Xu Wen, Jin Xin, Luo Shao-Hui, Feng Zhao-Zhong, Zhang Lin, Pan Yue-Peng, Liu Xue-Jun
College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China.
State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Huan Jing Ke Xue. 2017 Apr 8;38(4):1279-1288. doi: 10.13227/j.hjkx.201609237.
This study conducted a full two-year (2014 and 2015) measurements of dry and bulk deposition of atmospheric inorganic nitrogen (N) at the suburb of Xining city, Qinghai province. Dry N deposition fluxes were calculated by multiplying the atmospheric concentrations of NH and NO measured using passive samplers with the modeled dry deposition velocities provided by the GEOS-Chem global chemical transport model, while bulk N deposition fluxes were measured using precipitation gauge. Annual mean concentrations of gaseous NH and NO averaged 8.8 and 19.6 μg·m, respectively, with significantly higher values in 2015 than in 2014. Seasonal mean NH concentrations were higher in spring and summer than in autumn and winter, but the concentrations of NO changed little from season to season, with a small peak in autumn. Annual mean concentrations of NH-N and NO-N in precipitation averaged 2.2 and 1.8 mg·L, respectively. Concentrations of NH-N in autumn were55% lower than those in other seasons, whereas those of NO-N in autumn or winter were26% higher than those in spring and summer. Dry deposition of NH and NO was 9.0 and 2.8 kg·(hm·a), respectively. Bulk deposition of NH-N and NO-N in precipitation was 7.6 and 6.2 kg·(hm·a), respectively. Reduced N (gaseous NH and NH-N in precipitation) was the dominant form of N deposition. The total dry and wet N deposition was 25.6 kg·(hm·a), which represented significant nutrient input from the environment to the suburban farmland, but this amount of deposited N exceeded the critical loads[10-20 kg·(hm·a)] of terrestrial ecosystems, suggesting a risk of "N saturation" in the local natural environment.
本研究对青海省西宁市郊区进行了为期两年（2014年和2015年）的大气无机氮（N）干沉降和湿沉降测量。通过将使用被动采样器测量的大气中NH和NO浓度与由与GEOS-Chem全球化学传输模型提供的模拟干沉降速度相乘来计算干N沉降通量，而湿N沉降通量则使用雨量计进行测量。气态NH和NO的年均浓度分别平均为8.8和19.6μg·m，2015年的值显著高于2014年。春季和夏季的季节性平均NH浓度高于秋季和冬季，但NO浓度随季节变化不大，秋季有一个小峰值。降水中NH-N和NO-N的年均浓度分别平均为2.2和1.8mg·L。秋季NH-N的浓度比其他季节低约55%，而秋季或冬季NO-N的浓度比春季和夏季高约26%。NH和NO的干沉降分别为9.0和2.8kg·(hm·a)。降水中NH-N和NO-N的湿沉降分别为7.6和6.2kg·(hm·a)。还原态N（气态NH和降水中的NH-N）是N沉降的主要形式。干沉降和湿沉降的总N量为25.6kg·(hm·a)，这代表了环境对郊区农田的大量养分输入，但该沉降N量超过了陆地生态系统的临界负荷[10 - 20kg·(hm·a)]，表明当地自然环境存在“N饱和”风险。
