Intrinsic Flaws of Element Enrichment Factors (EFs) in Environmental Geochemistry

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• 作者：Clemens Reimann and Patrice de Caritat
• 刊名：Environmental Science & Technology
• 出版年：2000
• 出版时间：December 15, 2000
• 年：2000
• 卷：34
• 期：24
• 页码：5084 - 5091
• 全文大小：119K
• 年卷期：v.34,no.24(December 15, 2000)
• ISSN：1520-5851

文摘

The popular concept of enrichment factors (EFs) as ameans of identifying and quantifying human interferencewith global element cycles is evaluated. It is demonstratedthat the concept of normalizing element concentrationsto an average total crust value is of doubtful merit, fortheoretical considerations alone. Serious flaws withEFs include the variable composition of the Earth's crustat any given point compared to the global average, the naturalfractionation of elements during their transfer from thecrust to the atmosphere through processes such asweathering and winnowing of fines, and the differentialsolubility of minerals in the weak chemical digestions generallyused in environmental studies. Furthermore the impactof biogeochemical processes is neglected. A biomonitoringsurvey of atmospheric chemistry over a 1.5 million km²area in northern Europe is used to show that EFs are governedhere by completely different processes than anthropogenicactivities. As a simple means to assess the maximumpossible interference of human activities with global elementreservoirs, the mining interference factor (MIF = (totaltonnage mined annually/total tonnage in upper 2 km of crust)× 100%) is introduced. The elements C Br > Cu >Sb Ag > Cd > Pb show the highest MIFs, while Ga,Cs, Ge, K, In, I, and Rb show very low MIFs. We recommendindiscriminate usage of EFs in the scientific literature beabandoned and more large-scale surveys be supportedinternationally to collect quality, statistically significantenvironmental data. Only thus can human interference withnatural biogeochemical cycles be properly documented.