Using molecular-scale approaches to understand soil chemical processes

土壤中的化学反应通常控制着自然系统中养分和污染物的流动性、毒性和可用性。因此，准确了解土壤化学反应如何进行对于评估环境命运至关重要。土壤化学研究中反复出现的一个主题是，最活跃的土壤表面不是占土壤90-95%的大块结晶矿物，而是在较大土壤颗粒上形成涂层的高度活跃的低结晶纳米矿物。这项研究的目的是为了更好地了解导致这两种相（水合铁和磷酸二钙）的持久性和反应性的因素，这两种相对环境和农艺都很重要。为了实现这一目标，我们将在加拿大光源上使用基于同步加速器的x射线吸收光谱（XAS）。这种方法提供了纳米矿物结构的直接测量，以及在水合条件下污染物如何与这些矿物结合的细节。

Chemical reactions in soils often control the mobility, toxicity, and availability of nutrients and contaminants in natural systems. Understanding precisely how soil chemical reactions proceed is therefore vital in assessing environmental fate. A recurring theme in the study of soil chemistry is that the most reactive soil surfaces are not the bulk crystalline minerals that make up 90-95% of soil, but instead are the highly reactive poorly-crystalline nano-minerals that form coatings on larger soil particles. The objective of this research is to better understand the factors that lead to the persistence and reactivity of two of these phases (ferrihydrite and dicalcium phosphates) that are important for both environmental and agronomic reasons. To accomplish this objective, we will use synchrotron-based X-ray Absorption Spectroscopy (XAS) at the Canadian Light Source. This method provides direct measurement of both the nano-mineral structure and details of how contaminants bond to those those minerals under hydrated conditions.