Differential effects of low-molecular-weight
organic acids on the mobilization of soil-borne
arsenic and trace metals

Nworie, O; Qin, J; Lin, C

Abstract

A batch experiment was conducted to examine the effects of six low-molecular-weight organic acids on the mobilization of arsenic and trace metals from a range of contaminated soils. The results showed that the organic acids behaved differently when reacting with soil-borne As and trace metals. Oxalic acid and acetic acid had the strongest and weakest capacity to mobilize the investigated
elements, respectively. The solubilisation of iron oxides by the organic acids appears to play a critical role in mobilizing other trace metals and As. Apart from acidification and complexation, reductive dissolution played a dominant role in the dissolution of iron oxides in the presence of oxalic acid, while acidification tended to be more important for dissolving iron oxides in the presence of other organic acids. The unique capacity of oxalic acid to solubilize iron oxides tended to affect the mobilization of
other elements in different ways. For Cu, Mn, and Zn, acidification-driven mobilization was likely to be dominant while complexation might play a major role in Pb mobilization. The formation of soluble Fe and Pb oxalate complexes could effectively prevent arsenate or arsenite from combining with these metals to form solid phases of Fe or Pb arsenate or arsenite.

Citation

arsenic and trace metals. Toxics, 5(3), https://doi.org/10.3390/toxics5030018

• Journal Article Type: Article
• Acceptance Date: Aug 17, 2017
• Online Publication Date: Aug 21, 2017
• Publication Date: Aug 21, 2017
• Deposit Date: Sep 20, 2017
• Publicly Available Date: Sep 20, 2017
• Journal: Toxics
• Publisher: MDPI
• Volume: 5
• Issue: 3
• DOI: https://doi.org/10.3390/toxics5030018
• Publisher URL: http://dx.doi.org/10.3390/toxics5030018
• Related Public URLs: http://www.mdpi.com/journal/toxics