ARTIFACTS IN SORPTION EXPERIMENTS WITH TRACE-METALS

Laboratory studies of trace metal sorption by natural and synthetic pa rticles are frequently unrealistic due to the concentrations of sorbat e and sorbent being orders of magnitude above those found in nature. U ndertaking such experiments under more realistic conditions requires c areful quality assessment of the methods used. A series of systematic sorption experiments, based on filtration and measurement by atomic ab sorption spectrometry (AAS), showed that metal losses to container wal ls and filters were unavoidable in solutions which emulate freshwaters . These errors can be corrected by using multiple control solutions wh ich estimate metal losses at the appropriate pH and solution concentra tions. Without such corrections, sorption can be appreciably overestim ated.