a Spatial and Temporal Analysis of Nutrient Inputs Using Isotopes in North Carolina's Cape Fear River Basin
Abstract
Over recent decades, agricultural practices in the United States have transitioned from smaller family-owned farms, to industrial-scale concentrated animal farming operations (CAFOs). One of the highest concentrations of swine CAFOs is located on the Coastal Plain of North Carolina, a subtropical climate vulnerable to heavy rainfalls from storm events like hurricanes and nor'easters. This region contains the Cape Fear River watershed, which originates in the Piedmont, and eventually drains as the Cape Fear River Estuary into the Atlantic. The high density of CAFOs produces high amounts of swine effluent, increasing nutrient concentrations, which leads to eutrophication within the Cape Fear River ecosystem. These nutrient inputs can be tracked to a specific source using unique isotope signatures. Stable 13C and 15N isotopic signatures were determined from water samples collected from the Northeast Cape Fear, Black, and Lower Cape Fear River subbasins prior to Hurricane Florence and directly after. Samples collected from sites in close proximity to CAFOs exhibited high 15N signatures, and increased concentrations of DOC, nitrates, phosphates, and ammonium. At these high CAFO density sites, 15N signatures were attributed to swine waste. This suggests the swine CAFOs may be a major source of nutrients in the region. Dense CAFO sites also displayed elevated nitrate and organic phosphorus concentrations in comparison to the near pristine black water stream. In addition, waterways post Hurricane Florence had nitrogen concentrations higher than previously recorded.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMNH21D3538B
- Keywords:
-
- 4313 Extreme events;
- NATURAL HAZARDS