Session 6: Groundwater Quality, Degradation, and Protection, plus Caves and Karst

Tuesday, 19 May 2020
8:00 AM - 11:25 AM

SORPTION OF 2-NAPHTHALENE SULFONATE TO ORGANIC-RICH SEDIMENTS IN BATCH AND COLUMN EXPERIMENTS

Program: Virtual Meeting
Time: 8:00 AM – 11:25 AM

Authors

Abstract

Uranium contamination in the groundwater of the Western United States remains a legacy from the federal government’s activities related to the development of nuclear weapons during World War II and the Cold War. In order to minimize the impact that this legacy can have on humans and the environment, hydrogeologists must characterize the fate and transport of uranium in groundwater. Uranium is known to sorb to organic carbon in sediment, delaying its mean arrival time, therefore accurate characterization of the fraction of organic carbon in an aquifer is necessary to model uranium transport. The fraction of organic carbon is commonly measured by the analysis of sediment cores, which can be a costly and labor intensive process. A new method for quantifying the fraction of organic carbon in the subsurface is proposed here with the introduction of a novel tracer, 2-napthalene sulfonate (2-NS). Published data has shown that 2-NS sorbs to activated carbon, but no study has investigated the sorption potential of 2-NS as a function of the fraction of organic carbon in native sediment. Preliminary data obtained through batch microcosm tests showed negligible sorption to a silica-rich fine gravel, and surprisingly little to no sorption to an organic-bearing, vineyard soil from Wisconsin. Batch tests currently underway are utilizing various mass fractions of activated carbon with silica-rich fine gravels to develop sorption isotherms for 2-NS. The same fine gravel with varying mass fractions of a store-bought natural fertilizing soil will be used to then develop sorption isotherms for 2-NS with respect to the total fraction of organic carbon. Column tests will also be conducted to determine the mean arrival time of 2-NS as a function of organic carbon and these results will be compared to a non-reactive chloride tracer . The results from the batch microcosm tests, as well as those from the column experiments, will be presented and discussed along with their implications to the fate and transport of uranium species in the environment.

Geological Society of America Abstracts with Programs. Vol. 52, No. 5

doi: 10.1130/abs/2020NC-348131

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