【美国的氮沉积】Yi Lia Bret A. Schichtelb John T. Walkerc Donna B. Schweded Xi Chenc Christopher M. B. Lehmanne Melissa A. Puchalskif David A. Gaye and Jeffrey L. Collett Jr.a1. Increasing importance of deposition of reduced nitrogen in the United States. PNAS 2016 doi: 10.1073-pnas.1525736113
对来自美国各地的氮基化合物的测量揭示出了氮沉积已经从以硝酸盐为主转向了以铵为主的条件，它平均占了美国无机氮沉积的大约65%，在不同的地区，干氨沉积的贡献是19%到65%，这提示未来保护生态系统健康的政策应该包括致力于减少氨排放的策略。(来源：EurekAlert！)
Abstract
Rapid development of agriculture and fossil fuel combustion greatly increased US reactive nitrogen emissions to the atmosphere in the second half of the 20th century resulting in excess nitrogen deposition to natural ecosystems. Recent efforts to lower nitrogen oxides emissions have substantially decreased nitrate wet deposition. Levels of wet ammoniu
