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

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

Medienart:

E-Artikel

Erscheinungsjahr:

2023

Erschienen:

2023

Enthalten in:

Zur Gesamtaufnahme - volume:57

Enthalten in:

Environmental science & technology - 57(2023), 29 vom: 25. Juli, Seite 10686-10695

Sprache:

Englisch

Beteiligte Personen:

Yuan, Wei [VerfasserIn]
Wang, Xun [VerfasserIn]
Lin, Che-Jen [VerfasserIn]
Song, Qinghai [VerfasserIn]
Zhang, Hui [VerfasserIn]
Wu, Fei [VerfasserIn]
Liu, Nantao [VerfasserIn]
Lu, Huazheng [VerfasserIn]
Feng, Xinbin [VerfasserIn]

Links:

Volltext

Themen:

Air−soil mercury exchange
FXS1BY2PGL
Journal Article
Legacy mercury re-emission
Mass balance model
Mercury
Mercury isotope
Soil
Tropical forest

Anmerkungen:

Date Completed 23.10.2023

Date Revised 23.10.2023

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1021/acs.est.3c01222

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM359380026