AGRICULTURAL LAND USE EFFECTS ON NITRATE CONCENTRATIONS IN A MATURE KARST AQUIFER¹

Abstract

The impact on water quality by agricultural activity in karst terrain is an important consideration for resource management within the Appalachian Region. Karst areas comprise about 18 percent of the Region's land area. An estimated one‐third of the Region's farms, cattle, and agricultural market value are on karst terrain. Nitrate concentrations were measured in cave streams draining two primary land management areas. The first area was pasture serving a beef cow‐calf operation. The second area was a dairy. Nitrate‐N concentrations were highest in cave streams draining the dairy and a cave stream draining an area of pasture where cattle congregate for shade and water. The dairy contributed about 60 to 70 percent of the nitrogen load increase in the study section of the cave system. It was concluded that agriculture was significantly affecting nitrate concentrations in the karst aquifer. Best management practices may be one way to protect the ground water resource.

Frontiers of Karst Research: Proceedings and recommendations of the workshop held in San Antonio, Texas on 3-5 May 2007. Karst Waters Institute Special Publication 13

“…Additionally, the extreme isotropy and heterogeneity of karst systems complicates prediction of transport velocities and even direction of flow, and leaves traditional contaminant transport models inadequate to address these unique vulnerabilities and complexities. Numerous human activities, including urbanization, agriculture, waste-water discharge, and deforestation have resulted in a variety of anthropogenic changes and contamination to karst aquifers, including nitrates and other nutrients, pesticides, solvents and other volatile organic compounds, pathogens (viruses, protozoa, bacteria), suspended sediment and turbidity, and pharmaceuticals (Carey and Lloyd, 1985;Boyer and Pasquarell, 1996;Katz et al, 2001;Barrett and Williams, 1989;Pasquarell and Boyer, 1996;Mahler and Massei, 2007;Wolfe and Williams, 1999;Kuczynskaa et al, 2003;O'Reilly et al, 2007;Ryan and Meiman, 1996;Massei et al, 2003;Drysdale et al, 2004;Wicks et al, 2004;Mahler, et al, 2006).…”

Contaminant Transport in Two Central Missouri Karst Recharge Areas

“…In The Hole cave in West Virginia, Boyer and Pasquarell (1996) reported median NO 3 -N concentrations in the main cave stream and its tributaries ranging from 3.40 to 16.58 mg L 21 . Tributaries impacted by a dairy operation had much greater NO 3 -N concentrations than those in tributaries draining pasture land , which were similar to the NO 3 -N concentrations observed in Devils Icebox and Hunters Cave.…”

“…Of these studies, only two, Boyer and Pasquarell (1996) and Panno and Kelly (2004), were conducted in recharge areas with agricultural land use intensity comparable to the Devils Icebox and Hunters Cave recharge areas. Boyer and Pasquarell (1996) reported NO 3 -N loads for the basin drained by The Hole in West Virginia on three separate days.…”

“…Of these studies, only two, Boyer and Pasquarell (1996) and Panno and Kelly (2004), were conducted in recharge areas with agricultural land use intensity comparable to the Devils Icebox and Hunters Cave recharge areas. Boyer and Pasquarell (1996) reported NO 3 -N loads for the basin drained by The Hole in West Virginia on three separate days. These loads were divided by the known area of the basin (14.5 km 2 ) (Boyer, 2005) Currens (2002) was conducted in an intensively (69 to 78%) row-cropped recharge area, resulting in average NO 3 -N fluxes ranging from 3400 to 13,000 g km 22 d…”

“…The vulnerability of groundwater to contamination in karst recharge areas has been well established over the last 25 years (Hallberg et al, 1985;Boyer and Pasquarell, 1996;Younos et al, 2001;Vesper et al, 2001;Boyer, 2005), prompting the development of new methods to assess the vulnerability of karst aquifers (Gogu and Dassargues, 2000;Andreo et al, 2006). Contaminants such as nutrients (Hallberg et al, 1985;Boyer and Pasquarell, 1995;Currens, 2002;Panno and Kelly, 2004;Crain, 2006), pesticides Currens, 2002;Panno and Kelly, 2004;Crain, 2006), sediment (Hallberg et al, 1985;Mahler et al, 1999;Crain, 2006), heavy metals (Vesper and White, 2003;Vesper et al, 2001), organic solvents Vesper et al, 2001), petroleum products (Ruhe et al, 1980), fecal bacteria Lerch et al, 2002;Pronk et al, 2006), and endocrine disruptors (Wicks et al, 2004) have been documented in karst aquifers.…”