西藏农业面源TN、TP排放的空间差异与分布特征

SPATIAL DIFFERENCES AND DISTRIBUTION CHARACTERISTICS OF AGRICULTURAL NON POINT SOURCE POLLUTION OF TN AND TP IN TIBET

关键词:  西藏农业面源总氮总磷分布特征

Key words:  Tibet  agricultural non point source pollution  TN  TP  distribution characteristics

摘要:

［目的］农业面源污染已经成为西藏构建国家生态安全屏障的重要制约因素，揭示西藏农业面源污染的现状，探明其主要污染源和分布特征，能够为西藏农业面源污染防治政策的制定提供参考和依据。［方法］利用单元调查法，以西藏不同地区农田化肥、畜禽养殖和农村生活为污染单元，对2000—2016年西藏农业面源排放的总氮（TN）和总磷（TP）排放总量、构成及强度进行核算，并分析其空间差异与分布特征，反映西藏农业面源污染现状并把握其动态演变。［结果］西藏农业面源污染的TN、TP排放量基本呈现有增有减的平稳态势，畜禽养殖贡献率最大，占TN、TP排放总量的963%和945%，畜禽养殖是西藏农业面源污染防治的重点领域。西藏不同地区TN、TP排放量和强度差异明显，那曲市、昌都市、日喀则市的TN和TP排放总量位居前3位，拉萨市和昌都市的TN和TP排放强度位居前2位，阿里地区TN和TP排放总量和排放强度均最低。［结论］综合考虑到农业面源污染总量和负荷强度，拉萨市、昌都市、日喀则市、那曲市应当作为西藏农业面源污染治理的重点区域。

Abstract:

Agricultural non point source pollution has become an important restricting factor for Tibet to construct national ecological security barrier, and the purpose of this paper is to reveal the status quo of agricultural non point source pollution in Tibet, to identify its main pollution sources and distribution characteristics, which can provide references for the formulation of agricultural non point source pollution prevention and control policies in Tibet. Taking chemical fertilizer on farmland, livestock and poultry breeding and rural life in different areas of Tibet as pollution units, the total emissions and intensity of total nitrogen (TN) and total phosphorus (TP) from agricultural non point sources in Tibet from 2000 to 2016 were calculated by using unit analysis method. The results indicated that: TN and TP emissions of agricultural non point source pollution in Tibet showed a steady trend of increasing and decreasing, and livestock and poultry breeding was the largest contribution unit, which accounted for 96.3% and 94.5% of the total amount of TN and TP emissions by average. Livestock and poultry breeding were the key area of prevention and control of agricultural non point source pollution in Tibet. The regional difference of TN and TP emissions and intensity in Tibet was obvious. Nagqu, Changcheng and Shigatse were the top 3 of TN and TP emissions, while Lhasa and Chang ranked the top 2 in terms of TN and TP emission intensity. Total emissions and intensity of Ali were both the lowest. Considering the total amount and intensity of agricultural non point source pollution, Lhasa, Qamdo, Xigaze and Nagqu should be the key areas of agricultural non point pollution control in Tibet.