VARIABILITY OF METAL CONTENT IN SEDIMENTS IN AND AROUND AURORA, MISSOURI, A HISTORICAL MINING TOWN

The state of contamination of the historic mining town of Aurora, Missouri, was investigated. Sediments were collected in and around Aurora during 2014-2015 and analyzed for metal content (Fe, Pb, Zn) using the conventional method of ICP-MS after digestion with aqua regia. Once merged with other reported data, there were 81 data points scattered over an 8 x 6 mile area, yielding a coverage of 1 data point per 1.53 km². Data were analyzed to determine (a) the correlation among metals, (b) the variability in metal content between urban and non-urban areas, (c) the variability in metal content within Chat Creek, a stream crossing the town, and (d) the variability in metal content between Chat Creek and other streams. For these determinations, Pearson correlation, t-test, and spatial IDW (inverse distance method) were utilized. Of the total number of samples, 40% contained toxic levels of Pb and 82% of Zn, based on sediment quality guidelines (SQG) reported for the area. To better appraise the metal contamination of the area, maps showing the varying metal content for each Pb and Zn were created.