Abstract
The aragonite saturation state (Ωarag) was determined for the surface waters of the western Arctic Ocean over three years, from 2016 to 2018, in an investigation of the present state of acidification of its waters and the main factors controlling the spatial and temporal variations in the surface Ωarag. The study area was divided into the Chukchi marginal area (CMA) and the East Siberian marginal area (ESMA) along a longitude of 180°E. In the CMA, the surface Ωarag during the study period ranged from 0.86 to 1.77, with an average of 1.16, indicating near saturation with respect to aragonite. In the ESMA, the surface Ωarag during the study period ranged from 1.01 to 2.21, with a higher average (1.59) than the CMA. Aragonite undersaturation in the ESMA was not observed during any of the measurement periods, so ocean acidification was less serious there than in the CMA. The surface Ωarag of the CMA was mainly determined by the mixing of seawater and freshwater introduced from rivers and/or sea ice, whereas in the ESMA it was influenced by the mixing of seawater and freshwater but also biological production and lateral mixing.
Plain Language Summary
The study was conducted in the western Arctic Ocean and included the Northwind Ridge, Chukchi Plateau, Chukchi Abyssal Plain, Chukchi Sea Slope, East Siberian Sea Slope, and Mendeleyev Ridge. The waters encompassed by these sites are highly vulnerable to acidification because of the inflow of lower-pH water from the Pacific Ocean through the Bering Sea and the current rapid reduction in the amount of sea ice. The study area was divided into the Chukchi marginal area (CMA) and the East Siberian marginal area (ESMA) along a longitude of 180°E. In the CMA, the surface waters were almost saturated with respect to aragonite but in the ESMA they were undersaturated, indicating that oceanic acidification was more serious in the CMA than in the ESMA. In the near future, the aragonite undersaturation in the most of the surface waters of the CMA will prohibit the survival of calcareous organisms and may lead to their extinction from this area. However, a similar short-term scenario is not expected in the ESMA, due to its relatively high biological production, which favors aragonite saturation and will thus delay aragonite undersaturation of the surface water.
Kim D., Yang E.-J., Cho S., Kim H.-J., Cho K.-H., Jung J. & Kang S.-H., 2021. Spatial and temporal variations of aragonite saturation states in the surface waters of the western Arctic Ocean. Journal of Geophysical Research: Oceans 126: e2021JC017738. doi: 10.1029/2021JC017738. Article (subscription required).
