysis and principal component analysis suggested that DDT, HCH and chlordane in most soil samples derived from historical application except the slight fresh introduction at some locations. There exist a variety of OCPs residues in peri-urban vegetable soils of Changchun, but it is still safe and suitable for agricultural production for the most part, and some specific locations with high OCPs residues ought to be a cause for concern.     

The Health and Ecological Impacts of Organochlorine Pesticide Pollution in China: Bioaccumulation of Organochlorine Pesticides in Human and Fish Fats

The levels of organochlorine pesticides (OCPs) in the environment and foods have declined significantly in China since 1983, the year when their use in agriculture was officially banned. The levels today of these contaminants in soil, water, and agricultural products are well below 50 μg/kg in many parts of China. Yet in spite of such a decline, the current levels of pollution still pose a significant health risk to many people in China because OCPs are highly persistent and bioaccumulative substances. This preliminary study was conducted to monitor the levels of hexachlorocyclohexane (HCH) and dichloro-diphenyl-trichloroethane (DDT) in human and fish fats from southeast China in an effort to corroborate the above health concern. The data reconfirmed that pollution by HCH and DDT, which are the major components of OCPs, is a serious ecological problem in the study region, and likely in other parts of China as well. The HCH contents in the human samples were between 0.25 and 2.20 mg/kg, with an average of 0.90 mg/kg. The DDT contents in these human samples were much higher, between 0.54 and 9.22 mg/kg with an average of 3.50 mg/kg. The major isomers found in the human samples were β-HCH and p, p′-DDE, representing 94.9 to 99.5% of total HCH and 72.3 to 96.7% of total DDT, respectively. The HCH and DDT content in the grass carp samples averaged 0.03 and 0.67 mg/kg, respectively. The levels of bioaccumulation reflected in these human and fish samples were considered substantial, particularly when residents in the study region continue to be exposed to the OCPs remaining so persistently in their environment. It is therefore important for the health authorities to launch a large-scale investigation into the potential health and ecological impacts of OCP pollution in China. The data also suggested that the current national standards might need to be lowered for the levels of OCPs in the environment in China.     

Associations among organochlorine pesticides, Methanobacteriales, and obesity in Korean women

Background

Although Methanobacteriales in the gut has recently been linked to obesity, no study has examined the hypothesis that waist circumference, a marker of visceral obesity, are positively associated with Methanobacteriales in the general population. Since Methanobacteriales increase in a petroleum-contaminated environment to biodegrade petroleum as one way of autopurification, we also hypothesized that high body burden of highly lipophilic petroleum-based chemicals like organochlorine pesticides (OCPs) is associated with higher levels of Methanobacteriales in the gut.

Methodology/Principal Findings

Among 83 Korean women who visited a community health service center for a routine health checkup, quantitative real-time PCR (qPCR) based on 16S rDNA was used to quantify Methanobacteriales in feces. Nine OCPs were measured in both serum and feces of 16 subjects. Methanobacteriales were detected in 32.5% (27/83 women). Both BMI and waist circumference among women with Methanobacteriales were significantly higher than in women without Methanobacteriales (P = 0.04 and P = 0.01, respectively). Also, Methanobacteriales levels in feces were positively associated with BMI and waist circumference (r = +0.23 and P = 0.03 for both). Furthermore, there were significant correlations between feces Methanobacteriales levels and serum concentrations of most OCPs, including with cis-nonachlor (r = +0.53, P<0.05), oxychlordane (r = +0.46, P<0.1), and trans-nonachlor (r = +0.43, P<0.1). Despite high correlations of serum and feces concentrations of most OCPs, feces OCP concentrations were not clearly associated with feces Methanobacteriales levels.

Conclusion/Significance

In this cross-sectional study, the levels of Methanobacteriales in the human gut were associated with higher body weight and waist circumference. In addition, serum OCP concentrations were positively correlated with levels of Methanobacteriales. There may be a meaningful link among body burden of OCP, Methanobacteriales in the gut, and obesity in the general population.     

