Radiocesium Dating of Sediments from Lakes and Reservoirs of Different Hydrological Regimes

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• 作者：Achim Albrecht ; René ; Reiser ; Alfred Lü ; ck ; Jean-Marc A. Stoll ; and Walter Giger
• 刊名：Environmental Science & Technology
• 出版年：1998
• 出版时间：July 1, 1998
• 年：1998
• 卷：32
• 期：13
• 页码：1882 - 1887
• 全文大小：134K
• 年卷期：v.32,no.13(July 1, 1998)
• ISSN：1520-5851

文摘

Important information on the transport and depositionof anthropogenic substances in rivers and lakes can beassessed using sediment analyses. Dating is anecessaryprerequisite to calculate fluxes, to account for varyingsedimentation rates, and thus to allow comparison betweendifferent localities. For sediments not older than 40years,¹³⁷Cs dating has been successfully applied to naturalandartificial lakes representing a wide range in water-residence times and sediment-trapping characteristics.Sedimentation rates for the period 1986 to the time ofcoring(mid 1990s) vary as a function of distance to theinflowingrivers, between 0.5 and 2.5 cm yr^-1(0.13-1.0 g cm^-2yr^-1)in Greifensee and between 1.4 and 3.5 cm yr^-1(0.49-2.4 g cm^-2 yr^-1) inLake Biel. In reservoirs located alongthe major Swiss rivers Aare and Rhine, sedimentationrates are in the same range from 1.8 cm yr^-1(0.69 g cm^-2yr^-1) in Augst (Rhine) to 3.4 cmhr^-1 (1.8 g cm^-2yr^-1)in Klingnau (Aare). Sedimentation rates from the period1963-1986 are in some cases significantly lower. The datingis based on the identification of radiocesium depositionmaxima in sediment cores that are related to the globaldeposition of radiocesium during atmospheric nuclearweapons testing (maximum, 1963) and the accident ofthe Chernobyl nuclear reactor (April 1986). Additionalmarkersconfirm age determinations based on radiocesium. Theyare based on either known discharges of radioniclides bynuclear reactors or known maxima of anthropogenicorganic substances such as detergent-derived chemicals.In cases where the Cs dating technique fails (e.g.,inturbulent river sections with disturbed sedimentation),humanactivities can be used as time markers to estimatesedimentation rates, as documented for sediments from theAare and Rhône rivers, where sedimentation ratesbetween1.7 (Niederried reservoir) and 13 cm yr^-1(Chancyreservoir) were measured.