Acute toxicity of fluazinam to aquatic organisms and its bioaccumulation in Brachydanio rerio.

Fluazinam (FZN) is a dinitroaniline fungicide. To evaluate the environmental risk of FZN in aquatic environments and ascertain the potential danger to typical aquatic organisms in China, the acute toxicity of FZN to representative aquatic organisms, including Brachydanio rerio, Chlorella vulgaris Beij., Daphnia magna Straus, and Xenopus laevis, was measured, and its bioaccumulation properties in Brachydanio rerio were further investigated. The results showed that the acute toxicity of FZN to Brachydanio rerio and Xenopus laevis is extremely high, and the bioaccumulation factor BCF8d of FZN in Brachydanio rerio ranges between 2287 and 3570, implying that it has high bioaccumulation properties. FZN poses a strong environmental risk for aquatic organisms and possesses great bioaccumulation properties, which may cause pollution to aquatic environments.

Coupled modeling using PRZM/RICEWQ and SWAT for the North Tiaoxi Watershed.

Watershed exposure caused by the use of pesticide in farmland has become a major environmental concern. Currently, there are two major approaches to quantify the watershed exposure: monitoring and modeling. Watershed monitoring is expensive, and short-term monitoring is difficult to be used to address potential long-term exposure variability. Model simulation is widely used because not only can it save time and efforts, but it can also simulate the environmental transport process of pesticide over a long time frame to better understand temporal variability. Research on application of commonly used pesticide exposure assessment models such as PRZM, RICEWQ on watershed scale has found that those models need to be coupled together with waterbody models to assess pesticide exposure at the watershed level, and they are applied on a single crop in targeted area within a watershed, failing to consider the diversity of regional and watershed cropping conditions. To address pesticide exposure assessment in different waterbodies after application on multiple crops within a watershed, this study coupled PRZM, RICEWQ, and SWAT models simultaneously in North Tiaoxi watershed. PRZM model and RICEWQ model were used to simulate the exposure of pesticides in dryland and rice paddies separately, and the pesticide masses through runoff, overflow, spray drift, and other routes simulated by the above two models were set as the input of SWAT model which could simulate hydrology and pollutant transport at watershed scale. Pesticide use, cropping, hydrology, and watershed data were collected, and parameterized for exposure modeling of carbaryl in the North Tiaoxi River after uses on orchard, corn, and rice within the watershed. Model predictions showed high degree of agreement between the simulated results and the field monitoring data. The coupled PRZM, RICEWQ, and SWAT model could simulate reasonably well pesticide exposures in waterbodies with applications on multiple crops within a watershed.

The Role of Biochar in Reducing the Bioavailability and Migration of Persistent Organic Pollutants in Soil-Plant Systems: A Review.

The amendment of biochar in soils contaminated with persistent organic pollutants (POPs) is an environmentally friendly in situ remediation measure. Numerous studies focused on the application of biochars to reduce the uptake of POPs by plants in soils. In this review, we summarized the role of biochar in reducing the migration of POPs in soil-plant systems. The mechanisms of biochar reducing the bioavailability of POPs in the soil, i.e. immobilization and promoted biodegradation, and the influencing factors are fully discussed. Especially in rhizosphere amended with biochar, the synergistic effect of POPs-root exudates-microorganisms on the reduced bioavailability of POPs is analyzed. This paper suggests that future researches should focus on the long-term environmental fate of POPs sorbed on high-temperature biochars and the long-term impacts of low-temperature biochars on the interaction of POPs-root exudates-rhizosphere microorganisms. All the above are necessary for efficient and safe use of biochar for remediating POP-contaminated farmland soils.

Effects of long-term 4-nonylphenol dietary exposure on reproductive ability of Japanese quails (Coturnix japonica).

