Transport Of Persistent Organic Pollutants (POPs) In Sediments/waster System In Dagu Drainage River

The general purpose of this work is to study the transport of the sediments and associated contaminants , so as to provide gist for solving the problems of contaminated bottom sediments in aquatic systems. A study of the resuspension, deposition and transport of sediments and the transport and fate of POPs in the Dagu Drainage River in TianJin has been made. Calculations of sediment and contaminant transport and fate were made for steady flows at high flow rates as well as low flow rates.From April 2004 to August 2005 ,the measurements of physiochemical character of water and sediments at 13 transects were made. At the same time,the contamination of POPs in water and sediments was analyzed. From the transects,from measurements of water and sediment,an accurate description of the contamination of water and sediment has been made. It is also shown that the contamination of POPs is so serious. During low-flow conditions,POPs diffusional transport from sediment into the porewater,and then diffusional transport across the aqueous boundary layer at the sediment-water interface into river water. In this work,laboratory techniques were developed and applied to assess the diffusive release of HCB from sediments to water under low-flow conditions for surficial sediments with different HCB concentrations collected from the Dagu Drainage River. Data on HCB sediment-water equilibrium partitioning and HCB mass release flux from sediments were used to assess the extent and mass transfer rate of HCB release under low-flow conditions in the Dagu Drainage River. Microcosm studies were employed to evaluate the release flux of HCB under quiescent conditions for various sediments.The observed HCB release fluxes ranged from about 0.12 to 0.83mg/m2.year and the average HCB mass transfer coefficients ranged from 0.35 to 0.96cm/day.Of particular importance are the suspension/erosion of the sediments and associated contaminants after the sediments were eroded. Since most contaminants are sorbed to fine-grained sediments,it is the suspension/erosion properties of these sediments that need to be known,and that is the emphasis of the present paper. In flume experiments , the suspension properties of sediments and associated contaminants were obtained. The amount of sediment suspended was quantitatively...