Title: Metal complexation properties of freshwater dissolved organic matter are explained by its aromaticity and by anthropogenic ligands
Authors: Baken, Stijn ×
Degryse, Fien
Verheyen, Liesbeth
Merckx, Roel
Smolders, Erik #
Issue Date: 2011
Publisher: American Chemical Society
Series Title: Environmental Science & Technology vol:45 issue:7 pages:2584-2590
Abstract: Dissolved organic matter (DOM) in surface waters affects the fate and environmental effects of trace metals. We measured variability in the Cd, Cu, Ni, and Zn affinity of 23 DOM samples isolated by reverse osmosis from freshwaters in natural, agricultural, and urban areas. Affinities at uniform pH and ionic composition were assayed at low, environmentally relevant free Cd, Cu, Ni, and Zn activities. The C-normalized metal binding of DOM varied 4-fold (Cu) or about 10-fold (Cd, Ni, Zn) among samples. The dissolved organic carbon concentration ranged only 9-fold in the waters, illustrating that DOM quality is an equally important parameter for metal complexation as DOM quantity. The UV-absorbance of DOM explained metal affinity only for waters receiving few urban inputs, indicating that in those waters, aromatic humic substances are the dominant metal chelators. Larger metal affinities were found for DOM from waters with urban inputs. Aminopolycarboxylate ligands (mainly EDTA) were detected at concentrations up to 0.14 μM and partly explained the larger metal affinity. Nickel concentrations in these surface waters are strongly related to EDTA concentrations (R(2) = 0.96) and this is underpinned by speciation calculations. It is concluded that metal complexation in waters with anthropogenic discharges is larger than that estimated with models that only take into account binding on humic substances.
ISSN: 0013-936X
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Division Soil and Water Management
× corresponding author
# (joint) last author

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