As an endocrine disruptor, 4-nonylphenol (4-NP) is widespread in the environment. Here, we investigated the effect of long-term 4-NP dietary exposure on Japanese quails (Coturnix japonica). A total of 72 quails were evenly divided into 24 cages (12 cages for the reproductive toxicity study and 12 cages for the histopathology study, with one male quail and two female quails in each cage) and fed with various doses of 4-NP in diet. The body weight in quails administered with 4-NP was significantly decreased (P < 0.05) in a time- and dose-dependent manner. The egg fertilization rate significantly decreased (P < 0.05) in all treated groups, which was 91.4%, 86.5%, 85.4%, and 86.2% in the control group, 10 mg·kg-1, 20 mg·kg-1, and 50 mg·kg-1 treatment groups, respectively. Moreover, the hatching rate was also significantly decreased (P < 0.05) in the 50 mg·kg-1 treatment group compared with the control group. Furthermore, the 14-day survival rate of young quails was significantly decreased (P < 0.05) in all treated groups, which was 98.0%, 91.1%, 89.8%, and 86.8% in the control group, 10 mg·kg-1, 20 mg·kg-1, and 50 mg·kg-1 treatment groups, respectively. Damaged spermatogenesis in male quails was found in all treated groups. In conclusion, oral administration of 4-NP impaired the gonads of male quails, leading to reproduction performance damage of Japanese quails.

Ecotoxicity of the nonsteroidal ecdysone mimic RH-5849 to Daphnia magna.

The nonsteroidal ecdysone mimic 1,2-dibenzoyl-1-tert-butylhydrazine (RH-5849), a novel insect growth regulator, is mainly registered for use in rice fields. So far, its toxicity and ecological risks towards aquatic cladoceran invertebrates remain unclear. In this study, RH-5849 was evaluated for its acute and 21-day chronic toxicity towards Daphnia magna. The viability, morphology, growth, and reproduction of D. magna were observed to establish a concentration-toxicity relationship associated with the RH-5849 exposure. In addition, the relationship between the changes of physiological and biochemical indices and the chronic indices was analyzed in order to find potential early warning indicators in D. magna to the chronic risk of RH-5849 exposure. The results showed that the 48-h EC50 of acute immobilization and EC50 of 21-day survival of RH-5849 on D. magna were 45.3 and 1.34 mg/L, respectively. Chronic exposure to RH-5849 mainly affected the reproductive parameters of D. magna and the no observed effect concentration (NOEC) and the EC50 were 0.050 and 0.5423 mg/L, respectively. The number of offspring per female reduced significantly after 21-day exposure to 0.10 mg/L of RH-5849. The morphological changes, manifested in head width and body length, the length of the helmet or apical spine, and the curvature and transparency of the body, were observed in RH-5849-treated groups. Moreover, it was found that the alkaline phosphatase activity in D. magna after 5-7-day exposure was positively correlated with the number of offspring per female after 21 days. These results indicate the potential risk of RH-5849 towards aquatic crustaceans should be taken into consideration when applied to rice fields.

Behavior of antibiotic resistance genes under extremely high-level antibiotic selection pressures in pharmaceutical wastewater treatment plants.

Pharmaceutical wastewater treatment plants (PWWTPs), which receive wastewater containing extremely high levels of antibiotics, are regarded as potential hot spots for antibiotic-resistance development in the environment. Six sampling campaigns in six PWWTPs in Southeastern China were carried out to assess the prevalence and fate of antibiotic resistance genes (ARGs). Different genes were monitored in different PWWTPs (PWWTP A: lincosamides; PWWTP B: aminoglycosides and macrolides; PWWTP C: quinolones; PWWTP D: macrolides and quinolones; PWWTP E: cephalosporins; and PWWTP F: quinolones and macrolides) using real-time quantitative polymerase chain reactions (PCRs), according to the antibiotic type produced. The levels of typical ARG subtypes in the final effluents ranged from (1.03±0.91)×101 to (6.78±0.21)×107copies/mL. The absolute abundance of ARGs in effluents accounted for 0%-577% of influents to the six PWWTPs with a median value of 6%. Most of the ARGs are transported to the dewatered sludge, with concentrations from (1.38±0.21)×105 to (6.84±0.43)×1010copies/g dry weight (dw). In different treatment units (before/after biological units), a clear trend of proliferation or attenuation was not observed for the ARGs, aside from a strong attenuation in moving bed bio-film reactor (MBBR) in PWWTP C. Through correlation analyses, this study demonstrated that the bacterial abundance and antibiotic concentrations within the PWWTPs influenced the fate of the associated ARGs, and this was possibly related primarily to the intrinsic resistance mechanisms of corresponding ARGs. Macrolide ARGs, which tend to locate in plasmids and transposons, positively correlate weakly with total macrolide antibiotic concentrations but positively correlate strongly with 16S rRNA concentrations. Furthermore, ARG concentrations in the wastewater from fermentation were significantly higher than in the wastewater from chemical synthesis and preparation. This is the first comprehensive study on the behavior of antibiotic resistance genes under extremely high-level antibiotic selection pressures in pharmaceutical wastewater treatment plants (PWWTPs) in Southeastern China.

