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Effect of Ca on the solubility and molecular size distribution of DOC and Cu binding in soil solution samples

Lookup NU author(s): Dr Jan Dolfing

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Abstract

Flocculation of soil-derived dissolved organic carbon (DOC) was used as a tool to study the molecular size distribution of DOC and the native amount of copper bound to different size fractions. DOC was extracted from arable soils that had received varying amounts of animal manure, inorganic fertilizer, or CuSO4. Addition of calcium to the DOC extracts resulted in flocculation of up to 50% of the DOC originally present in the samples. High performance size exclusion chromatography (HPSEC) analysis revealed that the DOC removed mainly consisted of high molecular weight (HMW) organic acids. Low molecular weight (LMW) substances remained soluble even at high calcium concentrations. Copper solution concentrations decreased almost linearly with decreasing DOC levels, suggesting that copper remained bound to the flocculated material despite increasing calcium concentrations. The amounts of copper bound to both LMW and HMW components depended on the copper content of the soil and were described by two Langmuir sorption equations. Maximum binding capacities varied between 250 mu mol of copper g(-1) of C for HMW components and 450 mu mol of copper g(-1) of C for LMW components, but binding affinities were higher for HMW components. The Langmuir equation described the measured copper solution concentrations from the batch experiments very well (R-2 = 0.994). The observation that up to 50% of the DOC in solution was not removed by calcium indicates that a significant part of copper is potentially highly mobile in soils and can be prone to DOC-facilitated transport.


Publication metadata

Author(s): Römkens PFAM, Dolfing J

Publication type: Article

Publication status: Published

Journal: Environmental Science & Technology

Year: 1998

Volume: 32

Issue: 3

Pages: 363-369

Print publication date: 01/02/1998

ISSN (print): 1382-3124

URL: http://dx.doi.org/10.1021/es970437f

DOI: 10.1021/es970437f

Notes: Times Cited: 51 Cited Reference Count: 34 English Article ENVIRON SCI TECHNOL YU561


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