Organochlorine pesticides in agricultural soil and vegetables from Tianjin, China

Spatial pattern and compositional distribution of organochlorine pesticides in the black soil region of Shenyang

Organochlorine pesticides (OCPs) are persistent organic pollutants (POPs) prevalent in soils with carcinogenic, teratogenic and mutagenic hazards that are commonly found in soils and remain in the environment even though they have been banned. In order to fill the gap of fewer studies after the ban, soil samples were collected from 308 agricultural fields of cash crops and grain crops in the black soil area of Shenyang City (Liaozhong District, Faku County, Xinmin City and Kangping County) in this study. The aim was to determine, the use and distribution characteristics of OCPs in agricultural soils in the black soil region of Shenyang City. Compositional analysis showed that the detection rate of banned OCPs in agricultural soils was 71.75%, including contaminants such as technical dichloro-diphenyl-trichloroethane (DDT), chlordane and hexachlorobenzene (HCB), which were widely distributed in Liaozhong District, Faku County, Xinmin City and Kangping County, with 45.25% of the fields having compounded contamination of OCPs, and several areas were involved in the fresh inputs of contaminants such as technical DDT. Among them, Kangping County and Faku County are more seriously polluted, with 66.29% and 60.71% of OCPs exceeding the standard. Soil OCPs is more serious in cabbage and rice farmland among cash and food crop farmland. Based on Chinese policy on control, prevention and other pesticide management measures, it was concluded that the framework should be strengthened to prevent further illegal use of banned OCPs.

The effect of anthropogenic activities on the behavior of novel brominated flame retardants in surface soil of Northern China urbanized zone

Novel brominated flame retardants (NBFRs) have emerged as an alternative to traditional brominated flame retardants (BFRs) and may pose risks to the environment and human health. However, the distribution pattern of NBFRs in urbanized zones and their association with multiple socioeconomic variables have not been adequately explored. Herein, seven NBFRs were investigated in surface soil samples from Tianjin, China, a typical urbanized area. The ∑7NBFRs ranged from n.d. to 101 ng/g, dry weight (dw) (mean: 12.6 ± 17.6 ng/g dw), which exhibited a relatively elevated level compared to NBFRs in soils from other regions worldwide. Decabromodiphenylethane (DBDPE) was the main contaminant, and its concentration ranged from 0.378 to 99 ng/g, dry weight (dw) (mean: 11.4 ± 17.0 ng/g dw), accounting for 81 % of the ∑7NBFRs. Notably, NBFRs exhibited peak concentrations within residential zones, significantly surpassing those recorded in the remaining four regions (green, farmland, water environment and other) (p < 0.05). Furthermore, the concentration of NBFRs in the soil of the Binhai New District within Tianjin was the highest, significantly exceeding that of other administrative areas, which was closely related to the intensive industrial activities in this region. The above results indicate that human activities are a key factor affecting the concentration of NBFRs in the soil. Moreover, a variety of statistical methods were employed to investigate the correlation between socioeconomic variables and the distribution of NBFRs. The concentration of NBFRs showed a significant correlation with population density and the gross domestic product (GDP) (p < 0.05), and the incorporation of administrative regional planning into structural equation models demonstrated an indirect influence on the spatial distribution of NBFRs concentration, mediated by its impact on population density. These results emphasize the association between NBFRs contamination and the degree of urbanization, thereby providing valuable insights for assessing the exposure risk of NBFRs among urban residents.

Centurial deposition records of polychlorinated biphenyls and organochlorine pesticides in sediment cores from a plateau deep-water lake of China: Significance of anthropogenic impacts, transformation signals and ecological risks revealed by full congener analysis

Lake Fuxian, the largest deep freshwater lake in China, has been suffering from increasing ecological and environmental issues along with the rapid urbanization and industrialization in the past 40 years. To better understand the historical pollution of persistent organic pollutants (POPs) in Lake Fuxian, comprehensive analyses of 209 polychlorinated biphenyl (PCB) congeners and 20 organochlorine pesticides (OCPs) were conducted in two intact sediment cores (Core V1 and Core V2). The total mass concentrations of PCBs ranged from 7.60 to 31.47 ng/g (dry weight basis) and 5.55 to 28.90 ng/g during the period of 1908-2019 in Core V1 and 1924-2019 in Core V2, respectively. PCBs exhibited a consecutive increasing trend from 1940s to 2019 in Core V1. The temporal trend of PCBs in Core V2 basically matched to the history of PCB usage and prohibition in China (increasing from 1940s to mid-1960s, a remarkable drop in mid-1970s, and then increasing until 2019). Moreover, low-chlorinated PCBs were dominant among PCB homologues. Mono-CBs, di-CBs, tri-CBs and tetra-CBs accounted for 86.71 %-98.57 % in sediment segments. The PCB sources included unintentional emission and atmospheric deposition, as well as biological transformation. The total mass concentrations of OCPs ranged from 0.74 to 3.82 ng/g in Core V1 and 0.35 to 2.23 ng/g in Core V2, respectively. Similar trend was observed in the two sediment cores with peaks in the early 1990s. The predominant OCPs were γ-hexachlorohexane (γ-HCHs), dieldrin and p,p'-DDD. The ecological risks posed by PCBs and p-p'-DDD in Lake Fuxian were relatively low. In contrast, dieldrin might pose a potential threat to exposed organisms and apparently adverse ecological effects were caused by γ-HCH. This study will provide important baseline information on historical POPs contamination of Lake Fuxian.

Perennial Existence of Organochlorine Pesticides in the Soils of Amghara, Kuwait

A comprehensive study from the surface soil samples of 14 locations from Amghara, Kuwait were assessed for the investigation of organochlorine pesticides (OCPs). There is limited information regarding the distribution pattern of OCPs in the soil samples of Kuwait. The total concentration of OCPs was in the range of 209.39 pg/g -7449.18 pg/g with an average value of 1313.04 pg/g. DDT had higher concentrations in soil samples (969.52 pg/g) than the other pesticides, according to the findings. The distribution pattern of OCPs in the Amghara soils revealed their origin as both historical and recent applications of pesticides. The study extended, how residual quantities could be used to determine health risks of both children and adults. Children and adults in all the locations were subject to negligible cancer risk, according to the health risk evaluation.

Status, sources, and human health risk assessment of DDT pesticide residues in river sediments in a highly developed agricultural region in the upper Yangtze River in China

The concentrations of DDT and its metabolites in 19 sediment samples from a highly developed agricultural region in the upper reaches of the Yangtze River were measured. Non-carcinogenic hazard quotient for different age groups was evaluated using reference doses provided by the USEPA, and the excess lifetime cancer risk due to eating fish was assessed based on the local eating habits. The results showed that this region had a high level of residual DDT (12.84 ± 8.97 ng/g), which mainly came from the historically used technical DDT in agriculture. The non-carcinogenic risk was just acceptable in the region, but 11 of the 19 sites showed an unacceptable carcinogenic risk. Although DDT has been banned for decades, there were still notable health risks, especially for children. Special attention should be given to the potential health risks in historically developed agricultural regions.

