Amino acids is an important organic nitrogen compound class in aerosol. Its origins and transformation in the atmosphere remain poorly understood. The concentrations of free amino acids (FAAs) and combined amino acids (CAAs) and δ15N values of free and combined Glycine (Gly) in PM2.5 and main emission sources (plant, soil, and aerosol from biomass burning) were investigated from five sampling sites in Nanchang area (Jiangxi Province, China). Our results showed that the composition profiles of CAAs and FAAs were quite different from each other in PM2.5. For CAAs, percentages of individual combined amino acids were different between biomass burning sources and plant or soil sources, and we found that the composition profiles of aerosol CAAs could reflect the contribution of the main emission sources. For FAAs, a predominance of free Gly was observed in aerosol FAAs pool because atmospheric photooxidative processes could increase free Gly and decrease other reactive FAAs. This implied that the composition of aerosol FAAs could not reflect their origins. A strong correlation between δ15NF‐Gly values in aerosols or sources and the δ15NC‐Gly values in their parent CAAs was observed, indicating that the isotope effect associated with Gly transformation in aerosols may be small. Additionally, we found more positive δ15NGly in aerosols emitted by biomass burning, which was likely due to 15N‐depleted amino‐N loss from Gly molecule. The results suggested that δ15NGly values in aerosols might be used to identify biomass burning sources.
Primary biological aerosol particles (PBAPs) constitute a major fraction of the atmospheric aerosol (up to ∼20%-40%) (Fröhlich-Nowoisky et al., 2016;Hu et al., 2020). A large and rapidly growing scientific base exists regarding uncertainties associated with PBAPs, including their important role in cloud/ice nuclei processes and their sources (DeLeon-
Abstract. Amino acids (AAs) are relevant for nitrogen cycles, climate
change and public health. Their size distribution may help to uncover the
source, transformation and fate of protein in the atmosphere. This paper
explores the use of compound-specific δ15N patterns of
hydrolyzed amino acid (HAA), δ15N values of total hydrolyzed
amino acid (δ15NTHAA), degradation index (DI) and the
variance within trophic AAs (∑V) as markers to examine the sources and
processing history of different sizes of particle in the atmosphere. Two weeks of
daily aerosol samples from five sampling sites in the Nanchang area (Jiangxi
Province, China) and samples of main emission sources of AAs in aerosols
(biomass burning, soil and plants) were collected (Zhu et al., 2020). Here,
we measured the concentrations and δ15N values of each HAA in
two size-segregated aerosol particles (> 2.5 µm and PM2.5).
Our results showed that the average concentrations of THAA in fine particles
was nearly 6 times higher than that in coarse particles (p < 0.01)
and composition profiles of fine and coarse particles were quite different
from each other. The δ15N values of hydrolyzed glycine and THAA
in both fine and coarse particles were typically in the range of those from
biomass burning, soil and plant sources. Moreover, the average difference in
the δ15NTHAA value between fine and coarse particles was
smaller than 1.5 ‰. These results suggested that the
sources of atmospheric HAAs for fine and coarse particles might be similar.
Meanwhile, compared to fine particles, significantly lower DI values
(p < 0.05), “scattered” δ15N distribution in trophic AA
and higher ∑V values (p < 0.05) were observed in coarse
particles. But the difference in δ15N values of source AA
(glycine, serine, phenylalanine and lysine) and THAA between coarse
particles and fine particles was relatively small. It is likely that AAs in
coarse particles have advanced bacterial degradation states compared to fine
particles. Besides that, the significant increase in DI values and a
decrease in ∑V values for coarse particles were observed on days on which
precipitation fell (p < 0.05). This implies that “fresh” AAs in
coarse particles were likely released following the precipitation.
Abstract. The size distribution of amino acids (AAs) in atmospheric particles determines the atmospheric allergenicity, which may have deleterious effects on human health. This paper explores the use of compound-specific δ15N patterns of hydrolyzed amino acid (HAA), δ15N values of total hydrolyzed amino acid (THAA), degradation index (DI), and the variance within trophic AAs (ΣV) as markers to examine the sources and processing history of different sizes particle in the atmosphere. 2-weeks of daily aerosol samples from five sampling sites in the Nanchang area (Jiangxi Province, China) and samples of main emission sources of AAs in aerosols (biomass burning, soil and plants) were collected (Zhu et al., 2020). Here, we measured the concentrations and δ15N values of each HAA in two size segregated aerosol particles (> 2.5 μm and PM2.5). Our results showed that the average concentrations of THAA in fine particles was nearly 6 times higher than that in coarse particles (p
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