T-检验在杭州市不同环境介质中铅同位素组成及其来源判别中的应用

应用Microsoft Excel软件中数据分析工具之T-检验,对杭州地区不同环境介质的铅同位素组成(206Pb/207Pb比值)进行了均值相等假设检验。通过T-检验,揭示了杭州市哪些环境介质具有相似或不同的铅同位素组成。结果表明,汽车尾气铅具有独特的铅同位素组成而不同于其它环境介质;汽车尾气铅对环境的污染导致环境中铅同位素组成逐渐偏离原值,如城区表土污染最为严重,其206Pb/207Pb比值已与土壤的残渣显示有显著差异,西湖表层沉积淤泥也与深部沉积柱样品有明显的不同。大气和水与多个环境介质具有相似的铅同位素比值,说明大气与水在环境中能与多种环境介质进行同位素物质交换,对污染的扩散起了重要的作用;茶叶与大气有相似的铅同位素比值,说明大气(降尘)对茶叶铅有较大的贡献。而运河沉积物与城区表土铅同位素比值高度一致则说明运河沉积物可能就是来自城区流失的表土。通过实例,介绍了Excel中T-检验在地球化学研究中的应用。

The Application of T-test for Discrimination of Lead Isotope Sources in Different Environmental Media in Hangzhou, China

The T-test of ＂date analysis＂ tool in Microsoft Excel is applied to discriminate the lead isotopic composition（206Pb/207Pb ratio） of different environment media in Hangzhou city on the precondition of mean equal hypothesis.The results show that lead isotopic composition of automobile exhaust is very different from other environmental media.The environment pollution by automobile exhaust is reflected by the lead isotopic composition of the former is gradually apart from the original value,such as the 206Pb/207Pb of urban surface soil is significant different from the soil residue,and so does the surface sediment mud of West Lake to the deep sedimentary column.Air and water have got similar lead isotopic composition with various environmental medium,which means it maybe the agent for isotope exchanging and pollution diffusion.On the other hand,tea and the atmosphere are somewhat get the similar lead isotope ratio which showed the atmosphere（dust） have a great contribution to the lead composition of the tea leaves.Meanwhile,the lead isotope composition of canal sediments and the city surface soil have a high degree of agreement,which illustrated that the canal sediments may be come from the loss of city topsoil.The application of T-test of Excel in geochemistry is totally exampled in our work.