文獻信息：
Liu,M.X., Huang, X., Song, Y., Tang, J., Cao, J.J., Zhang, X.Y., Zhang, Q., Wang,S.X., Xu, T.T., Kang, L., Cai, X.H., Zhang, H.S., Yang, F.M., Wang, H.B., Yu,J.Z., Lau, A.K.H., He, L.Y., Huang, X.F., Duan, L., Ding, A.J., Xue, L.K., Gao,J., Liu, B., Zhu, T., 2019. Ammonia emission control in China would mitigatehaze pollution and nitrogen deposition, but worsen acid rain. Proceedings ofthe National Academy of Sciences of the United States of America, 116(16), 7760-7765. doi: 10.1073/pnas.1814880116
摘 要：近幾十年來，中國一直在遭受細顆粒（即空氣動力學直徑≤2.5μm; PM2.5）汙染和酸雨，對人類健康和生態系統產生了不利影響。最近，氨（即NH3）減排成為一種緩解霧霾汙染的戰略選擇。然而，大氣中的NH3也與氮沉降和酸雨密切相關，中國對NH3排放控制的綜合影響仍知之甚少。在這項研究中，通過將化學遷移模型與高解析度的NH3排放清單相結合，研究發現在中國NH3減排可以減輕PM2.5汙染和氮沉降，但會加劇酸雨。從數量上講，通過改善農業管理可將NH3排放量減少50％，並有針對性地將二氧化硫和氮氧化物的排放量減少15％，主要是通過抑制硝酸銨的形成，進而將PM2.5汙染減少11-17％。同時，據估計氮沉積減少了34％，中國超過臨界負荷的陸地面積從17％減少到9％。然而，這種NH3減排將顯著加劇降水酸化，使降雨pH值降低多達1.0個單位，而酸雨嚴重的地區相應大幅增加。經濟評估結果表明，酸雨加劇將部分抵消空氣品質改善和氮沉積減少帶來的總體經濟利益。在考慮了減排方案的成本之後，本研究提出了一個區域性的多汙染物控制策略，這將有利於人類和生態系統的健康。
圖1 （A）2005-2015年中國二氧化硫（SO2）、氮氧化物（NOx）、和氨（NH3）排放的年際變化趨勢。SO2排放量由中國生態環境部（MEE；www.mee.gov.cn/)，Lu等（35）和中國多解析度排放清單提供；NOx排放量來源於MEE和Liu等（12）；NH3排放量來源於Kang等（25）。（B）4個中國東亞臺站（金雲山、石湛、小平、香洲）酸沉降監測網中硫酸鹽、硝酸鹽和銨的溼沉降（mean±SD）年際變化趨勢。（C）相對於2005年水平的中國臭氧監測儀器測定的SO2和NO2歸一化垂直柱密度（VCDs）。（D）中國31個城市SO2和NO2的地面平均濃度。這些城市的年平均值由《中國環境統計年鑑》提供(www.stats.gov.cn/).
Fig. 1. (A) Interannual trends in SO2, NOx, and NH3 emissions in China during 2005–2015. SO2 emissions were provided bythe Ministry of Ecology and Environment of China (MEE; www.mee.gov.cn/), Lu etal. (35), and Multiresolution Emission Inventory for China; NOx emissions werederived from MEE and Liu et al. (12); and NH3 emissions were derivedfrom Kang et al. (25). (B) Interannual trends in wet deposition (mean ± SD) ofsulfate, nitrate, and ammonium averaged over four Acid Deposition MonitoringNetwork in East Asia stations (Jinyunshan, Shizhan, Xiaoping, and Xiangzhou) in China. (C) Normalized vertical column densities (VCDs) of SO2 and NO2 retrieved from ozone monitoring instrument measurements over Chinarelative to the 2005 levels. (D) Ground-based concentrations of SO2 and NO2 averaged over 31 cities in China. These annual averaged valuesfor each city were provided by the China Environmental Statistics Yearbook (www.stats.gov.cn/).
圖2 在Run_base、Run_15SN和Run_15SN50A情景下模擬PM2.5濃度（A–C）、氮臨界負荷超標（D–F）和降水加權後的平均pH值（G–I）的比較分析。中國南海的小島未被考慮在內。
Fig. 2. Comparison of simulated PM2.5 concentrations (A–C), critical load exceedance of nitrogen (D–F), andprecipitation-weighted mean pH (G–I) over China in the Run_base, Run_15SN, and Run_15SN50A scenarios. The small islands in the South China Sea were excluded.
圖3 中國華北、華南和四川盆地各NH3減排方案下總經濟效益（單位：百萬美元；即減少PM2.5和氮沉降的效益減去酸雨損失）NH3減排方案成本的比較分析。圖中顯示的情況是NH3減排0（■）、10%（Δ）、20%（★）、30%（□）、40%（▼）和50%（●）。
Fig. 3. Comparison of total economicbenefit (in millions of US dollars; i.e., benefit from reduced PM2.5 andnitrogen deposition minus loss from acid rain) vs. the costs of NH3 abatementoptions under each NH3 emission reduction scenario in northernChina, southern China, and the Sichuan Basin. The cases shown in the figure are NH3 emission reductions of 0 (■), 10% (Δ), 20% (★), 30% (□), 40% (▼),and 50% (●).