9. Aqueous Speciation and Geochemical Modeling Codes for Groundwater Geochemistry

Geochemistry, Groundwater and Pollution: "Learning by Modeling"

Predicting the fate of chemicals that leach from waste deposits and deciphering their transport in the invisible subsoil must rely on 1) understanding the pattern of groundwater flowlines and travel times, 2) insight in the chemical reactions which retard the solutes, and 3) the quality of the database of the geochemical model. Inhomogeneities in an aquifer can be deduced from tritium/helium ag...

Speciation and Geochemistry of Tungsten in Soil

In order to limit the dispersive use of lead on small arms firing ranges, 5.56-mm bullets with tungsten-nylon composite material cores have been fired at a number of Army training ranges. Tungsten in bullet residues oxidizes when exposed to the atmosphere, yielding an amorphous tungsten oxide (WO3) coating. This coating rapidly dissolves to yield the tungstate anion (WO4), which can migrate in ...

Modeling large scale geogenic contamination of groundwater, combination of geochemical expertise and statistical techniques

There is an increasing interest in modeling groundwater contamination, particularly geogenic contaminant, on a large scale both from the researcher’s as well as policy maker’s point of view. However, modeling large scale groundwater contamination is very challenging due to the incomplete understanding of geochemical and hydrological processes in the aquifer. Despite the incomplete understanding...

Laboratory simulations of Mars aqueous geochemistry

We report on laboratory experiments in which we allowed an SNC-derived mineral mix to react with pure water under a simulated Mars atmosphere for 7 months. These experiments were performed at one bar and at three different temperatures in order to simulate the subsurface conditions that most likely exist where liquid water and rock interact on Mars today. The dominant cations dissolved in the s...

Formation and Fate of Phyllosilicates on the Surface of Mars: Geochemical Modeling of Aqueous Weathering