Responses of Biogenic Sulfur Compound Concentrations to Dust Aerosol Enrichment and Ocean Acidification in the Western Pacific Ocean

Deck incubation experiments were conducted to investigate how the addition of atmospheric dust aerosols and ocean acidification (OA) affects phytoplankton growth and the production of dimethylsulfide (DMS), its precursor dimethylsulfoniopropionate (DMSP), and dimethylsulfoxide (DMSO) in the oligotrophic western Pacific Ocean. The incubation experiment showed that the deposition of simulated dust aerosols greatly influenced phytoplankton growth and the release of biogenic sulfur compounds (BSCs). Furthermore, it altered the N:P ratios in seawater and phytoplankton community composition, elevating the proportions of strong DMSP and DMSO producers (mainly haptophytes). The average Chl‐a and DMS/P/O concentrations in the acidified treatment (pH 7.9) were 86.76%, 82.53%, 84.17%, and 231.06% higher than in the control. The results indicated that lower pH promoted the growth of diatoms and to a certain extent, the release of the three BSCs. Plain Language Summary About 500 Mt of dust are deposited in the ocean each year. Atmospheric dust deposition can supply enough nutrients to the ocean to enhance marine primary productivity and affect the subsequent concentrations of the climate‐gas dimethylsulfide (DMS) and related biogenic sulfur compounds (BSCs). Besides, ocean acidification is increasingly severe and low pH can affect the growth of phytoplankton. Therefore, we carried out deck incubation experiments to determine how the deposition of atmospheric dust aerosols and ocean acidification (OA) alter the production of BSCs. We found that the addition of dust aerosols elevated the abundance of strong DMSP and DMSO producers (Phaeocystis sp. and Gephyrocapsa oceanica) and increased the concentrations of sulfur compounds. The lower pH accelerated the growth of diatoms in the early and mid‐late stages of treatments and promoted the production of BSCs. Key Points The concentrations of biogenic sulfur compounds (BSCs) in response to dust aerosol deposition and ocean acidification were examined The dust aerosol additions elevated the relative abundance of strong DMSP and DMSO producers The mean concentrations of the three sulfur compounds increased in the acidified treatments