比较四种提取技术分析沉积物中滴滴涕同系物

Four techniques, Soxhlet extraction （SOX）, ultrasonic extraction （USE）, fluidized-bed extraction （FBE） and accelerated solvent extraction （ASE） with different solvents （methanol, hexane/acetone and acetonitrile） were used for the extraction of DDT analogues in sediments. Results revealed that the four extraction techniques had high recoveries （〉 86.0%） with low standard deviations （〈 12.0%） for most of DDT analogues, meaning that they could all successfully extract DDT analogues in sediments. Accelerated solvent extraction using methanol and hexane/acetone （1：1）, fluidized-bed extraction using hexane/acetone （1：1） and the ultrasonic extraction using hexane/acetone （1：1） were comparable or better than Soxhlet extraction using hexane/acetone （1：1）. Considering solvent- and time-consumption, level of automation, and environmental risk, accelerated solvent extraction with hexane/acetone （1：1） was better than the other extraction techniques.     

土壤渗出液中DDT的光催化氧化降解反应条件研究

通过改变反应的催化剂条件,对土壤渗出液中有机氯农药DDT的光催化氧化降解反应进行对比试验,结果表明,在土壤渗出液中添加纳米TiO2对有机氯农药DDT的光催化氧化降解效果不明显;而过渡金属和大量营养元素肥料与纳米TiO2协同作用的降解效果则比较明显,DDT去除率高达93.26%。文中还讨论了影响土壤渗出液中DDT光催化氧化反应的主要因素。     

安徽农田有机氯农药污染现状

本文报道六六六停用几年后安徽省砀山等16县农田土壤中六六六、DDT污染水平。土壤中六六六平均残留0.150mg/kg;局部地区维持0.2—0.5mg/kg残留水平,说明存在新的污染;残留六六六以α-、γ-和σ-666为主,β—666呈降低消失趋势。全省农田土壤DDT平均残留0.361mg/kg,淮北旱地及沿江稻区水平较高,超过0.4mg/kg;残留形式以pp′—DDT和pp′—DDD为主。     

Voltage‐sensitive sodium channel mutations S989P + V1016G in Aedes aegypti confer variable resistance to pyrethroids,DDT and oxadiazines

BACKGROUND

Aedes aegypti is a vector of several important human pathogens. Control efforts rely primarily on pyrethroid insecticides for adult mosquito control, especially during disease outbreaks. A. aegypti has developed resistance nearly everywhere it occurs and insecticides are used. An important mechanism of resistance is due to mutations in the voltage‐sensitive sodium channel (Vssc) gene. Two mutations, in particular, S989P + V1016G, commonly occur together in parts of Asia.

RESULTS

We have created a strain (KDR:ROCK) that contains the Vssc mutations S989P + V1016G as the only mechanism of pyrethroid resistance within the genetic background of Rockefeller (ROCK), a susceptible lab strain. We created KDR:ROCK by crossing the pyrethroid‐resistant strain Singapore with ROCK followed by four backcrosses with ROCK and Vssc S989P + V1016G genotype selections. We determined the levels of resistance conferred to 17 structurally diverse pyrethroids, the organochloride DDT, and oxadiazines (VSSC blockers) indoxacarb (proinsecticide) and DCJW (the active metabolite of indoxacarb). Levels of resistance to the pyrethroids were variable, ranging from 21‐ to 107‐fold, but no clear pattern between resistance and chemical structure was observed. Resistance is inherited as an incompletely recessive trait. KDR:ROCK had a > 2000‐fold resistance to DDT, 37.5‐fold cross‐resistance to indoxacarb and 13.4‐fold cross‐resistance to DCJW.

CONCLUSION

Etofenprox (and DDT) should be avoided in areas where Vssc mutations S989P + V1016G exist at high frequencies. We found that pyrethroid structure cannot be used to predict the level of resistance conferred by kdr. These results provide useful information for resistance management and for better understanding pyrethroid interactions with VSSC. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Effects of DDT and its metabolites on soil algae and enzymatic activity

 The persistence of DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane] and its metabolites in soil, their toxicity to soil algae, and effects on microbial activities were studied in laboratory microcosms for 45 days. In non-sterile soils, removal of DDD [1,1-dichloro-2,2-bis(p-chlorophenyl)ethane] and DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] was less than 3%, while 4–8% of applied DDMU [1-chloro-2,2-bis(p-chlorophenyl)ethylene], DDA [2,2-bis(p-chlorophenyl)acetic acid] and DDT were lost. Added DDOH [2,2-bis(p-chlorophenyl)ethanol] was more labile, as 60% was degraded during the same period. Soil microalgae were not measurably affected by the compounds tested at 10–50 mg kg^–1, but at 100 mg kg^–1 soil, DDD, DBP (p,p′-dichlorobenzophenone) and DDA significantly reduced their growth. Phosphatase activity was not affected by DDT and its metabolites at the concentrations tested (≤50 mg kg^–1), but all compounds inhibited dehydrogenase activity at concentrations of 50 mg kg^–1 soil. The toxic effects of DDT and its metabolites were dose-related. Received: 9 January 1998