Spatial-temporal occurrence and sources of organochlorine pesticides in the sediments of the largest deep lake (Lake Fuxian) in China

Compared with shallow lakes, less attention has been paid on pollutions in deep lakes. Lake Fuxian is the largest deep lake and an important water resource in China. The knowledge on organochlorine pesticides (OCPs) in sediments of Lake Fuxian was rare. Fifteen surface sediments and one sediment core were collected from Lake Fuxian. Sediment chronology was dated with the activities of ¹³⁷Cs and ²¹⁰Pb. Twenty-one OCPs in the surface sediments and sediment core were analyzed by a GC-MS. Spatial and temporal occurrences of OCPs in the sediments of this lake were studied. Correlations, isomer ratios, and principal component analysis (PCA) were applied to apportion the sources of OCPs in the sediments of this lake. The OCPs in the sediments of Lake Fuxian were dominated by p,p'-DDT (4,4'-dichlorodiphenyltrichloroethane) and HCHs (hexachlorocyclohexane). The concentration of ΣOCPs in the surface sediments ranged from 0.42 to 67.5 ng g^-1, with an average of 42.3 ± 23.5 ng g^-1 (mean ± SD, n = 15). The concentration of ΣOCPs in the sediment core varied from 3.5 to 707.9 ng g^-1 in the period from 1950 to 2010, with an average of 167.7 ± 203.7 ng g^-1 (n = 24). The highest concentrations and fluxes of α-HCH, γ-HCH, and p,p'-DDT were found in the years of 1964 and 1967, respectively. The fluxes of HCH isomers in the sediment core decreased in the orders as γ-HCH > β-HCH > α-HCH in the period from 1950 to 2010. The concentrations of HCHs and p,p'-DDT in the sediments of Lake Fuxian were higher than those of most shallow and deep lakes in the world. HCHs and p,p'-DDT were derived from both the technical HCH and DDT and the usage of lindane and dicofol. Technical DDT and technical HCH may be used simultaneously, but technical DDT and lindane were not applied simultaneously in the catchment. Lindane was used not only in the period from 2002 to 2010 but also in the period from 1950 to 1964 in the catchment.

Dissolved legacy and emerging organochlorine pesticides in the Antarctic marginal seas: Occurrence, sources and transport

Polar regions are recognized as final sinks of the persistent contaminants, however, environmental investigations in the Antarctica are greatly limited by harsh field conditions. In this study, seawater samples were collected in the Antarctic marginal seas during the austral summer of 2021 to investigate the environmental behavior and fate of organochlorine pesticides (OCPs). The concentrations and source markers of representative legacy hexachlorocyclohexane (HCH), hexachlorobenzene (HCB) and dichlorodiphenyltrichloroethanes (DDTs) indicated the coexistent sources of historical residues and fresh inputs. While the emerging OCPs, including quintozene, pentachloroaniline and dichlobenil, showed relatively lower detection frequency. Due to the differences in temperature and sea ice coverage, dissolved OCPs generally displayed higher concentrations in the eastern Antarctic than those in the western Antarctic. The 'surface depleted and depth enrichment' vertical profile of representative OCPs in the continental shelf of Prydz Bay was jointly controlled by biological pump and water mass structure.

An overview of organic contaminants in indoor dust, their health impact, geographical distribution and recent extraction/analysis methods

People spend a substantial proportion of their time indoors; therefore, exposure to contaminants in indoor dust is persistent and profuse. According to the findings of recent studies, contaminants such as flame retardants (FRs), organochlorines (OCs), and phthalate esters (PAEs) are more prevalent in indoor dust. The discrepancy in the geographical distribution of these chemicals indicates country-specific applications. However, many studies have revealed that chlorophosphates, polychlorinated biphenyls (PCBs) and di-2-ethylhexyl phthalate are frequently detected in indoor dust throughout the world. Although some chemicals (e.g., OCs) were banned/severely restricted decades ago, they have still been detected in indoor dust. These organic contaminants have shown clear evidence of carcinogenic, neurotoxic, immunogenic, and estrogenic activities. Recent extraction methods have shown their advantages, such as high recoveries, less solvent consumption, less extraction time and simplicity of use. The latest separation techniques such as two-dimensional gas/liquid chromatography, latest ionization techniques (e.g., matrix-assisted laser desorption/ionization (MALDI)), and modern techniques of mass spectrometry (e.g., tandem mass spectrometry (MS/MS), time-of-flight (TOF) and high-resolution mass spectrometry (HRMS)) improve the detection limits, accuracy, reproducibility and simultaneous detection of organic contaminants. For future perspectives, it is suggested that the importance of the study of dust morphology for comprehensive risk analysis, introducing standard reference materials to strengthen the analytical methods, adopt common guidelines for comparison of research findings and the importance of dust analysis in the developing world since lack of records on the production and usage of hazardous substances. Such measures will help to evaluate the effectiveness of prevailing legislations and to set up new regulations.

Cooperative Evolution of China's Excellent Innovative Research Groups from the Perspective of Innovation Ecosystem: Taking an "Environmental Biogeochemistry" Research Innovation Group as a Case Study

Research, understanding, and prediction of complex systems is an important starting point for human beings to tackle major problems and emergencies such as global warming and COVID-19. Research on innovation ecosystem is an important part of research on complex systems. With the rapid development of sophisticated industries, the rise of innovative countries, and the newly developed innovation theory, innovation ecosystem has become a new explanation and new paradigm for adapting to today's global innovation cooperation network and the scientific development of complex systems, which is also in line with China's concept of building an innovative country and promoting comprehensive innovation and international cooperation with scientific and technological innovation as the core. The Innovative Research Group at Peking University is the most representative scientific and technological innovation team in the frontier field of basic research in China. The characteristics of its organization mechanism and dynamic evolution connotation are consistent with the characteristics and evolution of innovation ecosystem. An excellent innovative research group is regarded as a small innovation ecosystem. We selected the "Environmental Biogeochemistry" Innovation Research Group at Peking University as a typical case in order to understand and analyze the evolution of cooperation among scientific and technological innovation teams, improve the healthy development as well as internal and external governance of this special small innovation ecosystem, promote the expansion of an innovation team cooperation network and the improvement of cooperation quality, promote the linkage supports of funding and management departments, and improve their scientific and technological governance abilities. Through scientometrics, visual analysis of knowledge maps, and an exploratory case study, we study the evolution process and development law of team cooperation. It is found that the main node authors of the cooperation network maintain strong cooperation frequency and centrality, and gradually strengthen with the expansion of the cooperation network and the evolution of time. Driven by the internal cooperative governance of the team and the external governance of the funding and management departments, this group has gradually formed a healthy, orderly, open, and cooperative special innovation ecosystem, which is conducive to the stability and sustainable development of the national innovation ecosystem and the global innovation ecosystem.

The effect of anthropogenic activities on the environmental fate of chlorinated paraffins in surface soil in an urbanized zone of northern China

Chlorinated paraffins (CPs) have been widely used as halogenated flame retardants and plasticizers since the mid-20th century. The prevalence of CPs in soil has been widely reported, but the distribution pattern of CPs in urbanized zones and their association with multiple socioeconomic variables have not been adequately explored. Herein, short-chain and medium-chain chlorinated paraffins (SCCPs and MCCPs) were investigated in surface soil samples from Tianjin, China, a typical urbanized area. The concentration distributions of SCCPs and MCCPs showed similar trends in different administrative divisions and land use types: urban areas > suburbs > outer suburbs (p < 0.001) and residential areas > greenbelts > agricultural areas (p < 0.001). The CP congeners in residential surface soils mainly included those with longer carbon chains and high degree of chlorination, while the CP congeners in agricultural surface soils mainly consisted of those with shorter carbon chains and fewer chlorine substituents. Multiple statistical approaches were used to explore the association between socioeconomic factors and CP distribution. CP concentration was significantly correlated to population density and gross domestic product (GDP) (p < 0.001), and structural equation models incorporating administrative regional planning showed an indirect impact on the distribution of MCCP concentration due to the influence of regional planning on population density. These results highlight the association between CP contamination and the degree of urbanization, and this paper provides useful information toward mitigating the exposure risk of CPs for urban inhabitants.

