THE ROLE OF GAS EBULLITION IN THE TRANSPORT OF ORGANIC CONTAMINANTS FROM SEDIMENTS

Sediment box cores were collected from Lake Erie and Hamilton Harbour (Lake Ontario, Canada) to assess transport of sediment contaminants by gas ebullition. Sediment pore water was extracted by centrifugation. Gas (80% CH4/20% N2)/pore water partition coefficients for C-14-labeled lindane were measured with a wetted-wall column apparatus. Gas/water partition coefficients were found to be independent of dissolved organic carbon concentration. Therefore, Henry's law constants (air/water partition coefficients) were used to provide a first-order estimate of the annual flux of dichloromethane, chloroform, and three polynuclear aromatic hydrocarbons from Hamilton Harbour sediments. From these studies it is postulated that the flux of a sediment contaminant would be a function of the gas ebullition rate, Henry's law constant, and pore water concentration. Estimated annual fluxes for contaminants measured in the sediment pore water of Hamilton Harbour ranged from < 1 kg for pyrene to > 100 kg for dichloromethane.