Study of interaction of DOC with aluminium and hydrogen ion in soil- and surface water using a simple equilibrium model

Abstract

A simple equilibrium model involving the interaction of dissolved organic carbon (DOC) with Al and H + is applied to soil solution and surface water data from the experimental HUMEX catchment in western Norway and the acidified Birkenes catchment in southern Norway. The model covers the major covariation in the components. Model testing and calculations of uncertainties in the results were undertaken by use of synthetic data, i.e. data produced with the model taking estimated measurement errors into account. The DOC behaved only slightly different in various soil solutions and surface water within one catchment, but differred substantially from the Birkenses to the HUMEX catchment. The binding of Al and H + involved more sites per mg C of DOC in Birkenes, but the average binding strength was much weaker than in HUMEX. This difference may be induced by acidification and may increase the level of toxic inorganic Al in acidified areas. No significant difference has evolved at this stage between the experimentally acidified and the control side of the HUMEX catchment.