Biomass Burning Is a Non‐Negligible Source for Ammonium During Winter Haze Episodes in Rural North China: Evidence From High Time Resolution ¹⁵N‐Stable Isotope

Abstract

The refined source apportionment of ammonium (NH4+), especially for biomass burning emissions, is unclear. Hourly resolution δ15N‐NH4+ values for three winter haze episodes (EP1–EP3) were determined in the North China Plain (NCP) in 2019 to identify and quantify the contribution of biomass burning. A reasonable source‐resolved structure of NH4+ was obtained after using the corrected source signatures of 15N and considering biomass burning emissions. The time‐series variation in biomass burning and vehicle sources identified by δ15N was more reasonable and matched better with their tracers (e.g., levoglucosan). The non‐negligible contribution of biomass burning in the NCP was found and contributed 13.0% ± 11.4% to NH4+ in haze episodes, but in special stages was as high as 29% ± 11% in local emission of EP1 and 23% ± 15% in southwest transportation of EP2. The redistribution of NH4+ sources further emphasize the contribution of biomass burning to haze episodes, as its contribution to PM2.5 increased up to 5% (without considering SO42− and NO3−). Considering NH4+ uniqueness in the formation of new particles, the role of biomass burning during haze episodes should be considered. This study indicates that further studies need to be conducted to reduce biomass burning emissions in the NCP.

Exploring the Influence of 34S Fractionation From Emission Sources and SO2 Atmospheric Oxidation on Sulfate Source Apportionment Based on Hourly Resolution δ34S‐SO2/SO42−

“…Therefore, more attention should be paid to SO 2 emissions from traffic and biomass burning in Hebei Province. Compared with EP1, the contributions of biomass burning in EP2 and EP3 were 16% and 13% respectively, which were attributed to the air mass trajectory passing through a relatively sparse number of fire points in this region (Fire Information for Resource Management System, https://firms.modaps.eosdis.nasa.gov/map) (Feng et al., 2023). The coal combustion contributions to SO 4 2− in EP2 and EP3 were significantly higher than those of EP1, accounting for 51% and 62%, respectively.…”

Aqueous-Phase Reactions of Anthropogenic Emissions Lead to the High Chemodiversity of Atmospheric Nitrogen-Containing Compounds during the Haze Event

“…As depicted in Figure S3, the concentration of OC exhibited good correlations with the concentration of EC ( r 2 = 0.70, p < 0.01) and nonsea-salt Cl – (nss-Cl – , r 2 = 0.55, p < 0.01), respectively, However, weak correlations were observed between OC and monosaccharides ( r 2 = 0.1–0.3, p < 0.01). nss-Cl – is commonly used as an indicator of coal combustion , ; nevertheless, many studies have suggested that Cl – may also come from biomass and other combustion processes. , As indicated by our recent work, a relatively minor contribution of biomass burning to particulate pollution was found during the sampling campaign, , and nss-Cl – showed insignificant correlations with monosaccharides, probably suggesting that nss-Cl – was less affected by biomass burning in this study. Residential coal combustion is commonly adopted for winter heating and has been identified as the main source of anthropogenic pollution. , Additionally, the results obtained through 14 C analysis revealed that fossil sources contributed more than 50% of the total OC during the sampling campaign.…”

“…nss-Cl − is commonly used as an indicator of coal combustion 43,44 ; nevertheless, many studies have suggested that Cl − may also come from biomass and other combustion processes. 45,46 As indicated by our recent work, a relatively minor contribution of biomass burning to particulate pollution was found during the sampling campaign, 47,48 and nss-Cl − showed insignificant correlations with monosaccharides, probably suggesting that nss-Cl − was less affected by biomass burning in this study. Residential coal combustion is commonly adopted for winter heating and has been identified as the main source of anthropogenic pollution.…”

Dominant Contribution of NO3 Radical to NO3– Formation during Heavy Haze Episodes: Insights from High-Time Resolution of Dual Isotopes Δ17O and δ18O

“…A 30 cm 2 filter membrane was extracted with 20 mL of Milli-Q water for 30 min. The concentrations of water-soluble ions (Na + , K + , Ca 2+ , Mg 2+ , Cl – , NO 3 – , SO 4 2– , and NH 4 + ) were measured using an ion chromatograph (ICS 6000, Thermo Fisher, USA). , The dual oxygen isotopes (δ 18 O and Δ 17 O) were determined after converting NO 3 – (0.8 μgN) to N 2 O through denitrification bacteria (ATCC13985) . The N 2 O gas is catalytically decomposed to N 2 and O 2 by placing it in a gold tube at 800 °C .…”

“…Meteorological parameters such as temperature (T), humidity (RH), wind speed (WS), and pollutant concentrations, including PM 2.5 , SO , and NH 4 + ) were measured using an ion chromatograph (ICS 6000, Thermo Fisher, USA). 24,25 The dual oxygen isotopes (δ 18 O and Δ 17 O) were determined after converting NO 3 − (0.8 μgN) to N 2 O through denitrification bacteria (ATCC13985). 26 The N 2 O gas is catalytically decomposed to N 2 and O 2 by placing it in a gold tube at 800 °C.…”