SPATIAL ANALYSIS OF DAM SEDIMENT AND METAL CONTAMINATION IN THE NORTHERN NASHUA RIVER BASIN, MASSACHUSETTS USA

Fitchburg, Massachusetts is a heavily industrialized city with over 20 dams located within the North Nashua River basin. Many of the dams, which were constructed in the mid- to late-1800’s, are abandoned. Metal fluxes and accumulation in fluvial ecosystems reflect natural weathering and associated sediment fluxes from the basin; but in most cases this process is exacerbated by the progressive anthropogenic land-use intensification with human population increases. It is well established that sediments trapped behind dams are a sink for contaminants from various land uses, known point sources, and atmospheric deposition. Therefore, spatial analysis of sediments behind multiple dams at high resolution in a single basin enables characterization of the dynamics between modern urbanization and legacy industry. This study seeks to characterize the spatial variability of metal concentrations in sediments behind multiple dams on the North Nashua River in order to infer the impact of land use and legacy industry on fluvial systems. Data collection consisted of multiple sediment cores and grab samples from seven dams in upstream to downstream locations along the North Nashua River. Samples were prepared using the aqua regia digestion method (USEPA 3050B) and will be analyzed using an inductively coupled plasma mass spectrometer (ICP-MS) to determine metal concentrations in the surficial and core sediments of North Nashua River Basin. GIS based hotspot analysis, trace metals enrichment analysis, Principal Component Analysis and other statistical analyses will elucidate the role of legacy sediments and contemporary land-use intensification in influencing metal distribution and loading in the North Nashua River Basin. This knowledge will provide a base for future research relating to contamination from the region’s industrial legacy and aid in any potential future remediation activities.