Relationship between nitrogenous pollution of borehole waters and distances separating them from pit latrines and fertilized fields

Abstract

The occurrence of the following nitrogenous pollutants, namely ammonium, nitrite and nitrate ions, was investigated in groundwater (borehole) sources of two villages in North West Province of South Africa. The study was carried out for two reasons. The Department of Water Affairs and Forestry (DWAF) in Mmabatho had expressed anxiety over anomalous levels of nitrate ion (which can be reduced to the toxic nitrite ion) in some groundwater sources in the province (and this included some groundwater sources in the two villages). The concentrations of the nitrogenous pollutants were monitored by differential pulse polarography (DPP). This electrochemical method was selected because it is fast, has low detection limits and is virtually free of interferences. The study indicated that the main pollutant in the groundwater sources was nitrate ions whose concentrations were higher than 25 ppm in some borehole waters. This is more than two times higher than the 10 ppm N specification recommended by the South African National Standard (SANS) for drinking water. The study also indicated that the concentrations of ammonium and nitrite ions in the borehole waters studied are not a health risk to the communities. Important sources of groundwater pollution are pit latrines and maize fields treated with nitrogen fertilizers. It was found that groundwaters (borehole water) were polluted with nitrate ions when the distances of the pit latrines and fertilized maize fields were respectively less than 18 m and 13 m from the boreholes. The pollution was more pronounced when the water table was shallow. (Basie Vinger, Mbhuti Hlophe and Mailoo. Selvaratnam. Relationship between nitrogenous pollution of borehole waters and distances separating them from pit latrines and fertilized fields. Life Science Journal 2012;9(1):402- 407).(ISSN:1097-8135). http://www.lifesciencesite.com . 59