LIS phase 4 sediment core XRF chemical content data

The data set presents XRF (X-ray fluorescence) data of the sediment cores collected as part of the Long Island Sound mapping project Phase 4. The processed results of the sediment core chemical composition was measured with the Lamont ITRAX Core Scanner (Cox Analytical Systems, Mölndal, Sweden). For XRF measurements, an X−ray tube equipped with a molybdenum anode was operated at a voltage of 30kV and a current of 55mA. Each measurement was made for 30s integrated over a depth interval of 0.5cm by 17mm wide. After scanning was complete, any spectra flagged as invalid were removed and all remaining spectra were summed into a single spectrum. A full spectrum fundamental parameter peak fitting program, provided by the manufacturer, was used to calculate individual elemental abundances in terms of element rates (i.e., cps/mA). Variables in the fundamental parameter algorithm were adjusted to minimize the difference between the measured spectra and the model fit. Once the fitting routine was complete, the optimized parameters were used to calculate down-core elemental rates. The analytical uncertainty of the element signals is estimated based on the dead time corrected total counts for each element. Prior to calibration, elemental rates were first normalized to the coherent scattering peak signal to account for matrix variability and then standardized for each core/each element by subtracting the average element rate and dividing by the standard deviation of the element rate. The data set is presented as an Excel spreadsheet with one worksheet per core. Funding was provided by the Long Island Sound Mapping Fund administered cooperatively by the EPA Long Island Sound Study and the Connecticut Department of Energy and Environmental Protection (DEEP).