• 关键词：氮平衡  时空分布  盈余强度  人类活动  江西省

• 基金项目：中国科学院知识创新工程重要方向项目(No.KZCX2-YW-337);国家自然科学基金项目(No.40871238);研究所学科领域发展支持项目(No.NIGLAS2010XK02)

• 李新艳
• 中国科学院南京地理与湖泊研究所,湖泊与环境国家重点实验室,南京 210008

• 李恒鹏
• 中国科学院南京地理与湖泊研究所,湖泊与环境国家重点实验室,南京 210008

• 摘要：利用系统物质平衡模型,对1995—2005年江西省陆地生态系统的N收支平衡进行了核算,并分析了不同来源N收支量的时间序列特征以及N盈余强度的空间分布特征,探讨了自然灾害和政策实施对N平衡的影响.结果表明:江西省陆地生态系统的N输入量变化范围是(155.5~184.2)×10⁷ kg·a^-1,平均值为168.5×10⁷ kg·a^-1.在N输入源中,以生物固N为主,占N输入总量的43.1%;氮肥施用是氮输入的第二大来源,占N输入量的30.9%;大气硝态氮沉降和人畜排泄分别占N输入总量的17.0%和9.1%.人类活动来源的N输入量是自然来源N输入量的2.3~2.9倍.N盈余量变化范围是(39.6~59.0)×10⁷ kg·a^-1,平均值为47.3×10⁷ kg·a^-1.系统内N持续发生盈余,必然会导致系统内的N发生累积并最终达到饱和状态,从而增加系统中养分随地表径流和地下水流失和淋失的风险.N盈余强度较高的地区位于环鄱阳湖区,这与该地区农业生产和人口密集、施肥强度高有密切关系,直接威胁到鄱阳湖水体的水质.

• Abstract：Estimate of the nitrogen (N) mass balance of a terrestrial ecosystem in Jiangxi province for the period 1995—2005 has been made by using the mass balance model. Spatial distributions of the surplus intensities of N are displayed using a geographical information system. Results indicate that the mean annual N inputs vary between 155.5×10⁷ and 184.2×10⁷ kg·a^-1, with a mean value of 168.5×10⁷ kg·a^-1. Diffuse sources show that biological N fixation constituted the largest source of total N inputs accounting for about 43.1%, while chemical N fertilizer is the second largest contributor, accounting for about 30.9% of the total N inputs. Atmospheric nitrate N deposition and manure N application (including domestic animal and human) account for 17.0% and 9.1% of total N inputs, respectively with N surplus ranging from 39.6×10⁷ to 59.0×10⁷ kg·a^-1, showing a stable trend. The surplus intensities of N are highest in the region around the Poyang Lake owing to high intensity agricultural activities, high population intensity and fertilizer utilization. The continuous surplus of N is likely to lead to N saturation in the aquatic ecosystem thus resulting in eutrophication. The study concludes that anthropogenically enhanced N inputs into the ecosystem are about 2~3 times that from natural sources.

• Key words：nitrogen balance budget  temporal and spatial distribution  terrestrial ecosystem  human activity  Jiangxi Province

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