Principal biogeochemical factors affecting the speciation and transport of mercury through the terrestrial environment.
It is increasingly becoming known that mercury transport and speciation in the terrestrial environment play major roles in methyl-mercury bioaccumulation potential in surface water. This review discusses the principal biogeochemical reactions affecting the transport and speciation of mercury in the terrestrial watershed. The issues presented are mercury-ligand formation, mercury adsorption/desorption, and elemental mercury reduction and volatilization. In terrestrial environments, OH-, Cl- and S- ions have the largest influence on ligand formation. Under oxidized surface soil conditions Hg(OH)2, HgCl2, HgOH+, HgS, and Hg0 are the predominant inorganic mercury forms. In reduced environments, common mercury forms are HgSH+, HgOHSH, and HgClSH. Many of these mercury forms are further bound to organic and inorganic ligands. Mercury adsorption to mineral and organic surfaces is mainly dictated by two factors: pH and dissolved ions. An increase in Cl- concentration and a decrease in pH can, together or separately, decrease mercury adsorption. Clay and organic soils have the highest capability of adsorbing mercury. Important parameters that increase abiotic inorganic mercury reduction are availability of electron donors, low redox potential, and sunlight intensity. Primary factors that increase volatilization are soil permeability and temperature. A decrease in mercury adsorption and an increase in soil moisture will also increase volatilization. The effect of climate on biogeochemical reactions in the terrestrial watershed indicates mercury speciation and transport to receiving water will vary on a regional basis.
Gabriel
Mark C
MC
Department of Civil and Environmental Engineering, The University of Alabama, 260 MIB 7th Avenue and Campus Drive, Tuscaloosa, AL 35487-0205, USA.
Williamson
Derek G
DG
D000327:Adsorption; D001682:Biological Availability; D055593:Geological Phenomena; D005844:Geology; D006801:Humans; D008628:Mercury / Q000737:chemistry* / Q000378:metabolism*; D008767:Methylmercury Compounds / Q000737:chemistry* / Q000378:metabolism*; D009930:Organic Chemicals; D012989:Soil Pollutants / Q000378:metabolism*; D012995:Solubility; D014835:Volatilization; D014873:Water Pollutants / Q000378:metabolism*
D008767:Methylmercury Compounds; D009930:Organic Chemicals; D012989:Soil Pollutants; D014873:Water Pollutants; D008628:Mercury
Appl Microbiol. 1975 Apr;29(4):491-4
804851
Science. 1972 Mar 10;175(4026):1142-3
17797394
Arch Environ Contam Toxicol. 1981;10(2):193-201
7224671
Environ Pollut. 2001;111(1):67-74
11202716
Ecotoxicol Environ Saf. 1979 Mar;3(1):36-8
44244
Appl Environ Microbiol. 1985 Aug;50(2):498-502
16346866
Environ Sci Technol. 2002 Feb 15;36(4):690-5
11878384
Sci Total Environ. 2000 Oct 9;260(1-3):191-200
11032127
Bull Environ Contam Toxicol. 1994 May;52(5):691-8
8186639
Appl Environ Microbiol. 1993 Jan;59(1):290-5
8439155
Environ Health Perspect. 1993 Apr;100:31-8
8354179
Environ Pollut. 1991;71(2-4):131-69
15092118
Appl Environ Microbiol. 1997 Nov;63(11):4267-71
9361413
Environ Sci Technol. 1995 Jul 1;29(7):1867-75
22176462
Biotechnol Bioeng. 1984 Nov;26(11):1330-3
18551657
Environ Sci Technol. 1994 Dec 1;28(13):2366-71
22176056
Pestic Monit J. 1976 Dec;10(3):111-3
1005063
Environ Sci Technol. 2001 Dec 15;35(24):4773-82
11775152
Environ Sci Technol. 1973 Nov 1;7(11):1028-34
22263944
Science. 1974 May 24;184(4139):895-7
17782380