PARTICLE-WATER INTERACTIONS OF 2,2,5,5-TETRACHLOROBIPHENYL UNDER SIMULATED ESTUARINE CONDITIONS

A batch sorption technique for the determination of particle-water int eractions of hydrophobic organic micropollutants under simulated estua rine conditions is described. Results are presented for the behaviour of 2,2',5,5'-tetrachlorobiphenyl (2,2',5,5'-TCB) in river and sea wate rs, both in the presence and absence of estuarine suspended particles. Adsorption onto particles in sea water was enhanced compared with ads orption in river water owing to salting out of the compound, and possi bly of the particulate organic matter, in the presence of high concent rations of dissolved ions. The particle-water distribution coefficient , K,, decreased from about 120 X 10(3) to 10 X 10(3) ml g(-1), and fro m about 150 X 10(3) to 20 X 10(3) mi g-l, in river water and sea water , respectively, over a particle concentration range of 10-1000 mg 1(-1 ). incomplete recovery of compound from the reactor walls is partly re sponsible for a particle concentration effect, while artefacts relatin g to inadequate sediment and water phase separation were ruled out fol lowing further experiments. The particle concentration effect, which i s replicated in many field studies of hydrophobic organic micropolluta nts, including 2,2',5,5'-TCB, is incorporated into a simple partitioni ng model and is discussed in the context of the likely estuarine behav iour of such compounds. (C) 1998 Elsevier Science B.V. All rights rese rved.