Spatial Variability and Associated Risk Assessment of Nitrate and Ammonium Concentration in Hail Haor Wetland, Northeastern Bangladesh

Abstract

Nitrate-nitrogen and ammonium-nitrogen concentration were evaluated to assess the current nutrient condition of an ecologically as well as economically important wetland of Bangladesh. The contamination condition of surface water nitrate and ammonium of Hail Haor wetland was assessed to understand its probable risk to human health using the water samples collected from total-fifty monitoring stations, 25 each for two different seasons within 2018 to 2019. Nitrate concentration was measured using the spectrophotometer by colorimetric method, whereas ammonium was quantified using the micro Kjeldahl's distillation method. Statistical and geo-spatial analysis revealed an extensive understanding of the temporal and spatial variability as well as possible source identification of the nutrients in the studied area. Medium to a low level of nitrate ranging from 0.95 up to 9.25 mg/L and high ammonium with values from 0.32 up to 1.92 mg/L was a sporadic trend observed in wetland water, with low water season having more concentration than that of wet high water season. Hazard quotients (HQ) obtained from wetland water for four individual age groups recognized wetland water to be safe for consumption (HQ<1) based on its nitrate level. Wetlands can provide valuable ecosystem services, conserve the native and exotic wetland inhabitants and mitigate flood along with their purifying properties of nutrient removal to lessen the public health concerns about nitrate-nitrogen in drinking water. Therefore, appropriate rein in measures, incentivizing water use efficiency, and continuous monitoring of water quality will ensure safety for wetland habitats, also may aware of the risks or opportunities associated with using wetland water for both drinking and agricultural use.