Atmospheric gaseous elemental mercury and its sea-air evasion fluxes from the Sea of Okhotsk to the South China Sea: results of cruise studies in 2019

Abstract

At present, the behavior of mercury in the sea-atmosphere system in the north western Pacific Ocean is poorly understood. From September to December 2019, continuous measurements of atmospheric gaseous elemental mercury (Hg(0)) and point measurements of Hg(0) evasion fluxes from the sea to the atmosphere were carried out during two adjacent cruises from the South China Sea to the Sea of Okhotsk. The median concentration of Hg(0) (1.1 ng/m3) was below both the background of the Northern Hemisphere and the average values previously recorded in these areas. There was a trend of increasing Hg(0) concentration with decreasing latitude. The Yellow Sea with adjacent territories and northeast China were the Hg(0) source area for the Sea of Japan and the Sea of Okhotsk. The Kuril sector of the Pacific Ocean was identified as a source of Hg(0) for the Sea of Okhotsk. East China, Southeast China and Indochina were sources of Hg(0) for the East China and South China seas. A winter increase in Hg(0) concentrations was observed in the Sea of Japan and the East China Sea. Our data showed significant relationships between Hg(0) fluxes, latitude, and water temperature.