Abstract
—
Mercury (Hg) contamination of small human-made ponds
and surrounding terrestrial communities may be 1 of the largest
unstudied Hg-pollution problems in the United States. Humans have
built millions of small ponds in the Great Plains of the United States, and
these ponds have become contaminated with atmospherically deposited
mercury. In aquatic ecosystems, less toxic forms of Hg deposited from the
atmosphere are converted to highly toxic methylmercury (MeHg).
Methylmercury is incorporated into the aquatic food web and then can be
transferred to terrestrial food webs via emergent aquatic insects. The
authors present a conceptual model that describes the movement of
MeHg produced in aquatic ecosystems to terrestrial consumers via
insects emerging from small human-made ponds. The authors hypothe-
size that pond permanence and the level of Hg contamination of the food
web control this emergent insect-mediated
fl
ux of MeHg. The highest
insect-mediated
fl
ux of MeHg is predicted to be from
fi
shless
semipermanent ponds with food webs that are highly contaminated
with MeHg. Further development and testing of the conceptual model
presented in the present column, particularly in the context of a changing
climate, will require research at the regional, watershed, and pond
scales. Environ Toxicol Chem