Spatiotemporal variability in the oxidative potential of ambient fine particulate matter in the Midwestern United States
Spatiotemporal variability in the oxidative potential of ambient fine particulate matter in the Midwestern United States
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DOI：
10.5194/acp-21-16363-2021
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发表时间：
2021-11
影响因子：
6.3
通讯作者：
Haoran Yu;J. Puthussery;Yixiang Wang;V. Verma
中科院分区：
文献类型：
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作者：
Haoran Yu;J. Puthussery;Yixiang Wang;V. Verma
抽象。我们评估了氧化电位（OP）的水溶性和甲醇溶性馏分的环境细颗粒物（PM2.5）在美国中西部地区。从不同环境中设置的五个站点收集了大量PM2.5样本（N=241），即，2018年5月至2019年5月期间，伊利诺伊州、印第安纳州和密苏里州的城市、农村和路边。测量了所有PM2.5样本的五个非细胞OP终点，包括替代肺液（SLF）中抗坏血酸和谷胱甘肽的消耗率（分别为OPAA和OPGSH），二硫苏糖醇（DTT）消耗率（OPDTT）以及SLF和DTT中的羟色胺生成率（分别为OPOH−SLF和OPOH−DTT）。从这些样本中获得的美国中西部PM2.5质量浓度在空间上均匀分布，而大多数OP终点显示出显着的时空异质性。季节性，较高的活动发生在夏季的水和甲醇可溶性提取物的最OP终点。在空间上，路边站点表现出最高的活动，大多数OP端点的水溶性提取物，而只有偶尔的峰值，在城市站点中观察到的甲醇可溶性OP。大多数OP端点之间的质量和体积归一化活动在不同的网站和季节表现出类似的时空趋势。两种溶剂之间的比较（即，水和甲醇）表明，甲醇可溶性OP一般具有较高的活性水平比相应的水溶性OP。OP的站点到站点的比较显示，甲醇可溶性OP相比，水溶性OP的相关性更强，这表明水不溶性氧化还原活性化合物从各种排放源到甲醇中的提取更好。我们发现PM2.5质量和大多数OP终点之间存在弱相关性和不一致的斜率值。此外，不同OP终点之间的弱至中度相关性表明这些终点代表的OP机制不同，因此证明了分析多个非细胞终点以更好和更全面评估OP的基本原理。
Abstract. We assessed the oxidative potential (OP) of both water-soluble and methanol-soluble fractions of ambient fine particulate matter (PM2.5) in the Midwestern United States. A large set of PM2.5 samples (N=241) was collected from five sites set up in different environments, i.e., urban, rural, and roadside, in Illinois, Indiana, and Missouri during May 2018–May 2019. Five acellular OP endpoints, including the consumption rate of ascorbic acid and glutathione in a surrogate lung fluid (SLF) (OPAA and OPGSH, respectively), dithiothreitol (DTT) depletion rate (OPDTT), and ⚫OH generation rate in SLF and DTT (OPOH−SLF and OPOH−DTT, respectively), were measured for all PM2.5 samples. PM2.5 mass concentrations in the Midwestern US as obtained from these samples were spatially homogeneously distributed, while most OP endpoints showed significant spatiotemporal heterogeneity. Seasonally, higher activities occurred in summer for most OP endpoints for both water- and methanol-soluble extracts. Spatially, the roadside site showed the highest activities for most OP endpoints in the water-soluble extracts, while only occasional peaks were observed at urban sites in the methanol-soluble OP. Most OP endpoints showed similar spatiotemporal trends between mass- and volume-normalized activities across different sites and seasons. Comparisons between two solvents (i.e., water and methanol) showed that methanol-soluble OP generally had higher activity levels than corresponding water-soluble OP. Site-to-site comparisons of OP showed stronger correlations for methanol-soluble OP compared to water-soluble OP, indicating a better extraction of water-insoluble redox-active compounds from various emission sources into methanol. We found a weak correlation and inconsistent slope values between PM2.5 mass and most OP endpoints. Moreover, the poor to moderate intercorrelations among different OP endpoints indicate different mechanisms of OP represented by these endpoints and thus demonstrate the rationale for analyzing multiple acellular endpoints for a better and more comprehensive assessment of OP.