Nitrate pollution and its Natural Attenuation Processes in Groundwater

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The World Health Organization's recommendation is that drinking water should not contain more than 50 mg/L of nitrate (or 10 mg NO_3-N), based on its potential to cause methaemoglobinaemia. In the last decade as nitrate concentrations in public supply wells have reached unacceptable levels in many parts of the world, it has become obvious that more attention needs to be paid to linkages between human activities on the surface and groundwater quality. In this research, we studied the behaviors of nitrate in groundwater of Chiba, Miyakojima Island, Tottori and North China Plain with different climate, land use conditions to make clear the migration and attenuation processes of nitrate in groundwater flow system. Some conclusions can be summarized as the following.a)Wetland has one of its particular functions on denitrification with the Integrated system with groundwater and anaerobic condition. b)Nitrate migrates rapidly in sand dune which is one of most important landscape in Tottori Prefecture. c)Nitrate concentration in groundwater of underground dam in Miyako Island has not been increased alter the dam was completed, yet. More work should be done to monitor the effects of agricultural activities on groundwater quality in future. And d)The most significant effect of wastewater irrigation practices on groundwater quality is a high nitrate concentration. Groundwater in wastewater irrigated area have δ^<15>N values ranging from +5 to +13‰, and dominantly between +7 and +11‰. Wastewater irrigation practice had more negative impact on groundwater quality than irrigation with pumping wells in the NCP.