Contributions of Phosphorus from Groundwater to Streams in the Piedmont, Blue Ridge, and Valley and Ridge Physiographic Provinces, Eastern United States

摘要

Potential contributions of phosphorus from natural and anthropogenic sources to groundwater and from groundwater to streams in the Piedmont, Blue Ridge, and Valley and Ridge Physiographic Provinces in the eastern United States are described and discussed in this report. Water-quality data collected from 1991 through 2007 from more than 600 wells and more than 350 streams during base-flow conditions in various hydrogeologic and land-use settings from northern Alabama to New Jersey are presented. Graphical and statistical techniques are used to compare phosphorus concentrations in groundwater and streams among different hydrogeologic and land-use settings and to proposed ecoregion nutrient criteria. Interactions between groundwater and streams in various settings inferred through comparison of major-ion chemistry are described. Geochemical models are used to identify and evaluate potential contributions from various sources of phosphorus in different settings, and geochemical and hydrologic processes affecting phosphorus fate and transport through groundwater to streams. Implications of observations and conclusions for regional nutrient management and proposed criteria are discussed.