EXPLORATORY ANALYSIS OF METAL DISPERSION IN THE CHIHUAHUAN DESERT USING SEDIMENT GEOCHEMICAL DATA

Exploratory Data Analysis (EDA) was applied to a large data set (N = 2,584) of sediment geochemistry within the Chihuahuan Desert. Each data point contained information of location, composition (19 elements), and lithology. Box Plot analysis was applied to determine mild and extreme anomaly thresholds. The anomaly maps revealed areas of concentration of each of these anomalies as well as dispersion patterns for each element. Specific potential sources of contamination were identified after superimposing anomalies with map layers of mines, urban centers and hydrology. The anomaly maps revealed that the contamination is mainly due to natural enrichment in rock outcrops, and mining wastes second. Multi-element exploratory techniques yielded four principal components that accounted for 74% of total variance, exposing a strong association among Fe, Mn and Mg in PC1, Ca and Sr in PC2, Co, Cu, Cr, and Ni in PC3 and Pb in PC4. This detailed spatial information is a suitable tool for impact assessment studies aimed to minimize pollution and avoid further degradation of soil and aquatic environments.