Pesticides driven pollution in Kuwait: The first evidence of environmental exposure to pesticides in soils and human health risk assessment

Soil pollution from pesticide residues is a key concern due to the high soil accumulation of pesticides and their human toxicity. Pesticide concentration of surface soil samples from the Sulaibiya agricultural field located in Kuwait was assessed in the present study. The study also investigated health risk assessment for both children and adults based on the residual concentrations. The average concentration of ƩOCPs (sum of organochlorine pesticides) along the present study was 3062 pg/g. The residual concentration of ƩOCPs was comparatively lower as compared to other locations around the world. Out of the 11 observed locations, A, B, and D locations indicated higher concentrations of ƩOCPs. The results indicated that DDT showed higher concentrations 692.87 pg/g in soil samples as compared to the other pesticides. Cancer risks of OCP via ingestion, dermal contact and inhalation of soil particles suggested that all stations were in a safe zone. However, locations A, B and D were closer to the low-risk band. The distribution pattern for each form of organochlorine pesticides (OCP) was different in Sulaibiya, indicating the non-simultaneous use of different groups of OCPs in this region. Multivariate statistical analysis based on cluster analysis identified three classes, 1, 2 and 3 of pesticides, suggesting these are from the same sources. Principle component analysis (PCA) showed that soil physicochemical properties influence the pesticides in soil samples. The results provides the baseline data of pesticides in soils from Kuwait.

Organochlorine Pesticide Ban Facilitated Reproductive Recovery of Chinese Striped Hamsters

Organochlorine pesticides (OCPs) have been used worldwide on an enormous scale over the last century but are banned globally due to environmental persistence and ecotoxicity in recent decades. The long-term effects of OCP ban for agricultural use in China since 1983 on the reproductive health of small terrestrial mammals have never been evaluated in the field. We examined the residue dynamics of OCPs and the reproductive performance of Chinese striped hamsters (Cricetulus barabensis) in North China Plain during 1983-2010 and concluded that the exposure levels of OCPs in hamsters drastically decreased from 2900 ± 740 to 25.2 ± 6.88 ng/g with an average half-life of 5.08 yrs, coinciding with the observed reproductive recovery of hamsters. The population-based reproductive performance of hamsters was significantly and negatively associated with OCP exposure levels after adjusting the contributions from climate and population density factors, indicating that the ban of OCPs has facilitated the reproductive recovery of hamsters by up to 81% contribution. Our findings suggest that the OCP ban is effective to restore reproduction of small terrestrial mammals. Integration of population biology and environmental science is essential to assess the impacts of persistent organic pollutants on ecological safety and biodiversity loss under accelerated global change.

Persistent organic pollutants in sediments of the Wouri Estuary Mangrove, Cameroon: Levels, patterns and ecotoxicological significance

The anthropogenic impact in the Wouri Estuary Mangrove located in the rapidly developing urban area of Douala, Cameroon, Africa, was studied. A set of 45 Persistent Organic Pollutant were analysed in surficial mangrove sediments at 21 stations. Chlorinated Pesticides (CLPs), Polychlorinated Biphenyls (PCBs) and Polycyclic Aromatic Hydrocarbons (PAHs) have concentrations ranging from 2.2 - 27.4, and 83 - 544 ng/g, respectively. The most abundant CLPs were endosulfan, alachlor, heptachlor, lindane (γ-HCH) and DDT, which metabolites pattern revealed recent use. Selected PAHs diagnostic ratios show pyrolytic input predominantly. The sum of 7 carcinogenic PAHs (ΣC-PAHs) represented 30 to 50% of Total PAHs (TPAHs). According to effect-based sediment quality guidelines, the studied POPs levels imply low to moderate predictive biological toxicity. This study contributes to depict how far water resources are shifting within what is now termed the Anthropocene due to increasing local pressures in developing countries or African countries.

Uptake and dissipation of metalaxyl-M, fludioxonil, cyantraniliprole and thiamethoxam in greenhouse chrysanthemum

Production of chrysanthemum (Dendranthema grandiflora) in greenhouses often requires intensive pesticide use, which raises serious concerns over food safety and human health. This study investigated uptake, translocation and residue dissipation of typical fungicides (metalaxyl-M and fludioxonil) and insecticides (cyantraniliprole and thiamethoxam) in greenhouse chrysanthemum when applied in soils. Chrysanthemum plants could absorb these pesticides from soils via roots to various degrees, and bioconcentration factors (BCF_LS) were positively correlated with lipophilicity (log K_ow) of pesticides. Highly lipophilic fludioxonil (log K_ow = 4.12) had the greatest BCF_LS (2.96 ± 0.41 g g^-1), whereas hydrophilic thiamethoxam (log K_ow = -0.13) had the lowest (0.09 ± 0.03 g g^-1). Translocation factors (TF) from roots to shoots followed the order of TF_leaf > TF_stem > TF_flower. Metalaxyl-M and cyantraniliprole with medium lipophilicity (log K_ow of 1.71 and 2.02, respectively) and hydrophilic thiamethoxam showed relatively strong translocation potentials with TF values in the range of 0.29-0.81, 0.36-2.74 and 0.30-1.03, respectively. Dissipation kinetics in chrysanthemum flowers followed the first-order with a half-life of 21.7, 5.5, 10.0 or 8.2 days for metalaxyl-M, fludioxonil, cyantraniliprole and thiamethoxam, respectively. Final residues of these four pesticides, including clothianidin (a primary toxic metabolite of thiamethoxam), in all chrysanthemum flower samples were below the maximum residue limit (MRL) values 21 days after two soil applications each at the recommended dose (i.e., 3.2, 2.1, 4.3 and 4.3 kg ha^-1, respectively). However, when doubling the recommended dose, the metabolite clothianidin remained at concentrations greater than the MRL, despite that thiamethoxam concentration was lower than the MRL value. This study provided valuable insights on the uptake and residues of metalaxyl-M, fludioxonil, cyantraniliprole and thiamethoxam (including its metabolite clothianidin) in greenhouse chrysanthemum production, and could help better assess food safety risks of chrysanthemum contamination by parent pesticides and their metabolites.

Concentrations and uptake pathways of polychlorinated biphenyls from soil to grass

Field coupled samples in soil and grass were collected to determine the concentrations and identify the uptake pathways of PCBs into the grass at a pasture from Scotland, UK. Concentrations of indicator PCBs (∑₇PCBs) in soils ranged from 0.20 to 0.88 ng g^-1 dw (dry weight), with a mean of 0.33 ng g^-1 dw, and in grass ranged from 0.20 to 2.14 ng g^-1 dw, with a mean of 0.48 ng g^-1 dw. The comprehensive factors of low concentrations and detection rate (PCB28: 18.8%; PCB52: 37.5%) of PCBs in soil, as well as continuously declined air concentrations of PCBs in the UK since the 1990s suggested that the secondary emission from the soil is becoming the supplied source of PCBs to air and grass. The significant correlations between bioconcentration factor (BCF) values and the log K_OW (R = -0.850, p < 0.05) and log K_OA (R = -0.860, p < 0.05) of indicator PCB congeners were found in the present study, indicating that these two parameters are likely to affect the bioaccumulation and uptake of grass. A generic one-compartment model was employed to identify uptake pathways of grass and evaluate the uptake amounts for PCBs. This suggested that the most important pathway for uptake of PCBs by grass was at the aerial part, and the difference of PCBs concentrations between leaves and roots was about four orders of magnitude. Removing and risk transfer of PCBs or other organic pollutants by grass need to be investigated and assessed further.

Application and Selection of Remediation Technology for OCPs-Contaminated Sites by Decision-Making Methods

The production and use of organochlorine pesticides (OCPs) for agricultural and industrial applications result in high levels of their residues, posing a significant risk to environmental and human health. At present, there are many techniques for OCP-contaminated soil remediation. However, the remediation of contaminated sites may suffer from a series of problems, such as a long recovery cycle, high costs, and secondary pollution, all of which could affect land redevelopment and reuse. Therefore, the selection of an appropriate technology is crucial for contaminated sites. In order to improve and support decision-making for the selection of remediation techniques, we provide a decision-making strategy for the screening of remediation techniques of OCP-contaminated sites. The screening procedure is proposed based on combining the analytic hierarchy process (AHP) and the technique for order preference by similarity to ideal solution (TOPSIS). The screening indexes include economic indicator, environmental indicator, and technical indicator. The assessment results show that co-processing in cement kiln obtained the highest overall score and was thus considered to be the most sustainable option. This suggested remediation technology was similar to the practical remediation project, indicating that the screening method could be applied for the selection of remediation technologies for sites contaminated with persistent organic pollutants.

