Effects of pH, chloride and calcium(II) on adsorption of monomethylmercury by soils

Journal Article · Mon Dec 01 04:00:00 EST 1997 · Environmental Toxicology and Chemistry

DOI:https://doi.org/10.1002/etc.5620161204· OSTI ID:561951

Yin, Y; Allen, H E; Huang, C P ^[1]; Sanders, P F ^[2]

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1. Univ. of Delaware, Newark, DE (United States). Dept. of Civil and Environmental Engineering
2. New Jersey Dept. of Environmental Protection, Trenton, NJ (United States). Div. of Science and Research

Adsorption of monomethylmercury (MMHg) by soil from 2 {times} 10{sup {minus}7} and 1 {times} 10{sup {minus}6} M solutions was investigated to understand soil-water partitioning of MMHg. The effects of three factors--pH, Cl{sup {minus}}, and Ca{sup 2+}--on adsorption were examined. Adsorption as a function of pH followed a concave downward profile with the maximum adsorption occurring at pH between 5 and 6. Less adsorption at low pH values mainly resulted from the proton competition for surface sites and Cl{sup {minus}} complexation for MMHg. Decreases in adsorption at high pH values are attributed to the complexation of MMHg with soluble organic ligands whose concentrations increase with pH. Addition of 1.0 {times} 10{sup {minus}3} M Cl{sup {minus}} decreased adsorption at low pH where CH{sub 3}HgCl was dominant over CH{sub 3}HgOH, and exhibited no effect on adsorption at high pH when CH{sub 3}HgOH became predominant. The presence of a low concentration of Ca{sup 2+} (1.0 {times} 10{sup {minus}4} M) had no effect on MMHg adsorption; however, a high concentration of Ca{sup 2+} (3.3 {times} 10{sup {minus}3} M) increased adsorption at pH < 6 but had no effect at pH > 6. This is ascribed to the combined effects of pH and Ca{sup 2+} on the solubility of organic ligands.

• Sponsoring Organization: USDOE
• OSTI ID: 561951
• Journal Information: Environmental Toxicology and Chemistry, Journal Name: Environmental Toxicology and Chemistry Journal Issue: 12 Vol. 16; ISSN ETOCDK; ISSN 0730-7268
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ADSORPTION
CHLORIDES
METHYLMERCURY
ORGANIC MATTER
PH VALUE
SOIL CHEMISTRY