The use of diffusive gradients in thin-film (DGT) passive samplers for the measurement of bioavailable metals in river water

摘要

Ecotoxicology has become an important part of environmental assessment and consequently it is of great pertinence to determine the bioavailable fraction of a pollutant that can be linked to acute or chronic effects on biological organisms.The distribution of metals in the aquatic environment ranges from completely dissolved to particulate-bound species,the latter encompassing simple inorganic complexes,complexes with organic macromolecules (e.g.humic acids) and metal adsorbed onto or within microorganisms and suspended matter.This speciation affects the bioavailability of the metal in question.With these factors in mind,the measurement of total concentration is,therefore,inappropriate for the estimation of the fate and toxicity of heavy metals in the natural environment.In addition,classical methods for the determination of metal speciation involve additional treatment of samples and so often result in unrepresentative estimations.Indeed,metal speciation can be affected by variations in water temperature and dissolved oxygen,interactions with sampling bottle material,microbial activity,light exposure and artifacts associated with filtration.In addition,sample storage can also affect solution composition and result in altered heavy metal concentrations,thus providing unrepresentative environmental measurements.