Geochemistry of exp 210 Pb in the Southeastern, US Estuarine System

摘要

This study was an attempt to determine the geochemical behavior of exp 210 Pb in southeastern salt marsh estuaries. As a part of this study the exp 210 Pb dating technique was applied to natural and anthropogenic deposits of the region. exp 210 Pb activity of sediment and water from the Georgia coastal area was measured by alpha spectroscopy. The effects of grain size and carbon content of the sediment on exp 210 Pb concentrations was evaluated and the activity of exp 210 Pb in dissolved and particulate phases of rivers was measured as a function of salinity. Ages and sedimentation rates of sedimentary deposits were also determined for some deposits. exp 210 Pb activity in dissolved and particulate phases of rivers showed no clear trends as functions of salinity. River particulate activities were three to four times higher than dissolved activities. The relationship between exp 210 Pb activity in salt marsh sediments and grain size was highly significant. Direct application of the exp 210 Pb method to date and determine sedimentation rates of natural and anthropogenic deposits was partially successful. The anthropogenic deposits, however, had to be dated on the basis of normalizing exp 210 Pb activities to grain size (% silt and clay) and carbon content. (ERA citation 06:019411)