The Need for Strategic Environmental Assessment of Fishery Products Regulations in the Taiwan Strait: Taking Health Perspectives of Organochlorine Pesticides in Seafood as an Example

This article proposes an integrated Health Impact Assessment/Strategic Environmental Assessment (HIA/SEA) framework that can be applied to fishery products regulations in Taiwan Strait. In recent years, many studies with regards to organochlorine pesticides (OCPs), especially DDT and its derivatives, in Taiwan's environment and aquatic biota indicated that DDT, DDD, and DDE in seafood, especially oysters, in the Kinmen, Manchu area near China's Fu-Tzien Province, had relatively high concentrations. It was discussed that this may be caused by distribution of OCPs in China's vicinity. In this study, the concentration of DDT, DDD, and DDE reported by many researchers in the last two decades were compared and analyzed. The concentrations of these three chemicals were found to be as high as hundreds of ng/g-dw in seafood produced in Kimmen and Machu near China, whereas those for seafood caught in Taiwan's coastal areas were not significant. The need for trade agreements or regulations on fishery was then discussed. According to the viewpoints of health and environmental sustainability, HIA methodologies were incorporated in the SEA to help identify and analyze the potential impacts on human health caused by OCPs in seafood consumed in Taiwan, which may be caused by the lack of trade regulation mechanisms between Taiwan and China. The integrated HIA-SEA framework for fishery trade agreements or regulations in Taiwan was thus proposed and the procedures were discussed. It is anticipated that the health of Taiwan's residents can be protected through implementing this and the human health perspective can be emphasized in the HIA-SEA procedures.     

Ecological Risk Assessment of DDT Accumulation in Aquatic Organisms of Taihu Lake,China

DDT (Dichlorophenyltrichloroethane) is a toxic, ubiquitous, and persistent bioaccumulative pollutant in the global environment. Although its use as an insecticide has been banned in China since 1983, residual DDT levels in the Taihu Lake are evident. Aimed at the protection of fish resources, three species of high-value fish in the Taihu Lake (Protosalanx hylocranius (Abbott), Salangichthys tangkahkeii (Wu), and Coilia nasus Temminck et Schlegel) were selected and an ecological risk assessment was used to estimate the DDT threats to fish populations. Based on a food web model, a bioaccumulation model was used to estimate the DDT concentration in zooplankton, benthos, and fish and the Monte Carlo (MC) simulation method was used to analyze the uncertainty in the bioaccumulation process. Then the chronic toxicity dose-response relationship of DDT on the Protosalanx hyalocranius (Abbott) population, estimated by ICE and ACE software, was used to calculate the mortality rates in different fish stages with the DDT concentrations. Last, the demographic modeling (Leslie matrix) was used to assess the ecological risk of DDT damage on the Protosalanx hyalocranius (Abbott) population. The results show that the estimated DDT concentrations in benthos and zooplankton were 0.14–16.56 μ g/kg, 2.15–99.30 μ g/kg, respectively. The fish DDT concentration results are a series of increasing curves and the maximal values reach 266, 101, and 211 μ g/kg for Protosalanx hylocranius (Abbott), Salangichthys tangkahkeii (Wu), and Coilia nasus Temminck et Schlegel, respectively. In the process of ecological risk quantization, a 4.06–7.25% reduction in the biomass of the Protosalanx hyalocranius (Abbott) population was estimated in 10,000 MC imulations and 4.21%, 4.89%, and 5.69% reductions were estimated in 75%, 50%, and 25% probability, respectively.     

Organochlorine contaminants in freshwater mussels; occurrence,bioaccumulation pattern,spatio-temporal distribution and human health risk assessment from the tributaries of River Ravi,Pakistan

