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Characterizing cesium sorption in freshwater settings using fluvial sediments and characteristic water chemistries
Citation:
Ratliff, K., A. Mikelonis, AND J. Duffy. Characterizing cesium sorption in freshwater settings using fluvial sediments and characteristic water chemistries. JOURNAL OF ENVIRONMENTAL MANAGEMENT. Elsevier Science Ltd, New York, NY, 253:109688, (2020).
Impact/Purpose:
In this paper, we describe results from laboratory experiments conducted using sediment from a river adjacent to a US EPA Superfund Site and water chemistries characteristic of different parts of the US to investigate how radionuclides are transported in the environment. We find that sediment type (i.e., how much clay is present) plays a more important role than freshwater chemistry in mediating cesium sorption processes. The results suggest that conducting experiments using site-specific sediment and water quality is useful for predicting radionuclide mobility in the environment. These findings are useful for regional partners planning and conducting remediation activities, and they are of interest to scientists studying radionuclide fate and transport processes.
Description:
Cesium-137 (Cs-137) is a persistent contaminant that poses a significant risk to human health and the environment. Understanding the fate and transport of Cs-137 following a contamination incident is necessary for effective containment and remediation. In this study, we performed experiments to investigate how Cs+ sorption processes are affected by sediment type and varying water chemistries to better understand how Cs+ is transported in freshwater settings. Sediment was collected from various river deposits along the Susquehanna River adjacent to the Safety Light Corporation United States Environmental Protection Agency (US EPA) Superfund site (Bloomsburg, PA) and characterized prior to being used in batch reactor experiments with waters characteristic of different regions in the US (Central US and Northeast US) and with three different cation types (Mg2+, Na+, and K+) over a range of ionic strengths. Greater amounts of Cs+ sorption occurred with increasing sediment mud (silt and clay) content, although no major differences in sorption between the Central and Northeast US water types were observed. At an ionic strength (I) of 10 mM, K+ inhibited Cs+ sorption most effectively, followed by Mg2+, with Na+ having little effect on Cs+ sorption over the range of ionic strengths tested (I = 0.1, 1, and 10 mM). Our findings indicate that for the representative freshwater conditions tested here, sediment type (e.g., clay fraction) has a greater influence on Cs+ sorption processes than water chemistry. Additional reactions or processes occuring in relatively fresh water could buffer cation competition for sorption sites. Conducting experiments using site-specific sediment samples and water chemistries is useful for predicting Cs+ sorption and mobility in distinct environmental settings, particularly when the level of Cs+ contamination is high and if the waste or contaminated (or receiving) waters have a relatively high ionic strength.
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CHARACTERIZING CESIUM SORPTION IN FRESHWATER SETTINGS USING FLUVIAL SEDIMENTS AND CHARACTERISTIC WATER CHEMISTRIES
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