Kelly Victoria R, Lovett Gary M, Weathers Kathleen C, Likens Gene E
Institute of Ecosystem Studies, Millbrook, NY 12545, USA.
Environ Pollut. 2005 Jun;135(3):363-9. doi: 10.1016/j.envpol.2004.11.009.
Ammonium (NH(4)(+)) concentrations in air and precipitation at the Institute of Ecosystem Studies (IES) in southeastern New York, USA declined over an 11-year period from 1988 to 1999, but increased from 1999 to 2001. These trends in particulate NH(4)(+) correlated well with trends in particulate SO(4)(2-) over the 1988-2001 period. The NH(4)(+) trends were not as well correlated with local cattle and milk production, which declined continuously throughout the period. This suggests that regional transport of SO(4)(2-) may have a greater impact on concentrations of NH(4)(+) and subsequent deposition than local agricultural emissions of NH(3). Ammonium concentrations in precipitation correlated significantly with precipitation SO(4)(2-) concentrations for the 1984-2001 period although NH(4)(+) in precipitation increased after 1999 and SO(4)(2-) in precipitation continued to decline after 1999. The correlation between NH(4)(+) and SO(4)(2-) was stronger for particulates than for precipitation. Particulate NH(4)(+) concentrations were also correlated with particulate SO(4)(2-) concentrations at 31 of 35 eastern U.S. CASTNet sites that had at least 10 years of data. Air concentrations of NH(4)(+) and SO(4)(2-) were more strongly correlated at the sites that were located within an agricultural landscape than in forested sites. At most of the sites there was either no trend or a decrease in NH(4)(+) dry deposition during the 1988-2001 period. The sites that showed an increasing trend in NH(4)(+) dry deposition were generally located in the southeastern U.S. The results of this study suggest that, in the northeastern U.S., air concentrations of NH(4)(+) and subsequent deposition may be more closely linked to SO(4)(2-) and thus SO(2) emissions than with NH(3) emissions. These results also suggest that reductions in S emissions have reduced NH(4)(+) transport to and NH(4)(+)-N deposition in the Northeast.
在美国纽约东南部的生态系统研究所（IES），1988年至1999年的11年间，空气中和降水中的铵（NH₄⁺）浓度下降，但在1999年至2001年有所上升。在1988 - 2001年期间，颗粒态NH₄⁺的这些趋势与颗粒态SO₄²⁻的趋势密切相关。NH₄⁺趋势与当地牛群和牛奶产量的相关性不佳，在此期间当地牛群和牛奶产量持续下降。这表明，SO₄²⁻的区域传输对NH₄⁺浓度及后续沉降的影响可能大于当地农业NH₃排放的影响。在1984 - 2001年期间，降水中的铵浓度与降水SO₄²⁻浓度显著相关，尽管1999年后降水中的NH₄⁺增加，而1999年后降水中的SO₄²⁻继续下降。NH₄⁺与SO₄²⁻在颗粒态中的相关性强于在降水中的相关性。在美国东部35个拥有至少10年数据的CASTNet站点中，有31个站点的颗粒态NH₄⁺浓度也与颗粒态SO₄²⁻浓度相关。在位于农业区的站点，空气中NH₄⁺和SO₄²⁻的浓度相关性比在森林站点更强。在1988 - 2001年期间，大多数站点的NH₄⁺干沉降要么没有趋势，要么有所下降。显示NH₄⁺干沉降呈上升趋势的站点通常位于美国东南部。本研究结果表明，在美国东北部，空气中NH₄⁺浓度及后续沉降可能与SO₄²⁻以及因此与SO₂排放的联系比与NH₃排放更为密切。这些结果还表明，硫排放的减少降低了NH₄⁺向东北部的传输以及NH₄⁺ - N的沉降。
