|Abstract Title:||Elevated Gaseous Oxidized Mercury Revealed by an Hourly-Resolution Membrane-Coupled Monitoring System|
|Presenter Name:||qingru Wu|
|Session:||Analytical methods for Hg speciation to assess impacts of Climate Change|
Abstract Information :
Gaseous oxidized mercury (Hg2+) monitoring is one of the largest challenges in the mercury research field, where existing methods cannot simultaneously satisfy the measurement requirements of both accuracy and time precision. Here, we developed an hourly resolution Hg2+ monitoring system (HGOMS) by coupling a cation exchange membrane (CEM)-based sampler with Tekran 2537/1130/1135 analyzer. The two-stage CEMs coupled in this system can capture 100ñ7.1% of Hg2+ under HgBr2 exposure conditions and does not have gaseous elemental mercury (Hg0) uptake under Hg0 exposure. The HGOMS measured a Hg2+ concentration of 0.46ñ0.36 ng m-3 at urban Beijing in September 2021, which was approximately 23 times higher than the measurement by previous KCl-coated denuder (0.020ñ0.022 ng m-3). In addition, significantly elevated Hg2+ with diurnal amplitude of 0.37 ng m-3 was observed during the daytime, which could be attributed to the strong photochemical production of Hg2+. Given the current prevalent low bias of Hg2+ in observations, this study indicated the urgency to re-evaluate global Hg2+ measurements and mercury reaction mechanisms in both oxidation and reduction processes.