CRBCZO -- Climate, Electrical Conductivity, Lysimeter Water Samples Chemistry, Soil Porewater Chemistry, Stable Isotopes, Stream Water Temperatures, Stream Water Chemistry, Soil Water Chemistry, Soil Temperature -- White Clay Creek Transect A floodplain -- (2011-2012)

Olesya Lazareva, Donald L. Sparks, Anthony Aufdenkampe

The Christina River Basin-Critical Zone Observatory (CRB-CZO), located in the Piedmont region of Southeastern Pennsylvania and northern Delaware, is a partnership between the University of Delaware and the Stroud Water Research Center. At Transect A of the White Clay Creek Watershed (WCCW) of the CRB-CZO, the composition of soil pore-waters and stream was investigated to understand how the geochemical dynamics of Fe- and Mn- along redox gradients affect the C cycle within a floodplain aquifer.

Soil pore-water was collected with in-situ borosilicate glass samplers (50 mm long, 20 mm diameter, 1 μm pore size, Ecotech, Germany) with the attached PTFE (Teflon) tubes (3/1.5 mm i.d./o.d) to sampling bottle. Six samplers were deployed on both sides of the floodplain within a 10-40 cm thick dark organic-rich silty soil that represents a buried pre-settlement wetland soil, underlain gravel, and stream. No pore-water was extracted from the pre-settlement deposits due to unsaturated conditions. Water sampling was carried out for about 14 months (July, 2011 - September, 2012) on biweekly basis except last 2 months in order to evaluate temporal and spatial biogeochemical dynamics of floodplain aquifer under a variety of meteorological and hydrologic conditions. In total, 103 soil pore-water samples were collected and analyzed for DOC, Fe and Mn, pH, temperature, alkalinity, conductivity, major anions, major cations, δD, and δ18O.