Study on Nitrite, Nitrate and Ammonia (NNA) Pollution of Goundwater in Typical Urbanization Areas

In the urbanization process of Guangzhou, which was characterized by highly centered economy and fast utilized resources, groundwater environment was influenced severely. High concentration of NO₂^- and NH₄⁺ in groundwater concentrated in the city center, and samples with over proof NO₃^- distributed around the city and hilly areas, besides in the central region. Groundwater contaminations caused by human are complex. There have been various reasons for nitrite, nitrate and ammonia (NNA) pollution of the groundwater which are mainly resulted from human activities such as domestic, industrial and agricultural activities. In addition, the NNA contamination is also related to strata sedimentary features of the plain area, groundwater formation and occurrence conditions. The forms of nitrogen distribution in Guangzhou groundwater environment are affected significantly by hydrogeology conditions and hydrogeochemical factors, such as redox environment, lithology of vadose zone, recharge, runoff and discharge conditions, content of Fe and Mn in water and soil, the degree of acidification and so on.