New index of organic mass enrichment in sea spray aerosols linked with senescent status in marine phytoplankton

Abstract

Linking the amount of organic matter (OM) in sea spray aerosols (SSAs) to biological processes in ocean surface is essential for understanding marine aerosol formation and their potential to affect cloud formation. To date, chlorophyll (Chl) a concentration has been widely used as a surrogate for surface phytoplankton biomass or productivity to predict the relative abundance of OM in SSAs (OMSSA). Here we show a new index to present OMSSA using concentrations of Chl a and chlorophyllide (Chllide) a, which is a breakdown product of Chl a and has been used as a biomarker of senescent algal cells. The index was compared with submicrometer OMSSA, based on surface seawater and aerosol samples obtained during the pre-bloom in the western subarctic Pacific. Our results showed that the OMSSA was highly correlated with this unique index, suggesting that the OMSSA was closely linked with senescent algal cells and/or cell lysis. Furthermore, the hygroscopicity parameters κ derived from water-extracted SSA samples implied a reduction in the SSA hygroscopicity with increasing senescent status of phytoplankton. The index can represent OMSSA on a timescale of a day during the pre-bloom period, which should be further examined over different oceanic regions.

Origin of water-soluble organic aerosols at the Maïdo high-altitude observatory, Réunion Island, in the tropical Indian Ocean

“…To determine the water-soluble organic carbon (WSOC) concentration of the submicrometer filter samples, a filter cut of 39.25 cm 2 was extracted with 15 mL ultrapure water using an ultrasonic bath for 15 min. The extracts were filtered through a 0.22 µm pore syringe filter and then injected into a total organic carbon (TOC) analyzer (Model TOC-L CHP , Shimadzu) (Miyazaki et al, 2018(Miyazaki et al, , 2020.…”

“…To measure the stable carbon isotope ratio of WSOC (δ 13 C WSOC ), another filter cut (27.24 cm 2 ) for each sample was acidified to pH 2 with hydrochloric acid (HCl) to remove inorganic carbon prior to extraction (Miyazaki et al, 2018(Miyazaki et al, , 2020. The decarbonated filter samples were then dried under a nitrogen stream for approximately 2 h. WSOC was extracted from the filters in 20 mL of ultrapure water using the method described above to measure the WSOC concentration.…”

Origin of water-soluble organic aerosols at the Maïdo high-altitude observatory, Réunion Island in the tropical Indian Ocean

“…To determine the WSOC concentration of the submicrometer filter samples, a filter cut of 39.25 cm 2 was extracted with 15 mL ultrapure water using an ultrasonic bath for 15 min. The extracts were filtered through a 0.22 µm pore syringe filter and then injected into a total organic carbon (TOC) analyzer (Model TOC-LCHP, Shimadzu) (Miyazaki et al, 2018(Miyazaki et al, , 2020.…”

“…To measure the stable carbon isotope ratio of WSOC (δ 13 CWSOC), another filter cut (27.24 cm 2 ) for each sample was acidified 15 to pH 2 with hydrochloric acid (HCl) to remove inorganic carbon prior to extraction (Miyazaki et al, 2018(Miyazaki et al, , 2020. The decarbonated filter samples were then dried under a nitrogen stream for approximately 2 h. WSOC was extracted from the filters in 20 mL of ultrapure water using the method described above to measure the WSOC concentration.…”

Factors controlling the transfer of biogenic organic species from seawater to sea spray aerosol

“…SSA particles are comprised of a complex array of biogenic species, including intact microbes, which control the physicochemical properties of SSA and thus affect their atmospheric behavior 3 . In recent decades, significant effort has been aimed at trying to establish a link between the composition of SSA and the biological state of the ocean 5 – 9 , specifically related to phytoplankton growth 10 – 14 and the microbial loop 5 , 15 – 17 .…”