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(-1)) and MeHg (~120 mol y(-1)) 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.
Department of Marine Science, Skidaway Institute of Oceanography, University of Georgia , 10 Ocean Science Circle, Savannah, Georgia 31411, United States.
Clifton S
CS
Buck
Department of Earth & Environmental Sciences, Wright State University , 3640 Colonel Glenn Hwy., Dayton, Ohio 45435, United States.
Chad R
CR
Hammerschmidt
Department of Earth & Environmental Sciences, Wright State University , 3640 Colonel Glenn Hwy., Dayton, Ohio 45435, United States.
Katlin L
KL
Bowman
Marine Science Laboratory, Pacific Northwest National Laboratory , Sequim, Washington 98382, United States.
Gary A
GA
Gill
Department of Earth, Ocean, and Atmospheric Science, Florida State University , Tallahassee, Florida 32306, United States.
William M
WM
Landing
D004784:Environmental Monitoring / Q000379:methods; D063366:Estuaries; D060851:Gulf of America; D008628:Mercury / Q000032:analysis*; D008767:Methylmercury Compounds / Q000032:analysis*; D045483:Rivers / Q000737:chemistry; D054712:Salinity; D012621:Seasons; D015144:Southeastern United States; D014481:United States; D014874:Water Pollutants, Chemical / Q000032:analysis*
D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical; D008628:Mercury