Nitrate(NO_(3)^(−))has been the dominant ion of secondary inorganic aerosols(SIAs)in PM_(2.5) in North China.Tracking the formation mechanisms and sources of particulate nitrate are vital to mitigate air pollution.In ...Nitrate(NO_(3)^(−))has been the dominant ion of secondary inorganic aerosols(SIAs)in PM_(2.5) in North China.Tracking the formation mechanisms and sources of particulate nitrate are vital to mitigate air pollution.In this study,PM_(2.5) samples in winter(January 2020)and in summer(June 2020)were collected in Jiaozuo,China,andwater-soluble ions and(δ_(15)N,δ_(18)O)-NO_(3)^(−)were analyzed.The results showed that the increase of NO_(3)^(−)concentrations was the most remarkable with increasing PM_(2.5) pollution level.δ_(18)O-NO_(3)^(−)values for winter samples(82.7‰ to 103.9‰)were close to calculated δ_(18)O-HNO_(3)(103‰±0.8‰)values by N_(2)O_(5) pathway,while δ_(18)O-NO_(3)^(−)values(67.8‰ to 85.7‰)for summer samples were close to calculated δ_(18)O-HNO_(3) values(61‰±0.8‰)by OH oxidation pathway,suggesting that PM_(2.5) nitrate is largely from N_(2)O_(5) pathway inwinter,while is largely from OH pathway in summer.Averaged fractional contributions of P_(N2O5+H2O) were 70% and 39% in winter and summer sampling periods,respectively,those of POH were 30% and 61%,respectively.Higher δ_(15)N-NO_(3)−values for winter samples(3.0‰to 14.4‰)than those for summer samples(-3.7‰to 8.6‰)might be due to more contributions from coal combustion in winter.Coal combustion(31%±9%,25%±9%in winter and summer,respectively)and biomass burning(30%±12%,36%±12%in winter and summer,respectively)were the main sources using Bayesian mixing model.These results provided clear evidence of particulate nitrate formation and sources under different PM_(2.5) levels,and aided in reducing atmospheric nitrate in urban environments.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 41401029, U1704241)the Key Project of Research of Henan province in China (No. 19A170006)the Program for technical innovation on air pollution (H21-169)。
文摘Nitrate(NO_(3)^(−))has been the dominant ion of secondary inorganic aerosols(SIAs)in PM_(2.5) in North China.Tracking the formation mechanisms and sources of particulate nitrate are vital to mitigate air pollution.In this study,PM_(2.5) samples in winter(January 2020)and in summer(June 2020)were collected in Jiaozuo,China,andwater-soluble ions and(δ_(15)N,δ_(18)O)-NO_(3)^(−)were analyzed.The results showed that the increase of NO_(3)^(−)concentrations was the most remarkable with increasing PM_(2.5) pollution level.δ_(18)O-NO_(3)^(−)values for winter samples(82.7‰ to 103.9‰)were close to calculated δ_(18)O-HNO_(3)(103‰±0.8‰)values by N_(2)O_(5) pathway,while δ_(18)O-NO_(3)^(−)values(67.8‰ to 85.7‰)for summer samples were close to calculated δ_(18)O-HNO_(3) values(61‰±0.8‰)by OH oxidation pathway,suggesting that PM_(2.5) nitrate is largely from N_(2)O_(5) pathway inwinter,while is largely from OH pathway in summer.Averaged fractional contributions of P_(N2O5+H2O) were 70% and 39% in winter and summer sampling periods,respectively,those of POH were 30% and 61%,respectively.Higher δ_(15)N-NO_(3)−values for winter samples(3.0‰to 14.4‰)than those for summer samples(-3.7‰to 8.6‰)might be due to more contributions from coal combustion in winter.Coal combustion(31%±9%,25%±9%in winter and summer,respectively)and biomass burning(30%±12%,36%±12%in winter and summer,respectively)were the main sources using Bayesian mixing model.These results provided clear evidence of particulate nitrate formation and sources under different PM_(2.5) levels,and aided in reducing atmospheric nitrate in urban environments.
