A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides...A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides （OCPs） were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow land soils. Among all the pesticides, ΣDDX （DDD, DDE and DDT） had the highest concentration for all the soil samples, ranging from 3.10 ng/g to 166.55 ng/g with a mean value of 57.04 ng/g and followed by ΣHCH, ranging from 0.73 ng/g to 60.97 ng/g with a mean value of 24.06 ng/g. Dieldrin, endrin, HCB and α-endosulfan were also found in soils with less than 15 ng/g. Ratios of p,p＇-（DDD＋DDE）/DDT in soils under three land usages were： paddy field 〉 tree land 〉 fallow land, indicating that land usage inlfuenced the degradation of DDT in soils. Ratios of p,p＇-（DDD＋DDE）/DDT 〉1, showing aged residues of DDTs in soils of the Taihu Lake region. The results were discussed with data from a former study that showed very low actual concentrations of HCH and DDT in soils in the Taihu Lake region, but according to the chemical half-lives and their concentrations in soils in 1980s, the concentration of DDT in soils seemed to be underestimated. In any case our data show that the ban on the use of HCH and DDT resulted in a tremendous reduction of these pesticide residues in soils, but there are still high amounts of pesticide residues in soils, which need more remediation processes.展开更多
Four techniques, Soxhlet extraction (SOX), ultrasonic extraction (USE), fluidized-bed extraction (FBE) and acce-lerated solvent extraction (ASE) with different solvents (methanol, hexane/acetone and acetonitrile) were...Four techniques, Soxhlet extraction (SOX), ultrasonic extraction (USE), fluidized-bed extraction (FBE) and acce-lerated solvent extraction (ASE) with different solvents (methanol, hexane/acetone and acetonitrile) were used for theextraction 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 extractDDT analogues in sediments. Accelerated solvent extraction using methanol and hexane/acetone (1:1), fluidized-bedextraction using hexane/acetone (1:1) and the ultrasonic extraction using hexane/acetone (1:1) were comparable or betterthan 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 extractiontechniques.展开更多
基金Project supported by the Outstanding Young Scholar Fund and Innovative Research Group of the National Natural Science Foundation of China (No. 40325001, 40621001)the National Basic Research and Development Program of China (No. 2002CB410805) the Natural Science Foundation of Jiangsu Province (No. BK2005220).
文摘A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides （OCPs） were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow land soils. Among all the pesticides, ΣDDX （DDD, DDE and DDT） had the highest concentration for all the soil samples, ranging from 3.10 ng/g to 166.55 ng/g with a mean value of 57.04 ng/g and followed by ΣHCH, ranging from 0.73 ng/g to 60.97 ng/g with a mean value of 24.06 ng/g. Dieldrin, endrin, HCB and α-endosulfan were also found in soils with less than 15 ng/g. Ratios of p,p＇-（DDD＋DDE）/DDT in soils under three land usages were： paddy field 〉 tree land 〉 fallow land, indicating that land usage inlfuenced the degradation of DDT in soils. Ratios of p,p＇-（DDD＋DDE）/DDT 〉1, showing aged residues of DDTs in soils of the Taihu Lake region. The results were discussed with data from a former study that showed very low actual concentrations of HCH and DDT in soils in the Taihu Lake region, but according to the chemical half-lives and their concentrations in soils in 1980s, the concentration of DDT in soils seemed to be underestimated. In any case our data show that the ban on the use of HCH and DDT resulted in a tremendous reduction of these pesticide residues in soils, but there are still high amounts of pesticide residues in soils, which need more remediation processes.
基金the Outstanding Youth Fund of the National Natural Science Foundation of China (No. 40325001),the National Key Basic Research and Development Program of China (No. 2002CB410805) and the Ocean University ofChina.
文摘Four techniques, Soxhlet extraction (SOX), ultrasonic extraction (USE), fluidized-bed extraction (FBE) and acce-lerated solvent extraction (ASE) with different solvents (methanol, hexane/acetone and acetonitrile) were used for theextraction 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 extractDDT analogues in sediments. Accelerated solvent extraction using methanol and hexane/acetone (1:1), fluidized-bedextraction using hexane/acetone (1:1) and the ultrasonic extraction using hexane/acetone (1:1) were comparable or betterthan 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 extractiontechniques.
