Isotopic evaluation on relative contributions of major NO sources to nitrate of PM in Beijing.

Nitrate (NO) is a key component of secondary inorganic aerosols and PM. However, the contributions of nitrogen oxides (NO) emission sources to NO in PM remain poorly constrained. This study measured nitrogen (N) isotopes of NO (hereafter as δN-NO) in PM collected at Beijing in 2014.

Nitrogen isotope variations of ammonium across rain events: Implications for different scavenging between ammonia and particulate ammonium.

Enhanced ammonia (NH) emissions and deposition caused negative effects on air quality and ecosystems. Precipitation is an efficient pathway to remove NH and particulate ammonium (p-NH) from the atmosphere into ecosystems. However, precipitation scavenging of p-NH in chemical transport models has often considered fine p-NH, with inadequate constraints on NH and coarse p-NH.

Inter-species and intra-annual variations of moss nitrogen utilization: Implications for nitrogen deposition assessment.

Moss nitrogen (N) concentrations and natural N abundance (δN values) have been widely employed to evaluate annual levels and major sources of atmospheric N deposition. However, different moss species and one-off sampling were often used among extant studies, it remains unclear whether moss N parameters differ with species and different samplings, which prevented more accurate assessment of N deposition via moss survey. Here concentrations, isotopic ratios of bulk carbon (C) and bulk N in natural epilithic mosses (Bryum argenteum, Eurohypnum leptothallum, Haplocladium microphyllum and Hypnum plumaeforme) were measured monthly from August 2006 to August 2007 at Guiyang, SW China.

Stable isotope analyses of precipitation nitrogen sources in Guiyang, southwestern China.

To constrain sources of anthropogenic nitrogen (N) deposition is critical for effective reduction of reactive N emissions and better evaluation of N deposition effects. This study measured δN signatures of nitrate (NO), ammonium (NH) and total dissolved N (TDN) in precipitation at Guiyang, southwestern China and estimated contributions of dominant N sources using a Bayesian isotope mixing model. For NO, the contribution of non-fossil N oxides (NO, mainly from biomass burning (24 ± 12%) and microbial N cycle (26 ± 5%)) equals that of fossil NO, to which vehicle exhausts (31 ± 19%) contributed more than coal combustion (19 ± 9%).