速生桉种植中氮素对饮用水源地水质的影响

Effects of nitrogen element in fast-growing eucalyptus on water quality of drinking water source

【目的】研究速生桉种植中氮素对饮用水源地水质的影响，可为广西饮用水源地速生桉种植的污染防控提供科学依据。【方法】以广西横县六蓝水库饮用水源地为例，采样分析水源地取水口处水质。在为期5年（2011-2015年）的一个轮伐期内，以六蓝水库汇水区为研究尺度，实地调查汇水区各村屯林农的肥料施用情况，估算肥料用量及污染物氮的排放量，并分析氮的排放量与水质污染因子的相关性。【结果】采样结果显示，除第1年（2011年）的总氮监测数据达Ⅱ类水质标准外，其余4年（2012-2015年）的数据均未达Ⅱ类水质标准，氨氮的5年监测数据均能达Ⅱ类水质标准。六蓝水库汇水区速生桉林业面源总氮排放量占流域范围所有污染源总氮排放量的84.7%。速生桉施肥引起的总氮排放量与总氮监测数据显著相关（α=0.05，P=0.023），与氨氮监测数据不显著相关（α=0.05，P=0.106）；生活污染源和分散式畜禽养殖污染源的总氮排放量与氨氮监测数据极显著相关（α=0.01，P=0.009），与总氮监测数据不显著相关（α=0.05，P=0.072）。【结论】六蓝水库饮用水源地氮素主要污染源为速生桉林种植施肥，总氮排放量在一定程度上影响着水库总氮因子浓度。因此，采取科学测土配方施肥技术，合理控制和安排汇水区内速生桉的肥料用量与次数，进而减少氮素排放，对于预防饮用水源地水体富营养化起到重要作用。

Objective]Effects of nitrogen element in fast-growing eucalyptus on water quality of drinking water sources were studied to provid scientific references for prevention and control of pollution from fast-growing eucalyptus planta-tion in drinking water sources in Guangxi. [Method]Taking Liulan reservoir drinking water source in Hengxian county, Guangxi as an example, the water quality at water intakes was analyzed. During rotation period of 5 years（2011-2015）, taking Liulan reservoir catchment area as the research scale,fertilizer application situation in the villages within catchment area were investigated,the amount of fertilizer and emission of pollutant nitrogen were estimated,the correlation between nitrogen emissions and water pollution factors were analyzed. [Result]Results indicated that except the first year（2011）, the data in four years（2012-2015） failed to reach class II water standard. Ammonia nitrogen data in five years did not achieve class II water standard. The total nitrogen emission of eucalyptus forest non-point source in catchment area ac-counted for 84.7% of total nitrogen pollutant emission in basin perimeter. Total nitrogen emission induced by fast-growing eucalyptus fertilization was significantly correlated with total nitrogen monitoring data（α=0.05, P=0.023）, whereas it was not significantly correlated with ammonia nitrogen monitoring data （α=0 . 05 , P=0 . 106 ） . Total nitrogen emissions from domestic pollution sources and decentralized poultry breeding pollution sources were significantly correlated with ammonia nitrogen monitoring data（α=0.01, P=0.009）,but were not significantly correlated with total nitrogen monitoring data（α=0.05, P=0.072）. [Conclusion]The main pollution source of nitrogen element in Liulan reservoir drinking water source is fertilization for fast-growing eucalyptus plantation. Total nitrogen concentration is affected by total nitrogen emission from fertilization to a certain extent. Therefore, adopting formula fertilization by soil testing, controlling and arranging fertilizer dosage and times can reduce nitrogen emission and prevent water in water sources from eutrophication.