Risk of Nitrate in Groundwaters of the United StatesA National Perspective

Abstract

Nitrate contamination of groundwater occurs in predictable patterns, based on findings of the U.S. Geological Survey's (USGS) National Water Quality Assessment (NAWQA) Program. The NAWQA Program was begun in 1991 to describe the quality of the Nation's water resources, using nationally consistent methods. Variables affecting nitrate concentration in groundwater were grouped as “input” factors (population density and the amount of nitrogen contributed by fertilizer, manure, and atmospheric sources) and “aquifer vulnerability” factors (soil drainage characteristic and the ratio of woodland acres to cropland acres in agricultural areas) and compiled in a national map that shows patterns of risk for nitrate contamination of groundwater. Areas with high nitrogen input, well-drained soils, and low woodland to cropland ratio have the highest potential for contamination of shallow groundwater by nitrate. Groundwater nitrate data collected through 1992 from wells less than 100 ft deep generally verified the risk patterns shown on the national map. Median nitrate concentration was 0.2 mg/L in wells representing the low-risk group, and the maximum contaminant level (MCL) was exceeded in 3% of the wells. In contrast, median nitrate concentration was 4.8 mg/L in wells representing the high-risk group, and the MCL was exceeded in 25% of the wells.

Study of a combined sulfur autotrophic with proton-exchange membrane electrodialytic denitrification technology: Sulfate control and pH balance

“…Significant increase of nitrate in groundwater has been observed in many areas of the world (Nolan et al, 1997). Since nitrate has a deleterious effect on human health and environment, processes for nitrate removal have gained attention in recent years (Kleinjans et al, 1991;Nolan et al, 1997).…”

“…Since nitrate has a deleterious effect on human health and environment, processes for nitrate removal have gained attention in recent years (Kleinjans et al, 1991;Nolan et al, 1997). The conventional treatment methods used to remove nitrate are reverse osmosis (RO) (Brigita et al, 2009), ion exchange (IE) (Samatya et al, 2006), catalytic (Prüsse et al, 2000;Florence et al, 2001;Wan et al, 2009a) and biological (Anabela et al, 2000;Lucas et al, 2005;Liu and Koenig, 2002;Rezania et al, 2007) processes.…”

Using the combined bioelectrochemical and sulfur autotrophic denitrification system for groundwater denitrification

“…It was discovered that for ground water from 10% to 25% of the water-supply wells in large region of the US exceeded the maximum contaminant level for nitrate (10 mg NO À 3 -N /L) (Nolan et al, 1997). In China, the pollution of nitrate in ground water was even more severe, nitrate concentration of groundwater in some rural area even exceeded 130 mg NO À 3 -N /L.…”

Bio-geological processes of nitrogen transport and transformation in the aeration zone and aquifer

“…Nitrate pollution cases that exceed the threshold recommended by the World Health Organization (50 mg/L NO 3 ) and by the USA (10 mg/L N) for drinking water have been reported in many countries, such as UK, Denmark, Belgium, France (Strebel et al, 1989), USA (Nolan et al, 1997), and India (Agrawal et al, 1999). The agriculture-derived nitrate pollution of groundwater has become an environmental issue (Spalding & Exner, 1993) because it may cause eutrophication in aquifers and algal blooms in surface water, and even produce potential hazards to human health (Knobeloch et al, 1992;Fan & Steinberg, 1996;Gelberg et al, 1999;Gulis et al, 2002) though the link is still disputable (Forman et al, 1985;Van Loon et al, 1998).…”