3 resultados para clean water

em DRUM (Digital Repository at the University of Maryland)


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This study focuses on the intersection of the politics and culture of open public space with race relations in the United States from 1900 to 1941. The history of McMillan Park in Washington, D.C. serves as a lens to examine these themes. Ultimately, the park’s history, as documented in newspapers, interviews, reports, and photographs, reveals how white residents attempted to protect their dominance in a racial hierarchy through the control of both the physical and cultural elements of public recreation space. White use of discrimination through seemingly neutral desires to protect health, safety, and property values, establishes a congruence with their defense of residential property. Without similar access to legal methods, African Americans acted through direct action in gaps of governmental control. Their use of this space demonstrates how African-American residents of Washington and the United States contested their race, recreation, and spatial privileges in the pre-World War II era.

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To better address stream impairments due to excess nitrogen and phosphorus and to accomplish the goals of the Clean Water Act, the U.S. Environmental Protection Agency (EPA) is requiring states to develop numeric nutrient criteria. An assessment of nutrient concentrations in streams on the Delmarva Peninsula showed that nutrient levels are mostly higher than numeric criteria derived by EPA for the Eastern Coastal Plain, indicating widespread water quality degradation. Here, various approaches were used to derive numeric nutrient criteria from a set of 52 streams sampled across Delmarva. Results of the percentile and y-intercept methods were similar to those obtained elsewhere. Downstream protection values show that if numeric nutrient criteria were implemented for Delmarva streams they would be protective of the Choptank River Estuary, meeting the goals of the Chesapeake Bay Total Maximum Daily Load (TMDL).

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Geographically isolated wetlands, those entirely surrounded by uplands, provide numerous ecological functions, some of which are dependent on the degree to which they are hydrologically connected to nearby waters. There is a growing need for field-validated, landscape-scale approaches for classifying wetlands based on their expected degree of connectivity with stream networks. During the 2015 water year, flow duration was recorded in non-perennial streams (n = 23) connecting forested wetlands and nearby perennial streams on the Delmarva Peninsula (Maryland, USA). Field and GIS-derived landscape metrics (indicators of catchment, wetland, non-perennial stream, and soil characteristics) were assessed as predictors of wetland-stream connectivity (duration, seasonal onset and offset dates). Connection duration was most strongly correlated with non-perennial stream geomorphology and wetland characteristics. A final GIS-based stepwise regression model (adj-R2 = 0.74, p < 0.0001) described wetland-stream connection duration as a function of catchment area, wetland area and number, and soil available water storage.