Nitrate levels in drinking water in rural areas of Buenos Aires Province, Argentina

M. A. HERRERO, S. KOROL, M. FORTUNATTO, A. GONZALES CHAVES, A. FLORES, S. BEVILLAQUA, G. GALINDO, V. MALDONADO, G. SARDI Y A. FERNÁNDEZ CIRELLI

Melbourne, Australia

Congreso; Xth World Water Congress; 2000

International Water Resources Association

Nitrogen, in rural areas, is introduced through the use of fertilizers, the accumulation and application of animal manure, and from septic systems. It can leach into aquifers and contaminate groundwater, which is the primary source of drinking water for rural residents. Well characteristics and proximity to potential contamination sources were examined to establish their influence on the susceptibility of individual wells. Bacteriological quality was also tested. In this study, levels above 45 mg/L of nitrates and 3 faecal coliforms and total coliforms/ 100 ml were considered elevated. These standards were consistent with National Standards for Public water supplies. The farm families were asked to complete a questionnaire. It included  aspects such as type of farm, water and land management, well distance from contamination sources, kind of source, and depth, type and well age. This study found nitrates detectable in 91% of the drinking water wells sampled (n=69), with 29% of the wells having levels above the maximum contaminant level, and 28% of the wells contaminated with total coliforms and 19% with faecal coliforms. Although the percentages of nitrate and bacterial contamination are similar, most of them didn´t come from the same wells. Worst samples were found in  Schools and houses where the septic systems were close to the well, old and  damaged wells, and near livestock pens. The mean nitrate concentration was 41.9 mg/L ±36.5, the median was 32 mg/L, extremes values were 2 and 197 mg/L. The number and kind of contamination sources close to the well, the type of farm and land management were statistically associated with the level of nitrate concentration. Well characteristics were not statistically associated. Due to the association of well characteristics and productive activities, further research is important to be able to establish prevention strategies.