Dechlorane plus in greenhouse and conventional vegetables: Uptake, translocation, dissipation and human dietary exposure

In an attempt to evaluate the behavior of Dechlorane plus (DP) in soil-vegetable systems, this work investigated the uptake and translocation of DP by vegetables and the dissipation of DP in soil under greenhouse and conventional conditions. To address human dietary exposure to DP, estimated dietary intake via vegetable consumption was calculated. The uptake potential indexes of DP from soil into root for tomato and cucumber cultivated under different conditions ranged from 0.089 to 0.71. The ranges of uptake potential indexes of DP from resuspended soil particles into stem, leaf and fruit were 0.68-0.78, 0.27-0.42 and 0.39-0.75, respectively. The uptake potential indexes in greenhouse vegetables were generally higher than those in conventional vegetables when the vegetables had been planted in contaminated soil, indicating that greenhouse enhanced the uptake of DP with a high soil concentration by vegetables. The translocation factor (TF) values of DP in vegetables were in the range of 0.022-0.17, indicating that DP can be transported from root to fruit even though it has a high octanol water partition coefficient (K_OW). The half-lives of DP dissipation in soil ranged from 70 to 102 days. The dissipation of DP in greenhouse soil was slightly slower than that in conventional soil. Higher estimated dietary intake (EDI) values of DP via greenhouse vegetables were observed due to the higher concentration of DP in greenhouse vegetables than conventional vegetables. These results suggested that greenhouses should not be adopted for vegetable production in contaminated regions.

Integrating bioavailability and soil aging in the derivation of DDT criteria for agricultural soils using crop species sensitivity distributions

Although the agricultural use of dichlorodiphenyltrichloroethane (DDT) has been banned for decades in many countries around the world, the detection of DDT and its metabolites in soils is very common due to their persistence. DDTs (sum of DDT and its metabolites) in farmland soils can be absorbed by crops at different levels and accumulate in the edible parts of agricultural products, posing threats to the health of human being. However, no information on the species sensitivity distribution (SSD) of crops with regard to DDTs has been reported due to the lack of enough bioavailability data and models to normalize the bioavailability data from different sources. Based on the bioconcentration factors of 17 crop species in Chinese soils obtained from previous studies, the criteria of DDTs in soils was derived according to the quality standard of agricultural products using the SSD method. Corrections for water content and aging time were conducted to normalize the data from different sources. The risk values of agricultural products at different concentration levels of DDTs in soils were also evaluated. It was found that oil crops are able to take up more DDTs than non-oil crops, so the soil criteria were calculated separately for oil crops and non-oil crops, which were 0.083 mg/kg and 0.29 mg/kg, respectively. With the residual concentrations of DDTs in soils at the range of 0.01-0.5 mg/kg, 0-8% of the agricultural products exceeded the permissible limits for DDTs which were set in the National Food Safety Standard of China. The results also demonstrated the feasibility for applying SSDs to derive the soil criteria of DDTs in order to ensure the safety of agricultural products. This work will provide information for the risk assessment and the establishment of soil environmental quality standards to ensure safe agricultural production.

Bioconcentration factor-based management of soil pesticide residues: Endosulfan uptake by carrot and potato plants

Uptake characteristics of endosulfan (ED), including α-, β-isomers and sulfate-metabolites, from the soils by carrot and potato plants were investigated to establish a method that may be used to calculate recommended permissible soil contaminant concentrations (C_{s, permissible}) at time of planting so that maximum residue level (MRL) standards are not exceeded. The residues of ED were analyzed in soils treated with ED at concentrations of either 2 or 10 mg kg soil^-1 and in the plants (carrots and potatoes) grown in such soils for 60-90 d. Presence of plants increased ED dissipation rates in soils in patterns that were best fit to a double-exponential decay model (R² of 0.84-0.99). The ED uptake extent varied with type of crop, ED isomer, plant growth duration, and plant compartments. However, ED concentrations in all edible parts of crops eventually exceeded their maximum residue limits. Total ED bioconcentration factor (BCF), the ratio of soil ED concentration at planting time to that in edible part of each crop at harvest day, was found to decrease with time due to decreasing soil ED concentration and increasing plant biomass in a pattern that followed a first order kinetic model. Using this model, the C_{s, permissible} values, specific to the soils used in this study, were calculated to be 0.32 and 0.19 mg kg soil^-1 for carrots and potatoes, respectively. The results and methods developed in this study may be utilized as a prediction tool to ensure crop safety from pesticide residues.

Sources and transformation pathways for dichlorodiphenyltrichloroethane (DDT) and metabolites in soils from Northwest Fujian, China

Dicofol (2,2,2-trichloro-1,1-bis-(p-chlorophenyl)ethanol) found in the environment is not only a miticide originated from commercial use, but also a metabolite of dichlorodiphenyltrichloroethane (DDT), which is often overlooked. To verify the sources and transformation pathways of DDT and related metabolites in soils, we measured p,p'-(dicofol + DBP) (sum of p,p'-dicofol and 4,4'-dichlorobenzophenone), DDT and six metabolites in soils from Northwest Fujian, China. The ratios of 1,1,1-trichloro-2-(o-chlorophenyl)-2-(p-chlorophenyl)ethane (o,p'-DDT)/1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane (p,p'-DDT) and the mass balance demonstrated that p,p'-(dicofol + DBP) predominantly originated from p,p'-DDT transformation rather than from actual dicofol application. p,p'-(dicofol + DBP) accounted for 45.0% as the primary metabolites of DDT in this study, more than 1,1-dichloro-2,2-bis-(p-chlorophenyl)ethylene (p,p'-DDE) and 1,1-dichloro-2,2-bis-(p-chlorophenyl)ethane (p,p'-DDD), which might lead to large overestimations of the fresh DDT input by using the traditional ratio of (∑₂DDD + ∑₂DDE)/∑₂DDT (with all o,p'- and p,p'- isomers included). In paddy fields where the conditions alternate between aerobic (dry period) and anaerobic (wet period), both p,p'-DDD and p,p'-DDE were likely to degrade to 1-chloro-2,2-bis-(p-chlorophenyl)ethylene (p,p'-DDMU), which further transformed to 2,2-bis(p-chlorophenyl)ethylene (p,p'-DDNU). Degradation of p,p'-DDMU to p,p'-DDNU mainly occurred in waterlogged paddy soils. However, p,p'-DDNU might not transform to other higher-order metabolites in aerobic surface soils. Overall, our study confirmed p,p'-(dicofol + DBP) as metabolites of p,p'-DDT, suggested DDE and DDD were parallel precursors of DDMU, and further verified the transformation pathways of DDT in surface soils.

Using Isomeric and Metabolic Ratios of DDT To Identify the Sources and Fate of DDT in Chinese Agricultural Topsoil

The metabolic ratio of (p,p'-DDE + p,p'-DDD)/p,p'-DDT or p,p'-DDE/p,p'-DDT has been used previously to estimate the approximate half-life of p,p'-DDT, with a relatively unclear concept of "old" and "new" sources of p,p'-DDT and without paying attention to the influence by dicofol-type DDT contributed from the more recent usage of dicofol. Based on the isomeric ratio of o,p'-DDT/p,p'-DDT to distinguish the sources of DDT, this study used the corrected metabolic ratio of (p,p'-DDE + p,p'-DDD)/p,p'-DDT to estimate a more accurate half-life of p,p'-DDT using a model-based approach. This indicates the average half-life of p,p'-DDT in Chinese topsoils was 14.2 ± 0.9 years with dicofol-type DDT input considered. In deeper soil, the half-life was >30 years and the metabolic pathway of p,p'-DDT was significantly different with topsoil's. Further analysis on the fraction of DDT from technical DDT suggested that a region that had been sprayed with technical DDT was likely to have been sprayed with dicofol as well, but the monitoring residues of DDT in topsoil mainly derive from historical use of technical DDT.

