Preprints
https://doi.org/10.5194/acp-2019-161
https://doi.org/10.5194/acp-2019-161
18 Mar 2019
 | 18 Mar 2019
Status: this preprint has been withdrawn by the authors.

Soil emissions, soil air dynamics and model simulation of gaseous mercury in subtropical forest

Jun Zhou, Zhangwei Wang, Xiaoshan Zhang, Charles Driscoll, and Che-Jen Lin

Abstract. Evasion from soil is the largest source of mercury (Hg) to the atmosphere from terrestrial ecosystems. To reduce the uncertainty in estimates of Hg emissions from forest soils, soil-air total gaseous Hg (TGM) fluxes and vertical profiles of soil pore TGM concentrations were measured simultaneously for 130 days to improve parameterization of emission models. The soil-air TGM fluxes, measured using dynamic flux chambers (DFC), showed patterns of both emission and deposition at five study plots, with an area-weighted net emission rate of 3.2 ng m−2 hr−1. The highest fluxes and net soil Hg emission were observed for an open field, with lesser emission rates in coniferous (pine) and broad-leaved (camphor) forests, and net deposition in a wetland. Fluxes showed strong positive relationships with solar radiation, soil temperature and soil Hg concentrations, and negative correlations with ambient-air TGM concentration and soil moisture. Using experimental field flux observations and quadratic relationships with the five parameters, four empirical models were developed to estimate soil-air TGM fluxes. The highest TGM concentrations in soil gas consistently occurred in the upper mineral horizons in the coniferous (pine) forest and in the organic horizon in the broad-leaved forest. Strong correlations between fluxes and TGM concentrations in upper soil horizons (0–10 cm) suggest that TGM in the pores of surface soil acts as the source for diffusion to the atmosphere. The TGM diffusion coefficients (Ds) between soil and atmosphere was firstly investigated at the field sites, with the range of 0.0042–0.013 m2 hr−1. These values should provide a foundation for future model development.

This preprint has been withdrawn.

Jun Zhou, Zhangwei Wang, Xiaoshan Zhang, Charles Driscoll, and Che-Jen Lin

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Interactive discussion

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Jun Zhou, Zhangwei Wang, Xiaoshan Zhang, Charles Driscoll, and Che-Jen Lin
Jun Zhou, Zhangwei Wang, Xiaoshan Zhang, Charles Driscoll, and Che-Jen Lin

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Latest update: 17 Apr 2024
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This preprint has been withdrawn.

Short summary
Previous studies showed that Hg emissions from the natural resource exists large uncertainty, which was mainly derived from the forest with a large uncertainty range. Long-term and multi-plot (five) study of soil-air fluxes and the vertical distribution of Hg in a subtropical forest were conducted to reduce the uncertainty. Additionally, The Hg diffusion coefficients (Ds) between soil and atmosphere was investigated, which should provide a foundation for future model development.
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