Geological Survey of Norway, P.O. Box 6315, Torgarden, N-7491, Trondheim, Norway.
Geological Survey of Norway, P.O. Box 6315, Torgarden, N-7491, Trondheim, Norway.
Sci Total Environ. 2019 Mar 10;655:730-740. doi: 10.1016/j.scitotenv.2018.11.248. Epub 2018 Nov 17.
A realistic estimate of diffuse contamination requires to recognize and assess the dominant natural and anthropogenic element sources. For eight large-scale geochemical surveys, the relations between geogenic, anthropogenic and biogenic Cu and Zn sources are estimated by comparing the cumulative distribution functions (CDF) of the elements in top- and subsoil using cumulative probability (CP) diagrams. Strong local contamination distorts the high-concentration end of the distribution function considerably in topsoil. In contrast the impact of diffuse contamination can best be recognized at the lower end of the data distribution. Copper and Zn are important plant micronutrients, studying their concentrations in a variety of plant materials and soils along a number of transects demonstrates that both are adjusted to narrow concentration levels in many plant materials. Plants regulating the element concentrations to certain fixed levels will distort the low-concentration end of a topsoil CDF, the bio-adjustment thus limits the accuracy of diffuse contamination estimates. Combining CDF analysis with spatial mapping provides insight into the dominant contamination processes that distort the topsoil CDF relative to the subsoil CDF. For Cu a most likely diffuse contamination signal of 1-2 mg/kg with a maximum of 5 mg/kg is obtained for soils at the European scale. The higher estimate is clearly influenced by bio-adjustment. For Zn diffuse contamination appears to be higher on first glance, about 5-10 mg/kg, but again the lower end of the investigated CDFs is strongly shifted by biosphere adjustment, plants striving to avoid Zn deficiency. The true input through diffuse contamination will thus be considerably lower. Data from projects that sampled minerogenic instead of organogenic topsoil lead to lower estimates for diffuse Zn contamination in the range of <1-5 mg/kg at the continental scale.
对弥散性污染进行现实的评估需要识别和评估主要的自然和人为元素源。对于八项大规模地球化学调查，通过比较表层和次层土壤中元素的累积分布函数（CDF），使用累积概率（CP）图来估计地球成因、人为和生物成因 Cu 和 Zn 源之间的关系。强烈的局部污染会使表层土壤中分布函数的高浓度端发生很大的扭曲。相比之下，弥散污染的影响在数据分布的低端才能得到最好的识别。Cu 和 Zn 是重要的植物微量元素，研究它们在一系列横断线上各种植物材料和土壤中的浓度表明，两者在许多植物材料中都调整到狭窄的浓度水平。植物将元素浓度调节到一定的固定水平，会使表层土壤 CDF 的低浓度端发生扭曲，这种生物调节会限制弥散污染估计的准确性。将 CDF 分析与空间制图相结合，可以深入了解主导的污染过程，这些过程会使表层土壤 CDF 相对于次层土壤 CDF 发生扭曲。对于 Cu，在欧洲尺度上，获得了 1-2mg/kg 的最可能的弥散污染信号，最大值为 5mg/kg。较高的估计值显然受到生物调节的影响。对于 Zn，弥散污染似乎更高，约为 5-10mg/kg，但调查 CDF 的低端再次受到生物圈调节的强烈影响，植物努力避免 Zn 缺乏。因此，通过弥散污染真正的输入量会低得多。从采集矿质而非有机表层土壤的项目中获得的数据导致在大陆尺度上，弥散 Zn 污染的估计值较低，在<1-5mg/kg 的范围内。