Organic contamination and remediation in the agricultural soils of China: A critical review

Soil pollution is a global problem in both developed and developing countries. Countries with rapidly developing economies such as China are faced with significant soil pollution problems due to accelerated industrialization and urbanization over the last decades. This paper provides an overview of published scientific data on soil pollution across China with particular focus on organic contamination in agricultural soils. Based on the related peer-reviewed papers published since 2000 (n=203), we evaluated the priority organic contaminants across China, revealed their spatial and temporal distributions at the national scale, identified their possible sources and fates in soil, assessed their potential environmental risks, and presented the challenges in current remediation technologies regarding the combined organic pollution of agricultural soils. The primary pollutants in Northeast China were polycyclic aromatic hydrocarbons (PAHs) due to intensive fossil fuel combustion. The concentrations of organochlorine pesticides (OCPs) and phthalic acid esters (PAEs) were higher in North and Central China owing to concentrated agricultural activities. The levels of polychlorinated biphenyls (PCBs) were higher in East and South China primarily because of past industrial operations and improper electronic waste processing. The co-existence of organic contaminants was severe in the Yangtze River Delta, Pearl River Delta, and Beijing-Tianjin-Hebei Region, which are the most populated and industrialized regions in China. Integrated biological-chemical remediation technologies, such as surfactant-enhanced bioremediation, have potential uses in the remediation of soil contaminated by multiple contaminants. This critical review highlighted several future research directions including combined pollution, interfacial interactions, food safety, bioavailability, ecological effects, and integrated remediation methods for combined organic pollution in soil.

Association of in utero exposure to organochlorine pesticides with thyroid hormone levels in cord blood of newborns

Organochlorine pesticides (OCPs) had been widely used in agriculture and disease prevention from the 1940s-1960s. Currently, OCPs are raising global concerns due to their associated prevalent contamination and adverse health effects, such as endocrine disruption. Several epidemiological studies have explored the underlying association of OCPs on thyroid hormone (TH) status in adults and newborns, but the results of studies performed on newborns are often inconclusive. This exploratory study was conducted with the purpose of assessing the potential association of the prenatal exposure to OCPs with the concentrations of TH in the cord blood of newborns from China. Cord blood and information on demographic characteristics were collected from 115 newborns between November 2013 and June 2014. The exposure levels of 17 OCPs were measured with a gas chromatography/mass spectrometry, and TH levels including free triiodothyronine (FT3), free thyroxine (FT4), and thyroid-stimulating hormone (TSH) were detected using electrochemiluminescence immunoassay methods. After adjusting for confounding factors (the age of pregnant mothers, education level, monthly household income, parity, and sex of the newborns), we found marginally significant inverse associations of cord plasma measurements of ∑hexachlorcyclohexanes (∑HCHs), 1,1-dichloro-2,2-di(4-chlorophenyl)ethylene (ρ,ρ'-DDE) and methoxychlor with FT4 levels, but not with FT3 and TSH levels. Moreover, higher cord plasma levels of aldrin, dieldrin, ∑dichlorodiphenyltrichloroethanes (∑DDTs), ∑Drins, and ∑OCPs were found to be related to the increase in cord plasma TSH levels after the adjustment for confounders. The results of this exploratory study indicate that in utero exposure to certain OCPs may affect TH status in newborns, and therefore, pose potential effects on early human development. Further research, with larger sample sizes, should be conducted to confirm these findings.

Pollution characteristics and ecological risk assessment of HCHs and DDTs in estuary wetland sediments from the Bohai Bay, North China

Hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) tend to persist in the environment for long periods of time. The concentration and distribution of HCHs and DDTs were investigated in surface sediments of Yongdingxinhe wetland and Binhai wetland by gas chromatography-mass spectrometer (GC-MS). All isomers of HCHs and DDTs were detected in all of the samples. The concentrations of total HCHs (ΣHCHs) in two wetland sediments ranged from 69.81 to 379.28 ng · g ^-1, with a mean value of 224.55 ng · g ^-1. The concentrations of total DDTs (ΣDDTs) ranged from 98.32 to 129.10 ng · g ^-1, with a mean value of 113.71 ng · g ^-1. The results of an ecological risk assessment demonstrated that there was high-risk ecological effect of organochlorine pesticides (OCPs) on the estuary wetlands. Lindane and technical DDTs were found to be the main sources of OCPs.

Depth-distribution, possible sources, and toxic risk assessment of organochlorine pesticides (OCPs) in different river sediment cores affected by urbanization and reclamation in a Chinese delta

Sediment cores were collected in urban (0-50 cm), rural (0-40 cm) and reclamation-affected river (0-40 cm) environments in the Pearl River Delta. Concentrations of 16 organochlorine pesticides (OCPs) were determined in all collected samples to identify the depth-distribution, possible sources and ecotoxicological risks of OCPs in river sediments affected by urbanization and reclamation in a Chinese delta. The results showed that the top 10 cm of rural river sediments had slightly lower concentrations of the 16 OCPs compared to urban and reclamation-affected rivers, whereas the 30-40 cm sediment layers in the rural river showed higher levels of the 16 OCPs. However, higher OCPs levels were observed in the 20-30 cm sediment layers in the urban river than in the rural and reclamation-affected rivers. The principal OCPs in most deeper sediment layers were hexachlorobezene (HCB), the combination of aldrin, endrin and dieldrin (ΣDRINs) and the combination of α-HCH, β-HCH and γ-HCH (ΣHCHs). The predominant OCPs in surface sediments were HCB, ΣDRINs and the combination of p,p'-DDD, o,p'-DDT, p,p'-DDT and p,p'-DDE (ΣDDTs). Generally, OCP concentrations decreased with depth along sediment profiles at most sampling sites in the three types of rivers. The source analyses indicated that some sampling sites were still suffering from the recent use of hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs) and aldrin. According to the soil quality thresholds of China, the levels of HCHs and DDTs at most sampling sites were below class Ⅰ criteria. Based on the sediment quality guideline quotient (SQGQ), the combined ecotoxicological risk of OCPs (γ-HCH, dieldrin, p,p'-DDD, p,p'-DDE and p,p'-DDT) in surface sediments (0-10 cm) was higher than deeper sediments, and the rural river sediments exhibited a higher combined ecotoxicological risk than the sediments in urban and reclamation-affected rivers.

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.

Residues, spatial distribution and risk assessment of DDTs and HCHs in agricultural soil and crops from the Tibetan Plateau

Due to its high elevation and cold temperature, the Tibetan Plateau (TP) is regarded as the "Third Pole". Different from other polar regions, which are truly remote, the TP has a small population and a few agricultural activities. In this study, agricultural soil and crop samples (including highland barley and rape) were collected in the main farmland of the TP to obtain the contamination levels of dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) in the Tibetan agricultural system as well as the relevant human exposure risks. The average concentrations of DDTs and HCHs in the agricultural soil, highland barley and rape were 1.36, 0.661, 1.03 ng/g dw and 0.349, 0.0364, 0.0225 ng/g dw, respectively. In the agricultural soil, DDTs and HCHs metabolism (DDE, DDD and β-HCH) were abundant, which indicated a "historical" source, whereas crops contained a similar composition ((DDE + DDD)/DDT, α/β-HCH and α/γ-HCH) to that of wild plants, suggesting that the DDTs and HCHs in crops are likely from long range atmospheric transport. The human health risks via non-dietary and dietary to DDTs and HCHs in the farmland were assessed. All of the hazard index (HI) values of DDTs and HCHs for non-carcinogenic risks were <1, and most of the cancer risk values were <10(-6), suggesting that DDTs and HCHs in the farmland will not pose non-carcinogenic risks and will pose only very low cancer risks to the Tibetan residents.

