PDF(Pubmed)
Abstract：
Fertilizer-intensive agriculture leads to emissions of reactive nitrogen (Nr), posing threats to climate via nitrous oxide (N2O) and to air quality and human health via nitric oxide (NO) and ammonia (NH3) that form ozone and particulate matter (PM) downwind. Adding nitrification inhibitors (NIs) to fertilizers can mitigate N2O and NO emissions but may stimulate NH3 emissions. Quantifying the net effects of these trade-offs requires spatially resolving changes in emissions and associated impacts. We introduce an assessment framework to quantify such trade-off effects. It deploys an agroecosystem model with enhanced capabilities to predict emissions of Nr with or without the use of NIs, and a social cost of greenhouse gas to monetize the impacts of N2O on climate. The framework also incorporates reduced-complexity air quality and health models to monetize associated impacts of NO and NH3 emissions on human health downwind via ozone and PM. Evaluation of our model against available field measurements showed that it captured the direction of emission changes but underestimated reductions in N2O and overestimated increases in NH3 emissions. The model estimated that, averaged over applicable U.S. agricultural soils, NIs could reduce N2O and NO emissions by an average of 11% and 16%, respectively, while stimulating NH3 emissions by 87%. Impacts are largest in regions with moderate soil temperatures and occur mostly within two to three months of N fertilizer and NI application. An alternative estimate of NI-induced emission changes was obtained by multiplying the baseline emissions from the agroecosystem model by the reported relative changes in Nr emissions suggested from a global meta-analysis: -44% for N2O, -24% for NO and +20% for NH3. Monetized assessments indicate that on an annual scale, NI-induced harms from increased NH3 emissions outweigh (8.5-33.8 times) the benefits of reducing NO and N2O emissions in all agricultural regions, according to model-based estimates. Even under meta-analysis-based estimates, NI-induced damages exceed benefits by a factor of 1.1-4. Our study highlights the importance of considering multiple pollutants when assessing NIs, and underscores the need to mitigate NH3 emissions. Further field studies are needed to evaluate the robustness of multi-pollutant assessments.
摘要：
化肥密集型农业导致活性氮(Nr)的排放，通过一氧化二氮（N2O）对气候构成威胁，通过顺风形成臭氧和颗粒物（PM）的一氧化氮（NO）和氨（NH3）对空气质量和人类健康构成威胁。向肥料中添加硝化抑制剂（NIs）可以减轻N2O和NO的排放，但可能会刺激NH3的排放。量化这些权衡的净影响需要在空间上解决排放和相关影响的变化。我们引入了一个评估框架来量化这种权衡效应。它部署了一个农业生态系统模型，该模型具有增强的功能，可以在使用或不使用NI的情况下预测Nr的排放，以及将N2O对气候的影响货币化的温室气体的社会成本。该框架还纳入了复杂性降低的空气质量和健康模型，以通过臭氧和PM将NO和NH3排放对顺风方向人类健康的相关影响货币化。根据可用的现场测量结果对我们的模型进行的评估表明，它捕获了排放变化的方向，但低估了N2O的减少，高估了NH3排放的增加。该模型估计，在适用的美国农业土壤上的平均值，NIs可以平均减少11%和16%的N2O和NO排放，分别,同时刺激87%的NH3排放。影响在土壤温度适中的地区最大，并且大多发生在氮肥和NI施用的两到三个月内。通过将农业生态系统模型的基线排放乘以全球荟萃分析建议的Nr排放的报告相对变化，获得了NI引起的排放变化的替代估计：N2O的-44％，NO为-24%，NH3为+20%。货币化评估表明，在年度规模上，NI引起的NH3排放增加的危害超过（8.5-33.8倍）所有农业区域减少NO和N2O排放的好处，根据基于模型的估计。即使在基于荟萃分析的估计下，NI引起的损害比收益高出1.1-4倍。我们的研究强调了在评估NIs时考虑多种污染物的重要性，并强调了减少NH3排放的必要性。需要进一步的实地研究来评估多污染物评估的稳健性。
