Purpose and Scope

The purposes of the project, which began in 1990 in cooperation with the Arizona Department of Environmental Quality, were

• to attempt to develop a geochemical technique to identify sources of contaminants in ground water on the basis of the chemical and isotopic composition of both the ground water and suspected nitrate sources, and
• to establish the best geostatistical methods for unbiased and reproducible spatial estimates (maps) of existing nitrate contamination in ground water. Because ground-water under large areas of the valley contains more than 10 mg/L nitrate nitrogen, accurate estimates of nitrate distribution are beneficial to effective management or at least monitoring of the problem.

The purpose of this poster is to present some aspects of work done to achieve these two objectives. In particular, we want to show how the Public Domain GIS GRASS has aided us in answering our questions.

We also present the geostatistical methodology chosen for making our maps, and some of the preliminary findings of our study.