Geological Survey of Norway (NGU) , P.O. Box 6315 Sluppen, N-7491 Trondheim, Norway.
Research School of Earth Sciences, Australian National University , Canberra, Australian Capital Territory 2601, Australia.
Environ Sci Technol. 2017 Jun 20;51(12):6719-6726. doi: 10.1021/acs.est.7b00741. Epub 2017 May 14.
A new method for detecting and quantifying diffuse contamination at the continental to regional scale is based on the analysis of cumulative distribution functions (CDFs). It uses cumulative probability (CP) plots for spatially representative data sets, preferably containing >1000 determinations. Simulations demonstrate how different types of contamination influence elemental CDFs of different sample media. It is found that diffuse contamination is characterized by a distinctive shift of the low-concentration end of the distribution of the studied element in its CP plot. Diffuse contamination can be detected and quantified via either (1) comparing the distribution of the contaminating element to that of an element with a geochemically comparable behavior but no contamination source (e.g., Pb vs Rb), or (2) comparing the top soil distribution of an element to the distribution of the same element in subsoil samples from the same area, taking soil forming processes into consideration. Both procedures are demonstrated for geochemical soil data sets from Europe, Australia, and the U.S.A. Several different data sets from Europe deliver comparable results at different scales. Diffuse Pb contamination in surface soil is estimated to be <0.5 mg/kg for Australia, 1-3 mg/kg for Europe, and 1-2 mg/kg, or at least <5 mg/kg, for the U.S.A. The analysis presented here also allows recognition of local contamination sources and can be used to efficiently monitor diffuse contamination at the continental to regional scale.
一种用于在大陆到区域尺度上检测和量化弥散性污染的新方法基于累积分布函数（CDF）的分析。它使用具有空间代表性的数据集的累积概率（CP）图，最好包含>1000 个测定值。模拟表明，不同类型的污染如何影响不同样品介质的元素 CDF。结果发现，弥散性污染的特征在于，在所研究元素的 CP 图中，分布的低浓度端发生明显的偏移。可以通过以下两种方法之一检测和量化弥散性污染：（1）将污染元素的分布与具有地球化学可比行为但没有污染源的元素（例如 Pb 与 Rb）的分布进行比较，或者（2）将元素的表层土壤分布与来自同一地区的相同元素的亚表层样本的分布进行比较，同时考虑土壤形成过程。这两种程序都在来自欧洲、澳大利亚和美国的地球化学土壤数据集上进行了演示。来自欧洲的几个不同数据集在不同尺度上给出了可比的结果。估计澳大利亚表层土壤中的弥散性 Pb 污染<0.5mg/kg，欧洲为 1-3mg/kg，美国为 1-2mg/kg，或者至少<5mg/kg。本文提出的分析方法还可以识别局部污染源，并可用于有效地监测大陆到区域尺度上的弥散性污染。
