|Abstract Title:||Continuous monitoring on Hg evasion flux in air-sea interfaces using a gas-liquid equilibrator system|
|Presenter Name:||Kohji Marumoto|
|Company/Institution:||National Institute for Minamata Disease|
|Session:||Atmospheric Hg cycling: Source and Emissions|
|Co-Authors:||Kohji Marumoto,Fumiyoshi Kondo,Chenchen Tang,Kosuke Noborio,Yuya Tada|
Abstract Information :
Re-emission of gaseous mercury (Hg) from surfaces of land, forest and ocean is one of the important processes for global Hg cycle. Total emission amount of Hg through this process could be estimated at 5,500 tons globally and, in particular, approximately 60% of the total could be emitted from ocean surfaces. In this study, we conducted the continuous monitoring of Hg evasion flux from the sea surfaces of the Izu-Ogasawara region in the western North Pacific Ocean and the Seto Inland Sea using a gas-liquid equilibrator system. First, we confirmed the accuracy of Hg concentrations in the equilibrium air in this system by comparing with a dissolved gaseous Hg (DGHg) concentrations obtained from a manual method which DGHg from seawaters is collected into a gold amalgamation trap by N2 bubbling using and the Hg is detected by a cold vapor atomic fluorescence spectrometry following the trap heating. In the survey at the Seto Inland Sea, the Hg concentrations calculated from the Hg concentrations in the equilibrium air and Henry?s constants had good agreement with the DGHg values obtained by the manual method. However, the Hg fluxes could not be calculated due to the trouble on a surface seawater monitoring system. On the other hand, in the survey at the Izu-Ogasawara region in November 2020, the Hg concentrations in the equilibrium air were lower than those at the Seto Inland Sea and the other coastal areas in Japan, such as the Minamata Bay and the Tsushima Strait. The Hg evasion fluxes in this region were averaged at 3.7 ñ 3.1 ng m-2 hr-1, ranging from 0.1 to 19 ng m-2 hr-1. These fluxes were slightly higher than the other coastal areas probably because of strong winds peculiar to open oceans. This work is supported by JSPS KAKENHI Grant Number 21H04935.