The origin of speciation: Trace metal kinetics over natural water/sediment interfaces and the consequences for bioaccumulation
article
The speciation of heavy metals was measured over a variety of natural and undisturbed water/sediment interfaces. Simultaneously, two benthic species (oligochaete Limnodrilus spp. and the midge Chironomus riparius) were exposed to these sediments. Under occurring redox conditions, free ion activities of trace metals Cd, Cu, Ni, Pb, and Zn were measured with a chelating exchange technique, while geochemical conditions (i.e., redox) remained in tact. Free ion activities were compared with total dissolved concentrations in pore waters and surface waters in order to relate speciation to bioaccumulation. Limnodrilus spp. and C. riparius have accumulation patterns that could be linked to time-dependent exposure concentrations, expressed as chemical speciation, in the surface water and the sediment's pore water. Concentrations of free metal ions in the overlying surface water, rather than in sediment pore water, proved to be the best predictor for uptake. For the first time, measurements are obtained from sediments without disturbing physical-chemical conditions and thus bioavailability, a major restriction of other studies so far. © 2008 Elsevier Ltd. All rights reserved.
Topics
AvailabilityBiotic ligand model, Water Framework DirectiveFree ion activityRisk assessmentUptakeBio availabilitiesBiotic ligand model, Water Framework DirectiveChemical conditionsChironomus ripariusExposure concentrationsFree ion activityFree ionsFree metalsGeochemical conditionsPore watersRedox conditionsSediment pore watersTrace metalsUptakeBioaccumulationBiochemistryCadmium compoundsChemical speciationDissolutionHeavy metalsIon exchangeIonsLeadMetal ionsMetalsRisk assessmentRisk managementSedimentationSedimentologySurface watersTrace analysisTrace elementsWaterZincHeavy water
TNO Identifier
241373
ISSN
02697491
Source
Environmental Pollution, 157(2), pp. 519-527.
Pages
519-527
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