Influences of dissolved organic carbon on the partitioning and bioconcentration oif polychlorinated biphenyls(PCBs) in Huaihe River

The partitioning of hydrophobic organic contaminants within the enviroment is fundamental importance in determining their fate and transport.A number of studies have examined the bioconcentration of organic chemicals to biota and adsorption of orangic contaminants to sediments or to suspended particulates and have shwon the affinity for association of a contaminant with a sediment or biota is well correlated with the hydrophobicity of the contaminant (K_(OW)) and with the organic content of the sediment.Another potentially important,it has been observed frequently that at the high log K_(OW) end of the range as well as at the very low end,the linear correlation of BCF with log K_(OW) seems to break down,resulting in a constant BCF at the hydrophilic end and in a leveling off or even decreasing BCF at the hydrophobic end of the range.Numerous studies have shown that the bioconcentration and adsorption of organic chemicals has been related to the concentrations of dissolved organic matter(DOM).It has been suggested that the relation between the concentration of DOC and partitioning coefficients(sediment organic carbon normalized, or K_(OC)) or the bioconcentration factors (or BCF).The aim of the present study was to determine the effects of dissolved organic matter(DOM) in natural water on the bioconcentration and adsorption of PCBs using methods described by Burkhard L.P.Partitioning coefficients and bioconcentration factors of polychlorinated biphenyls were calculated based on concentrations of PCBs in water,sediment and fish simultaneously sampled from 4 sites along Huaihe River,China.The results showed that there were no correlations between partitioning coefficients (K_(OC) and BCF) and the octanol/water partitioning coefficients(or K_(OW)) under field condition.However when the interaction between PCBs and DOM was assumed and the both log K_(OC) and log K_(OW) were recalculated using corrected free concentrations of PCBS in water,they could be linearly correlated to the hydrophobicity of PCB congeners( or log K_(OW)).It was concluded that DOM in water affected the mobility and ecological risks of PCBs in aquatic environment.