2024年9月23日出版的《自然—地球科学》杂志发表了美国达特茅斯学院Chalif, Jacob I.团队的新成果，他们最新的研究揭示了污染引起亚北极地区数十年的甲磺酸下降。

据介绍，格陵兰冰芯甲烷磺酸在工业化时代的下降，被认为预示着北大西洋海洋浮游植物种群的崩溃，这与大西洋经向翻转环流的减弱有关。相比之下，海洋生物硫总量的稳定水平与这一解释相矛盾，研究人员指出，大气氧化的变化是甲烷磺酸下降的潜在元凶。然而，氧化对甲磺酸生产的影响还没有被量化，这一假设也没有得到严格的检验。

研究人员展示了来自阿拉斯加德纳里冰芯的长达几个世纪的甲烷磺酸记录，该记录显示甲烷磺酸的下降幅度相似，但相对于格陵兰记录延迟了93年。更新的二甲基硫醚氧化途径的箱式模型结果表明，由污染驱动的硝酸盐自由基的氧化，抑制了大气中甲烷磺酸的产生，这解释了迪纳利岛和格陵兰岛甲烷磺酸减少的大部分原因，而不需要改变浮游植物的产量。

相对于北大西洋，北太平洋甲烷磺酸下降的时间延迟，反映了逆风地区工业化的独特历史，并与德纳里和格陵兰冰芯硝酸盐记录相一致。这些结果表明，工业化时代北极冰芯甲磺酸的多年代际趋势反映了人为污染的增加，而不是海洋初级生产力的下降。

附：英文原文

Title: Pollution drives multidecadal decline in subarctic methanesulfonic acid

Author: Chalif, Jacob I., Jongebloed, Ursula A., Osterberg, Erich C., Koffman, Bess G., Alexander, Becky, Winski, Dominic A., Polashenski, David J., Stamieszkin, Karen, Ferris, David G., Kreutz, Karl J., Wake, Cameron P., Cole-Dai, Jihong

Issue&Volume: 2024-09-23

Abstract: An industrial-era decline in Greenland ice-core methanesulfonic acid is thought to herald a collapse in North Atlantic marine phytoplankton stocks related to a weakening of the Atlantic meridional overturning circulation. By contrast, stable levels of total marine biogenic sulfur contradict this interpretation and point to changes in atmospheric oxidation as a potential cause of the methanesulfonic acid decline. However, the impact of oxidation on methanesulfonic acid production has not been quantified, nor has this hypothesis been rigorously tested. Here we present a multi-century methanesulfonic acid record from the Denali, Alaska, ice core, which shows a methanesulfonic acid decline similar in magnitude but delayed by 93years relative to the Greenland record. Box-model results using updated dimethyl sulfide oxidation pathways indicate that oxidation by pollution-driven nitrate radicals has suppressed atmospheric methanesulfonic acid production, explaining most, if not all, of Denali’s and Greenland’s methanesulfonic acid declines without requiring a change in phytoplankton production. The delayed timing of the North Pacific methanesulfonic acid decline, relative to the North Atlantic, reflects the distinct history of industrialization in upwind regions and is consistent with the Denali and Greenland ice-core nitrate records. These results demonstrate that multidecadal trends in industrial-era Arctic ice-core methanesulfonic acid reflect rising anthropogenic pollution rather than declining marine primary production.

DOI: 10.1038/s41561-024-01543-w

Source: https://www.nature.com/articles/s41561-024-01543-w