Transport Of Organochlorine Pesticides Between Sediment And Water In The Eutrophic Water

Hexachlorocyolohexane isomers (HCHs) are typical persistent organic pollutants (POPs). In this thesis, Haihe River was selected as the typical contaminated area. The transport dynamics ofα-HCH andγ-HCH between sediment and the overlying water was studied by simulating laboratory experiments. Effects of composition and content of organic matter and temperature on the transport were considered. The purpose is to reveal the transport mechanism of organochlorine pesticides (OCPs) between sediment and water in eutrophic waters.The transport of HCH in sediment / water interface was simulated in this thesis. The results provide theoretical basis for in-depth study of the distribution and fate of HCH in Haihe River mainstream, which is significantly important for the ecological environment risk assessment, toxic chemical management and environmental restoration. It also plays an important guiding role for the economic development and the health of residents in the Haihe River basin.The results showed that enrichment of organic matter in sediments increased the degradation ofα-HCH andγ-HCH. Along with the increase of temperature, the degradation on HCH in sediments was enhanced.The enrichment of organic matter increased the sediment's sorption of hydrophobic organic compounds, and the non-linear adsorption was more obvious when the degree of carbonization of organic matter is higher. With the content of organic matter in sediments increased, the adsorption capacity of pollutants increased. The organic matter relieved the release of HCH from sediments and reduced the mass transfer flux. As the temperature decreased, the release rate and mass transport flux decreased. As the content of dissolved organic carbon (DOC) in overlying water increased, the mass transfer flux increased. With the increase of depth, the probability of HCH in sediments releasing into overlying water decreased.The calculated results showed that, As the add of organic matter in the sediments, the transport parameters (DSW, KT) were greater than the control group. With the temperature decreased, the fugacity capacity ofα-HCH andγ-HCH in various environmental media increased.