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

在环境现场评估(ESA)中，绝大多数关于污染土壤采样的指南都要求样品的代表性。然而，由于普遍缺乏抽样理论(ToS)的知识，它从未被给予适当的描述或定量的定义。在我们之前的探索基金中，我们衡量了几种抽样技术的代表性。我们开发了基于ToS原则的抽样策略，将抽样代表性提高了几个数量级。我们将ToS提供的采样方差模型(MoSV)扩展到含有污染物包裹颗粒的土壤，从而实现了对污染土壤的实验室采样方案的定量设计，这是到目前为止只能定性执行的事情。拟议的2019-2023年研究计划通过重点解决以下问题来开展这项工作。首先，被液态污染物(如石油碳氢化合物、卤代溶剂)污染的土壤的异质性没有被我们扩展的MOSV明确地表示出来。第二，实地抽样仍然是一个难以解决的问题，而这是抽样过程中至关重要的第一步。第三，土壤水分对许多颗粒物中的颗粒分布有明显的影响，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推广到液态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。我们还将通过在实验室用模型土复制纵向桩形成的现场取样阶段来研究纵向桩的离析机理。我们将重点研究隔离对异质性、采样重复性和方案设计的影响。将使用µCT扫描成像观察偏析，并使用离散元素建模(DEM)进行研究。分离程度(DS)将使用图像分析或利用现有指数(例如Lacey‘s指数或配位数指数)从DEM中量化。土壤水分对分离和采样不确定度的影响将被描述和建模。将对成堆的模型土进行采样，并将采样变异性与DS关联。本研究项目的创新之处在于开发了一种适用于受固相和液态污染物污染的土壤的通用MOSV。它还将提供有关大量颗粒物中分离动力学的新知识。通过使用尖端技术，即微CT扫描图像和DEM。它将改进我们以前用于设计抽样程序和分析抽样方法在欧空局领域代表性的ToS框架。这将提高欧空局和补救措施在每年500亿美元的国际市场上的代表性和成本效益，这些结果也将对该行业产生重大影响。

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.