Distribution of nitrate in the water resources of Pakistan
Water quality monitoring activities have recognized the nitrate contamination in the drinking water sources as one of the major quality issue of Pakistan. Adopting a uniform sampling design, 747 samples were collected from a wide range of irrigated or non-irrigated regions having distribution of samples in sixteen cities as Lahore (79), Kasur (46), Faisalabad (30), Khushab (50), Chakwal (51), Mianwali (30), Jhelum (53), Bahawalpur (60), Karachi (60), Mirpur Khas (55), Peshawar (38), Risalpur (35), Quetta (81), Ziarat (21), Loralai (21), Mastung (37). The results showed that 19% of the total samples have nitrate concentration beyond the permissible safe limit of 10 mg/L falling in the concentration range of 11-160 mg/L of nitrate. The highest percentage contamination (23%) is found in water samples collected from both the Balochistan and Punjab provinces. Comparatively higher nitrate levels of <70 % in the groundwater sources like hand pumps and wells support the possibilities of increased contamination in the areas cultivated using heavy doses of fertilizers. Findings of the study provide support for further epidemiological investigations and potential strategy for mitigating the issue in the
Key words: Nitrate-N, groundwater contamination, hand pumps, methemoglobinemia, Pollution, nutrients, fertilizer, agriculture.