thumbnail

Nitrogen loads through baseflow, stormflow, and underflow to Rehoboth Bay, Delaware

Journal of Environmental Quality

By:
, , , , and
DOI: 10.2134/jeq2005.0373

Links

Abstract

A detailed study of water and nitrogen (N) discharge from a small, representative subwatershed of Rehoboth Bay, Delaware, was conducted to determine total N loads to the bay. The concentrations of ammonium (NH 4+), nitrate + nitrite (NO3- + NO2-), and dissolved and particulate organic N were determined in baseflow and storm waters discharging from Bundicks Branch from October 1998 to April 2002. A novel hydrographic separation model that accounts for significant decreases in baseflow during storm events was developed to estimate N loads during unsampled storms. Nitrogen loads based on gauged flows alone (7100-19100 kg/yr) significantly underestimated those based on land use-land cover (LULC) and estimated N export factors from different classes of LULC (32000-40600 kg/yr). However, when ungauged underflow and associated N loads were included in the total loads (25500-33800 kg/yr), there was much better agreement with LULC export models. This suggests that in permeable coastal plain sediments, underflow contributes significantly to N fluxes to estuarine receiving waters, particularly in drier years. Based on the similarity in LULC, N loads from the Bundicks Branch subwatershed were used to estimate upland loads to the entire Rehoboth Bay Watershed (259000-316000 kg/yr). These N loads from the watershed were much greater than those from direct atmospheric deposition (49000-64500 kg/yr) and from a local wastewater treatment plant (9700-13700 kg/yr). While the watershed was the principal source of N at all times during the year, the relative contributions from the watershed, wastewater, and direct atmospheric deposition varied predictably with season. ?? ASA, CSSA, SSSA.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Nitrogen loads through baseflow, stormflow, and underflow to Rehoboth Bay, Delaware
Series title:
Journal of Environmental Quality
DOI:
10.2134/jeq2005.0373
Volume
35
Issue:
5
Year Published:
2006
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Environmental Quality
First page:
1742
Last page:
1755
Number of Pages:
14