Gaseous mercury evasion from bare and grass-covered soils contaminated by mining and ore roasting (Isonzo River alluvial plain, Northeastern Italy).

Autor: Floreani F; Department of Mathematics and Geosciences, University of Trieste, Via E. Weiss 2, Trieste, Italy; Department of Life Sciences, University of Trieste, Via L. Giorgieri 5, Trieste, Italy. Electronic address: federico.floreani@phd.units.it., Zappella V; Department of Mathematics and Geosciences, University of Trieste, Via E. Weiss 2, Trieste, Italy., Faganeli J; Marine Biology Station, National Institute of Biology, Fornace 41, Piran, Slovenia., Covelli S; Department of Mathematics and Geosciences, University of Trieste, Via E. Weiss 2, Trieste, Italy.
Jazyk: angličtina
Zdroj: Environmental pollution (Barking, Essex : 1987) [Environ Pollut] 2023 Feb 01; Vol. 318, pp. 120921. Date of Electronic Publication: 2022 Dec 21.
DOI: 10.1016/j.envpol.2022.120921
Abstrakt: High amounts of mercury (Hg) can be released into the atmosphere from soil surfaces of legacy contaminated areas as gaseous elemental mercury (Hg 0 ). The alluvial plain of the Isonzo River (NE Italy) suffered widespread Hg contamination due to the re-distribution of Hg-enriched material discharged by historical cinnabar mining at the Idrija mine (Slovenia), but an assessment of Hg 0 releases from the soils of this area is still lacking. In this work, Hg 0 fluxes at the soil-air interface were evaluated using a non-steady state flux chamber coupled with a real-time Hg 0 analyser at 6 sites within the Isonzo River plain. Measurements were performed in summer, autumn, and winter both on bare and grass-covered soil plots at regular time intervals during the diurnal period. Moreover, topsoils were analysed for organic matter content and Hg total concentration and speciation. Overall, Hg 0 fluxes tracked the incident UV radiation during the sampling periods with daily averages significantly higher in summer (62.4 ± 14.5-800.2 ± 178.8 ng m -2 h -1 ) than autumn (15.2 ± 4.7-280.8 ± 75.6 ng m -2 h -1 ) and winter (16.9 ± 7.9-187.8 ± 62.7 ng m -2 h -1 ) due to higher irradiation and temperature, which favoured Hg reduction reactions. In summer and autumn significant correlations were observed between Hg 0 fluxes and soil Hg content (78-95% cinnabar), whereas this relationship was not observed in winter likely due to relatively low emissions found in morning measurements in all sites coupled with low temperatures. Finally, vegetation cover effectively reduced Hg 0 releases in summer (∼9-68%) and autumn (∼41-78%), whereas the difference between fluxes from vegetated and bare soils was not evident during winter dormancy due to scarce soil shading. These results suggest the opportunity of more extended spatial monitoring of Hg 0 fluxes particularly in the croplands covering most of the Isonzo River alluvial plain and where bare soils are frequently disturbed by agricultural practices and directly exposed to radiation.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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Databáze: MEDLINE
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