EVALUATING MOBILIZATION AND TRANSPORT OF TRACE ELEMENTS ALONG MINE BROOK SEDIMENTS WITHIN COBALT LEGACY MINE WATERSHED, EAST HAMPTON, CT

Abandoned mine sites are sources of anthropogenic inputs to the environment. These sites allow the transport of concentrated trace metals to various hydrologic units. There is a growing concern worldwide regarding contaminations resulting from legacy mine sites. The Cobalt legacy mine site is located in East Hampton, Connecticut, which was historically mined for cobalt, nickel, and gold. At this site, there are two main shafts with various test shafts around the area. The mining operation stopped in the late 1800s and has been abandoned since then. Various contaminations of groundwater wells have been reported in this locality; however, no correlation has been made with the mine site. This study examined the impact of the Cobalt legacy mine site on the concentrations, and transport of trace elements along Mine Brook. A total of twenty-eight (28) stream sediment samples were collected along the Mine Brook from upgradient from the main mine shaft, downgradient through a forested area and residential areas to the point where Mine Brook emptied into the Connecticut River. Samples were air-dried, thoroughly homogenized, and sieved through a 2-mm sieve size, and analyzed for particle sizes, and organic matter fractions. In addition, samples were digested with aqua regia and analyzed for seventeen (17) chemical elements using an ICP-OES at the CCSU Geochemical laboratory. Results showed trace element concentrations were related to the abundance of both the clay and OM fractions within sediments with the average decreasing order of abundance: Fe>Al>Mg>K>Ca>Mn>S>Na>P>Pb>As>Zn, respectively. Notable positive significant correlations exist mostly between Al, Fe, Cr, and Zn suggestive of the possible partitioning of ions to fine sediment sizes, or association among elements under similar geochemical processes to which they are exposed. The data showed that there were undetectable levels of Cobalt and Nickle in the sediments tested but Arsenic at multiple sites ranging from 0 gm/kg to 320.99 gm/kg with an average of 23.4596 mg/kg of the testing area. Calculations of element enrichment and geoaccumulation index showed most locations are not enriched suggestive of a high dilution and transport rate within the watershed