Introduction
Mercury cycles through the atmosphere, sediment and soil, and water. Volcanic eruptions and industrial pollution and/or malpractice (e.g., improper waste disposal), contribute to atmospheric emission. From the atmosphere, mercury can be deposited onto the soil and water. In water, mercury can be sedimented; methylation and demethylation can occur to mercury in soil, water and sediment. Methylmercury can bioaccumulate in aquatic organisms (Government of Canada, 2013). Credit: Government of Canada (2013): The Biogeochemical Cycle
The Two Main Types of Reactions in Mercury Cycle
These two reactions convert mercury through its differing states. They are, oxidation-reduction and methylation-demethylation
Oxidation-Reduction:
Mercury
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Hg0 (elemental mercury) can become unstable and diffuse into the atmosphere without difficulty (depending upon environmental conditions) and be transported via wind currents (a year or more), where it is deposited into the environment. Hg2+ however, resides in the atmosphere for less than two weeks (due to water-solubility, low reactive properties, and changeability).
So, when mercury is oxidized (Hg0→ Hg2+ ), rain water, snow, and small particles can absorb it rapidly - through wet or dry deposition it is then, re-deposited into the environment (Government of Canada,
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Low-acidity aquatic environments that contain organic matter facilitate methylation (Government of Canada, 2013).
The availability of mercuric ions and population-size of methylating microbes, depend on environmental variables, which ultimately influences the methylation process. PH (acidity level, ex: acid rains), affects adsorption (adhesion of compounds from their changed form to a solid surface) – ion availability is influenced by this. Organic matter can mimic microbial populations, low-oxygen environments, thus contributing to biomethylation. Biomethylation increases in warmer temperatures and decreases during the winter (Government of Canada,