VALIDATION AND APPLICATION OF IN-SITU IRON-MANGANESE OXIDE COATED STREAM PEBBLES AS SENSORS FOR ARSENIC SOURCE MONITORING

Arsenic is a contaminant of major concern in the world’s drinking and surface waters due to its health effects on humans and aquatic biota. Because arsenic contamination can be the result of several natural and anthropogenic sources, it can be difficult to trace and identify major areas of arsenic in natural systems. Therefore, identifying a useful source indicator for arsenic is a crucial step for environmental remediation efforts. It has been found that iron-manganese oxide coated streambed pebbles can be useful as source indicators due to their high attraction for heavy metals in water. In this study, pebbles, surface water, and nearby rocks were sampled from four Pennsylvania streams to test the ability of coated streambed pebbles as environmental source indicators for arsenic. In addition to natural sources, possible anthropogenic sources of arsenic were investigated at each sample site. Two streams were chosen in close proximity to areas with high arsenic concentration in groundwater while two streams were selected from areas where little arsenic data exist (Peters and Burkert 2008). Coatings were leached from pebbles using 4M nitric acid with 0.1% concentrated hydrochloric acid. Following sample processing, analyses were performed using an ICP-MS and the resulting data were spatially organized using ArcGIS software. Preliminary results suggest small pebbles (5-7 cm in diameter) are the most effective at adsorbing arsenic especially when high amounts of iron-manganese oxide coatings are present.