An integrated approach for assessing the migration behavior of chlorpyrifos and carbaryl in the unsaturated soil zone

Chlorpyrifos (O, O-diethyl O-3,5,6-trichloropyridin-2-yl phosphorothioate) and carbaryl (1-naphthyl methylcarbamate) are often applied concurrently as insecticides in food production. The aim of this study was to research their migration behavior in a real environment. We researched the leaching of both pesticides by setting up field lysimeters on a farm with the typical soil used in fruit production today. In order to analyze the variables involved in this process, we performed complementary adsorption studies, we performed complementary adsorption studies using batches and undisturbed soil laboratory columns for both compounds. The results for pesticide transport through the lysimeters showed that less than 1% of chlorpyrifos was recovered in the leachates, while almost 17% was recovered for carbaryl. Having completed the experiment in undisturbed laboratory columns, soil analysis showed that chlorpyrifos mainly remained in the first 5 cm, while carbaryl moved down to the lower sections. These results can be explained in view of the sorption coefficient values (K_D) obtained in horizons A and B for chlorpyrifos (393 and 184 L kg^?1) and carbaryl (3.1 and 4.2 L kg^?1), respectively. By integrating the results obtained in the different approaches, we were able to characterize the percolation modes of these pesticides in the soil matrix, thus contributing to the sustainable use of resources.     

围生期毒死蜱暴露致子代8周雄鼠睾丸组织的氧化损伤

毒死蜱是目前全世界使用和销售量最大的有机磷杀虫剂之一。为探讨围生期毒死蜱暴露致8周雄性子鼠睾丸组织的氧化损伤,选择健康Wistar妊娠母鼠于妊娠期(gestation days,GD)第6天至子鼠出生后(postnatal days,PND)21天通过灌胃染毒0、0.75、1.35和2.70 mg·kg~(-1)剂量的毒死蜱,待雄性子鼠8周龄取左侧睾丸实施组织病理学检查,右侧睾丸用以检测丙二醛(maleic dialdehyde,MDA)的含量和谷胱甘肽S转移酶(glutathione S transferases,GST)、谷胱甘肽过氧化物酶(glutathione peroxidase,GSH-Px)、总超氧化物歧化酶(total superoxide dismutase,T-SOD)的活力。结果表明,与对照组比较,随着染毒剂量的增加子鼠体重和睾丸、附睾脏器系数有下降的趋势(P0.05);而MDA呈升高趋势(P0.05)。各组T-SOD和1.35、2.70 mg·kg~(-1)剂量组GSH-Px活力的下降及2.70 mg·kg~(-1)剂量组GST活力的升高均有统计学意义(P0.05)。睾丸组织病理学检查结果可见2.70mg·kg~(-1)剂量组睾丸组织有明显的损伤,管腔中精液量减少,生精细胞脱落增多。上述研究结果提示母鼠于围生期暴露于毒死蜱,可通过氧化损伤诱导子代雄性大鼠睾丸的毒性作用。     

利用N-乙酰-β-D-氨基葡萄糖苷酶含量评价农药对花翅摇蚊种群发育的影响

为了进一步探索种群水平的生态风险评估方法,本文利用β-N-Acetyl-D-glucosaminidase(NAGase)的变化量来监测农药对摇蚊种群发育的影响。从花翅摇蚊Chironomus kiiensis体内分离纯化得到电泳纯的NAGase,并通过免疫大白兔制得NAGase的多克隆抗体。运用间接非竞争ELISA法检测抗体特异性,结果表明其与共同存在于水体的一些生物的NAGase的交叉反应率为隆线溞4.41%、老年低额溞3.12%、多刺裸腹溞3.40%、中华薄壳介4.17%、日本沼虾3.23%、白纹伊蚊7.50%、小球藻0.5%。运用抗体测得毒死蜱、氰戊菊酯和阿维菌素3种杀虫剂对于摇蚊NAGase释放量的12 d-EC50分别为1.2012、0.0043和0.6281μg·L-1,以NAGase活力作为测试终点,测得相应的12 d-EC50:1.4765、0.0051和0.6756μg·L-1,两者差异不显著,但均显著低于以死亡作为测试终点的12 d-LC50:4.8171、0.0954和2.1340μg·L-1,且毒力大小均为氰戊菊酯阿维菌素毒死蜱。上述结果表明,利用NAGase多克隆抗体可以特异性地检测农药对花翅摇蚊种群发育的影响。     

