Arsenic in Drinking Water Supply Wells: A Geographical and Statistical Investigation of the Southern San Joaquin Valley (original) (raw)

2013, International Journal of Hydraulic Engineering

To investigate arsenic distribution, a prevailing problem in drinking water, arsenic concentrations in the drinking water supply for the southern San Joaquin Valley were mapped to show both current and historical concentration trends. This research was also to analyze the significance of the effect of water quality and environmental factors on arsenic concentrations in groundwater. These well construction factors included the total well depth, total length of the annular seal, average screened interval depth, as well as both iron and manganese concentrations in selected wells. The results of the correlation testing between arsenic and iron and manganese concentrations provided for a very weak correlation. Correlations between the arsenic concentration and well construction were much stronger. Different statistical methods were used to test the correlations between the arsenic concentration and the three well construction parameters. Pearson's r provided the weakest correlations with the correlation coefficients of 0.2237, 0.122, and 0.228, respectively. Kendall's tau and Spearman's results show stronger correlations with coefficients of 0.302, 0.13, and 0.311. Using Spearman's rho, the correlation coefficients were 0.405, 0.155, and 0.414. Kendall's tau was not determined to be statistically significant at a 5% confidence interval for all three variables. Spearman's rho was determined to be statistically significant at a 5% confidence interval for well depth and average screened depth.