Developments in the investigation of nitrogen and oxygen stable isotopes in atmospheric nitrate

Under the influence of human activities and the rapid development of industry and agriculture, atmospheric nitrate (NO⁻₃) pollution is becoming increasingly serious and has become an environmental problem worldwide. The stable isotopic composition of atmospheric NO⁻₃ (δ¹⁵N, δ¹⁸O, and Δ¹⁷O) can provide a strong basis for understanding the atmospheric nitrogen cycle to effectively control atmospheric NO_x pollution. In this work, the δ¹⁵N values associated with different sources of atmospheric NO⁻₃, the seasonal variation characteristics of δ¹⁵N-NO⁻₃, and the main influencing factors are reviewed. The δ¹⁸O and Δ¹⁷O values of different oxidants in the atmosphere and the spatiotemporal distribution characteristics and possible influencing factors of the δ¹⁸O and Δ¹⁷O values ​​of atmospheric NO⁻₃ are summarised. In addition, key advances in NO⁻₃ isotopic analysis technique is reviewed. Based on previous work, it is suggested that more attention should be given to the oxidative formation mechanism of NO⁻₃ (spatio-temporal differences in the isotopic compositions of different types of oxidants), the δ¹⁵N composition of different NOx sources, and the processes of formation, transport, depositional/chemical loss ofatmospheric NO⁻₃ with the help of observation and chemical models.