SORPTION OF CHLOROBENZENES TO CAPE-COD AQUIFER SEDIMENTS

Sorption of tetra- and pentachlorobenzene by sediment from a glacial o utwash aquifer on Cape Cod, MA, was evaluated. Particle size and miner alogical fractions (separated based on paramagnetic susceptibility) we re characterized with respect to sediment organic carbon (SOC), minera logy, surface area, metal oxide coatings, and spatial variability. SOC increases by a factor of 10 as particle size decreases from 500-1000 to <63 mum. Magnetic mineral abundance is a function of particle size and increases from <5% in the 500-1000-mum fraction to >25% in the <63 -mum fraction, and SOC is preferentially associated with the magnetic minerals. Sorption increases with decreasing particle size (increasing SOC, magnetic minerals, surface area, and metal oxyhydroxides), and t he magnetic mineral fraction has greater sorption than the bulk or non magnetic fractions. Removal of SOC decreases sorption proportional to the decrease in SOC and results in a nonlinear isotherm.