Statistical analysis to characterize transport of nutrients in groundwater near an abandoned feedlot

Surface water from a dugout pond and groundwater samples from seven shallow wells installed within an abandoned feedlot in northwestern Minnesota, USA. were analyzed for nutrients, ammonia, pH, temperature, and electrical conductivity (EC). In the study, multivariate statistical techniques including cluster and factor analyses were used to evaluate the interrelationship between the analyzed chemical species. The cluster and factor analyses grouped the analyzed chemical species into three different groupings or clusters based on the concentrations of the chemical species and physical parameters. From the factor analysis, approximately 78% of the variability in the factor 1 was caused by electrical conductivity (EC), ammonium (NH4+, total carbon (TC), and total phosphorus (TP), while within factor 2; approximately 82% of the variability was caused by temperature (T), pH, nitrate-nitrogen (NO3-N), and ammonium (NH4+. The contribution of nitrate-N and ammonium could be attributed to the high rate of denitrification and/or the dissimilatory nitrate reduction to ammonium. The change in the concentration of nutrients is attributed to redox conditions, temperature variation, and the movement of nutrients from manure.