广州市地下水环境三氮污染初探

A tentative discussion on nitrite, nitrate and ammonia (NNA) pollution of groundwater in typical urbanized areas of Guangzhou City

广州市在以经济高度集中、资源快速利用为标志的城市化过程中,对地下水环境的影响是巨大的,其地下水NH4+和NO2-高浓度区主要集中分布于城市中心区,NO3-超标点除相对集中分布在城市中心区外,在城市外围地带和丘陵区都有分布。造成广州市不同地区的地下水环境三氮污染的原因各不相同,主要为生活和工农业生产等人类活动影响,与河网发育平原区地层沉积特点、地下水形成和赋存条件等自然因素也相关,人类活动对地下水环境的污染途径复杂多样。广州市地下水环境中三氮形态分布受水文地质条件和水文地球化学作用影响明显,主要影响因素有氧化还原环境、包气带岩性、补径排条件、水土环境中的铁锰含量和酸化程度等。

In the urbanizati on process of Guangzhou,which is characterized by highly centered economy and fast utilization of resources,groundwater environment has been influenced severely.High content of NO2-and NH4＋ in groundwater is concentrated in the city center,and samples with quota-exceeding NO3-is distributed around the city and hilly areas,besides in the downtown area.Groundwater contaminations caused by human activities are complex.There have been various causes for nitrite,nitrate and ammonia（NNA） pollutions of the groundwater,and the human activities such as domestic,industrial and agricultural activities have played the dominant role.In addition,the NNA contamination is also related to such factors as stratigraphic sedimentary features in the plain area and the formation and modes of occurrence of groundwater.The nitrogen distribution in Guangzhou groundwater environment is affected significantly by hydrogeological conditions and hydrogeochemical factors,such as redox environment,lithology of the vadose zone,recharge,runoff and discharge conditions,content of Fe and Mn in water and soil,and the degree of acidification.