The present study was conducted to investigate the bioavailable levels and human health risk of organochlorine contaminants (OCs), particularly organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in freshwater mussels from northern three tributaries of River Ravi, Pakistan that provides the pioneer data for the occurrence of POPs in the freshwater mussels from Pakistan. The Σ₂₃OCPs and Σ₃₅PCBs concentrations in mussels were ranged from 189.66–2049.40 ng/g and 25.81 to 135.38 ng/g, respectively. The comparison of current bioavailable levels of OCs with maximum residual limits (MRLs) established by Food and Agricultural Organization and European Union revealed that Σendosulfan (100%), ΣDDTs (93%), HCB (87%), β-HCH (77%), endrin (77%), γ-HCH (70%), heptachlor (67%), aldrin (67%), dielrin (67%), Chlordane (70%), α-HCH (40%), and WHO-TEQ (2005) values for PCB-126, PCB-169 and Σ₈DL-PCBs were exceeding the permissible limits. The human health risk assessment revealed the occurrence of substantial lifetime carcinogenic risk for OCPs and PCBs at both 50th and 95th percentile concentrations in freshwater mussels from the tributaries of River Ravi. Therefore, the freshwater mussels are recommended to be used in environmental toxicological studies to assess the bioavailable levels of pollution in hostile environment.     

Distribution Characteristics and Risk Assessments of PAHs in Fish from Lake Taihu,China

The concentrations of PAHs in four species of fish (Common carp, Crucian carp, Bighead carp, and Topmouth culter) from Lake Taihu were tested, and the human health risks of PAHs by fish consumption were evaluated. Results showed that concentrations of PAHs in fish from Lake Taihu were 52.5–247.6 ng/g wet weight (ww), and the BaP equivalent concentrations of total PAHs (B[a]P_eq) were 0.2–0.6 ng/g ww, which were less than the screening value of 2.6 ng/g wet for human consumption. The concentration sequences of PAHs in fish from Lake Taihu from high to low were Bighead carp > Crucian carp > Common carp > Topmouth culter. The human health risk level of PAHs by fish consumption was 5.8 ± 2.5 × 10^?6, which was less than the maximum acceptable risk level of 1 × 10^?5 for human health set by the U.S. Environmental Protection Agency. The tissue residue guideline (TRG) of PAHs for protecting aquatic wildlife was 1.3 mg/kg diet ww, which was higher than the concentrations of PAHs in fish from Lake Taihu. The results indicated that fish consumption from Lake Taihu would not cause health risk or harmful effects on wildlife that consume aquatic biota.     

PAHs,OCPs and PCBs in sediments from three catchments in Durban,South Africa

Polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were analysed from sediment samples collected in 2012 from rivers, surface runoff canals and estuaries in three highly urbanised catchments in durban, KwaZulu-Natal, South Africa. PAHs were ubiquitous, at concentrations between 36–6 800 ng g^?1 dry mass (dm). Congener ratio diagnosis suggests the PAHs were derived predominantly from pyrogenic sources. Four OCPs and/or their metabolites were detected at varying frequencies and concentrations. Of these, dichlorodiphenyltrichloroethane (ddT) and metabolites were most frequently detected and were at a high concentration in sediment in some systems. Toxaphene was detected at a high concentration at some sites. The total PCB concentration varied widely, from below the method detection limit to 110 ng g^?1 (dm). Based on the comparison of chemical concentrations to international sediment quality guidelines, PAH, OCP and PCB concentrations in most sediment samples posed a low risk to sediment-dwelling organisms. However, in some instances the risk was moderate or high. It is recommended that these compounds be monitored more frequently and comprehensively in aquatic ecosystems to better understand the ecological and human health implications.     

Ecological Risk Assessment of Organochlorine Pesticides in Surface Waters of Lake Taihu,China

The residues of organochlorine pesticides (OCPs) in surface waters from Meiliang Bay, Gonghu Bay, and Xukou Bay of Lake Taihu, China, were investigated, and their ecological risks were assessed using the risk quotient method and probabilistic risk assessment. Environmental concentrations of OCPs in surface water of these bays were relatively lower compared with other rivers or lakes in China. Calculation of risk quotient associated with taxonomic groups indicates moderate ecological risks from OCPs for crustaceans and insects in these bays, while the ecological risks were low for fish and negligible for phytoplankton. The ecological risk quotients associated with individual OCPs were lower than 0.01 in these bays, suggesting a negligible risk to aquatic organisms. Ecological risk from α-HCH was relatively lower compared with DDTs, endosulfans, and γ-HCH. The combined ecological risks were evaluated using probabilistic risk assessment for only eight OCPs owing to a lack of available toxicity data for β-HCH and δ-HCH. The percentage of species with the potential to be at risk from mixture of OCPs was lower than the criteria of 5% in each bay, indicating that the combined ecological risks were acceptable.     

