[Characterization of free and bound organochlorine pesticides in four soil/sediments of the Pearl River Delta, China].
Free and bound residues are the main form of organochlorine pesticides (OCPs) in soils/sediments. Four surface soil/sediments from the Pearl River Delta, China, were selected to characterize free and bound OCPs in different fractions of organic matters in the samples through alka-extraction, HCl/HF demineralization and organic solvent extraction. Total OCPs concentrations of samples were 20.96-134.22 microg x kg(-1), total HCHs concentrations were 5.66-22.87 microg x kg(-1), and total DDTs concentrations were 1.51-11.70 microg x kg(-1). beta-HCH, heptachlor, aldrin, endrin, endosulfan sulfate and methoxychlor were the dominate compounds which took 53.56%-77.26% of total OCPs. Concentrations of free OCPs were 8.46-88.45 microg x kg(-1) and took 40.37%-65.90% of total OCPs while concentrations of bound OCPs were 11.46-45.77 microg x kg(-1) and took 34.10%-59.63% of total OCPs. Most of bound OCPs were in the humic acid and humin fractions of the samples which shows the significantly occurrence of bound OCPs in environment. Distributions of free DDTs and HCHs showed that there were no fresh HCHs poured into these samples but there were fresh DDTs poured into some of the samples. The distribution of OCPs in these two fractions were associated with the organic C content of the fractions, and 94.78%-97.48% of bound OCPs were in humin fraction which took 57.71%-80.55% of total organic C in the samples. Environmental risk estimate showed that some free OCPs such as gamma-HCH, aldrin, endrin and DDTs may have risk to environment and total of free and bound concentration of each compound were 1-30 times higher than free concentration of each compound. Therefore bound OCPs should be considered while making the environmental risk estimate and establishing environmental criteria.
He
Lu-lu
LL
State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China. helulu122@126.com
Song
Jian-zhong
JZ
Yu
Chi-ling
CL
Peng
Ping-an
PA
D002681:China; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry*; D006843:Hydrocarbons, Chlorinated / Q000032:analysis* / Q000737:chemistry; D010573:Pesticide Residues / Q000032:analysis* / Q000737:chemistry; D045483:Rivers / Q000737:chemistry; D012987:Soil / Q000032:analysis*; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry
D006843:Hydrocarbons, Chlorinated; D010573:Pesticide Residues; D012987:Soil; D012989:Soil Pollutants