期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2020
卷号：117
期号：18
页码：9771-9775
DOI：10.1073/pnas.1920068117
出版社：The National Academy of Sciences of the United States of America
摘要：Human activities and population growth have increased the natural burden of reactive nitrogen (N) in the environment. Excessive N deposition on Earth’s surface leads to adverse feedbacks on ecosystems and humans. Similar to that of air pollution, emission control is recognized as an efficient means to control acid deposition. Control of nitrogen oxides (NO x = NO NO 2 ) emissions has led to reduction in deposition of oxidized nitrogen (NO y , the sum of all oxidized nitrogen species, except nitrous oxide [N 2 O]). Reduced forms of nitrogen (NH x = ammonia [NH 3 ] ammonium [NH 4 ]) deposition have, otherwise, increased, offsetting the benefit of reduction in NO y deposition. Stringent control of NH 3 emissions is being considered. In this study, we assess the response of N deposition to N emission control on continental regions. We show that significant reduction of NH x deposition is unlikely to be achieved at the early stages of implementing NH 3 emission abatement. Per-unit NH 3 emission abatement is shown to result in only 60–80% reduction in NH x deposition, which is significantly lower than the demonstrated 80–120% benefit of controlling NO x emissions on NO y deposition. This 60–80% effectiveness of NH x deposition reduction per unit NH 3 emission abatement reflects, in part, the effects of simultaneous reductions in NO x and SO 2 emissions.
关键词：nitrogen deposition ; reduced forms of nitrogen ; ammonia emission ; emission control strategy
