CONTAMINATION OF NITRATE AND FLUORIDE IN HUB DAM RESERVOIR, LASBELLA DISTRICT/ KARACHI , PAKISTAN.

ABSTRACT: Nitrate–N and Fluoride concentrations were assessed at Hub dam from selected sites such as main dam, hub canal, spill way and shallow water, in seasons of (summer, monsoon and winter) during 2011. The result showsthat concentrations of these nutrients are within the permissible limit of the NEQS (National Environmental Quality Standard) i.e., 50 mg/l as nitrate–N and WHO Standard i.e. 50 mg/l during the monitoring period 2011.The histogram of nitrate–N demonstrates a skewed (normal) frequency distribution. Direct and indirect sources contribute to the water reservoir contamination. In shallow water, sources could be accredited due to animal wastes derived from cows and sheep, and other sources possibly by the widespread agricultural land near by these sampling site and water drain during rains. Fluoride concentration were also within prescribed value of WHO i.e. 1.5 mg/l.A good correlation exist between nitrate and fluoride at all sampling point, except in shallow water which is possibly due toexcessive concentration of nitrate.This study does not show any significant seasonal variation with respect to of nitrate and fluoride. The objective of present research was to analysis the concentration of nitrate and fluoride in selected areas of hub reservoir.Overall results ofthis study demonstrates that the water of Hub dam is currently safe for drinking and domestic use but there is chances of anthropogenic influences associated with this reservoir near future.