摘要
以丹江口水库淅川库区为研究区,于2021年1~12月设置5个监测点进行干沉降样品采集,分析了样品中硝酸盐浓度、通量及其氮氧同位素,基于稳定同位素模型(SIAR)量化了硝酸盐的主要来源.结果表明,库区干沉降中硝酸盐月均浓度为0.16mg/L,全年硝酸盐干沉降通量为2.49kg/(hm^(2)·a),δ15N-NO_(3)^(-)和δ^(18)O-NO_(3)^(-)月均值分别为(+0.17±4.10)‰、(+56.6±9.18)‰.干沉降中硝酸盐浓度、沉降通量和氮氧同位素的季节性差异显著,秋冬季节的硝酸盐浓度和沉降通量均高于春夏季节,主要与寒冷季节化石源排放量增加、大气边界层稳定性增强以及气粒转化平衡趋于颗粒态硝酸盐生成有关;冬季最高的δ15N-NO_(3)^(-)与冬季燃煤取暖和低温导致的氮同位素平衡分馏效应增加有关,夏季最低的δ^(18)O-NO_(3)^(-)则与NO_(2)+·OH途径形成硝酸盐占主导有关.SIAR分析结果发现,库区干沉降中硝酸盐主要来自化石源(交通排放及煤燃烧),贡献率为69.3%,其中交通排放源和煤燃烧源贡献率分别为51.1%和18.2%.冬季化石源的贡献率最高(72.0%),其中70.4%来源于交通排放.进一步证实交通排放和冬季燃煤取暖是影响库区干沉降中硝酸盐的主要因素,控制交通移动源污染排放和煤燃烧是今后减少大气中硝酸盐的重要举措.此外,较为稳定的生物质燃烧源对硝酸盐的贡献率表明外源输入也是库区硝酸盐干沉降中的重要来源.
The research focused on the Xichuan Reservoir area of the Danjiangkou Reservoir,where five monitoring points were established for collecting dry deposition samples from January to December 2021.Analyses were conducted on the samples,including assessments of nitrate concentration,flux,and nitrogen and oxygen isotopes.The Stable Isotope Analysis in R(SIAR)model was employed to quantify the primary sources of nitrate.The results indicated that the monthly average nitrate concentration in dry deposition within the reservoir area was 0.16mg/L.The annual flux of nitrate dry depositions was determined to be 2.49kg/(hm^(2)⋅a),with monthly mean values ofδ15N-NO_(3)^(-)andδ^(18)O-NO_(3)^(-)being(+0.17±4.10)‰and(+56.6±9.18)‰,respectively.Significant seasonal variations were observed in nitrate concentration,deposition flux,and nitrogen and oxygen isotopes.During the autumn and winter seasons,both nitrate concentration and deposition flux were higher than those in the spring and summer,primarily attributed to the increased emissions from fossil sources during cold seasons,enhanced atmospheric boundary layer stability,and a shift towards particle-phase nitrate formation in aerosol-gas conversion equilibrium.The highestδ15N-NO_(3)^(-)in winter was associated with increased nitrogen isotope fractionation due to winter coal-fired heating and low temperature,while the lowestδ^(18)O-NO_(3)^(-)in summer was linked to the dominance of the NO_(2)+·OH pathway in nitrate formation.The results of SIAR analysis revealed that the main sources of nitrate in dry deposition within the reservoir area were fossil sources(traffic emissions and coal combustion),with a contribution rate of 69.3%,of which the contribution rates of traffic emissions and coal combustion sources were 51.1%and 18.2%,respectively.The contribution of fossil sources was highest in winter(72.0%),with 70.4%originating from traffic emissions.This further confirmed that traffic emissions and winter coal combustion were the primary factors influencing nitrate in
作者
肖春艳
孙艺萌
赵同谦
陈晓舒
李朋波
陈飞宏
XIAO Chun-yan;SUN Yi-meng;ZHAO Tong-qian;CHEN Xiao-shu;LI Peng-bo;CHEN Fei-hong(Institute of Resources and Environment,Henan Polytechnic University,Jiaozuo 454003,China;School of Surveying and Land Information Engineering,Henan Polytechnic University,Jiaozuo 454003,China)
出处
《中国环境科学》
EI
CAS
CSCD
北大核心
2024年第3期1515-1525,共11页
China Environmental Science
基金
国家自然科学基金资助项目(U1704241,42007175)
中原科技创新领军人才项目(194200510010)
高等学校基本科研业务费(NSFRF200326)。
