Monoterpenes are the second largest biogenic volatile organic compounds (BVOCs) in the atmosphere. Marine monoterpenes can significantly affect the atmospheric oxidation capacity and climate change. Monoterpenes in seawater have rarely been investigated, with no data available from the Northwest Pacific Ocean (NWPO), additionally, in situ biological production rates of monoterpenes in seawater have not been reported. Better limits on the production rates and fluxes of monoterpenes are needed to determine their importance in global climate change through seawater observations and more comprehensive spatial and temporal datasets. The distribution and biological production rates of three monoterpenes (α-pinene, camphene, and limonene) and the factors that drive these processes were determined in the NWPO in spring 2022 and summer 2023. The concentrations of individual monoterpenes ranged from ND (not detected) to 29.2 pmol L^-1, with average concentrations of between 0.9 and 2.2 pmol L^-1. The high-value center of the three monoterpenes occurred in the Kuroshio-Oyashio Extension (KOE) region. The net biological production rates of α-pinene, camphene and limonene in the deck incubation experiments were 2.9 ± 2.8, 5.0 ± 0.6 and 2.4 ± 3.1 pmol L^-1 day^-1, respectively, which were affected by Chl-a and sea water temperature. Furthermore, no obvious photochemical monoterpene production was observed.

monoterpenes, northwest Pacific Ocean, distribution, sea-to-air flux, biological production