In the context of climate change, the organic component of marine aerosols has received widespread attention. On the one hand, marine organic aerosols can affect climate through direct or indirect effects. On the other hand, changes in environmental factors, such as rising sea surface temperatures and accelerated melting of sea ice, can affect the composition and distribution of marine organic aerosols. Marine organic aerosols have both natural and anthropogenic sources. Globally, climate change is more rapid in the Northern Hemisphere, and human activities are more frequent. Therefore, investigating the spatiotemporal distribution characteristics of typical organic components in marine aerosols in the Northern Hemisphere against the backdrop of climate change, as well as the key factors affecting their concentrations, can help us better understand climate change and their interrelationships.

This study, through the total suspended particulate (TSP) samples from the Chinese National Arctic Research Expeditions (CHINARE), combined with the backward trajectory model, and statistical analyses such as principal component analysis (PCA), multiple linear regression (MLR), and the generalized additive model (GAM), has conducted an in-depth analysis of the spatiotemporal distribution characteristics, sources, and influencing factors of lipids and secondary organic aerosol (SOA) tracers in the marine atmospheric aerosols of the Northern Hemisphere. Specifically for the Arctic region, which is most sensitive to climate change, the study explored the response of biological secondary organic carbon (BSOC) in the aerosols of the Arctic Ocean to sea ice changes. Building on this, to further understand the relationship between organic aerosols and sea ice changes, we investigated the response of different persistent organic pollutants (POPs) in the Arctic atmosphere to sea ice changes using data on POPs concentrations in aerosols provided by the Arctic Monitoring and Assessment Programme (AMAP) and sea ice extent data from the National Snow and Ice Data Center (NSIDC), along with cross-correlation analysis. This research provided an observational basis and cognitive framework for properly understanding the relationship between marine organic aerosols and climate change. The main results were summarized below:

(1) Based on the summer aerosol samples collected during the CHINARE in 2014, 2016, and 2018, this study explored the spatiotemporal distribution and sources of n-alkanes and fatty acids in the aerosols over the Bering Sea (BS) and the western North Pacific (WNP). The results indicated that lipid concentrations were the highest in 2018, with the WNP influenced by neighboring Eurasia and the BS influenced by the transport of aerosols from the WNP as well as an increased primary productivity. The sources of n-alkanes and fatty acids were found to be similar, and the qualitative assessment of the characteristic parameters indicated that temporally, n-alkanes were more derived from higher plant wax in 2016 and 2018 relative to 2014, as well as fatty acids in 2018 relative to the other two years. Furthermore, the quantitative assessment of PCA-MLR showed that spatially, the WNP and BS were most influenced by terrestrial natural sources (57.8%) and anthropogenic sources (58.8%), respectively, and the contribution of marine emissions to BS was higher. In addition, the evaluation of organic carbon (OC) contribution revealed that lipids from BS contributed more OC and that the contribution of fatty acids to OC was higher than that of n-alkanes.

(2) Based on the summer aerosol samples collected during the CHINARE in 2014, 2016, and 2018, this study examined the spatiotemporal distribution and influencing factors of SOA tracers over the BS and the WNP. The results showed that temporally, atmospheric concentrations of isoprene-derived SOA (SOAI) tracers were the lowest in 2014 regardless of the marine region, while atmospheric concentrations of monoterpenes-derived SOA (SOAM) tracers in this year were the highest and the aerosols were more aged than those in the other two years. In comparison, the concentrations of β-caryophyllene-derived and toluene-derived SOA (SOAC and SOAA) tracers were relatively low overall. Spatially, the concentrations of SOA tracers were significantly higher over the WNP than over the BS, with SOA tracers over the BS mainly coming from marine sources, while the WNP was strongly influenced by terrestrial inputs. In particular, for land-influenced samples from the WNP, NOx-channel products of SOAI were more dependent on O3 and SO2 relative to HO2-channel product, and the high atmospheric oxidation capacity and SO2 could promote the formation of later-generation SOAM products. The extent of terrestrial influence was further quantified using a PCA-generalized additive model (GAM), which showed that terrestrial emissions explained more than half of the BSOA tracers’ concentrations and contributed almost all of the anthropogenic secondary organic aerosols (ASOA) tracer. In addition, the assessment of secondary organic carbon (SOC) highlighted the key role of anthropogenic activities in organic carbon levels in offshore areas.

(3) Based on the summer aerosol samples collected during the CHINARE in 2014, 2016, and 2018, this study investigated the sources, influencing factors, and response to sea ice changes of biogenic secondary organic aerosol (BSOA) tracers in the Arctic Ocean (AO). The results indicated that methyltetrols were the most abundant SOAI tracers, while the main oxidation products of monoterpenes varied over the years owing to different aerosol aging. The results of the PCA-GAM combined with correlation analysis suggested that SOAI tracers were mainly generated by the oxidation of isoprene from marine emissions, while SOAM tracers were probably more influenced by terrestrial transport. Estimation of SOC indicated that monoterpenes oxidation contributed more than isoprene and that sea ice changes had a relatively small effect on biogenic SOC concentration levels in the AO.

(4) Based on nearly 30 years of data on POPs concentrations in atmospheric aerosols and sea ice area data, by comparing the variability of typical POPs such as organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) at four Arctic stations (i.e. Alert, Zeppelin, Stórhöfði, and Pallas), and combining cross-correlation analysis, the study explored the response of POPs to sea ice changes. The findings revealed that at the Zeppelin station, which is surrounded by pack ice zones, OCPs (especially hexachlorobenzene (HCH) and α-hexachlorocyclohexane (α-HCH)) showed a significant negative correlation with sea ice changes after 2009, whereas other stations exhibited lower or no correlation. PCBs at the Stórhöfði and Pallas stations preceded sea ice changes, possibly due to long-range atmospheric transport and soil acting as a secondary source, while a phenomenon of lagging sea ice changes similar to that of dichlorodiphenyltrichloroethane (DDT) was observed at the Zeppelin station. Therefore, different types of POPs exhibit varying spatiotemporal responses to sea ice changes, and the melting of sea ice does not necessarily lead to an increase in POPs atmospheric concentrations.