Development of Environmental Proxies for Coastal Environments Grant uri icon

abstract

  • Recent studies have suggested that groundwater may discharge directly into the coastal ocean (Moore, 1996), thus altering the in situ porewater chemical composition. In order to evaluate the potential interaction of groundwater at each site selected, we will employ down-core porewater chloride concentrations. In many cases, the presence of upland groundwater can be verified by measuring changes in salinity or conductivity at or below the sediment/water interface (Valiela et al., 1990; Simmons, 1992; Bugna et al., 1996; Corbett et al., 1999). The groundwater advection rate can then be estimated using a steady-state, one dimensional advection-diffusion model (Berner, 1980), assuming there is some freshening down-core. As part of a larger study evaluating the use of forams as environmental indicators, sediment cores will be collected for depth-distributions of porewater parameters (CI-, F-, S042-, Ca2+, Mg2+) at each study site. Sediment samples for porewater analysis will be collected with a modified gravity core device fitted with a 10-cm o.d. Plexiglass core liner to ensure that the upper 2 cm of material remain undisturbed. Cores (- 1 m in length) will be subsectioned into 2-cm intervals on board ship immediately after retrieval. These samples will be transferred into preweighed, 50-mL screw-top centrifuge tubes and stored on ice during transport to the laboratory. Porewater will be separated from the solid phase by cetrifugation and filtered through 0.45-mm syringe filters before analysis on a Shimadzu VP Series ion chromatograph.

date/time interval

  • June 2003 - May 2008