Iron and aluminium phases in softwater lakes: identity and significance for copper binding
2009 (English)Conference paper (Other academic)
Aluminium and iron have been found to compete with copper for binding sites to dissolved organic matter (DOM) in soil systems and when using geochemical modelling. However, the knowledge of the phases of Al, Fe and DOM in natural waters is uncertain. The aim of this ongoing work is to advance the knowledge on the geochemistry of iron and aluminium so that the speciation of copper in lake water can be more accurately assessed. Water samples from three softwater lakes in Tyresta (Stockholm) (Fig. 1),Sweden, are filtered using 0.45 µm and using 1 kDa cross-flow ultrafiltration. The particles on the filters and the colloidal phases of iron are investigated by extended X-ray absorption fine structure (EXAFS) spectroscopy. Aluminium phases are investigated by Fourier transform infrared (FTIR) spectroscopy. Field-flow fractionation (FFF) is used to study the colloidal composition of iron, aluminium and DOM. The competition of Al and Fe with Cu on binding to DOM is explored with Cu titrations using an ion selective electrode. The results will be used to improve geochemical modelling.
Preliminary results from EXAFS spectroscopy for an acid lake rich in DOM (Lake Trehörningen; pH 4.8, DOC = 22 mg/l) indicate that Fe is not present as a mineral in the colloids, instead it is bound as monomeric Fe(III) complexes to organic matter, which means that it probably competes with Cu for binding sites on DOM. Additional results will be presented at the conference.
Place, publisher, year, edition, pages
IdentifiersURN: urn:nbn:se:kth:diva-85869OAI: oai:DiVA.org:kth-85869DiVA: diva2:500227
Biogeomon: 6th International Symposium on Ecosystem Behaviour, BIOGEOMON 2009. Helsinki, Finland. June 29th –July 3rd 2009
FunderSwedish Research Council, 2007-4468
QC 201204272012-02-132012-02-132012-04-27Bibliographically approved