Biogenic, anthropogenic, and sea salt sulfate size-segregated aerosols in the Arctic summer

Abstract

<p><strong>Abstract.</strong> Size-segregated aerosol sulfate concentrations were measured on board the Canadian Coast Guard Ship (CCGS) Amundsen in the Arctic during July 2014. The objective of this study was to utilize the isotopic composition of sulfate to address the contribution of anthropogenic and biogenic sources of aerosols to the growth of the different aerosol size fractions in the Arctic atmosphere. Non-sea salt sulfate is divided into biogenic and anthropogenic sulfate using stable isotope apportionment techniques. A considerable amount of the average sulfate concentration in the fine aerosols with diameter < 0.49 μm was from biogenic sources (> 70 %) which is higher than previous Arctic studies measuring above the ocean during fall (< 15 %) (Rempillo et al., 2011) and total aerosol sulfate at higher latitudes at Alert in summer (> 30 %) (Norman et al., 1999). The anthropogenic sulfate concentration was less than biogenic sulfate, with potential sources being long range transport and, more locally, the Amundsen’s emissions. Despite attempts to minimize the influence of ship stack emissions, evidence from larger-sized particles demonstrates a contribution from local pollution. A comparison of δ<sup>34</sup>S values for SO<sub>2</sub> and fine aerosols was used to show that gas-to-particle conversion likely occurred during most sampling periods. δ<sup>34</sup>S values for SO<sub>2</sub> and fine aerosols were similar suggesting the same source for SO<sub>2</sub> and aerosol sulfate, except for two samples with a relatively high anthropogenic fraction in particles < 0.49 μm in diameter (July 15–17 and 17–19). The high biogenic fraction of sulfate fine aerosol and similar isotope ratio values of these particles and SO<sub>2</sub> emphasize the role of marine organisims (e.g. phytoplankton, algea, bacteria) in the formation of fine particles above the Arctic Ocean during the productive summer months.</p>

Investigating Source Contributions of Size‐Aggregated Aerosols Collected in Southern Ocean and Baring Head, New Zealand Using Sulfur Isotopes

“…First, substantial amounts of SO 4 2− NSS had been observed in the coarse aerosols (0.9–16 μm) sampled at Baring Head originating from the biologically productive subtropical frontal region of the Chatham Rise (Sievering et al, ), suggesting SO 4 2− NSS was mainly formed on coarse sea‐salt particles. This is in contrast with observations in the Northern Hemisphere (Ghahremaninezhad et al, ; Norman et al, ; Rempillo et al, ; Seguin et al, ) and modeling results (Alexander et al, ), all of which suggested SO 4 2− NSS should mainly distributed in the fine particles (<0.95 μm). Second, the contribution of anthropogenic emission to the Southern Ocean sulfate is uncertain.…”

“…Previous studies have investigated the sources and size distributions of marine sulfate aerosols in several locations (Calhoun & Bates, ; Calhoun et al, ; Faloona, ; Ghahremaninezhad et al, ; Norman et al, ; Novák et al, ; Rempillo et al, ; Seguin et al, ); however, several questions remain unanswered. First, substantial amounts of SO 4 2− NSS had been observed in the coarse aerosols (0.9–16 μm) sampled at Baring Head originating from the biologically productive subtropical frontal region of the Chatham Rise (Sievering et al, ), suggesting SO 4 2− NSS was mainly formed on coarse sea‐salt particles.…”

Frequent ultrafine particle formation and growth in Canadian Arctic marine and coastal environments

“…6) was located in the Nares Strait, where an event was also observed in 2014, suggesting the possibility of a substantial, consis- (Wentworth et al, 2016), gas-phase DMS (Mungall et al, 2016), and evidence of an ocean source for oxygenated volatile organic compounds (Mungall et al, 2017) that may act as precursors for growth. Previous detailed studies in the Arctic have shown that the occurrence of UFP formation and growth events was associated with biogenic sulfur compounds like DMS, which has a substantial oceanic source, and its lower vapour pressure oxidation products, methanesulfonic acid, and sulfuric acid (H 2 SO 4 ) Ghahremaninezhad et al, 2016;Leaitch et al, 2013;Quinn et al, 2002;Rempillo et al, 2011). Other studies have shown that the duration of contact that the air mass had with open water along its backward trajectory was positively correlated with the occurrence of UFP formation Heintzenberg et al, 2015) and aerosol biogenic sulfur concentrations (Sharma et al, 2012).…”

“…Ultrafine particles (UFP), defined in this study as aerosol particles with d p = 4-20 nm, have a vertical profile maximum in the Arctic boundary layer both in the Canadian Archipelago and in the vicinity of Svalbard (Burkart et al, 2017;Engvall et al, 2008b), suggesting a source of UFP at or near the Earth's surface. While the source regions and precursor components are still a topic of active research, studies have shown that ammonia (NH 3 ) and dimethyl sulfide (DMS) are associated with the formation and growth of UFP in the Arctic Croft et al, 2016a;Ferek et al, 1995;Ghahremaninezhad et al, 2016;Giamarelou et al, 2016;Heintzenberg and Leck, 1994;Leaitch et al, 2013;Leck and Persson, 1996), with likely contributions from organic material during particle growth . Biogenic iodine compounds have also been implicated in UFP formation in temperate coastal areas and in polar regions (Allan et al, 2015;Sipilä et al, 2016) due to emissions from marine macroalgae within intertidal zones.…”

Atmospheric DMS in the Arctic Ocean and Its Relation to Phytoplankton Biomass

“…Ocean biology may influence the Earth's climate through its effects on atmospheric composition due to the release of various organic compounds into the atmosphere (Gantt & Meskhidze, ; Meskhidze & Nenes, ; O'Dowd et al, ; Yoon & Brimblecombe, ). In particular, sulfur‐containing aerosols provide an important source of cloud condensation nuclei in marine atmosphere in the polar region (Andreae et al, ; Chang et al, ; Chen et al, ; Ghahremaninezhad et al, ). The production of sulfate from the oxidation of dimethyl sulfide (DMS) was proposed as a negative feedback mechanism by which phytoplankton can modulate the properties of marine clouds (Charlson et al, ).…”