Water Supply Processes Are Responsible for Significant Nitrogen Fluxes Across the United States
Water Supply Processes Are Responsible for Significant Nitrogen Fluxes Across the United States
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DOI：
10.1029/2022gb007340
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发表时间：
2022-08
影响因子：
5.2
通讯作者：
Elizabeth M. Flint;M. Ascott;D. Gooddy;M. Stahl;B. Surridge
中科院分区：
文献类型：
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作者：
Elizabeth M. Flint;M. Ascott;D. Gooddy;M. Stahl;B. Surridge
淡水中营养物质浓度过高是一个全球性的长期问题。制定有效的养分管理策略需要改善氮 (N) 质量平衡，包括识别和量化以前未被识别的人为氮通量。利用公开数据，我们确定，从地表水和地下水抽取的淡水以及公共供水网络的总水管泄漏，是造成美国本土大量硝酸盐-N (NO3-N) 通量的原因。在全国范围内，淡水抽取量暂时保留了 417（最小-最大：190-857）kt NO3-N yr-1，相当于牧场氮吸收量的 21% 和之前全球抽取氮通量估计值的 2%。灌溉、火力发电和公共供水产生的通量合计占总量的87%。我们发现区域归一化抽水通量存在较大的县际差异（最小值-最大值：0-8,267 kg NO3-N km−2 yr−1），东部地区通常与较大的通量相关。水管泄漏将 7（最小-最大：6.3-7.7）kt NO3-N yr-1 返回到环境中，相当于最初为公共供应提取的 NO3-N 的 13% 和之前全球泄漏通量估计值的 1.3%。我们的分析揭示了区域归一化泄漏通量的县际差异（最小值-最大值：0-576 kg NO3-N km−2 yr−1），该通量超过了一些城市化和沿海县的其他主要氮输入（农业氮肥），凸显了它们在这些地区的重要性。这些通量对地方和国家的重要性对旨在更好地管理氮对环境影响的政策制定者和水资源管理者具有影响，并呼吁将其纳入美国和全球氮预算。
Excessive nutrient concentrations within fresh waters are a globally persistent problem. Developing effective nutrient management strategies requires improvements to nitrogen (N) mass balances, including the identification and quantification of previously unrecognized anthropogenic N fluxes. Using publicly available data, we establish that freshwater abstractions from both surface waters and groundwaters, alongside watermains leakage from public distribution networks, are responsible for significant nitrate‐N (NO3‐N) fluxes across the contiguous United States. Nationally, freshwater abstraction temporarily retains 417 (min‐max: 190–857) kt NO3‐N yr−1, equivalent to 21% of pastureland N uptake and 2% of previous global abstraction‐N flux estimates. Fluxes due to irrigation, thermoelectric power, and public water supply collectively account for 87% of this total. We find large intercounty variation in area‐normalized abstraction fluxes (min‐max: 0–8,267 kg NO3‐N km−2 yr−1), with eastern regions generally associated with larger fluxes. Watermains leakage returns 7 (min‐max: 6.3–7.7) kt NO3‐N yr−1 back to the environment, equivalent to 13% of NO3‐N initially abstracted for public supply and 1.3% of previous global leakage flux estimates. Our analyses reveal inter‐county variations in area‐normalized leakage fluxes (min‐max: 0–576 kg NO3‐N km−2 yr−1), with this flux exceeding other major N inputs (agricultural N fertilizer) in some urbanized and coastal counties, highlighting their importance in these areas. The local and national importance of these fluxes has implications for policy makers and water resource managers aiming to better manage the impacts of N within the environment and calls for their inclusion in both US and global N budgets.