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Uptake of Gaseous Elemental Mercury by a Rainforest: Insights from a Tropical Glasshouse Used as a Dynamic Flux Chamber

Year: 2025

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide Vegetation uptake of gaseous elemental mercury (Hg 0 ) is the main deposition pathway to terrestrial environments. However, the fluxes and processes of forest-atmosphere Hg 0 exchange remain ill-constrained, especially in rainforests. To help address this, we used the 1 ha Masoala Rainforest hall of the Zoo Zurich as a dynamic flux chamber to measure net rainforest Hg 0 fluxes and even calibrate Hg 0 deposition velocities with turbulence measurements. The net Hg 0 flux correlated well with CO 2 assimilation, showing peak Hg 0 uptake at noon. The interquartile range of Hg 0 uptake spanned from 1.69 to 3.45 ng m –2 h –1 during the day and from 0.01 to 0.44 ng m –2 h –1 at night. The study results revealed a Hg 0 -specific canopy resistance ( R c = 1000 s m –1 ), which underlined the importance of stomatal uptake as a dominant Hg 0 deposition pathway in the rainforest. Even though a dynamic flux chamber, however large, is only an approximation of a real rainforest, our findings underline the value of whole-rainforest flux studies both for constraining Hg exchange with the atmosphere and resolving the role of specific mechanisms.

Source: Environmental Science & Technology

DOI: 10.1021/acs.est.5c05823