Groundwater Nitrate Concentrations and Its Relation to Landcover, Buncombe County, NC

Abstract

High concentrations of nitrate (NO3) 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 NO3 in groundwater for 610 private drinking water wells in Buncombe County, North Carolina was modeled. While NO3 concentration in the sampled wells did not exceed the 10 mg/L limit established by the United States Environmental Protection Agency, some wells had NO3 concentrations approaching this limit (as high as 8.5 mg/L). Kriging interpolation was implemented within a Geographic Information System to predict NO3 concentrations 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 NO3 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. NO3 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 NO3 concentration between these landcover types, indicating they all relate to high NO3 content.