Constitutional and distributional heterogeneity of contaminated soil and its influence on sampling uncertainty

在环境现场评价（ESA）中，绝大多数污染土壤取样指南都要求样品的代表性。然而，由于普遍缺乏对抽样理论（ToS）的了解，它从未被给予适当的描述或定量定义。在我们之前的发现基金中，我们测量了几种抽样技术的代表性。我们开发了基于ToS原则的采样策略，将采样代表性提高了几个数量级。我们将ToS提供的采样方差（MoSV）模型扩展到含有污染物包覆颗粒的土壤，从而使污染土壤的实验室采样方案的定量设计成为可能，这是迄今为止只能定性进行的。建议的2019-2023年研究计划将重点关注以下问题。首先，被液相污染物（如石油烃，卤化溶剂）污染的土壤的异质性没有被我们扩展的MoSV明确表示。其次，现场采样是采样过程中至关重要的第一步，但仍然是一个难以解决的问题。第三，土壤湿度在很多颗粒物中明显影响颗粒分布，但在采样方案设计中仍不能明确考虑。我们将首先将我们的MoSV推广到液相污染物携带的非均质性，并通过在模型土壤上进行的采样实验来验证它。我们还将研究在现场取样阶段发生的纵向桩形成的隔离机制，通过在实验室中用模型土壤再现它。我们将重点研究隔离对异质性、采样可重复性和方案设计的影响。分离将使用微ct扫描成像观察，并使用离散元素建模（DEM）进行研究。将使用图像分析或从具有可用指数（例如Lacey's或配位数指数）的DEM中量化分离程度（DS）。土壤湿度对分离和采样不确定度的影响将被表征和建模。将对模型土桩进行采样，并将采样变异性与DS进行关联。本研究计划的独创性在于开发一种适用于固相和液相污染土壤的通用MoSV。它还将为许多颗粒物质的分离动力学提供新的知识。通过使用尖端技术，即微ct扫描图像和DEM。它将改进我们以前的ToS框架，用于设计采样过程和分析采样方法在欧空局领域的代表性。这将增加ESA和补救的代表性和成本效益。在每年500亿美元的国际市场上，这些成果对该行业也将具有重要意义。

In environmental site assessment (ESA), sample representativeness is required by a vast majority of guidelines on contaminated soil sampling. However, it is never given a proper description or quantitative definition because of a general lack of knowledge of the Theory of Sampling (ToS). During our previous Discovery Grant, we measured the representativeness of several sampling techniques. We developed sampling strategies based on ToS principles, which improve sampling representativeness by several orders of magnitude. We extended the model of sampling variance (MoSV) provided by ToS to soil containing contaminant-coated particles, thereby enabling the quantitative design of laboratory sampling protocols for contaminated soil, something which could only be performed qualitatively thus far. The proposed research program for 2019-2023 pursues this work by focusing on the following issues. First, the heterogeneity of soil contaminated by liquid-phase contaminants (e.g. petroleum hydrocarbons, halogenated solvents) is not explicitly represented by our extended MoSV. Second, field sampling remains a difficult problem to solve, while being the crucial first step in the sampling process. Third, soil moisture clearly affects particle distribution in a lot of particulate matter, but it still cannot be explicitly considered in sampling protocol design. We will first generalize our MoSV to the heterogeneity carried by liquid-phase contaminants and validating it with sampling experiments performed on model soils. We will also study the segregation mechanisms occurring in longitudinal pile formation at the field sampling stage by reproducing it with model soils in the laboratory. We will notably study the effects of segregation on heterogeneity, sampling reproducibility and protocol design. Segregation will be observed using µCT-scan imaging and also studied using Discrete Element Modeling (DEM). The degree of segregation (DS) will be quantified using image analysis or from DEM with available indices (e.g. Lacey's or coordination number index). The influence of soil moisture on segregation and sampling uncertainty will be characterized and modeled. Piles of model soils will be sampled and sampling variability will be correlated to DS. The originality of this research program lies in the development of a generalized MoSV for soil contaminated by solid-phase and liquid-phase contaminants. It will also provide new knowledge on the dynamics of segregation in lots of particulate matter. by using cutting-edge technology, namely µCT-scan imagery and DEM. It will improve our previous ToS framework for designing sampling processes and analysing the representativeness of sampling methods in the field of ESA. This will increase the representativeness and cost effectiveness of ESA and remediation In an international market of US$50 billions annually, these outcomes will also be significant for the industry.