TNF inhibits production of stromal cell-derived factor 1 by bone stromal cells and increases osteoclast precursor mobilization from bone marrow to peripheral blood

Introduction

The objective of the present study was to investigate the role of the stromal cell-derived factor 1 (SDF-1)/CXCR4 axis in TNF-induced mobilization of osteoclast precursors (OCPs) from bone marrow.

Methods

OCPs were generated from bone marrow cells of TNF-transgenic mice or wild-type mice treated with TNF or PBS. The percentage of CD11b⁺/Gr-1^-/lo OCPs was assessed by fluorescence-activated cell sorting. OCP migration to the SDF-1 gradient and the osteoclast forming potency were assessed in chemotaxis/osteoclastogenic assays. SDF-1 expression was assessed by real-time RT-PCR, ELISA and immunostaining in primary bone marrow stromal cells, in the ST2 bone marrow stromal cell line, and in bones from TNF-injected mice.

Results

OCPs generated in vitro from wild-type mice migrated to SDF-1 gradients and subsequently gave rise to osteoclasts in response to RANKL and macrophage colony-stimulating factor. TNF reduced SDF-1 expression by ST2 cells. Bone marrow stromal cells from TNF-transgenic mice produced low levels of SDF-1. TNF treatment of wild-type mice decreased the SDF-1 concentration in bone marrow extracts and decreased the SDF-1 immunostaining of bone marrow stromal cells, and it also increased the circulating OCP numbers. The percentage of bone marrow CXCR4⁺ OCPs was similar in TNF-transgenic mice and wild-type littermates and in TNF-treated and PBS-treated wild-type mice.

Conclusion

Systemically elevated TNF levels inhibit bone marrow stromal cell production of SDF-1 and increase the release of bone marrow OCPs to the peripheral blood. Disruption of the SDF-1/CXCR4 axis by TNF may play an important role in mediating OCP mobilization from the bone marrow cavity in chronic inflammatory arthritis.     

Pollution assessment of organochlorine pesticides in urban agricultural soils of Jilin City,China

The content, source, and pollution level of organochlorine pesticides (OCPs) in soils are necessary to assess potential risks to eco-environment and human health, and to target environment-friendly policies. A total of 50 surface soil samples were collected from urban vegetable fields of Jilin City and thirteen OCPs were analyzed. The concentrations were in the ranges of 3.16–48.35 ng·g^?1 for Dichloro-Diphenyl-Tricgloroethanes (DDTs, sum of o, p′-DDT, p, p′-DDT, p, p′-DDD, and p, p′-DDE), 4.37–44.77 ng·g^?1 for Hexachlorocyclohexanes (HCHs, sum of α-HCH, β-HCH, γ-HCH, and δ-HCH), 1.19–13.17 ng·g^?1 for Chlordanes (sum of heptachlor, t-chlordane, and c-chlordane), 0.24–2.60 ng·g^?1 for aldrin, and nd–3.43 ng·g^?1 for dieldrin, respectively. The different compositions indicated that the residues of DDTs and HCHs originated mainly from the historical application, while chlordanes were mostly from recent input. On the basis of soil quality standards of China and the Netherlands, DDTs and chlordanes in this study were categorized as light pollution, and HCHs were classified as no pollution for the majority of soil samples. There are a variety of OCPs residues in urban vegetable soils of Jilin City, but it is still safe and suitable for agricultural production.     

