2004～2009年我国典型陆地生态系统地下水硝态氮评价

Assessment of Shallow Groundwater Nitrate Concentrations in Typical Terrestrial Ecosystems of Chinese Ecosystem Research Network(CERN) During 2004-2009

利用中国生态系统研究网络(CERN)2004～2009年31个典型陆地生态系统38个浅层地下水井硝态氮(NO 3--N)的监测数据,评价我国典型陆地生态系统地下水NO 3--N污染状况.结果表明,农田(4.85 mg.L-1±0.42 mg.L-1)、绿洲农田(3.72mg.L-1±0.42 mg.L-1)、城市(3.77 mg.L-1±0.51 mg.L-1)生态系统NO 3--N质量浓度平均值显著高于草地(1.59 mg.L-1±0.35 mg.L-1)、森林(0.39 mg.L-1±0.03 mg.L-1)生态系统NO 3--N质量浓度平均值.在监测的农田、绿洲农田和城市生态系统浅层地下水中NO 3--N质量浓度占总氮质量浓度比率分别为56%、74%、88%,为水中氮的主要存在形态.安塞、盐亭、禹城农田生态系统和策勒、临泽、阿克苏绿洲农田生态系统浅层地下水NO 3--N超过10 mg.L-1的超标率分别为84.6%、41.6%、35%和50%、50%、14.3%.利用相对高频率监测数据分析发现,安塞、封丘、盐亭农田生态系统浅层地下水和北京城市生态系统浅层地下水NO 3--N质量浓度有明显的季节变化,在夏季和冬季各有一个高值期.监测结果表明,我国农田生态系统受到施肥等农业活动影响,浅层地下水NO 3--N存在一定程度污染,而森林生态系统地下水NO 3--N基本处在自然水平,未受人类活动污染.

The nitrate-N（NO-3-N） concentrations of 38 shallow groundwater wells from 31 of the typical terrestrial ecosystems on Chinese Ecosystem Research Network（CERN） were assessed using the monitoring data from 2004 to 2009.The results showed that the average values of NO-3-N concentrations were significantly higher in the agricultural（4.85 mg·L-1±0.42 mg·L-1）,desert（oasis）（3.72 mg·L-1±0.42 mg·L-1） and urban ecosystems（3.77 mg·L-1±0.51 mg·L-1） than in the grass（1.59 mg·L-1±0.35 mg L-1） and forest ecosystems（0.39 mg·L-1±0.03 mg·L-1）.Nitrate was the major form of nitrogen,with between 56% to 88% of nitrogen in the nitrate-N form in the shallow groundwater of desert（oasis）,urban and agricultural ecosystems.Nitrate-N concentrations for some agricultural ecosystems（Ansai,Yanting,Yucheng） and desert（oasis） ecosystems（Cele,Linze,Akesu） analysis exceeded the 10 mg·L-1 World Health Organization drinking water standards between 14.3% and 84.6%.Significant seasonality was found in Ansai,Fengqiu,Yanting agricultural ecosystems and the Beijing urban ecosystem using the relatively high frequency monitoring data,with the higher nitrate concentrations usually found during summer and winter months.The monitoring results indicated that the shallow groundwater of agricultural ecosystems was contaminated by agricultural management practices,i.e.fertilization,while the shallow groundwater of forest ecosystems was under natural condition with no contamination from human activities.