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Mapping the Distribution of the Bioaccessible Fraction of Trace Metals in the Sediments of an Urban Stream, Park River Watershed, Connecticut
2014
Semrod, Kelsey A. | Gourley, Jonathan R.
The Park River watershed (PRW), a sub-basin of the Lower Connecticut River watershed, has experienced increased urbanization over the last century as the city of Hartford and its surrounding towns have grown and developed. We present watershed-wide and outflow scale maps of the trace metals Cd, Cu, Zn, and Pb to determine patterns of contamination in fine (<63 μm) stream sediment. Results are compared to established sediment quality guidelines (SQG) and probable effect concentrations (PEC) for each metal. Throughout the watershed, higher concentrations of trace metals are observed in the more urbanized south branch of the PRW. In this sub-basin, there are more industries that use, and waste, metals in their manufacturing processes that contribute to acutely high concentrations of metals in the fine bedload sediments. Impervious surfaces are examined as well in the context of the entire watershed. While an increase in metals can be attributed to an increase in impervious surfaces, these increases do not generally exceed SQGs and PECs. Two focused mapping studies were conducted at the storm water outflow of the West Hartford Landfill and the Trout Brook Sanitary Sewer Overflow (SSO). The purpose of these studies was to analyze the local effects of natural stream features such as channel bar deposits next to the outfalls. We determined that the sediment directly below the two outfalls often exceeded the PEC, while the accumulated sediment around the channel bar deposits was not contaminated beyond background stream levels. We believe mapping at both the small (watershed) and large (outfall) scale can be helpful in future urban studies to determine the extent of trace metal sediment contamination in both channelized and natural sections and may provide a useful method for sediment mitigation endeavors.
Mostrar más [+] Menos [-]Spatial Risk Assessment of Farming on Wetland Habitats in Watershed System
2014
Sekar, I. | Randhir, Timothy O.
Natural resource habitats, which are isolated from the surface water bodies, are often unregulated and face a higher risk of degradation. Vernal pools, habitats for amphibians, are vulnerable to external stressors that often lead to decline in biodiversity. There is a need to protect these through conservation measures at a spatially targeted level. This study is conducted in the Middle Connecticut River Watershed of Massachusetts State. We evaluate the risk faced by isolated vernal pools at the subwatershed scale. The assessment involves the impact of agricultural intensity and vernal pool distribution in proximity to agriculture parcels. This is performed using geoprocessing techniques within a geographic information system (GIS). The spatial data are used in a nonlinear regression model to evaluate potential stressors to vernal pool existence. The model included land use, geographic features, and hydrographic factors. Agriculture and open land positively influence vernal pool existence, because of vernal pool association with low-lying areas. In addition, elevation showed a negative influence on the number of vernal pool habitats. The results of the spatial risk evaluation of habitat are helpful to target efforts on specific subwatersheds in conserving vernal pool habitats.
Mostrar más [+] Menos [-]A comparison of the pollution and natural purification of the Connecticut and Delaware rivers and the Brandywine Creek
1932
Setter, Lloyd R. (Lloyd Richard)