Spatial and Temporal Variations of Aragonite Saturation States in the Surface Waters of the Western Arctic Ocean

Abstract

The aragonite saturation state (Ωarag) was determined for the surface waters of the western Arctic Ocean over 3 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.