Iodine-129 enrichment in sediment of the Baltic Sea

Sediments are an excellent archive for evaluation of time-series environmental contamination of water systems. Measurements of ultra-trace radioactive species, such as I-129, provide information for both chronologic calibration and anthropogenic emissions during the nuclear era. Here data are presented on I-129 and other chemical parameters from two sediment cores collected in the Baltic Sea during 1997. The sediment sections have a relatively uniform grain size (claymud) and cover a period of about 50 a. Distribution of I-129 in the sediment strongly relates to the liquid release records from the nuclear reprocessing facilities at Sellafield and La Hague. However, syn- and post-depositional alteration of organic matter at the sediment water interface and within the sediment column may have contributed to slightly obliterating the anthropogenic I-129 signals. Indication of Chernobyl-derived I-129 occurs in the sediment profile, but is apparently overridden by the overwhelming flux from the nuclear reprocessing facilities. Although the record did not cover the pre-nuclear era (before 1945) sections, the ultra sensitive I-129 profile provides a potential tool for relative dating and monitoring sources of water and sediment to the region. (c) 2006 Elsevier Ltd. All rights reserved.