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Nature:中国水体氮排放空间模式估算

来源:农业环境科学 作者: 人气: 发布时间:2019-03-03 14:30:19

清华大学喻朝庆副教授团队将水体中总氮浓度的观测数据与来自农业和其他来源的模拟氮排放数据相结合,估算了1955年至2014年间中国的氮排放模式,相关成果在线发表于Nature。

阅读论文全文请点击文末阅读原文。Abstract

The nitrogen cycle has been radically changed by human activities. China consumes nearly a third of the world’s nitrogen fertilizers. The excessive application of fertilizers and increased nitrogen discharge from livestock, domestic and industrial sources have resulted in pervasive water pollution. Quantifying a nitrogen ‘boundary’ in heterogeneous environments is important for effectively managing local water quality. Here we use a combination of water quality observations and simulated nitrogen discharge from agricultural and other sources to estimate spatial patterns of nitrogen discharge into water bodies across China from 1955 to 2014. We find that the critical surface-water quality standard (1.0 milligrams of nitrogen per litre) was being exceeded in most provinces by the mid-1980s, and that current rates of anthropogenic nitrogen discharge (14.5 ± 3.1 megatonnes of nitrogen per year) to fresh water are about 2.7 times the estimated ‘safe’ nitrogen discharge threshold (5.2 ± 0.7 megatonnes of nitrogen per year). Current efforts to reduce pollution through wastewater treatment and improving cropland nitrogen management can partially remedy this situation. Domestic waste water treatment has helped to reduce net discharge by 0.7 ± 0.1 megatonnes in 2014, but at high monetary and energy costs. Improved cropland nitrogen management could remove another 2.3 ± 0.3 megatonnes of nitrogen per year, about 25 per cent of the excess discharge to fresh water. Successfully restoring a clean water environment in China will further require transformational changes to boost the national nutrient recycling rate from its current average of 36 per cent to about 87 per cent, which is a level typical of traditional Chinese agriculture. Though ambitious, such a high level of nitrogen recycling is technologically achievable at an estimated capital cost of approximately 100 billion US dollars and operating costs of 17–25 billion US dollars per year, and could provide co-benefits such as recycled wastewater for crop irrigation and improved environmental quality and ecosystem services.

人类活动大幅改变了氮循环过程。中国消耗了世界上近三分之一的氮肥。肥料的过量施用,以及养殖业、生活污水、工业中的氮排放导致了普遍存在的水污染。在不同环境中量化氮污染阈值对于有效管理当地水质非常重要。本研究结合水体中总氮浓度的观测数据和农业及其他来源的模拟氮排放数据估算了1955年至2014年间中国各地水体氮排放的空间模式。研究发现,在20世纪80年代中期,大部分省份地表水质氮浓度均超过了标准阈值(1.0 mg/L),而现在,人为向淡水排放的氮(1450±310万t/年)约为氮排放“安全”阈值的2.7倍(520±70万t/年)。目前通过污染废水处理和改善农田氮管理措施可以部分缓解这一问题。生活污水处理能够减少70±10万t/年的氮排放,但需要消耗高昂的货币和能源成本。改进农田氮管理措施可以减少230±30万t/年的氮排放,即进入水体的氮的约25%。要成功恢复中国水环境的清洁,需要做出一些改变,使中国的氮循环利用率从目前的平均36%提高到87%左右。这个目标是宏大但可行的,高水平的氮循环利用在技术上可以实现,估计资本成本约为1000亿美元/年,运营成本为170-250亿美元/年,能够实现使用再循环废水进行作物灌溉等衍生效益,并改善环境质量,提升生态系统服务。

(编辑:Nicola)

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