Key Laboratory of Poyang Lake Environment and Resource Utilization of Ministry of Education, School of Resource, Environmental and Chemical Engineering, Nanchang University, Nanchang 330031, China.
School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Environ Sci Technol. 2020 Jun 2;54(11):6551-6561. doi: 10.1021/acs.est.0c00421. Epub 2020 May 20.
Atmospheric proteinaceous matter is characterized by ubiquity and potential bioavailability. However, little is known about the origins, secondary production processes, and biogeochemical role of proteinaceous matter in wet deposition. Precipitation samples were collected in suburban Guiyang (southwestern China) over a 1 year period to investigate their chemical components, mainly including dissolved combined amino acids (DCAAs), dissolved free AAs (DFAAs), and nonleachable particulate AAs (PAAs). Glycine was most abundant in the DFAAs, while the dominant species in DCAAs and PAAs was glutamic acid (including deaminated glutamine). The total DCAA, DFAA, and PAA concentrations peaked on average in spring (min. in summer). On average, the contribution of DCAA-nitrogen (median of 3.44%) to dissolved organic nitrogen was 5-fold higher than that of DFAA-nitrogen (median of 0.60%). Correlation analyses of AAs with ozone, nitrogen dioxide, and the quantitative degradation index suggest that DC(/F)AAs are linked with both abiotic and biological degradation of proteinaceous matter. Moreover, the high FAA scavenging ratios indicate the presence of postdepositional degradation of atmospheric proteinaceous matter. Further, the positive matrix factorization results suggest that the degradation of atmospheric proteinaceous matter markedly contributes to DCAAs and DFAAs in precipitation. Overall, the results suggest that the secondary processes involved in the degradation of atmospheric proteinaceous matter significantly promote direct bioavailability of AA-nitrogen.
大气蛋白质物质的特点是普遍存在和潜在的生物可利用性。然而，关于蛋白质物质在湿沉降中的起源、次生生产过程和生物地球化学作用知之甚少。在过去的一年里，我们在中国西南部的贵阳郊区收集了降水样本，以研究它们的化学成分，主要包括溶解的结合氨基酸（DCAAs）、溶解的游离氨基酸（DFAAs）和不可提取的颗粒氨基酸（PAAs）。在 DFAAs 中，甘氨酸最为丰富，而 DCAAs 和 PAAs 中的主要物质是谷氨酸（包括脱氨谷氨酰胺）。DCAAs、DFAAs 和 PAAs 的总浓度平均在春季达到峰值（夏季最低）。平均而言，DCAA-氮（中位数为 3.44%）对溶解有机氮的贡献是 DFAA-氮（中位数为 0.60%）的 5 倍。氨基酸与臭氧、二氧化氮和定量降解指数的相关分析表明，DC（/F）AA 与蛋白质物质的非生物和生物降解都有关。此外，高 FAA 清除率表明大气蛋白质物质在沉积后发生了降解。进一步的正矩阵因子分析结果表明，大气蛋白质物质的降解显著促进了降水 DCAAs 和 DFAAs 的形成。总的来说，这些结果表明，大气蛋白质物质降解过程中涉及的次生过程显著促进了氨基酸氮的直接生物可利用性。