Distribution and risk assessment of suspected endocrine-disrupting pesticides in creek water of Mumbai, India

The present study deals with the investigation of existing pollution levels and potential ecological risk assessment of endocrine-disrupting organochlorine and organophosphorous pesticide residues in the Vasai Creek water near Mumbai. The average concentration of α- and β-endosulfan (137.75 ng·L(-1)) exceeds the chronic criteria level of α- and β-endosulfan (6.5 ng·L(-1)) set by US EPA for freshwater aquatic organisms. The concentration levels of aldrin (75.31 ng·L(-1)), dieldrin (71.19 ng·L(-1)) and endrin (76.60 ng·L(-1)) was found to exceed the respective criteria levels of <0.13, 65.1, and 61 ng·L(-1) as set by US EPA for protection of freshwater aquatic organisms. In addition, the level of chlorpyrifos (208.77 ng·L(-1)) exceeds the recommended concentration value of <35 ng·L(-1) set by Ministry of Environment of British Colombia. The results of our study give an indication of probable ecotoxicological risk to the marine breeding organisms of creek.

Persistent organic pesticide residues in sediments of Vasai Creek near Mumbai: Assessment of sources and potential ecological risk

Thirteen persistent organic pesticides were investigated in the sediments of Vasai Creek near Mumbai to evaluate their pollution levels and potential risks. It was observed that ΣOCPs level was in the range of 597-1538ng/g dw, with an average value of 1115.25ng/g dw. The level of ΣOPPs was in the range of 492-1034ng/g dw, with an average value of 798.15ng/g dw. The values o,p'-DDT/p,p'-DDT ratio gives an indication of use of technical DDT as the prime source of DDT, while the α/γ-BHC ratio indicate that BHCs in study area might have been received from fresh lindane. The results of an ecological risk assessment showed that sediment bound organic pesticides are of more ecotoxicological concern as they might create adverse ecological risk to the marine breeding habitats. These pesticides residues may get remobilize and released to overlying waters creating adverse effects on terrestrial and aquatic organisms.

DDT Vertical Migration and Formation of Accumulation Layer in Pesticide-Producing Sites

Soil samples were collected at various depths (0.5-21.5 m) from ten boreholes that were drilled with a SH-30 Model Rig, four of which were at a dicofol production site while six were at a dichlorodiphenyltrichloroethane (DDT) production site. In industrial sites, the shallow soils at depths of 0-2 m were mostly backfill soils, which cannot represent the contamination situation of the sites. The contaminated levels in the deep original soil can represent the situation in contaminated sites. All the soil samples investigated at the DDT and dicofol production sites were found to be seriously polluted. The contents of both DDT (0.6-6071 mg/kg) and dicofol (0.5-1440 mg/kg) were much higher at the dicofol production site than at the DDT production site (DDTs, 0.01-664.6 mg/kg; dicofol, <0.1 mg/kg), even in the deep soil. DDTs had a different distribution in the soil of the pesticide production site from that in the soil outside the sites and that in agricultural soils. The results of the investigation revealed that DDTs were easily enriched in cohesive soil and in the bottom zone of aquifers, where the concentration was higher than in above the layers. DDTs were found to be hard to degrade, and their degradation speed was slower than their vertical migration, despite the fact that hydrophobic DDTs did not migrate easily in soils. In the dicofol production site, the value of DDE/DDD cannot indicate the degradation condition of DDTs, nor can the value of (DDE + DDD)/DDT identify how long DDTs have remained in the soil. It is debatable that the half-life of DDT inputted to soils is about 20-30 years, maybe longer than the generally recognized time.

Comparison of Different Extraction Methods for Analysis of 10 Organochlorine Pesticides: Application of MAE-SPE Method in Soil from Beijing

Four commonly applied extraction techniques for organochlorine pesticides, microwave-assisted extraction (MAE), accelerated solvent extraction (ASE), quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction and ultrasonic solvent extraction, were applied on soil samples in order to evaluate their performances. The extracts were analyzed by GC-ECD and confirmed by GC-MS/MS. The MAE and QuEChERS extraction methods generally yielded higher results compared to the ultrasonication and ASE methods, while the lowest recovery (56.8 %) for o,p'-DDD was obtained using the QuEChERS method. The MAE method was further applied to six different soils from Beijing. In the soil samples only α-endosulfan and β-endosulfan were not detected. The ratios of α-HCH/γ-HCH and α-HCH/β-HCH indicated HCH residues likely originated from historical use of HCHs, and that technical HCHs were not likely being currently applied in Beijing.

Human exposure to soil contaminants in subarctic Ontario, Canada

BACKGROUND

Chemical contaminants in the Canadian subarctic present a health risk with exposures primarily occurring via the food consumption.

OBJECTIVE

Characterization of soil contaminants is needed in northern Canada due to increased gardening and agricultural food security initiatives and the presence of known point sources of pollution.

DESIGN

A field study was conducted in the western James Bay Region of Ontario, Canada, to examine the concentrations of polychlorinated biphenyls, dichlorodiphenyltrichloroethane and its metabolites (ΣDDT), other organochlorines, and metals/metalloids in potentially contaminated agriculture sites.

METHODS

Exposure pathways were assessed by comparing the estimated daily intake to acceptable daily intake values. Ninety soil samples were collected at random (grid sampling) from 3 plots (A, B, and C) in Fort Albany (on the mainland), subarctic Ontario, Canada. The contaminated-soil samples were analysed by gas chromatography with an electron capture detector or inductively coupled plasma mass spectrometer.

RESULTS

The range of ΣDDT in 90 soil samples was below the limit of detection to 4.19 mg/kg. From the 3 soil plots analysed, Plot A had the highest ΣDDT mean concentration of 1.12 mg/kg, followed by Plot B and Plot C which had 0.09 and 0.01 mg/kg, respectively. Concentrations of other organic contaminants and metals in the soil samples were below the limit of detection or found in low concentrations in all plots and did not present a human health risk.

CONCLUSION

Exposure analyses showed that the human risk was below regulatory thresholds. However, the ΣDDT concentration in Plot A exceeded soil guidelines set out by the Canadian Council of Ministers of the Environment of 0.7 mg/kg, and thus the land should not be used for agricultural or recreational purposes. Both Plots B and C were below threshold limits, and this land can be used for agricultural purposes.

Distribution and uptake pathways of organochlorine pesticides in greenhouse and conventional vegetables

The application of greenhouse vegetable cultivation has dramatically expanded worldwide during the last several decades. However, little information is available on the distribution and uptake of pesticides in greenhouse vegetables. To bridge this knowledge gap, the present study was initiated to investigate the distribution and uptake of organochlorine pesticides (OCPs) in vegetables from plastic greenhouse and conventional cultivation methods. The uptake pathways of OCPs were not significantly different between these two cultivation methods. The arithmetic means of OCP concentrations in greenhouse vegetables were higher than those in conventional vegetables, although there was no significant difference. This small difference raised the concern of whether the tiny difference could be magnified to a significant difference by bioaccumulation in the food chain. The issue should be addressed by a well-designed scheme in future studies.

