Dataset: water and sediment geochemistry

Sampling for the Cape Fear River Estuary (CFRE) was conducted using 20-foot center console boats at University of North Carolina Wilmington (UNCW).

Fifteen stations were demarcated about every two kilometers along the estuarine salinity gradient of the CFRE. Sampling was conducted in April and October of 2009. Sediments were collected using a Petite Ponar® grab from west to east along a cross-estuary transect at each station including, where possible, both banks (depth less than two meters) and both sides of the channel (~12 m). Samples were defined as either east or west bank (EB, WB) (0-2 m water column depth), east or west channel (EC, WC) (8-15 m), as well as east mid-bank (EMB), west bank-shore (WBS) and east bank-shore (EBS) at stations where more than 4 samples were collected. Salinity was measured with a YSI model 650 MDS (YSI Inc., Yellow Springs, OH, USA) in the field at the surface and at the bottom when depths were greater than 1 meter. Sediment samples were treated with 35% H2O2 until all organic matter was dissolved. Samples were then run on a Coulter Counter (model LS-200, Beckman) to measure the distribution of sediment grain sizes. Organic content was measured as a percentage of the ashed weight/pre-ashed weight. Fe (II) and H2S were measured spectrophotometrically from porewater that was fixed with ferrozine and/or diamine immediately after centrifugation the day after they were collected from the CFRE (Stookey, 1960, Cline, 1969). Filtered surface and bottom water was analyzed for NO3- and NH4+ with the standard colorimetric method using a Bran Lubbe continuous flow autoanalyzer.