Determination of glyphosate in soil/sludge by high performance liquid chromatography.

In order to evaluate the pollution caused due to glyphosate (Glyp) in soils and sludge, it is important to establish a set of standard determination techniques. In this work, the previously reported HPLC analytical method for determination of Glyp has been improved in order to be applied for all kinds of soils/sludge. The soil/sludge samples were extracted using sodium phosphate and trisodium citrate aqueous solutions. The extract was adjusted to pH 9 and contaminations were removed by washing with n-hexane. The method developed in this work further involves derivatization with 9-fluorenylmethylchloroformate (FMOC-Cl) followed by high performance liquid chromatography (HPLC) coupled with fluorescence detection. The method was validated in three soil (red soil, black soil and paddy soil) and two sludge samples (lake and river sludge) from China and verified in six laboratories. A good linear relationship (correlation coefficients ≥0.999) was observed within the range of 0.005-0.5mg/L. The limit of detection (LOD) and the limit of quantitation (LOQ) were determined to be 0.01mg/kg and 0.04mg/kg, respectively. The precision and accuracy were satisfactory with the relative standard deviation (RSD) lower than 15% and the mean recovery values ranging from 75% to 110% (n=6), that spiked at three levels (0.1, 0.5 and 1.0mg/kg).

Effects of 4-nonylphenol in drinking water on the reproductive capacity of Japanese quails (Coturnix japonica).

4-nonylphenol (4-NP), a major degradation product of Nonylphenol ethoxylates (NPEOs), is widespread in environment. In this study, the effects of long-term 4-NP exposure in drinking water on Japanese quails (Coturnix japonica) were investigated. A total of 45 quails were evenly divided into 15 groups and administrated with various doses (0.1 µg L-1, 1.0 µg L-1, 10 µg L-1 and 100 µg L-1, which reflected the environmental concentrations of 4-NP) of 4-NP in drinking water. The results showed that 4-NP in drinking water had no effect on quails' food intake, but significantly decreased the quails' body weights (P < 0.05) in a time- and dose-dependent manner. The egg fertilization rates were also significantly decreased (P < 0.05) in all treatment groups. Moreover, the hatchability was significantly reduced (P < 0.05) in 10 µg L-1 and 100 µg L-1 groups, and the 14 d survival rates of young quails were significantly decreased (P < 0.05) in 1.0 µg L-1, 10 µg L-1 and 100 µg L-1 groups. Damaged spermatogenesis in male quails was observed in all treatment groups. Therefore, administration of 4-NP in drinking water impaired the reproductive ability of Japanese quails, and led to pathological lesions in the male gonads.

Removal mechanisms for extremely high-level fluoroquinolone antibiotics in pharmaceutical wastewater treatment plants.

