Molecular Characterization of Organosulfates in Arctic Ocean and Antarctic atmospheric aerosols

Abstract

<p><strong>Abstract.</strong> Organic aerosols are ubiquitous components of atmospheric aerosols. Organosulfate aerosols have been detected in the Arctic Ocean atmosphere and may play an important role in the radiative balance in Polar Regions. Aerosol samples from the Arctic Ocean and Antarctic atmosphere during 2014/2015 CHINARE were analysed by ultrahigh resolution mass spectrometry coupled with negative ion mode electrospray ionization (ESI(-)-UHRMS). Hundreds of organic compounds were detected and tentatively determined by their formulas, including organosulfates (OSs), nitrooxy-organosulfates (NOSs), organonitrates (ONs) and oxygenated hydrocarbons (OxyCs). The number of OSs/NOSs accounted for 28–32 % of the total number of detected molecules at polar sites and ONs were 28–40 %. Organic compounds of Arctic Ocean and Antarctic aerosols had high oxidation states for carbon and a large percentage of high molecular weight formulas; this indicated that <q>aged</q> organic aerosols likely comprise a significant part of the polar atmosphere. We hypothesized that highly oxidized HMW compounds tend to be transported to the polar area from stratospheric reservoirs. Dramatic differences of the molecular characteristics were observed when we compared aerosol samples between polar sites and Guangzhou sites, reflecting the different oxidation mechanisms and atmospheric transmission. The polar sites contained higher fractions of OSs/NOSs and lower fractions of ONs than the Guangzhou sites did; this indicated that the oxidation of NO<sub><i>x</i></sub> was weaker in the polar region. Observing that the fraction and oxidation states of polycyclic aromatic OSs/NOSs polar regions were similar to the Guangzhou urban area but not the rural area implied an anthropogenic influence on OSs/NOSs in remote polar areas. In addition, the contribution of potential precursors (anthropogenic and biogenic volatile organic compounds) to OS and NOS formation as well as the effects of nss-SO<sub>4</sub> aerosols, pH and RH on OS formation in polar areas were discussed. Our study presents the first overview of OSs and ONs in the Arctic Ocean and Antarctic atmosphere and promotes the understanding of their characteristics and sources.</p>

Size Distribution and Secondary Formation of Particulate Organic Nitrates in Winter in a Coastal Area

“…Previous PON observations in the urban and rural areas of China have demonstrated that there is a significant variation in PON abundance and concentrations range from below detection limits to several micrograms per cubic meter [17,[25][26][27][28][29]. PON abundance varies markedly by season and location owing to the effects of natural conditions and anthropogenic activities.…”

Particulate organic nitrates in eastern China: variation characteristics and effects of anthropogenic activities

“…PONs ranging from below detection limits to several micrograms per cubic meter found that mixed urban fossil fuel combustions were primarily responsible for the high concentrations of PONs in southern California. On the basis of latest observations of PONs in China, large disparity exist and the concentrations of PONs range from below detection limit to several micrograms per cubic meter (He et al, 2014;Ma et al, 2014;Zhang et al, 2016;Li et al, 2018;Ye et al, 2019). suggested that future reduction in anthropogenic emissions would help to reduce the 70 biogenic SOA loading because the abundances of organosulfates and nitrooxy-organosulfates increased significantly in acidic sulfate aerosols under high humidity.…”