Elemental mercury production from contaminated riparian soil suspensions under air and nitrogen bubbling conditions

• Published in: Environmental science and pollution research international Vol. 31; no. 22; pp. 32407 - 32415
• Main Authors: Zhao, Shuting, Terada, Akihiko, Nakashima, Makoto, Komai, Takeshi, Riya, Shohei, Hosomi, Masaaki, Hou, Hong
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.05.2024; Springer Nature B.V
• Subjects: air; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Climate change; Dissolved organic carbon; Earth and Environmental Science; Ecotoxicology; Emission measurements; Emissions; Environment; Environmental Chemistry; Environmental Health; Environmental science; Floods; Iron; Mercury; Mercury (metal); Mercury - analysis; Nitrogen; Organic matter; Oxidation-Reduction; Pollution; Research Article; riparian soils; Soil - chemistry; Soil contamination; Soil Pollutants - analysis; Soil pollution; Soil solution; Waste Water Technology; Water Management; Water Pollution Control; Wetlands; Redox condition; Riparian soil; Elemental mercury
• ISSN: 1614-7499; 0944-1344; 1614-7499
• DOI: 10.1007/s11356-024-33384-w

The dynamic change of redox conditions is a key factor in emission of elemental mercury (Hg 0 ) from riparian soils. The objective of this study was to elucidate the influences of redox conditions on Hg 0 emission from riparian soils. Soil suspension experiments were conducted to measure Hg 0 emission from five Hg-contaminated soil samples in two redox conditions (i.e., treated with air or with N 2 ). In four of the five samples, Hg 0 emission was higher in air treatment than on N 2 treatment. Remaining one soil, which has higher organic matter than other soils, showed no distinct difference in Hg 0 production between air and N 2 treatment. In soil suspensions subject to N 2 treatment, the dissolved organic carbon (DOC) and Fe 2+ concentrations were 3.38- to 1.34-fold and 1.44- to 2.28-fold higher than those in air treatment, respectively. Positive correlations were also found between the DOC and Fe 2+ ( r  = 0.911, p  < 0.01) and Hg 2+ ( r  = 0.815, p  < 0.01) concentrations in soil solutions, suggesting Fe 2+ formation led to the release of DOC, which bound to Hg 2+ in the soil and, in turn, limited the availability of Hg 2+ for reduction to Hg 0 in N 2 treatment. On the other hand, for remaining one soil, more Hg 2+ might be adsorbed onto the DOM in the air treatment, resulted in the inhibition of Hg 0 production in air treatment. These results imply that the organic matter is important to prevent Hg 0 production by changing redox condition. Further study is needed to prove the role of organic matter in the production of Hg 0 .