es202068b_si_002.pdf (988.55 kB)
Mercury Export from the Yukon River Basin and Potential Response to a Changing Climate
journal contribution
posted on 2011-11-01, 00:00 authored by Paul F. Schuster, Robert G. Striegl, George
R. Aiken, David P. Krabbenhoft, John F. Dewild, Kenna Butler, Ben Kamark, Mark DornblaserWe measured mercury (Hg) concentrations and calculated export and
yield from the Yukon River Basin (YRB) to quantify Hg flux from a
large, permafrost-dominated, high-latitude watershed. Exports of Hg
averaged 4400 kg Hg yr–1. The average annual yield
for the YRB during the study period was 5.17 μg m–2 yr–1, which is 3–32 times more than Hg
yields reported for 8 other major northern hemisphere river basins.
The vast majority (90%) of Hg export is associated with particulates.
Half of the annual export of Hg occurred during the spring with about
80% of 34 samples exceeding the U.S. EPA Hg standard for adverse chronic
effects to biota. Dissolved and particulate organic carbon exports
explained 81% and 50%, respectively, of the variance in Hg exports,
and both were significantly (p < 0.001) correlated
with water discharge. Recent measurements indicate that permafrost
contains a substantial reservoir of Hg. Consequently, climate warming
will likely accelerate the mobilization of Hg from thawing permafrost
increasing the export of organic carbon associated Hg and thus potentially
exacerbating the production of bioavailable methylmercury from permafrost-dominated
northern river basins.