Pharmaceutical wastewater treatment plants (PWWTPs) receive industrial effluents from the plant that contain extremely high levels of antibiotics and are regarded as one of the major sources of antibiotics in the environment. Two PWWTPs have been selected in Zhejiang Province, China, to assess the removal mechanisms of fluoroquinolone antibiotics (FQs). PWWTP A uses activated sludge with biocarriers in a moving bed biofilm reactor in anoxic and aerobic units, and PWWTP B uses biological units under anaerobic, aerobic, and anoxic conditions. The wastewater samples and solid samples (sludge and suspended solid matter) were analyzed using solid-phase extraction and ultra-performance liquid chromatography-mass spectrometry. Ofloxacin (OFX) was detected in each stage of PWWTP A, and enrofloxacin and ciprofloxacin were detected in PWWTP B. The concentrations of FQs ranged from 0.32 µg/L to 5.7 mg/L. Although the FQs were largely removed in the biological units (94.5 to 99.9%), large amounts were still discharged in the final effluent (up to 88.0 ± 7.0 µg/L) and dewatered sludge (up to 0.85 ± 0.24 mg/kg). Mass balance analyses of samples from PWWTP A indicated that biodegradation (93.8%) was the major mechanism responsible for the removal of OFX, whereas the contribution of sorption by sludge (0.79%) was less significant, deviating from the findings of most similar studies. Using linear analysis and correlation analysis, we found that the log10 values of the FQ concentration in the sludge were positively related with the log10 values of the equilibrium concentration in water (C w ). These relationships can be described by a Freundlich-like equation. However, these relationships were negative when the C w values were high. Our preliminary explanation is that the equilibrium C w plays an important role in controlling the sorption behavior of FQs in activated sludge.

Metagenomic analysis of bacterial community composition and antibiotic resistance genes in a wastewater treatment plant and its receiving surface water.

The presence of pathogenic bacteria and the dissemination of antibiotic resistance genes (ARGs) may pose big risks to the rivers that receive the effluent from municipal wastewater treatment plants (WWTPs). In this study, we investigated the changes of bacterial community and ARGs along treatment processes of one WWTP, and examined the effects of the effluent discharge on the bacterial community and ARGs in the receiving river. Pyrosequencing was applied to reveal bacterial community composition including potential bacterial pathogen, and Illumina high-throughput sequencing was used for profiling ARGs. The results showed that the WWTP had good removal efficiency on potential pathogenic bacteria (especially Arcobacter butzleri) and ARGs. Moreover, the bacterial communities of downstream and upstream of the river showed no significant difference. However, the increase in the abundance of potential pathogens and ARGs at effluent outfall was observed, indicating that WWTP effluent might contribute to the dissemination of potential pathogenic bacteria and ARGs in the receiving river.

Oxidative stress and histopathological alterations in liver of Cyprinus carpio L. induced by intraperitoneal injection of microcystin-LR.

Microcystins (MCs) are a group of cyclic heptapeptide hepatotoxic peptides produced by cyanobacteria. Microcystins-LR (MC-LR) can inhibit the activities of protein phosphatase type 1 and type 2A (PP1 and PP2A) and induce excessive production of reactive oxygen species (ROS). However, the detailed toxicological mechanism involving oxidative stress in carp (Cyprinus carpio L.) remains largely unclear. In our present study, the effects of sublethal intraperitoneal doses of MC-LR on the oxidative stress and pathological changes in carp liver were investigated. No significant changes of xanthine oxidase were observed, suggesting it might not contribute to over-production of ROS in the liver of fish during 48 h exposure to sublethal intraperitoneal doses of MC-LR. Superoxide dismutase activity in the 50 µg kg(-1) group was significantly induced at 1-24 h. The strongest inhibition of the catalase activity was shown at 48 h after 120 µg kg(-1) MC-LR exposure, with an inhibition rate of 33.7% compared to the control group. In general, a significant depletion of intracellular reduced glutathione was found at 5-12 h after 50 and 120 µg kg(-1) MC-LR exposure, which was mainly due to the conjugation reaction to MC-LR catalyzed by glutathione-S-transferase and its subsequent excretion. Oxidative damages induced by MC-LR were evidenced by the significant elevation in malondialdehyde levels. In addition, a series of histopathological alterations in fish livers were observed, and the most severe hepatic injuries were found at 5-12 h, which could contribute to the efflux of intracellular GSH. Our study further supports the important role of oxidative stress involved in MC-LR induced liver injury in aquatic organisms.

Environmental fate of tetracycline resistance genes originating from swine feedlots in river water.

