Pine forests increase mercury contamination of fish
Studies have found that mercury deposition under forest canopies is greater than mercury deposition in open areas without forests. Mercury in the air adheres to the leaves of deciduous trees and the needles of coniferous trees. It is transported to the ground if it is washed off the leaves or needles by rainfall (throughfall) or when the leaves or needles drop to the ground (litterfall). Conifer forests increase mercury deposition more than deciduous forests.
We examined the spatial patterns of mercury deposition adjusted for the presence of conifers (mostly pine trees) in ecoregions of the south central U.S.
We compared those patterns to the spatial patterns of mercury concentrations in largemouth bass and found that average mercury concentrations in fish are highest in ecoregions where mercury deposition, adjusted for the presence of conifers, is highest.
Most ecoregions have average mercury concentrations in largemouth bass above 300 ppb, the threshold concentration of mercury in fish recommended by the U.S. EPA for the issuance of fish consumption advisories to protect human health. Some ecoregions had average mercury concentrations in largemouth bass above 500 ppb.
Sources of Information:
- Drenner, R.W., M.M. Chumchal, C.M. Jones, Christopher M. B. Lehmann, David A. Gay, David I. Donato. 2013. Drenner et al 2013 Hg in the south central US. Environmental Science and Technology, 47: 1274-1279.
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