Recent Changes in Stable Lead Isotope Ratios in Sediments of Lake Zug, Switzerland

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• 作者：H. Christoph Moor ; Tobias Schaller ; and Michael Sturm
• 刊名：Environmental Science & Technology
• 出版年：1996
• 出版时间：October 1996
• 年：1996
• 卷：30
• 期：10
• 页码：2928 - 2933
• 全文大小：290K
• 年卷期：v.30,no.10(October 1996)
• ISSN：1520-5851

文摘

In Switzerland, unleaded gasoline was introducedin 1985. In order to study the effects of decreasingleademissions from gasoline on a lake sediment, profilesof lead concentrations and²⁰⁶Pb/²⁰⁷Pb ratios havebeen determined in cores from Lake Zug. Sedimentsamples were digested and analyzed using inductively coupled plasma mass spectrometry (ICP-MS).Accurate dating of sediment cores was achievedusing four independent methods showing the resultswithin a range of <10%. Pb emissions in Switzerlandand Pb concentrations in the sediment correlated well.Background Pb concentrations in pre-industrial sediments were 16 µg/g in Lake Zug and 13 µg/g in LakeBaldegg (for comparison); background²⁰⁶Pb/²⁰⁷Pbratios were 1.20 in both lakes. In Lake Zug, leadconcentrations reached a maximum of 110 µg/g ina depth corresponding to ca. 1970, the time of highestlead emissions. The²⁰⁶Pb/²⁰⁷Pbratio profile providedadditional information because this ratio of Pb usedfor gasoline additives in Europe ranges from 1.04to 1.10, and the ratio of background Pb in central Europeis about 1.20. The ratios in the sediment had aminimum of 1.13 ca. 1980 and an increase up to 1.16since ca. 1990. The isotope ratios reflected the fraction of Pb emissions from gasoline.