Intrinsic flaws of element enrichment factors (EFs) in environmental geochemistry
Intrinsic flaws of element enrichment factors (EFs) in environmental geochemistry
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DOI：
10.1021/es001339o
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发表时间：
2000-12-15
影响因子：
11.4
通讯作者：
De Caritat, P
中科院分区：
文献类型：
--
作者：
Reimann, C;De Caritat, P
评估了富集因子（EF）作为识别和量化人类对全球元素循环干扰的一种手段的流行概念。它表明，归一化元素浓度的平均总壳值的概念是值得怀疑的优点，仅从理论上考虑。EF的严重缺陷包括与全球平均水平相比，地壳在任何给定点的可变成分，元素在通过风化和细粉的筛选等过程从地壳转移到大气中时的自然分馏，以及矿物在环境研究中通常使用的弱化学溶解度中的差异。此外，地球化学过程的影响被忽略了。对北方150万平方公里区域的大气化学进行的生物监测调查表明，这里的EFs受与人类活动完全不同的过程控制。作为评估人类活动对全球元素库可能造成的最大干扰的一种简单方法，采用了采矿干扰系数（MIF =（每年开采的总吨数/地壳上部2公里的总吨数）x100%）。元素C >> Br > Cu > Sb >> Ag > Cd > Pb显示最高的MIFs，而Ga、Cs、Ge、K、In、I和Rh显示非常低的MIFs。我们建议放弃在科学文献中不加区别地使用环境因子，并在国际上支持更大规模的调查，以收集高质量的、具有统计意义的环境数据。只有这样，人类对自然生态地球化学循环的干扰才能得到适当的记录。
The popular concept of enrichment factors (EFs) as a means of identifying and quantifying human interference with global element cycles is evaluated. It is demonstrated that the concept of normalizing element concentrations to an average total crust value is of doubtful merit, for theoretical considerations alone. Serious flaws with EFs include the variable composition of the Earth's crust at a ny given point compared to the global average, the natural fractionation of elements during their transfer from the crust to the atmosphere through processes such as weathering and winnowing of fines, and the differential solubility of minerals in the weak chemical digestions generally used in environmental studies. Furthermore the impact of biogeochemical processes is neglected. A biomonitoring survey of atmospheric chemistry over a 1.5 million km(2) area in northern Europe is used to show that EFs are governed here by completely different processes than anthropogenic activities. As a simple means to assess the maximum possible interference of human activities with global element reservoirs, the mining interference factor (MIF = (total tonnage mined annually/total tonnage in upper 2 km of crust) x 100%) is introduced. The elements C >> Br > Cu > Sb >> Ag > Cd > Pb show the highest MIFs, while Ga, Cs, Ge, K, In, I, and Rh show very low MIFs. We recommend indiscriminate usage of EFs in the scientific literature be abandoned and more large-scale surveys be supported internationally to collect quality, statistically significant environmental data. Only thus can human interference with natural biogeochemical cycles be properly documented.