The nitrogen footprint tool (NFT) provides a novel way for communities to understand the environmental impacts of their collective activities and consumption. Reactive nitrogen (Nr; all N species except N2) is created by the Haber-Bosch process for food production and as a by-product of fossil fuel combustion and two natural processes, biological nitrogen fixation and lightning. While it is a vital input for food production, too much Nr has a negative effect on the environment. Calculating the amount of Nr released to the environment as a result of an entity's resource consumption is the first step in reducing those Nr losses. The nitrogen (N) footprint method has previously taken this approach at the personal and institution scale. In this study, the nitrogen footprint approach is extended, for the first time, to the community level to calculate the N footprint of Baltimore City, Maryland, USA. The total N footprint of Baltimore City was ~19,000 MT N or 30 kg N per capita in 2016, dominated by the food production sector (73%), followed by the energy and transportation sectors (15% combined). There was geographic variability among census block groups' per capita N footprint within Baltimore City; likely driven primarily by economic factors. Several management scenarios were assessed to better understand what actions may reduce the Baltimore City N footprint over time. The study explored the effect and efficacy of reducing meat consumption, increasing the use of renewable energy sources, and reducing electricity consumption on the city's total N footprint. The model for the Baltimore City N footprint calculation can be applied to other communities in the United States at the spatial grain of the census block group or any country with this level of data to provide an indicator of nitrogen sustainability.

中文翻译：

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马里兰州巴尔的摩市的社区氮足迹分析

氮足迹工具 (NFT) 为社区提供了一种了解其集体活动和消费对环境影响的新方法。活性氮（Nr；除 N2 外的所有 N 物种）是由 Haber-Bosch 过程产生的，用于食品生产，是化石燃料燃烧和两个自然过程（生物固氮和闪电）的副产品。虽然它是粮食生产的重要投入，但过多的 Nr 会对环境产生负面影响。计算因实体资源消耗而释放到环境中的 Nr 量是减少这些 Nr 损失的第一步。氮 (N) 足迹方法以前曾在个人和机构范围内采用这种方法。在这项研究中，氮足迹方法首次被扩展，到社区层面来计算美国马里兰州巴尔的摩市的 N 足迹。2016 年巴尔的摩市的氮足迹总量约为 19,000 吨氮或人均 30 公斤氮，主要是食品生产部门（73%），其次是能源和交通部门（合计 15%）。巴尔的摩市内人口普查街区组的人均氮足迹存在地理差异；可能主要受经济因素驱动。评估了几种管理方案，以更好地了解随着时间的推移哪些行动可能会减少巴尔的摩市 N 的足迹。该研究探讨了减少肉类消费、增加使用可再生能源和减少电力消耗对城市总氮足迹的影响和功效。