Occurrence of Nitrate in Groundwater—A Review

Abstract

The results of federal, state, and local surveys, which included more than 200 000 NO3‐N data points, are summarized in this review of NO3 in groundwater in the USA. The levels of NO3‐N are associated with source availability and regional environmental factors. In regions where well‐drained soils are dominated by irrigated cropland, there is a strong propensity toward the development of large areas with groundwater that exceeds the maximum contaminant level of 10 mg/L NO3‐N. Most of these areas are west of the Missouri River where irrigation is a necessity. Aquifers in highly agricultural areas in the southeastern USA reportedly are not contaminated. Vegetative uptake and denitrification in this warm, wet, C‐rich environment are responsible for the natural remediation of NO3 in shallow aquifers. In the Middle Atlantic states and the Delmarva Peninsula, localized contamination occurs beneath cropped, well‐drained soils that receive excessive applications of manure and commercial fertilizer. Extensive tile drainage has for the most part prevented a NO3 problem in the groundwater of the Corn Belt states. Throughout the USA there are recurring themes. They include a decrease in NO3‐N levels with depth; lower NO3‐N levels in shallow wells (< 8 m); and a significant increase in NO3‐N in older wells and in wells with poor construction. The factors affecting the distribution of NO3 in aquifers are complex and poorly understood. Interdisciplinary studies using discrete depth sampling, hydrogeological indicators, isotopic tracers, and microbiological techniques are necessary to unravel the complex dynamics.

Influences of natural and anthropogenic factors on surface and groundwater quality in rural and urban areas

“…Poorly managed agricultural operations can lead to contamination of surface water and groundwater by nutrients and pesticides (Spalding and Exner 1993;Pereira et al 1996;Kolpin et al 1998;Novotny 1999;Gunningham and Sinclair 2005). Periodic use of these products in agriculture will cause dispersion within the environment by means of drift, run-off and drainage (Kolpin et al 1998;Guzzella et al 2006;Papastergiou and Papadopoulou-M 2001).…”

Nitrate pollution of groundwater; all right…, but nothing else?

“…Nitrate occurrence and transport in aquifers have been widely studied since it is one of the 39 major threats in groundwater, and most aquifers in agricultural areas are affected by this 40 contaminant (Spalding and Exner, 1993;EEA, 2012). Most of the papers that focused on 41 nitrate pollution study, by means of hydrochemical and isotopic data, nitrate trends in 42 groundwater at different scales to identify potential sources of pollution and build-up 43 hydrogeochemical models to understand the behavior of nitrate polluted aquifers (for 44 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 reported that the concentration of some major inorganic components in pig manure, the most 64 used organic fertilizer in the studied areas in Catalonia (NE Spain), is notably larger than 65 their natural values in groundwater.…”

Nitrate, sulphate and chloride contents in public drinking water supplies in Sicily, Italy

“…Also, the World Health Organization (WHO) indicates a guideline value (GV) of 50 mg/l for drinking water (WHO 2004), which has been integrated into Italian national law as a MAC. A high nitrate concentration is always related to anthropogenic contamination, the main sources being fertilizers and human or animal bodily waste (Spalding and Exner 1993). Nitrate can be the main anionic species in both agricultural and urban areas.…”