Tetracyclines are antibiotics commonly used in swine farms to treat disease and promote growth. However, there are growing concerns regarding the discharge of animal feces into the environment owing to the potential for development and dissemination of tetracycline resistance genes (TRGs). In this study, farming wastewater from one Chinese swine farm as well as river water from seven locations downstream of the farm was sampled. Polymerase chain reaction (PCR) showed that 12 TRGs, including six efflux pump genes (tet(B), tet(C), tet(D), tet(E), tet(G) and tet(L)), five ribosomal protection proteins (RPPs) genes (tet(O), tet(M), tet(Q), tet(W) and tet(S)), and one enzymatic modification gene (tet(X)), were present in all wastewater and river water samples. Quantitative real-time PCR (qPCR) showed that the abundance of tet(C), tet(X), tet(O), tet(M), tet(Q) and tet(W) decreased with downstream flow. Among the detected TRGs, tet(C) had the highest abundance, ranging from 459.5 copies/16S rRNA gene copies in wastewater to 33.8 copies/16S rRNA gene copies in river water samples collected from the last location. Furthermore, pig-specific Bacteroidales 16S rRNA genetic marker was quantified by qPCR to determine the level of fecal pollution in the river water. Bivariate correlation analysis confirmed that the total relative abundance of the six TRGs was significantly correlated with the level of swine feces in the aquatic environment (R(2) = 0.63, P < 0.05), suggesting that swine feces mainly contributed to the spread of TRGs in the river water.

Pollution characteristics and environmental risk assessment of typical veterinary antibiotics in livestock farms in Southeastern China.

Scientific interest in pollution from antibiotics in animal husbandry has increased during recent years. However, there have been few studies on the vertical exposure characteristics of typical veterinary antibiotics in different exposure matrices from different livestock farms. This study explores the distribution and migration of antibiotics from feed to manure, from manure to soil, and from soil to vegetables, by investigating the exposure level of typical antibiotics in feed, manure, soil, vegetables, water, fish, and pork in livestock farms. A screening environmental risk assessment was conducted to identify the hazardous potential of veterinary antibiotics from livestock farms in southeast China. The results show that adding antibiotics to drinking water as well as the excessive use of antibiotic feed additives may become the major source of antibiotics pollution in livestock farms. Physical and chemical properties significantly affect the distribution and migration of various antibiotics from manure to soil and from soil to plant. Simple migration models can predict the accumulation of antibiotics in soil and plants. The environmental risk assessment results show that more attention should be paid to the terrestrial eco-risk of sulfadiazine, sulfamethazine, sulfamethoxazole, tetracycline, oxytetracycline, chlorotetracycline, ciprofloxacin, and enrofloxacin, and to the aquatic eco-risk of chlorotetracycline, ciprofloxacin, and enrofloxacin. This is the first systematic analysis of the vertical pollution characteristics of typical veterinary antibiotics in livestock farms in southeast China. It also identifies the ecological and human health risk of veterinary antibiotics.

Proteomic analysis of hepatic tissue of Cyprinus carpio L. exposed to cyanobacterial blooms in Lake Taihu, China.

With the rapid development of industry and agriculture and associated pollution, the cyanobacterial blooms in Lake Taihu have become a major threat to aquatic wildlife and human health. In this study, the ecotoxicological effects of cyanobacterial blooms on cage-cultured carp (Cyprinus carpio L.) in Meiliang Bay of Lake Taihu were investigated. Microcystins (MCs), major cyanobacterial toxins, have been detected in carp cultured at different experimental sites of Meiliang Bay. We observed that the accumulation of MCs in carp was closely associated with several environmental factors, including temperature, pH value, and density of cyanobacterial blooms. The proteomic profile of carp liver exposed to cyanobacterial blooms was analyzed using two-dimensional difference in-gel electrophoresis (2D-DIGE) and mass spectrometry. The toxic effects of cyanobacterial blooms on carp liver were similar to changes caused by MCs. MCs were transported into liver cells and induced the excessive production of reactive oxygen species (ROS). MCs and ROS inhibited protein phosphatase and aldehyde dehydrogenase (ALDH), directly or indirectly resulting in oxidative stress and disruption of the cytoskeleton. These effects further interfered with metabolic pathways in the liver through the regulation of series of related proteins. The results of this study indicated that cyanobacterial blooms pose a major threat to aquatic wildlife in Meiliang Bay in Lake Taihu. These results provided evidence of the molecular mechanisms underlying liver damage in carp exposed to cyanobacterial blooms.

