Print Email Facebook Twitter Groundwater chemistry of Al under Dutch sandy soils: Effects of land use and depth Title Groundwater chemistry of Al under Dutch sandy soils: Effects of land use and depth Author Fest, E.P.M.J. Temminghoff, E.J.M. Griffioen, J. van der Grift, B. van Riemsdijk, W.H. TNO Bouw en Ondergrond Publication year 2007 Abstract Aluminium has received great attention in the second half of the 20th century, mainly in the context of the acid rain problem mostly in forest soils. In this research the effect of land use and depth of the groundwater on Al, pH and DOC concentration in groundwater under Dutch sandy soils has been studied. Both pH and DOC concentration play a major role in the speciation of Al in solution. Furthermore, the equilibrium with mineral phases like gibbsite, amorphous Al(OH)3 and imogolite, has been considered. Agricultural and natural land use were expected to have different effects on the pH and DOC concentration, which in turn could influence the total Al concentration and the speciation of Al in groundwater at different depths (phreatic, shallow and deep). An extensive dataset (n = 2181) from the national and some provincial monitoring networks on soil and groundwater quality was used. Land use type and groundwater depth did influence the pH, and Al and DOC concentrations in groundwater samples. The Al concentration ranged from <0.4 μmol L-1 at pH > 7 to 1941 μmol L-1 at pH < 4; highest Al concentrations were found for natural-phreatic groundwater. The DOC concentration decreased and the median pH increased with depth of the groundwater. Natural-phreatic groundwater showed lower pH than the agricultural-phreatic groundwater. Highest DOC concentrations were found for the agricultural-phreatic groundwater, induced by the application of organic fertilizers. Besides inorganic complexation, the NICA-Donnan model was used to calculate Al3+ concentrations for complexation with DOC. Below pH 4.5 groundwater samples were mainly in disequilibrium with a mineral phase. This disequilibrium is considered to be the result of kinetic constraints or equilibrium with organic matter. Log K values were derived by linear regression and were close to theoretical values for Al(OH)3 minerals (e.g. gibbsite or amorphous Al(OH)3), except for natural-phreatic groundwater for which lower log K values were found. Complexation of Al with DOC is shown to be an important factor for the Al concentrations, especially at high DOC concentrations as was found for agricultural-phreatic groundwater. © 2007 Elsevier Ltd. All rights reserved. Subject GeosciencesAcid rainGroundwater geochemistryLinear regressionpH effectsSandSoilsGibbsiteGroundwater chemistryImogoliteSandy soilsAluminumacid rainaluminumdissolved organic carbongroundwaterland usepHphreatic zonesandy soilspeciation (chemistry)twentieth centurywater chemistrywater qualityBeneluxEurasiaEuropeNetherlandsWestern Europe To reference this document use: http://resolver.tudelft.nl/uuid:ebfc55bf-8046-44fb-b7bb-732673a37c69 TNO identifier 240045 ISSN 0883-2927 Source Applied Geochemistry, 22 (7), 1427-1438 Document type article Files To receive the publication files, please send an e-mail request to TNO Library.