Occurrence and possible sources of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) along the Chao River, China

To analyze the possible influence of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) on Miyun Reservoir, 14 soil samples and 1 water sample were collected along the Chao River, which is the main upstream source of the reservoir. A total of 24 kinds of OCPs and 12 kinds of dioxin-like PCBs were measured. Results showed that the ∑OCPs concentration ranged from 0.8145 to 16.8524 ng g(-1), and the ∑PCBs ranged from 0.0039 to 0.0365 ng g(-1). Dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs) and hexachlorobenzene (HCB) were the three dominant kinds of OCPs in this region, and the majority component of the PCBs was PCB-118 in both water and soil samples. The OCP ratios suggest that new inputs of lindane exist. DDTs mainly come from old technical inputs. HCHs might come from a new application of lindane, which highlights the importance of prohibited pesticide control. OCP concentrations were higher in corn fields and orchards and lower in forest lands and grasslands, which indicated that OCPs were very much influenced by human activities. The proportion of PCB components in this study area suggested that they mainly came from atmospheric deposition.

Distribution, partitioning and sources of polycyclic aromatic hydrocarbons in the water-SPM-sediment system of Lake Chaohu, China

The residual levels of polycyclic aromatic hydrocarbons (PAHs) in the water, suspended particular matter (SPM) and sediment from Lake Chaohu were measured with a gas chromatograph-mass spectrometer (GC-MS). The spatial-temporal distributions and the SPM-water partition of PAHs and their influencing factors were investigated. The potential sources and contributions of PAHs in the sediment were estimated by positive matrix factorization (PMF) and probabilistic stable isotopic analysis (PSIA). The results showed that the average residual levels of total PAHs (PAH16) in the water, SPM and sediment were 170.7 ± 70.8 ng/L, 210.7 ± 160.7 ng/L and 908.5 ± 1878.1 ng/g dry weight, respectively. The same spatial distribution trend of PAH16 in the water, SPM and sediment was found from high to low: river inflows>western lake>eastern lake>water source area. There was an obvious seasonal trend of PAH16 in the water, while no obvious seasonal trend was found in the SPM. The residues and distributions of PAHs in the water, SPM and sediment relied heavily on carbon content. Significant Pearson correlations were found between LogKoc and LogKow as well as some hydro-meteorological factors. Three major sources of PAHs including coal and biomass combustions, and vehicle emissions were identified.

Assessing spatial distribution, sources, and human health risk of organochlorine pesticide residues in the soils of arid and semiarid areas of northwest China

Thirty-two topsoil samples were collected to analyze the residue levels of organochlorine pesticides (OCPs) in topsoil of arid and semiarid areas of northwest China in 2011. Results showed that DDTs were the dominant contaminants with a mean concentration of 12.52 ng/g. The spatial distribution characteristics indicated that α-hexachlorocyclohexanes (HCHs) were mainly used in rural sites, whereas hexachlorobenzene (HCB) and endosulfan were detected mostly in urban areas. DDTs, heptachlor, and chlordane were found almost equally in both urban and rural areas. Source identification revealed that the current levels of HCHs in soils were attributable to the residues from their historical use and fresh usage of lindane (γ-HCH). DDTs were mainly from historical use and fresh usage of dicofol, and HCB was emitted from the chemical industry. It was also found that the current soil levels of heptachlor were mainly from its historical usage, endosulfan from fresh input, and chlordane from long-range atmospheric transport, respectively. The noncarcinogenic health risk assessment with a model was also conducted using USEPA standards for adults and children. Results indicated that health risk under nondietary exposure to OCPs decreased in the sequence of ΣDDT > ΣHCH > HCB > Σheptachlor > Σendosulfan > Σchlordane. According to the reference dose from the USEPA, the health risk under nondietary exposure to OCPs in the soil samples was at a relatively safe level.

Uptake and accumulation of antimicrobials, triclocarban and triclosan, by food crops in a hydroponic system

Commonly used in personal care products, triclocarban (TCC) and triclosan (TCS) are two chemicals with antimicrobial properties that have recently been recognized as environmental contaminants with the potential to adversely affect human health. The objective of the study described herein was to evaluate the potential of food crops to uptake TCC and TCS. Eleven food crops, grown in hydroponic nutrient media, were exposed to a mixture of 500 μg L(-1) TCC and TCS. After 4 weeks of exposure, roots accumulated 86-1,350 mg kg(-1) of antimicrobials and shoots had accumulated 0.33-5.35 mg kg(-1) of antimicrobials. Translocation from roots to shoots was less than 1.9 % for TCC and 3.7 % for TCS, with the greatest translocation for TCC observed for pepper, celery, and asparagus and for TCS observed for cabbage, broccoli, and asparagus. For edible tuber- or bulb-producing crops, the concentrations of both TCC and TCS were lower in the tubers than in the roots. Exposure calculations using national consumption data indicated that the average exposure to TCC and TCS from eating contaminated crops was substantially less than the exposure expected to cause adverse effects, but exceeded the predicted exposure from drinking water. Exposure to antimicrobials through food crops would be substantially reduced through limiting consumption of beets and onions.

Bioaccumulation and tissue distribution of organochlorine pesticides (OCPs) in freshwater fishes: a case study performed in Poyang Lake, China's largest lake

Concentrations and tissue distribution of organochlorine pesticides (OCPs) in different tissues of freshwater fish, silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis), collected from Poyang Lake, China's largest shallow lake, and were studied. OCPs were detected with the observed concentrations ranging from 280.67 to 1,006.58 ng/g wet weight (ww) for bighead carp and from 67.28 to 930.06 ng/g ww for silver carp. Composition analysis demonstrated OCPs in both fish were from the same polluted environment, and then, the species-specific bioaccumulation might be mainly due to the different fish age as well as the different feeding habits elucidating from the stable carbon (δ(13)C) and nitrogen (δ(15)N) isotope analysis. Tissue distribution indicated that dietary intake was the major exposure route of OCPs for both fish and higher accumulation potency of OCPs by the hepatobiliary-related tissues (such as liver, kidney, bile, and heart). The higher metabolic activities of these tissues elucidating from the higher values of δ(15)N might be the potential-determined factor responsible for the tissue-specific accumulation.

Influence of plants on the distribution and composition of PBDEs in soils of an e-waste dismantling area: evidence of the effect of the rhizosphere and selective bioaccumulation

Rhizosphere effects on the distribution of PBDEs in e-waste contaminated soils were investigated. The geometric means of the PBDEs in the rhizosphere and non-rhizosphere soils were 32.6 ng/g and 12.2 ng/g, whereas the geometric means of the PBDEs in vegetable shoots and roots were 2.15 ng/g and 3.02 ng/g, respectively. PBDEs in soil at different distances from the root surface may first rise appreciably and then decrease to a non-rhizosphere level for long-term contaminated soils. Different PBDE compositions in roots and shoots indicated that PBDEs in shoots may be mainly taken up from the air. The ratios of BDE99/100 and BDE153/154 in plants and their corresponding soils were different. The bioaccumulations of BDEs 100 and 154 were much higher than those of BDEs 99 and 153, respectively. This indicated that the bioaccumulation was selective and influenced by the substitution pattern, with ortho-substituted isomers being more prevalent than meta-substituted isomers.

Residues and enantiomeric profiling of organochlorine pesticides in sediments from Xinghua Bay, southern East China Sea

The spatial distribution and chiral signatures of organochlorine pesticides (OCPs) in the surface sediments of Xinghua Bay, southern East China Sea, were investigated. The total OCP concentrations ranged from 9.15 to 40.5 ng/g dry weight, with a predominance of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs). The isomer ratios of α-HCH/γ-HCH (less than 1.0) and the predominant β-HCH implied that HCH residues were derived not only from historical technical HCH use but also from the additional use of lindane in this area. The isomer ratios of p,p'-DDT/(p,p'-DDD + p,p'-DDE) and o,p'-DDT/p,p''-DDT, and a strong correlation (R = 0.83, P < 0.001) between p,p'-DDE and o,p'-DDT depicted a cocktail input pattern of dicofol-type DDT and technical DDT. Moreover, the fact that only cis-chlordane was detectable for all sampling stations suggested the past application of technical chlordane. Based on the sediment quality guidelines (SQG), γ-HCH is the main OCP species of ecotoxicological concern in Xinghua Bay. Enantiomeric analysis showed that the (+)-enantiomers of α-HCH and o,p'-DDT were more prevalent than the (-)-enantiomers in most samples, whereas both racemic and nonracemic residues existed for o,p'-DDD. These results implied that the SQG of chiral OCPs should be reassessed using concentrations of their individual enantiomers.

