Many fundamental processes in Earth’s geological systems, such as chemical weathering, diagenesis, and the movement, distribution, and global cycling of chemical elements are related to these interactions. My research has addressed water quality (what chemicals are in water, how did they get there, and where are they going to end up), water quantity (how much water recharges an aquifer and whether the amount of withdrawal is environmentally sustainable), arsenic, antimony, and uranium contamination of surface and ground water, and large scale numerical models of water flow and contaminant transport.