Transmission of Solar Light according the Relative CDOM Concentration of the Sea-ice-covered Pacific Arctic Ocean

Abstract

The transmission of solar light according to the distribution of chromophoric dissolved organic matter (CDOM) was measured in the Pacific Arctic Ocean. The Research Vessel Araon visited the icecovered East Siberian and Chukchi Seas in August 2016. In the Arctic, solar [ultraviolet-A (UV-A), ultraviolet-B (UV-B), and photosynthetically active radiation (PAR)] radiation reaching the surface of the ocean is primarily protected by the distribution of sea ice. The transmission of solar light in the ocean is controlled by sea ice and dissolved organic matter, such as CDOM. The concentration of CDOM is the major factor controlling the penetration depth of UV radiation into the ocean. The relative CDOM concentration of surface sea water was higher in the East Siberian Sea than in the Chukchi Sea. Due to the distribution of CDOM, the penetration depth of solar light in the East Siberian Sea (UV-B, 9 ± 2 m; UV-A,13 ± 2 m; PAR, 36 ± 4 m) was lower than in the Chukchi Sea (UV-B, 15 ± 3 m; UV-A, 22 ± 3 m; PAR, 49 ± 3 m). Accelerated global warming and the rapid decrease of sea ice in the Arctic have resulted in marine organisms being exposed to increased harmful UV radiation. With changes in sea ice covered areas and concentrations of dissolved organic matter in the Arctic Ocean, marine ecosystems that consist of a variety of species from primary producers to high-trophic-level organisms will be directly or indirectly affected by solar UV radiation.