Bioavailability Concentrations And Fluxes Of Hydrophobic Organic Contaminates In Sediment Porewater

Hydrophobic Organic Contaminants (HOCs) are carcinogenic, teratogenic and mutagenic, harmful to the organisms. HOCs easily accumulate in the soil and river, lake sediments. Understand and evaluate the sediment pore water flux of hydrophobic organic pollutants and biological effectiveness is a very important basic research work.The Grand Calumet River (Hammond, Indiana, USA) was chosen as the research site in this study. The seepage meter was successfully installed at study site to measure sediment-water interface flux. The concentration of HOCs in sediment-water interface was determined by indirect method. Then HOCs flux in sediment pore water was also evaluated.Also, the main focus of this study was to evaluate the relationship between the changes in mass transfer flux and pore water Darcy velocity in sediment, and estimation of HOCs fluxes in the river sediment. The main results are summarized as follows:The parameters have been optimized by finding the relationship between the heat pulse of seepage meter and water temperature. The system was successfully attempt to measure sediment-water interface flux in the field.Use of surfactant (Brij 30) as an indirect medium, a novel method was used to determine the LDPE-water partition coefficients (KPE-w) for 63 kinds of HOCs by measuring KPE-mic coefficient of HOCs in Low Density Polyethylene (LDPE) and surfactant aqueous concentration. The accuracy of Kmic-w and KPE-w (nearly three weeks) was determined in water for high hydrophobic compounds. This method has been successfully resolved the problem longer period determination (nearly 6 to 12 months). In present study, combined measurement of the KPE-w values and calculation results were consistent with previous studies.An in-situ passive sampler was successfully developed to examine the feasibility of assessing the bioavailability of HOCs in the sediment pore water. Combined with the sediment-water interface flux, HOCs flux of sediment-water interface was estimated in current study. It provided a simple and feasible approach for the assessment of toxicity and bioavailability in the river sediment.Gas fluxes in water-air interface were also investigated at the Grand Calumet river sediment. Results indicate that when the sediment gas flux was higher, the HOCs flux was also higher at the same the study sites. Comparatively a simple relationship was existed between gas flux and measured parameters (GF= 0.316 T+300.66/, R2= 0.82), it was evaluated by analyzing the relationship between the pore water concentration of pollutants in different water level and temperature conditions under different gas fluxes in the sediment.Current results provided an important basic data for carrying out river sediments pollution monitoring and control.