Deposition and Re-Emission of Atmospheric Elemental Mercury over the Tropical Forest Floor

• DOI: 10.1021/acs.est.3c01222
• Publication Date: 2023-07-12T19:19:45Z
• Authors: Wei Yuan; Xun Wang; Che-Jen Lin; Qinghai Song; Hui Zhang; Fei Wu; Nantao Liu; Huazheng Lu; Xinbin Feng
• Keywords: Biogeochemical Cycle; Sink (geography); Forest floor; Mercury; Plant litter; Tropical rain forest; Wet season; Dry season; Deposition

Significant knowledge gaps exist regarding the emission of elemental mercury (Hg0) from tropical forest floor, which limit our understanding Hg mass budget in ecosystems. In this study, biogeochemical processes Hg0 deposition to and evasion soil a Chinese rainforest were investigated using stable isotopic techniques. Our results showed mean air-soil flux as -4.5 ± 2.1 ng m-2 h-1 dry season +7.4 1.2 rainy season. re-emission, i.e., legacy evasion, induces negative transitions Δ199Hg δ202Hg evaded vapor, while direct atmospheric does not exhibit fractionation. Using an balance model, was estimated be 48.6 13.0 μg year-1. Soil re-emission 69.5 10.6 year-1, 63.0 9.3 year-1 is surface 6.5 5.0 pore gas diffusion. Combined with litterfall (∼34 year-1), we ∼12.6 net sink forest. The fast nutrient cycles rainforests lead strong therefore relatively weaker sink.