کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5771102 1629900 2017 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Research papersDirect groundwater discharge and vulnerability to hidden nutrient loads along the Great Lakes coast of the United States
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات فرآیندهای سطح زمین
پیش نمایش صفحه اول مقاله
Research papersDirect groundwater discharge and vulnerability to hidden nutrient loads along the Great Lakes coast of the United States
چکیده انگلیسی


- 43% of the U.S. Great Lakes' coast is vulnerable to groundwater-borne nutrients.
- Lake Erie has the greatest fraction of vulnerable shoreline.
- Lake Superior has the smallest fraction of vulnerable shoreline.
- Lakebed sediments are a source of dissolved phosphorous at discharge zones.

Direct groundwater discharge delivers nutrients from land and lakebed sediments to the Great Lakes, which impacts lake water quality. Broad spatial distributions of discharging groundwater are often difficult to measure directly. We present high resolution estimates of direct groundwater discharge across 43% of the Great Lakes coastline based on a water budget approach that uses hydroclimatic models and high-resolution hydrographic data available within the United States. We also integrate land use data to identify coastal areas vulnerable to high groundwater-borne nutrient loads. Estimated rates of direct groundwater discharge along the Great Lakes coast are highly variable, but generally are greatest for Lake Erie and Lake Michigan. Almost one-third of Lake Erie's United States coastline is vulnerable to groundwater sources of nutrients. To assess uncertainties and limitations in our vulnerability analysis, a vulnerable site along Lake Erie was selected for detailed field measurements of direct groundwater discharge rates and nutrient fluxes. Measured discharge rates were significantly lower than water budget-based estimates (354 ± 25 m3 y−1 m−1 compared to 588 ± 181 m3 y−1 m−1). Dissolved phosphorous concentrations in the lakebed were elevated compared to onshore groundwater, while nitrate concentrations were lower, indicative of a highly reactive sediment-water interface. Some of the measured phosphorus may be locally sourced from desorption of legacy P or mineralization of organic matter in the lakebed, which our vulnerability framework does not include. Much of the land-derived nitrogen may be transformed along groundwater flow paths prior to discharge. While model-based estimates of direct groundwater discharge and vulnerability to nutrient loading are important for managing Great Lakes water quality, direct field observations remain essential for quantifying fluxes.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Hydrology - Volume 554, November 2017, Pages 331-341
نویسندگان
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