Histological assessment of selected tissues in tigerfish (Hydrocynus vittatus Castelnau, 1861) from the Sanyati Basin,Lake Kariba,Zimbabwe: a DDT-sprayed area

A pilot investigation was conducted in 2014 in the Sanyati Basin of Lake Kariba to ascertain whether long-term DDT spraying in the Kariba catchment had a negative effect on fish health. The aim was to assess the health of tigerfish, Hydrocynus vittatus, by means of histological analysis and to analyse water, sediment and tissue samples for bioaccumulated levels of chlorinated pesticides, including DDT. Eighteen tigerfish were collected by seine netting along the north-eastern shoreline of the Sanyati Basin in April 2014 and samples of their gill, liver, kidney, muscle and brain tissue were processed for histology and assessed using light microscopy. No detectable levels of DDT and/or its metabolites were found in the water or sediment samples and only a low concentration of p,p′-DDE in fish tissues. No major histological alterations were observed in the fish tissues. Consequently, there seems to be no risk of DDT exposure following the consumption of tigerfish from the Sanyati Basin of Lake Kariba. These results were unexpected, given the historical use of DDT within the current study area. It is recommended that these findings be compared with those from other regions of Lake Kariba.     

Historical record of human impact in a lake of northern China: Magnetic susceptibility,nutrients, heavy metals and OCPs

The historical record (1859–2011) of magnetic susceptibility, total organic carbon, total nitrogen, δ¹³C_org, δ¹⁵N, As, Cd, Hg, Pb, and organochlorine pesticide (OCP) signatures in Baiyangdian Lake was used to analyze the water environmental changes due to human activities. The results indicate the following: the status of the lake approaches the background condition in 1859–1950s; the lake suffered increasing anthropogenic effects from the 1950s because of increasing human activities such as coal-fired power plant operations since 1958, fertilizer use in the agriculture and land transformation since the 1950s, steelmaking between the 1960s and 1970s, machinery manufacturing since the 1970s, use of petrol containing alky-lead since 1990; the lake has been in a contaminated condition since the 2000s. This study confirms that OCPs have been effectively controlled in the area, the level of nutrient and heavy metal pollution is increasing, coal-fired power plants are an important source of Hg, and the use of petrol containing alky-lead has accelerated the accumulation of Pb in the environment. The study indicates that magnetic susceptibility can be used as a rapid, simple, and non-destructive tool for assessment of organic and heavy metal pollution in the lake.     

巢湖流域生态安全评价研究

目前,巢湖流域的生态安全问题非常突出,已严重影响流域社会经济的可持续发展。基于巢湖流域社会经济、水体环境质量及水生生态系统的数据资料,应用驱动力-压力-状态-影响-响应(DPSIR)模型,提出了基于水环境和水生态的巢湖流域生态安全评价框架模型和指标体系,并采用熵权物元模糊评价法进行巢湖流域生态安全评价研究。研究结果表明,2003和2007年巢湖流域整体处于生态安全中度风险状态,水体环境质量的变化和水生生态系统的演替将严重威胁巢湖流域的生态安全,水体中的TP浓度、NH-N浓度以及TN浓度是决定巢湖流域生态安全的最关键因子。     

Tissue Residue Guideline for ∑DDT for Protection of Aquatic Birds in China

DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) is a chlorinated hydrocarbon insecticide that has been used worldwide. While the use of DDT has been phased out in many countries, it is still produced in some parts of the world for use to control vectors of malaria. DDE (1,1,-dichloro-2,2-bis(p-chlorophenyl)ethylene) and DDD (1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) are primary metabolites of DDT and have similar chemical and physical properties. DDT and its metabolites (DDE and DDD) are collectively referred to as ∑DDT. The lipophilic nature and persistence of the ∑DDT result in biomagnification in wildlife that feed at higher trophic levels in the food chain. Wildlife in aquatic ecosystems depend on aquatic biota as their primary source of food, which provide the main route of exposure to ∑DDT. Studies about effects of ∑DDT on birds were reviewed. The tissue residue guidelines for DDT (TRGs) for protection of birds in China were derived using species sensitivity distribution (SSD) and toxicity percentile rank method (TPRM) based on the available toxicity data. Risks of ∑DDT to birds were assessed by comparing the TRGs and ∑DDT concentrations in fishes from China. The tissue residue guideline for protection of birds in China is recommended to be 12.0 ng ∑DDT/g food.