The impact of agriculture on water resources
1997
Metsur, M. (Estonian Agricultural Univ., Tartu (Estonia). Inst. of Water Management)
Contamination of ground water with nitrates has been a serious problem in Estonia. In the end of the 1980's, the nitrate ion concentration in dug wells and shallow drill wells exceeded the permitted concentration limit (45 mg NO (-3)/l) as follows: 40-70 per cent of wells in southern Estonia; 30-60 per cent in central Estonia; 20-40 per cent in the Pandivere Upland; and less than 10 per cent of wells in the Lahemaa region and Muhu Island. In the limestone outcrop area, the connection between the fertilizatiaon of fields, crop yields and nitrate content was studied in the aquifer closest to the surface. Depressed economic conditions have resulted in an improvement in water quality in the upper aquifers. However, this problem remains in intensive agricultural areas in central Estonia, where nitrate ion concentrations are over 45 mg/l in dug and drill waters
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