铜、毒死蜱单一与复合暴露对蚯蚓的毒性作用

土壤环境中重金属-农药复合污染已经对土壤生态和人类生存环境构成严重威胁.其中重金属铜和有机磷农药毒死蜱作为土壤环境中两类常见的污染物,其复合污染的环境效应值得关注.本文采用OECD标准滤纸接触法、人工土壤法研究了铜-毒死蜱单一及复合暴露对蚯蚓急性致死作用及回避行为的影响.结果表明,滤纸法和人工土壤法Cu对蚯蚓急性毒性的48h-LC50和14 d-LC50分别为2.23μg·cm-2和496.05 mg·kg-1;而毒死蜱对蚯蚓急性毒性的48 h-LC50和14 d-LC50分别为5.94μg·cm-2和186.07 mg·kg-1.滤纸法和人工土壤法铜、毒死蜱浓度单位配比1∶1时,铜、毒死蜱对蚯蚓急性毒性联合作用类型均近似表现为相加作用,而毒性单位配比1∶1的滤纸法和人工土壤法试验结果分别为协同作用和拮抗作用.回避行为试验结果表明,铜、毒死蜱对蚯蚓回避行为的联合作用类型为拮抗作用.     

Biodegradation of chlorpyrifos by either single or combined cultures of some soilborne plant pathogenic fungi

Abstract

Biodegradation of chlorpyrifos was studied in liquid culture media amended with either single or combined eight different plant pathogenic fungi isolated from the continuous cropping wheat fields. The average recovery of chlorpyrifos from the liquid media was found to be 86.1%. The detection limit of chlorpyrifos by the analytical method used was 19 ppb. Data showed that the growth of mixed fungi at concentrations up to 200 ppm of chlorpyrifos was higher than in the control treatment. Chlorpyrifos concentrations declined in the medium of combined fungi more than it did in the medium of any single fungus with increase in the incubation period. The amount of chlorpyrifos recovered was 79.8 ppm (39.9%) in the combined fungal cultures after 21 days. However, those recovered from the media of Fusarium graminearum, F. oxysporum, Rhizoctonia solani, Cladosporhim cladosporiodes, Cephalosporium sp., Trichoderma viridi, Alternaria alternata, and Cladorrhinum brunnescens, ranged from 48.0 to 74.8%. The half‐life value (T_1/2) for chlorpynfos was 15.8 day in the medium amended with mixed fungi. However, for the single cultures it ranged from 19.3 to 33.0 day.     

Individual and combined toxic effects of cypermethrin and chlorpyrifos on earthworm

Toxicities were assessed for a pyrethroid (cypermethrin) and an organophosphate insecticide (chlorpyrifos) individually and in combination. A series of tests were conducted on di erent responses (acute, chronic, behavioral) of earthworms of species Eisenia fetida andrei in the ecological risk assessment of these pesticides. The results showed that the toxicity of the mixture of cypermethrin and chlorpyrifos was significantly higher than either of these pesticides individually, especially on the earthworm’s chronic responses. At a concentration of 5 mg/kg, the mixture caused significant reductions on the growth and reproduction rates of earthworms, but did not cause any significant e ect when the individual was tested. The increase in toxicity of the pesticide mixture means that the use of toxicity data obtained exclusively from single-pesticide experiments may underestimate the ecological risk of pesticides that actually present in the field.     

