Agriculture and Groundwater Quality

by Herman Bouwer, (M.ASCE), Laboratory Director; U.S. Water Conservation Lab., 4331 E. Broadway Rd., Phoenix, AZ 85040,

Serial Information: Civil Engineering—ASCE, 1989, Vol. 59, Issue 7, Pg. 60-63

Document Type: Feature article


Nitrates and pesticides used in agriculture cause groundwater degradation. Agricultural practices in the U.S. will have to be changed to alleviate the health effects of these chemicals. Nitrates can react with amines in the body after reduction to nitrites to form nitrosamines, some of the most potent carcinogens known to man. Numerous pesticides have been detected in groundwater at many locations and thousands of wells have been closed. Ingestion of pesticide residues is associated with nervous system disorders, cancer, birth defects and male sterility. More research is needed on chemical movement in the vadose zone for accurate predictive modelling of pollutant transport. Water in the vadose zone can move through preferential flow paths. Water and dissolved chemicals may move 2 to 20 times faster than indicated by the pore velocity calculated as Darcy velocity divided by water content and there could be less contact with the soil matrix when flows move through preferential paths, reducing the adsorption of chemicals to the soil.

Subject Headings: Groundwater quality | Pesticides | Irrigation water | Nitrates | Chemical degradation | Vadose zone | Model accuracy | Water flow

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