Microcystin-LR induced reactive oxygen species mediate cytoskeletal disruption and apoptosis of hepatocytes in Cyprinus carpio L.

Microcystins (MCs) are a group of cyclic hepatotoxic peptides produced by cyanobacteria. Microcystin-LR (MC-LR) contains Leucine (L) and Arginine (R) in the variable positions, and is one of the most common and potently toxic peptides. MC-LR can inhibit protein phosphatase type 1 and type 2A (PP1 and PP2A) activities and induce excessive production of reactive oxygen species (ROS). The underlying mechanism of the inhibition of PP1 and PP2A has been extensively studied. The over-production of ROS is considered to be another main mechanism behind MC-LR toxicity; however, the detailed toxicological mechanism involved in over-production of ROS in carp (Cyprinus carpio L.) remains largely unclear. In our present study, the hydroxyl radical (•OH) was significantly induced in the liver of carp after a relatively short-term exposure to MC-LR. The elevated reactive oxygen species (ROS) production may play an important role in the disruption of microtubule structure. Pre-injection of the antioxidant N-acetyl-cysteine (NAC) provided significant protection to the cytoskeleton, however buthionine sulfoximine (BSO) exacerbated cytoskeletal destruction. In addition, the elevated ROS formation induced the expression of apoptosis-related genes, including p38, JNKa, and bcl-2. A significant increase in apoptotic cells was observed at 12-48 hours. Our study further supports evidence that ROS are involved in MC-LR induced damage to liver cells in carp, and indicates the need for further study of the molecular mechanisms behind MC-LR toxicity.

Simultaneous determination of pesticides, polycyclic aromatic hydrocarbons, polychlorinated biphenyls and phthalate esters in human adipose tissue by gas chromatography-tandem mass spectrometry.

This paper describes a method for the simultaneous determination of 284 environmental contaminants, including 57 pesticides, 15 polycyclic aromatic hydrocarbons (PAHs), 209 polychlorinated biphenyls (PCBs) and 3 phthalate esters (PAEs), in adipose tissue samples. For the first time, a gas chromatography-tandem mass spectrometry (GC-MS/MS) method following a homogenised extraction using acetonitrile and purification by gel permeation chromatography (GPC) was used. Various performance characteristics, such as the limit of detection (LOD), limit of quantification (LOQ), linear range, recovery and precision, were determined for each analyte. The LOD for most analytes was below 0.01 mg/kg. The recoveries and relative standard deviations (RSDs) were determined by spiking untreated samples with the analytes at the LOQ, 2×LOQ and 4×LOQ levels. The average recovery for most pesticides was between 70% and 120% and the precision values, expressed as RSD, were all below 20.4% (n=6). This method may provide an efficient tool for evaluating the extent of exposure to organic contaminants using human adipose tissue.

Bioaccumulation, oxidative stress and HSP70 expression in Cyprinus carpio L. exposed to microcystin-LR under laboratory conditions.

Microcystin-LR (MC-LR) produced by cyanobacteria are potent specific hepatotoxins. So far the pathogenesis of environmental MC-LR toxicity to aquatic organisms has not been fully elucidated. In the present study the accumulation of MC-LR was investigated in various organs/tissues of Cyprinus carpio L. (C. carpio) following exposure to MC-LR for 14 d at environmentally relevant concentrations (0.1 to 10 µg L(-1)). Results showed that the presence of MC-LR enhanced toxin accumulation in all investigated organs and the highest accumulation was found in the liver of fish exposed to 5.0 µg L(-1) of MC-LR. An EPR analysis indicated ·OH intensity in liver was significantly induced at 0.1 µg L(-1) of MC-LR and then restored when the MC-LR concentration was greater than 0.1 µg L(-1). After 14-day exposure, MC-LR (1.0-10.0 µg L(-1) of MC-LR) caused a pronounced promotion of glutathione S-transferase (GST) activity and a depletion of reduced glutathione (GSH) content in fish liver, which indicated that GSH was involved in detoxification of MC-LR and the conjugation reaction of MC-LR and GSH occurred. A mild oxidative damage was evidenced by the accumulation of malondialdehyde (MDA) level at 5.0 µg L(-1) of MC-LR exposure, but which was restored when the MC-LR concentration was increased to 10.0 µg L(-1). The responses of antioxidant enzymes and the induction of HSP70 expression might contribute to MC-LR tolerance of C. carpio. However, the protein phosphatase (PP) activities were strikingly inhibited in all treated groups. Thus, the overall toxicity of environmental MC-LR on C. carpio seems to be initiated in the liver via both the ROS pathway and the PP inhibition pathway, and the latter might be more important when ambient MC-LR concentration is greater than 0.1 µg L(-1). More importantly, these results can help to support the evaluation on the potential effects of MC-LR under common environmental concentrations.

