1 research outputs found
Flux of Total Mercury and Methylmercury to the Northern Gulf of Mexico from U.S. Estuaries
To
better understand the source of elevated methylmercury (MeHg)
concentrations in Gulf of Mexico (GOM) fish, we quantified fluxes
of total Hg and MeHg from 11 rivers in the southeastern United States,
including the 10 largest rivers discharging to the GOM. Filtered water
and suspended particles were collected across estuarine salinity gradients
in Spring and Fall 2012 to estimate fluxes from rivers to estuaries
and from estuaries to coastal waters. Fluxes of total Hg and MeHg
from rivers to estuaries varied as much as 100-fold among rivers.
The Mississippi River accounted for 59% of the total Hg flux and 49%
of the fluvial MeHg flux into GOM estuaries. While some estuaries
were sources of Hg, the combined estimated fluxes of total Hg (∼5200
mol y<sup>–1</sup>) and MeHg (∼120 mol y<sup>–1</sup>) from the estuaries to the GOM were less than those from rivers
to estuaries, suggesting an overall estuarine sink. Fluxes of total
Hg from the estuaries to coastal waters of the northern GOM are approximately
an order of magnitude less than from atmospheric deposition. However,
fluxes from rivers are significant sources of MeHg to estuaries and
coastal regions of the northern GOM