Abstract
Isomers of hexachlorocyclohexanes (HCHs) and metabolites of dichlorodiphenyltrichloroethanes (DDTs) are still frequently detected worldwide in considerable amounts, even decades after their prohibition. Carbonaceous materials (CMs) have been shown to significantly reduce risks of propagation to humans by binding the hydrophobic organochlorine pesticides (OCPs) present in aquatic sediments. In the present study, black carbons extracted from natural sediments, and artificially produced black carbons, including black carbons by burning rice straw at 450 and 850 °C, and a commercial activated carbon were compared to investigate the factors affecting the sorption of γ-HCH (lindane) and p,p’-dichlorodiphenyldichloroethylene (p,p’-DDE) on CMs. The results indicated that when the proportion of CMs to total organic carbon (ƒCM/ƒOC) was greater than 0.35, CMs played a leading role in the sorption of lindane and p,p’-DDE by the sediments. The sorption contribution rate of CMs could reach up to 64.7%. When the ratio of ƒCM/ƒOC was less than 0.10, CMs played a minor role in the sorption. In addition, the nonlinearity of the sorption isotherms was strengthened with the increasing the proportion of CMs to total organic carbon. Our findings show that ƒCM/ƒOC value is a principal parameter for assessing the sorption capacity of sediments added by CMs for OCPs.
Highlights
Organochlorine pesticides (OCPs) are a class of persistent organic pollutants (POPs) used extensively from the 1940s through the 1960s in agriculture and mosquito control
The order of f Carbonaceous materials (CMs) and specific surface area (SSA) of the four CMs showed that activated carbon (AC) and BC850 had better SSA and f CM than SC and burning rice straw at 450 (BC450), which could be related to their structures, given that BC850 was mainly consisted of an aromatic lamellar structure and had many irregular holes; compared with BC850, AC had smaller grain size, more pores, and less inorganic minerals [23]
The factors affecting the sorption of lindane and p,p’-DDE by CMs were explored by comparing the four CMs including SC, BC450, BC850, and AC
Summary
Organochlorine pesticides (OCPs) are a class of persistent organic pollutants (POPs) used extensively from the 1940s through the 1960s in agriculture and mosquito control. They have been prohibited for over 40 years, they and their metabolites still persist, propagate in food chains and have adverse effects on aquatic organisms and human beings [1,2]. Hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) are two classic OCPs that are frequently used as insecticides They were banned in 1983 for agricultural use in China, they still pose a serious threat to human health and aquatic environment because of their historical use and reemissions [3,4,5,6].
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