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Decreasing DOC trends in soil solution along the hillslopes at two IM sites in southern Sweden

geochemical modeling of organic matter solubility during acidification recovery

Löfgren, Stefan and Gustafsson, Jon Petter and Bringmark, Lage (2010). Decreasing DOC trends in soil solution along the hillslopes at two IM sites in southern Sweden. Science of the total environment. 409:1, 201-210
[Journal article]

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Official URL: http://dx.doi.org/10.1016/j.scitotenv.2010.09.023

Abstract

Numerous studies report increased concentrations of dissolved organic carbon (DOC) during the last two decades in boreal lakes and streams in Europe and North America. Recently, a hypothesis was presented on how various spatial and temporal factors affect the DOC dynamics. It was concluded that declining sulphur deposition and thereby increased DOC solubility, is the most important driver for the long-term DOC concentration trends in surface waters. If this recovery hypothesis is correct, the DOC levels should increase both in the soil solution as well as in the surrounding surface waters as soil pH rises and the ionic strength decline due to the reduced input of SO42- ions. In this project a geochemical model was set up to calculate the net humic charge and DOC solubility trends in soils during the period 1996-2007 at two integrated monitoring sites in southern Sweden, showing clear signs of acidification recovery. The Stockholm Humic Model was used to investigate whether the observed DOC solubility is related to the humic charge and to examine how pH and ionic strength influence it. Soil water data from recharge and discharge areas, covering both podzols and riparian soils, were used. The model exercise showed that the increased net charge following the pH increase was in many cases counteracted by a decreased ionic strength, which acted to decrease the net charge and hence the DOC solubility. Thus, the recovery from acidification does not necessarily have to generate increasing DOC trends in soil solution. Depending on changes in pH, ionic strength and soil Al pools, the trends might be positive, negative or indifferent. Due to the high hydraulic connectivity with the streams, the explanations to the DOC-trends in surface waters should be searched for in discharge areas and peatlands.

Authors/Creators:Löfgren, Stefan and Gustafsson, Jon Petter and Bringmark, Lage
Title:Decreasing DOC trends in soil solution along the hillslopes at two IM sites in southern Sweden
Subtitle:geochemical modeling of organic matter solubility during acidification recovery
Series/Journal:Science of the total environment (0048-9697)
Year of publishing :2010
Volume:409
Number:1
Page range:201-210
Publisher:Elsevier
ISSN:0048-9697
Language:English
Additional Information:Originally published by Elsevier. http://www.sciencedirect.com/science/journal/00489697
Publication Type:Journal article
Refereed:Yes
Full Text Status:Public
Subjects:Obsolete subject words > FORESTRY, AGRICULTURAL SCIENCES and LANDSCAPE PLANNING > Soil science > Soil chemistry
Keywords:DOC trends, forest soils, soil water, recovery from acidification, Stockholm Humic Model, integrated monitoring
URN:NBN:urn:nbn:se:slu:epsilon-8-928
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-8-928
ID Code:5573
Department:(NL, NJ) > Dept. of Aquatic Sciences and Assessment
Deposited By:INVALID USER
Deposited On:13 Jan 2011 00:00
Metadata Last Modified:02 Dec 2014 10:41

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