Distribution of 137Cs in the Lena River estuary-Laptev Sea system.
Surface sediment samples in the Laptev Sea have average 137Cs content of 7.1 Bq kg(-1), a value intermediate between that of the western Kara Sea (23 Bq kg(-1) and the East Siberian Sea (4.2 Bq kg-'). Both surface sediment content and sediment inventory of 137Cs in the Laptev Sea sediments show significant variability, and the influence of a variety of environmental factors.137Cs concentrations in the Laptev Sea surface sediments range from 0.8 to 16 Bq kg(-1). There is a marked increase in 137Cs content of surface sediment samples collected near the Lena River delta, and a local enrichment in the 137Cs inventories at these sites is also evident. Fine-grained mixed-layer illite/ smectite rich sediments in the estuary provide effective adsorption sites to fix 137Cs, in spite of desorption processes associated with low salinities in estuarine mixing. The Lena River-Laptev Sea mixing zone is a major site of sea-ice production. River and shelf sediments are incorporated into sea-ice formed in this region (Holmes and Creager, 1974). The irregular 137Cs activity profiles of the Lena River estuary cores indicate disturbance or removal of 137Cs-laden sediments via sea-ice related processes. Lena River and Estuary sediments may have served as a secondary source (i.e. other than direct fallout) of 137Cs in sea-ice. North-east of the Lena River estuary, sediment contains a thin layer of 137Cs-bearing material over an erosion surface. The 137Cs-laden surface layer may be the result of transient deposition of estuarine sediments being delivered by sea-ice or spring floods.
Johnson-Pyrtle
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Department of Oceanography, Texas A&M University, College Station TX 77843-3146, USA.
Scott
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D002588:Cesium Radioisotopes / Q000032:analysis*; D004190:Disasters; D005618:Fresh Water / Q000737:chemistry*; D019015:Geologic Sediments / Q000737:chemistry*; D007053:Ice; D009501:Neutron Activation Analysis; D011210:Power Plants; D011847:Radioactive Fallout; D018788:Radioactive Hazard Release; D012623:Seawater / Q000737:chemistry*; D012800:Siberia; D014455:Ukraine; D014875:Water Pollutants, Radioactive / Q000032:analysis*; D014961:X-Ray Diffraction
D002588:Cesium Radioisotopes; D007053:Ice; D011847:Radioactive Fallout; D014875:Water Pollutants, Radioactive