摘要
It is feasible for widely distributed mosses to monitor atmospheric nitrogen deposition in northern China,a global hotspot of atmospheric nitrogen pollution.Based on the nitrogen contents and nitrogen isotope values of mosses collected at Mengshan,Shandong Province in 2012,2018 and 2022,we established a bottom-up method to calculate local atmospheric nitrogen deposition levels and source contributions.Moss nitrogen contents increased from 1.9±0.2%in 2012 to 2.1±0.4%in 2018,and to 2.4±0.3%in 2022.On the contrary,moss nitrogen isotope values decreased from−7.5±1.5‰in 2012 to−8.6±1.6‰in 2018 and to−9.6±1.3‰in 2022.From 2012 to 2022,the total nitrogen deposition fluxes increased significantly(from 34.2 to 39.9 kg N ha^(−1) yr^(−1)),especially the fluxes of ammonium-nitrogen deposition increased.Based on the results of Bayesian stable isotope analysis,volatilization-related ammonia(mainly from fertilizer applications and wastes)was predominant in ammonium-nitrogen deposition in the last decade.Fossil fuel nitrogen oxides contributed more than non-fossil fuel nitrogen oxides to nitrate-nitrogen deposition.Our results reveal that it is urgent to control volatilization-related ammonia and fossil fuel nitrogen oxides emission sources,which are the major contributors to atmospheric nitrogen deposition in the Mengshan area.
中国北部地区是全球大气氮污染的热点区域,广泛分布的苔藓植物可作为该区域大气氮沉降的有效监测工具。本研究于2012、2018和2022年在山东蒙山地区采集苔藓样品,并测定其氮含量和氮同位素比值。在此基础上,建立了一种自下而上的分析方法,量化了该区域大气氮沉降水平及其来源。结果表明,2012至2018年,蒙山地区苔藓氮含量从1.9±0.2%增加至2.1±0.4%,并在2022年进一步上升至2.4±0.3%。与此同时,苔藓氮同位素比值呈降低趋势,2012、2018和2022年的数值分别为−7.5±1.5‰,−8.6±1.6‰和−9.6±1.3‰。2012至2022年间,蒙山地区总氮沉降速率显著增加(从34.2增至39.9 kg N ha^(-1) yr^(-1)),其中铵态氮沉降速率的增长尤为明显。进一步基于贝叶斯稳定同位素分析发现,过去10年间铵态氮沉降的主要来源为氨排放(主要来自化肥施用和废弃物焚烧),而化石燃料燃烧产生的氮氧化物对硝态氮沉降的贡献高于非化石燃料来源。上述结果表明,挥发性氨和氮氧化物排放是蒙山地区大气氮沉降的主要来源,亟需加强其排放源管控力度。
基金
supported by the National Natural Science Foundation of China(42003011).