The residual levels and health risks of hexachlorocyclohexanes (HCHs) and dichloro-diphenyl-trichloroethanes (DDTs) in the fish from Lake Baiyangdian, North China

The tissue and organs (muscle, brain, liver, and gill) of four species of freshwater fish from Lake Baiyangdian were analyzed for hexachlorocyclohexanes (HCHs) and dichloro-diphenyl-trichloroethanes (DDTs). The distribution characteristics were analyzed for HCHs and DDTs in various tissue and organs, which determined the health risks for humans. The research results showed that the wet weight content of all HCHs (∑HCHs) ranged from 0.05 ∼ 14.53 ng g(-1), with a mean of 3.47 ng g(-1). The wet weight content of all DDTs (∑DDTs) ranged from ND to 8.51 ng g(-1), with a mean of 2.41 ng g(-1). For the various species of fish, the residual level of ∑HCHs was relatively higher in chub and grass carp and lowest in snakehead. The residual level of ∑DDTs was the highest in snakehead and did not exhibit a significant variance in the other three species. For the various tissues and organs, the contents of HCHs and DDTs were both highest in the fish liver, second highest in the fish gill, and lowest in the fish brain and muscle. Among the four types of isomers, the residual level of γ-HCH was relatively higher, while the residual level of α-HCH was the lowest. The content of p,p'-DDE was significantly greater to other forms of DDT and its isomer. The residual levels of HCHs and DDTs in fish were both below the national standard. However, the carcinogenic risk from the HCHs in parts of the tissue and organs of four fish species in Lake Baiyangdian exceeded the screen value threshold set by USEPA.

Soil contamination by phthalate esters in Chinese intensive vegetable production systems with different modes of use of plastic film

The concentrations of six priority phthalic acid esters (PAEs) in intensively managed suburban vegetable soils in Nanjing, east China, were analyzed using gas chromatography-mass spectrometry (GC-MS). The total PAE concentrations in the soils ranged widely from 0.15 to 9.68 mg kg(-1) with a median value of 1.70 mg kg(-1), and di-n-butyl phthalate (DnBP), bis-(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DnOP) were the most abundant phthalate esters. Soil PAE concentrations depended on the mode of use of plastic film in which PAEs were incorporated as plasticizing agents and both the plastic film and poultry manure appeared to be important sources of soil PAEs. Vegetables in rotation with flooded rice led to lower concentrations of PAEs in soil. The results indicate that agricultural plastic film can be an important source of soil PAE contamination and further research is required to fully elucidate the mechanisms of PAE contamination of intensive agricultural soils with different use modes of use of plastic film.

Time-dependent movement and distribution of chlorothalonil and chlorpyrifos in tomatoes

Determining the distribution of pesticides in fruits is essential to eliminate pesticide residues during food processing. In this study, the dynamic distribution of two pesticides, chlorothalonil (CHT) and chlorpyrifos (CHP), were determined in different tomato parts following immersion in pesticide solutions. The concentrations of CHT and CHP in tomato followed an order of cuticle>plasma>pulp. However, the plasma initially accumulated the highest pesticide concentration. And the ratio of CHT concentration to that of CHP in plasma was about 2.1:1, similar to the ratio in solution, which suggested carpopodium as the entry site for the pesticides tested. The ratio in the cuticle was 0.02:1-0.06:1. This was consistent with the ratio of Kow for the two pesticides, manifesting the direct pesticide transfer from solution to cuticle. Following pesticide injection into tomato, the degradation of CHT over 96h was described by a first-order decay equation, Ctomato(t)CHT=C0×e(-0.0239t). The CHP concentration in tomato remained nearly constant with little degradation detected. Deducting the amount of degradation and migration, volatilization appeared to contribute the most amount of migration of CHT and CHP in tomato.

Organochlorine pesticides and polychlorinated biphenyls in soils surrounding the Tanggu Chemical Industrial District of Tianjin, China

The spatial distribution of persistent organic pollutants (POPs) was examined in soils surrounding the Tanggu Chemical Industrial District in Tianjin, China. The concentrations of hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs), hexachlorobenzenes (HCBs), and polychlorinated biphenyls (PCBs) were determined in 70 surface soils using accelerated solvent extraction and gas chromatography with electron capture detection. The results showed that the ranges of ∑HCH, ∑DDT, ΣHCB, and ∑PCB concentrations in soils were 2.1-12,549 μg kg(-1) (average, 965 μg kg(-1)), n.d.-2,033 μg kg(-1) (average, 88.4 μg kg(-1)), n.d.-1,924 μg kg(-1) (average, 349 μg kg(-1)), and n.d.-373 μg kg(-1) (average, 46.2 μg kg(-1)), respectively. Of these, HCHs were the dominant POPs, accounting for 75 % of the total organochlorine pesticide (OCP) residues. Overall, the spatial distribution of OCP concentrations showed a decreasing trend from the center of the Tanggu District to the surrounding areas. Two major pollution sources were Tianjin Dagu Chemical Co., Ltd. in the district center and the Tianjin Chemical Plant in Hangu District. In contrast, PCB concentrations were relatively high in the Haihe estuary to the east and low to the west of the study area. Component analysis of OCPs in these soils showed that they mainly came from industrial point sources. Compared with soils in other regions, soil DDT pollution was at a medium level in the Tanggu Chemical Industrial District, but associated HCH, HCB, and PCB pollution was relatively heavy. By multivariate statistical analyses, Tianjin Dagu Chemical Co., Ltd. was recognized as the main source of POPs, and soil properties were clarified to play an important role on the distribution and composition of POPs, especially the organic carbon content.

Distributions, sources, and ecological risks of hexachlorocyclohexanes in the sediments from Haihe Plain, Northern China

The levels of hexachlorocyclohexanes (HCHs) in the sediments from Haihe Plain, China, were measured by a gas chromatograph with a (63)Ni microelectron capture detector. The spatial distributions, possible sources, and potential ecological risks of these compounds were analyzed. The residual level of total HCHs was 33.84 ± 173.37 ng g(-1) dry weight (d.w.) with ranges of 0.13 ~ 1,107.41 ng g(-1) d.w. Much higher ΣHCH contents were found in the lower reaches of some rivers and in the mouth of the main stream receiving tributaries. The predominance of β-HCH (36%) in the sediments was similar to that in the soils from Haihe Plain. The high percentages of γ-HCH (23-41%) could be detected at 25% of the sampling sites in the seven river systems. There were statistically significant positive relationships between the contents of HCHs and total organic carbon. Lindane was identified as the primary source of HCHs in the sediments, and it seemed that recent illegal lindane inputs still existed in some areas in Haihe Plain, as indicated by the α-/γ-HCH and β-/(α + γ)-HCH ratios. Severe potential ecological risks of γ-HCH to benthic organisms at some sampling sites were found based on the consensus-based sediment quality guidelines.

Accumulation and phytoavailability of hexachlorocyclohexane isomers and cadmium in Allium sativum L. under the stress of hexachlorocyclohexane and cadmium

The effects of Cd and HCHs with single and combined forms on Cd and HCHs phytoavailability of Allium sativum L. were investigated. The results indicated that the coexistence of Cd and HCHs presented antagonistic interactions mostly, which might be partly due to the formation of Cd-HCHs complex, compared with single stress. The bioaccumulation of Cd and HCHs in plants depended largely on their concentrations applied in pot soils, and the phytoavailability of HCH isomers was in the sequence: δ- > γ- ≥ β- > α-HCH.