Soil Biology

Another important environmental issue is the fate of cyanide. Hydrogen cyanide, if spilled, evaporates quite readily. That which does not evaporate is soon decomposed or rendered nonha2ardous by complexing with iron in the soil, biological oxidation, or polymeri2ation. 

There are several environmentally significant mercury species. In the lithosphere, mercury is present primarily in the +II oxidation state as the very insoluble mineral cirmabar (HgS), as a minor constituent in other sulfide ores, bound to the surfaces of other minerals such as oxides, or bound to organic matter. In soil, biological reduction apparently is primarily responsible for the formation of mercury metal, which can then be volatilized. Metallic mercury is also thought to be the primary form emitted in high-temperature industrial processes. The insolubility of cinnabar probably limits the direct mobilization of mercury where this mineral occurs, but oxidation of the sulfide in oxygenated water can allow mercury to become available and participate in other reactions, including bacterial transformations. 

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Phillips RL, Podrebarac F. Net fluxes of CO2, but not N20 or CH4, are affected following agronomic-scale additions of urea to prairie and arable soils. Soil Biology Biochemistry. 2009 41 2011-2013. DOI 10.1016/j.soilbio.2009.06.014... 

Kool DM., Dolfing J, Wrage N, Van Groenigen JW. Nitrifier denitrification as a distinct and significant source of nitrous oxide from soil. Soil Biology Biochemistry. 2011 43 174-178. DOI 10.1016/j.soilbio.2010.09.030... 

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CCP3 Soil biological activity and structural stability... 

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