Investigation of chemical and physical processes on Arctic aerosols through a combined approach of field and laboratory studies
The causes and effects of recent global warming have been studied extensively; but, the role of atmospheric aerosols in the Arctic biogeochemistry has not been widely explored yet.The water-soluble Arctic aerosols directly impact the climate by participating in cloud formation and influencing its ra...
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2018
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Online Access: | https://dx.doi.org/10.7282/t3-bmq6-q097 https://rucore.libraries.rutgers.edu/rutgers-lib/59332/ |
Summary: | The causes and effects of recent global warming have been studied extensively; but, the role of atmospheric aerosols in the Arctic biogeochemistry has not been widely explored yet.The water-soluble Arctic aerosols directly impact the climate by participating in cloud formation and influencing its radiative property. Moreover, the amplified Arctic warming may significantly influence the solubility and bio-availability of aerosol iron (Fe)—which is a limiting nutrient for phytoplankton growth, an important sink for atmospheric carbon dioxide (CO2). This research investigates the chemical and physical processes on aerosols that were collected during the US Geotraces Arctic cruise in summer 2015 and natural snow samples from Newark, New Jersey in conjunction with laboratory experiments involving Fe minerals and organic ligands. We hypothesize that the Arctic aerosols were modified by various natural and anthropogenic processes, affecting the concentrations and hygroscopic properties of the cloud condensation nuclei and soluble Fe input to the Arctic Ocean. Laboratory studies with hematite and major organic ligands showed that oxalate, when present above a threshold amount, had a significant effect on the absorptive dissolution of Fe. The results from the Arctic Ocean expedition showed that coarse mode sea-salt was the major aerosol component and non-sea-salt-sulfate was significantly present in fine mode aerosol particles. Among the organic species, oxalate, acetate, and formate were the major components among the species examined at the pole. Calcium was enriched on the sea-spray aerosols, pre-dominantly in the fine mode, leading to significant modification of the aerosol hygroscopic growth factor. Analysis of the natural snow and ice-melts showed that freezing could induce compaction and clustering of particles, but had negligible effect on modulating Fe solubility.This study provides significant insight into the water soluble component of Arctic summer aerosols regarding their concentrations, sources, and possible formation mechanisms, and their effects on the Arctic climate via cloud formation. The laboratory based experiments increase our understanding of the effects of various processes occurring in Arctic aerosols—including the accumulation and reactions of organic components in aerosols and the freeze concentration effect on iron chemistry, which could affect the biogeochemical cycles in the Arctic Ocean. |
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