Nutrients in groundwaters of the conterminous United States, 1992-1995
Environmental Science & Technology
By: B. T. Nolan and J.D. Stoner
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Abstract
Results of a national water quality assessment indicate that nitrate is detected in 71% of groundwater samples, more than 13 times as often as ammonia, nitrite, organic nitrogen, and orthophosphate, based on a common detection threshold of 0.2 mg/L. Shallow groundwater (typically 5 m deep or less) beneath agricultural land has the highest median nitrate concentration (3.4 mg/L), followed by shallow groundwater beneath urban land (1.6 mg/L) and deeper groundwater in major aquifers (0.48 mg/L). Nitrate exceeds the maximum contaminant level, 10 mg/L as nitrogen, in more than 15% of groundwater samples from 4 of 33 major aquifers commonly used as a source of drinking water. Nitrate concentration in groundwater is variable and depends on interactions among several factors, including nitrogen loading, soil type, aquifer permeability, recharge rate, and climate. For a given nitrogen loading, factors that generally increase nitrate concentration in groundwater include well-drained soils, fractured bedrock, and irrigation. Factors that mitigate nitrate contamination of groundwater include poorly drained soils, greater depth to groundwater, artificial drainage systems, intervening layers of unfractured bedrock, a low rate of groundwater recharge, and anaerobic conditions in aquifers.
Suggested Citation
Nolan, B.T., and Stoner, J., 2000, Nutrients in groundwaters of the conterminous United States, 1992-1995: Environmental Science & Technology, v. 34, no. 7, p. 1156-1165, https://doi.org/10.1021/es9907663.
ISSN: 1520-5851 (online)
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Nutrients in groundwaters of the conterminous United States, 1992-1995 |
| Series title | Environmental Science & Technology |
| DOI | 10.1021/es9907663 |
| Volume | 34 |
| Issue | 7 |
| Publication Date | February 26, 2000 |
| Year Published | 2000 |
| Language | English |
| Publisher | ACS |
| Publisher location | Washington, DC, United States |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Environmental Science and Technology |
| First page | 1156 |
| Last page | 1165 |