This is the third in a series of posts designed to elicit feedback. Once I’ve heard from ASE’s environmental corps, I will add this page to our Conservation area.

Mercury, chemical symbol Hg, atomic number 80, is one of the more dangerous contaminants found in the Everglades ecosystem. Found in its methylated form in the Everglades, mercury accumulates in the tissues of every organism exposed to it, leading to higher and higher concentrations the higher you go in the food chain. From a 2003 NOAA report on how Everglades restoration might affect Florida Bay:

Methylmercury, an organic form of mercury derived from inorganic mercury released into the environment, accumulates up the food chain, reaching high concentrations in predatory fish and leading to increased risks to humans when they consume those fish. […]

Mercury in the environment comes both from natural sources and human activities. Solid waste incineration and fossil fuel combustion facilities account for approximately 87% of airborne emissions of mercury in the United States. Mercury is released into surface waters by naturally occurring processes, and industrial activities such as pulp and paper mills, leather tanning, electroplating, and chemical manufacturing.

In addition, mercury in soils results from direct application of fertilizers and fungicides and from disposal of solid wastes, including such common household items as batteries and thermometers.

Once released into the aquatic environment, inorganic mercury can be converted to an organic form of mercury, methylmercury, which is the primary form that accumulates in fish and shellfish.

It’s not just fish and wading birds that are at risk. Larger predators such as the Florida panther, are also seen to be at risk, although the authors of one study suggest that the risk is much less now that mercury has been much more tightly controlled than in the past.

Links:

• It would be hard to find a more comprehensive account of mercury in the Everglades than this USGS website, although the study is a bit dated now.
• Florida DEP site on the South Florida Mercury Science Program, including links to advisories about fish consumption (latest update July 2008).