A synthesis of mercury research in the Southern Hemisphere, part 1: Natural processes

• Published in: Ambio Vol. 52; no. 5; pp. 897 - 917
• Main Authors: Schneider, Larissa, Fisher, Jenny A., Diéguez, María C., Fostier, Anne-Hélène, Guimaraes, Jean R. D., Leaner, Joy J., Mason, Robert
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.05.2023; Springer Nature B.V
• Subjects: Atmospheric Sciences; Biogeochemical cycles; Biogeochemistry; Context; Cycles; Earth and Environmental Science; Ecology; Ecosystem; Emissions; Environment; Environmental Engineering/Biotechnology; Environmental Management; Environmental Monitoring; Global Mercury Impact Synthesis: Processes in the Southern Hemisphere; Heterogeneity; Hot spots (geology); Mercury; Mercury - analysis; Methylation; Physical Geography; Reviews; Southern Hemisphere; Tropical environments; Uniqueness; Vegetation; Vegetation type; Volcanic activity; Southern Hemisphere; Soils; Geogenic sources; Methylation processes; Background; Oceans; Litterfall
• ISSN: 0044-7447; 1654-7209
• DOI: 10.1007/s13280-023-01832-5

Recent studies demonstrate a short 3–6-month atmospheric lifetime for mercury (Hg). This implies Hg emissions are predominantly deposited within the same hemisphere in which they are emitted, thus placing increasing importance on considering Hg sources, sinks and impacts from a hemispheric perspective. In the absence of comprehensive Hg data from the Southern Hemisphere (SH), estimates and inventories for the SH have been drawn from data collected in the NH, with the assumption that the NH data are broadly applicable. In this paper, we centre the uniqueness of the SH in the context of natural biogeochemical Hg cycling, with focus on the midlatitudes and tropics. Due to its uniqueness, Antarctica warrants an exclusive review of its contribution to the biogeochemical cycling of Hg and is therefore excluded from this review. We identify and describe five key natural differences between the hemispheres that affect the biogeochemical cycling of Hg: biome heterogeneity, vegetation type, ocean area, methylation hotspot zones and occurence of volcanic activities. We review the current state of knowledge of SH Hg cycling within the context of each difference, as well as the key gaps that impede our understanding of natural Hg cycling in the SH. The differences demonstrate the limitations in using NH data to infer Hg processes and emissions in the SH.