Nitrate Concentration in Wells Supplying Drinking Water for Bojnord city in 2007

The high concentration of nitrate in water is one of the pollutants in ground waters. In recent years due to the increase of wastewater and agriculture and urban development, its amount in water source has been increased. High nitrate concentration in drinking water is dangerous for children's health and causes Methemoglobinomia. The aim of this research was measure the nitrate concentration in water wells which supply the drinking water in Bojnord and compare it with ommon standards. Marerials and This was a descriptive research to investigate nitrate concentration in vater sources in Bojnord in 2007. Thus the result of nitrate tests was considered in 82 samples from water supplying source and drinking water reservoirs in Bojnord. All the samples were tested by using spectrophotometric methods in the chemistry lab of Northern Khorasan's Water and wastewater Company. The final results were studied and analyzed by statistical methods. The results showed that there was a significant difference between concentration of nitrate ions in inner wells and concentration of nitrate ions in outer wells (P=0.003). The average oncentration of nitrate ions in inner wells was higher than those of the outer wells. The average itrate concentration indicated that 2 from 8 (25 %) outer water wells and 8 from 9 (88.8 %) inner vater wells had an average higher than the standard specified by Iranian Standard Industry esearch Institute. It was shown that there was a significant negative relationship between the depth of well and nitrate concentration (P<O.OOl). The average of nitrate concentration in the outlet of eservoir was 34.4 mg/I. Disscussion: According to the results, the average of nitrate concentration in many drinking water vells of Bojnord was more (50 mg/I) than the standard approved by Institute of Standards & dustrial Research of Iran. Because of health threats of high nitrate in drinking water wells, some asic measures should be taken such as refining water of polluted wells or taking out polluted wells om consumption cycles and using better quality sources. Regular examination and control of itrate in supplying sources and water distribution nets is also necessary.