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Role Of The Atchafalaya River Basin In Regulating Export Fluxes Of Dissolved Organic Carbon, Nutrients, And Trace Elements To The Louisiana Shelf, Dongjoo Joung, Laodong Guo, Alan M. Shiller

Faculty Publications

The abundance and fluxes of selected dissolved trace elements (TE), nutrients, and dissolved organic carbon (DOC) were quantified in the Atchafalaya River Basin to better understand its influence on the chemical regime of the Louisiana Shelf, a region where bottom water hypoxia occurs annually during late spring to early fall. Water samples were collected from throughout the entire Atchafalaya River Basin including from the Mississippi and Red Rivers as well as basin swamp waters during April and November 2010, and June 2011, which represent “typical” high and low, and “unusual” high river discharges, respectively. Within the total dissolved (< 0.45 µm) pool, most of the TEs were mainly partitioned to the < 0.02 µm dissolved phase with the exception of Cr, Cs, Fe, Pb and Zn which were dominantly in the colloidal (0.02-0.45 µm) phase. In the Atchafalaya River, seasonal concentration variations in nutrients, DOC and most TEs were similar to those in the Mississippi River, reflecting a major contribution of water from the Mississippi River. Contributions of the Red River to the Atchafalaya River’s DOC and nutrients were estimated to be 1-35%, similar to previous estimates for this system. The Red River contribution to the fluxes of Co, Cr, Cs, Fe, Mn, Pb, Rb, and Zn was generally disproportionally high (>20%), …