Potential Sources of Monomethyl Mercury in Arctic and Subarctic Seawater

Abstract

(Hg) IS A HEAVY METAL that exists in many different forms in the environment. One of these forms, monomethyl mercury (MMHg), is a strong vertebrate neurotoxin that bioaccumulates through food webs. In some Canadian Arctic marine mammals, MMHg has increased to levels that may be toxic to northern peoples who consume these species as traditional foods (INAC, 2003). Unfortunately, it is difficult to determine the sources of Hg contamination in northern food webs because the cycling of Hg is complex and not well characterized in Arctic marine ecosystems. Mercury may enter the Arctic via a number of pathways (see general schematic). For example, gaseous Hg(0) released by industrial processes such as coal combustion and waste incineration is relatively stable in the atmosphere and can be transported to the Arctic on air currents (Shroeder and Munthe, 1998). Gaseous Hg(0) can flux into or out of waterbodies, such as lakes and oceans, depending on where concentrations of Hg(0) are higher. Inorganic Hg(II) and MMHg may also enter Arctic marine ecosystems in precipitation, river inflow, and glacial melt, as well as via ocean currents.