Uranium values from ion-filter water sampling compared with values from bulk-water sampling

Abstract

Analytical values of uranium from well water sampled by means of ion-filters were compared with analytical values of the same water sampled by the standard bulk (1-liter) water-sampling technique (Brown, Skougstad and Fishman, 1970). A fluorometric extraction method of analysis was used on both sets of samples. Duplicate samples from pumped wells in Pueblo County, Colorado were used. Regression and correlation statistical analysis indicated that while analytical results of the two sets of samples had a highly significant correlation (r = 0.98), the ion-filter samples yielded only 20 percent as much uranium as the 1-liter water samples. It is possible to predict U values from the ion-filter analysis results that would be comparable with the values for the 1-liter samples, using the linear regression formula. The predicted values, however, compared with the 1-liter values, using a chi-square test, were found to be significantly different at the 5-percent level. Major deviations were found in two pairs, 10 percent of the samples, suggesting that the predicted values might be used if one were willing to accept the fact that an average of 10 percent of the samples would yield erroneous results. Sources of the absolute deviations between the two sets of samples may lie in chemical characteristics of the filters, or waters, or extraction method of the analytical technique or some combination of these. The results of the chi-square test also indicate that uranium values from at least 10 percent of the ion-filter samples that we obtained, deviate significantly from those obtained from the 1-liter samples. Sources of the deviations may lie in chemical characteristics of the filters, or waters, or extraction technique, part of the analytical technique or some combination of these.