Groundwater Nitrate Concentrations and Its Relation to Landcover, Buncombe County, NC Adu Agyemang, Adela Beauty, Arpita Nandi, Ingrid Luffman, and Andrew Joyner Abstract High concentrations of nitrate (NO 3 ) in groundwater can be harmful to human health if ingested, and the primary cause of blue baby syndrome, among other health impacts. In this study, the spatial distribution of NO 3 in groundwater for 610 private drinking water wells in Buncombe County, North Carolina was modeled. While NO 3 concentration in the sampled wells did not exceed the 10 mg/L limit established by the United States Environmental Protection Agency, some wells had NO 3 concentrations approaching this limit (as high as 8.5 mg/L). Kriging interpolation was implemented within a Geographic Information System to predict NO 3 con- centrations across the county, and a cokriging model using land cover type. Cross validation statistics of root mean square and root mean square standardized for both models were compared and the results showed that the predicted NO 3 map was improved when land cover type was integrated into the model. The cokriging interpolated surface with land cover as a covariate had the lowest root mean square (0.979) when compared to the kriging interpolated surface (0.986), indicating a better fit for the model with land cover. NO 3 concentrations equal or greater than 2 mg/L were concentrated in 37% hay/pasture land, 34% developed open space, and 29% deciduous forest. The study did not reveal any statistically significant difference in the presence of high NO 3 concentration between these landcover types, indicating they all relate to high NO 3 content. Keywords Nitrate Á Spatial statistics Á Kriging 1 Introduction Groundwater provides about 80% of usable water storage in the world. The quality of groundwater is as important as that of its availability and quantity because it represents our main source of drinking water (Rahman 2008). Groundwater is an important source of water supply because of its low sus- ceptibility to pollution compared to surface water (U.S. Environmental Protection Agency 1995). Groundwater is vulnerable to pollution from underlying bedrock, human activities, and sewage discharge from industrial and agri- cultural sites (Rahman 2008; Babiker et al. 2004). Nitrate (NO 3 ) is a widespread pollutant that enters the groundwater through the surface and is not naturally contained in the groundwater. Predicting areas that are likely to contain high levels of NO 3 may help to prevent the use of NO 3 con- taminated water, and provide developers and planners with information about areas in need for additional testing. Nitrogen is a primary component of fertilizers based on its ability to boost the productivity of crops. Global increase in the use of nitrogen fertilizer over the last few decades has led to increased NO 3 in groundwater, threatening water quality (Burow et al. 2010). When nitrogen in fertilizer exceeds the demand of plants and the ability of the soil to retain it, nitrogen leaches into groundwater in the form of NO 3 through infiltration of precipitation, irrigation, and other processes (Shamrukh et al. 2001). Agricultural areas are susceptible to high levels of NO 3 concentrations due to the use of NO 3 rich fertilizers (Zhang et al. 1996; Thorburn et al. 2003). Factors that affect NO 3 concentration in groundwater include land use operations, shallow water table, water chemistry like redox potential and pH, and subsurface clay thickness (Townsend and Young 1995). Increased concentration of NO 3 in groundwater may repre- sent a loss of fertility in the overlying soil, cause eutrophi- cation from the discharge of groundwater into surface water, and become a health hazard to animals and humans (McLay et al. 2001). Environmental Protection Agency (EPA) has A. Agyemang Á A. Beauty Á A. Nandi (&) Á I. Luffman Á A. Joyner Department of Geosciences, East Tennessee State University, Johnson City, TN 37614, USA e-mail: nandi@etsu.edu © Springer Nature Switzerland AG 2019 A. Shakoor and K. Cato (eds.), IAEG/AEG Annual Meeting Proceedings, San Francisco, California, 2018—Volume 2, https://doi.org/10.1007/978-3-319-93127-2_14 91