Degradation of chlorpyrifos in laboratory soil and its impact on soil microbial functional diversity

Degradation of chlorpyrifos at different concentrations in soil and its impact on soil microbial functional diversity were investigated under laboratory conditions. The degradation half-lives of chlorpyrifos at levels of 4, 8, and 12 mg/kg in soil were calculated to be 14.3, 16.7, and 18.0 d, respectively. The Biolog study showed that average well color development (AWCD) in soils was significantly (P < 0.05) inhibited by chlorpyrifos within the first two weeks and thereafter recovered to the similar level as the control. A similar variation in the diversity indices (Simpson index 1/D and McIntosh index U) in chlorpyrifos-treated soils was observed, no significant difference in the Shannon-Wiener index H' was found in these soils. With increasing chlorpyrifos concentration, the half-lives of chlorpyrifos were significantly (P ≤ 0.05) extended and its inhibitory effects on soil microorganisms were aggravated. It is concluded that chlorpyrifos residues in soil had a temporary or short-term inhibitory effect on soil microbial functional diversity.     

Toxicity assessing for chlorpyrifos-contaminated soil with three different earthworm test methods

Earthworm toxicity tests are useful tools for terrestrial risk assessment but require a hierarchy of test designs that differ in effect levels (behavior, sublethal, lethal). In this study, the toxicity of chlorpyrifos contaminated soil on earthworms was assessed. In addition to the acute and chronic tests, an avoidance response test was applied. Earthworms were exposed to sublethal and lethal concentration of chlorpyrifos, and evaluated for acute toxicity, growth, fecundity and avoidance response after a certain exposure period. The test methods covered all important ecological relevant endpoints (acute, chronic, behavioral). Concentration of 78.91 mg/kg, chlorpyrifos caused significant toxic effects in all test methods, but at lower test concentrations, only significant chronic toxic effects could be observed. In the present study, chlorpyrifos had adverse effect on growth and fecundity in earthworm exposed to 5 mg/kg chlorpyrifos after eight weeks. The avoidance response test, however, showed significant repellent effects concentration of 40 mg/kg chlorpyrifos. For chlorpyrifos, concentration affecting avoidance response was far greater than growth and fecundity, it seemed likely that earthworms were not able to escape from pesticide-contaminated soil into the clean soil in field and hence were exposed continuously to elevated concentrations of pesticides.     

Dissipation of chlorpyrifos in pakchoi-vegetated soil in a greenhouse

The dissipation of chlorpyrifos in pakchoi-vegetated soil was investigated in the summer and autumn in a greenhouse and field, respectively. The dissipation of chlorpyrifos in pakchoi-grown soil was comparatively described by fitting the residue data to seven models （lst-order, 1.5th-order, 2nd-order, RF lst-order, RF 1.5th-order, RF 2nd-order, and bi-exponential or two-compartment models）. Statistical analysis was performed using the SPSS 11.5 statistical package. The bi-exponential model was selected as the optimal model according to the coefficient of determination r^2. The dissipation half-lives （DT50） of chlorpyrifos in pakchoi-vegetated soil at the recommended dose in the summer and autumn, calculated by the bi-exponential model, were 0.6 and 1.2 d in a greenhouse, 0.4 and 1.0 d in a field, respectively; the corresponding values at double dose were 1.2 and 2.1 d in a greenhouse, 0.5 and 1.3 d in a field, respectively. The kinetic data indicate the dissipation of chlorpyrifos in pakchoi-grown soil in a greenhouse is slower than that in a field, and dissipates slower in the autumn than in the summer.     

3株真菌对毒死蜱的降解特性

从污水排放口污泥中分离到3株以毒死蜱为唯一碳源生长的真菌WZ-Ⅰ、WZ-Ⅱ、WZ-Ⅲ,鉴定均为镰孢霉属(FusariumLK. exFx). 3株菌5d内对50mgL-1毒死蜱的降解率分别高达93. 5%、91. 4%和83. 5%.测定了不同碳源、pH、温度及毒死蜱浓度对真菌降解能力和生长量的影响.结果表明,以毒死蜱为唯一碳源且其浓度为20~200mgL-1,pH6. 5~9. 0,温度30 ~40℃时,真菌的降解效果较好;真菌生长量随外加碳源浓度的增加而增加,在pH 6. 5 ~9. 0时生长量较大,且当毒死蜱浓度为50mgL-1,温度40℃时其生长量最大. 图5表1参18