[Effects of multiple environmental factors on triflulsulfuron-methyl degradation in soils].

Triflulsulfuron-methyl, a widely used sulfonylurea herbicide, has done harm to the soil and crop. Its environment fate was affected by many factors such as physicochemical or biological factors. In order to understand the effects of different environmental factors on the degradation of triflulsulfuron-methyl in soil, simulated indoor incubation experiments were carried out to explore the effects of soil microbe, soil type, dissolved organic matter (DOM), temperature, and soil moisture on triflulsulfuron-methyl degradation in soils. The results showed that different environmental factors such as temperature, soil moisture, soil microorganisms and soil type influenced triflulsulfuron-methyl degradation in different degrees. The increased soil microbial biomass, soil organic matters and DOM were beneficial to the soil degradation of triflulsulfuron-methyl, meanwhile, the decrease in soil pH could accelerate its degradation in soils. The results showed that soil microorganisms were the main factor effecting the degradation of triflulsulfuron-methyl in soil. Our results provided initial data for the conclusion that a set of biological and physiochemical factors coordinately regulate the decay of triflulsulfuron-methyl in soils.

Pollution level and human health risk assessment of some pesticides and polychlorinated biphenyls in Nantong of Southeast China.

Food consumption is one of the key exposure routes of humans to contaminants. This article evaluated the residue levels of 51 pesticides and 16 polychlorinated biphenyls (PCBs) in selected fish and food items which were commonly consumed in the Nantong area of Jiangsu Province, Southeast China. The 51 pesticides and 16 PCBs were analyzed by highly sensitive gas chromatography-tandem mass spectrometry (GC-MS/MS). The results showed that organochlorine pesticides such as dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB) and mirex and other pesticides including chlorpyrifos, pyrethroid pesticides, metolachlor, pyridaben and trifluralin were frequently detected in the samples, which was consistent with the accumulation level and characteristics of these toxic chemicals in human adipose tissue of people living in Nantong. Meanwhile, correlation of the residue level of toxic chemicals with their physical chemical properties and historic use pattern in Nantong area was observed. Combined with dietary survey results at the same sampling locations, human health risk assessment of ingestion through the dietary route was performed. The results suggested that the non-cancer risks of the chemicals investigated can be considered negligible in the Nantong area, however, the cancer risks from lifetime dietary exposure to DDTs and HCB have exceeded the acceptable levels.

Effects of ß-endosulfan on the growth and reproduction of zebrafish (Danio rerio).

Because of persistent organic pollution in aquatic environments, the widely used organochlorine pesticide endosulfan, which is a potential endocrine disruptor, is expected to pose a significant risk to aquatic organisms. In the present study, we explored the potential endocrine-disrupting risk of ß-endosulfan by investigating its effect on the growth, reproduction, plasma vitellogenin, and organ histology of adult zebrafish. We found that, although ß-endosulfan did not significantly affect the growth of zebrafish, it greatly decreased the hatching rate, even at a concentration as low as 10 ng/L. Interestingly, the decrease of the hatching rate was highly correlated with pathological alterations of the testes. Additionally, the values of the gonadosomatic index were significantly reduced in female zebrafish treated with 200 ng/L ß-endosulfan, which was also closely associated with ovarian histological changes. More importantly, a significant increase in the level of vitellogenin was observed in all male fish treated with ß-endosulfan. Based on these findings, we conclude that ß-endosulfan severely affects the reproductive function of zebrafish and the synthesis of vitellogenin in the liver, and thus, ß-endosulfan has a serious endocrine disruption function in zebrafish.