Assessment of nitrate contamination of karst springs, Bani Kanana, northern Jordan

Abstract

Contamination of groundwater from point and non-point sources is one of the major problems of water resources in Jordan. Altogether one hundred and six groundwater samples were collected from twenty six karst springs emerging from Umm Rijam aquifer and three wells tapping Amman-Wadi As Sir aquifer, and investigated for NO3  concentrations. Results showed that NO3  concentration in spring water ranged from 8 to 192 mg/L with an average of 33 mg/L. Seventy seven percent of the samples collected from the springs had nitrate concentrations exceeding the threshold value of 20 mg/L of anthropogenic source, and eight percent of the samples collected had nitrate concentrations higher than 50 mg/L, the maximum acceptable nitrate concentration for drinking water. About eighty percent of the sampled springs had nitrate concentrations higher than 20 mg/L. The K-means cluster analysis performed on the collected samples revealed the presence of three major clusters. The data were processed for the possible presence of discordant outliers using the unpublished computer program UDASYS by Verma and Díaz-González. There is a wide spatial variation in the nitrate concentration in spring water. Monitoring the water quality of these springs showed that the lowest concentrations of nitrate were found in the wet season (January, February, and December), while the highest concentrations were found in the dry season (August, September). Nitrate concentration in Amman-Wadi As Sir aquifer ranges from <1 mg/L to 19.2 mg/L, with an average of 9.8 mg/L. Untreated domestic wastewater is most probably the major source of the nitrate in the spring water, as the study area is not served with sewer system, and domestic wastewater is collected in cesspools dug in the kartsed Umm Rijam Formation. Moreover, in the area under consideration there are no major industries or intensive agricultural activities. The results of this study are useful to highlight one of the most important environmental problems, namely the degradation of the water quality, and may serve to alert and encourage local and national authorities to take substantial steps and actions to protect and manage water quality.