Experimental assessment of the daily exchange of atmospheric mercury in Epipremnum aureum
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ORIGINAL PAPER
Experimental assessment of the daily exchange of atmospheric mercury in Epipremnum aureum Rocio Naharro . Jose´ Marı´a Esbrı´
. Jose´ Angel Amoro´s
. Pablo L. Higueras
Received: 17 September 2019 / Accepted: 2 April 2020 Springer Nature B.V. 2020
Abstract Mercury (Hg) exchange at the plant leaf– atmosphere interface is an important issue when considering vegetation as a sink or source of this global pollutant. The aim of the study described here was to clarify this process by studying Hg exchange under laboratory conditions with a plant model, namely Epipremnum aureum. The desorption and absorption processes were studied under similar conditions in natural daylight. Hg exchange was measured at the foliar surface, and micrometeorological parameters and stomatal conductance were assessed. The results of the Hg exchange study showed different rhythms for the two processes, i.e. desorption (14–196 ng m-2 day-1) was slower than absorption (170–1341 ng m-2 day-1). The daily cycle was more complex in the desorption process, with a maximum when stomatal conductance was high but also with high values during nocturnal hours and a trend to absorption in the mornings. The daily absorption cycles were relatively simple, with values
that coincided with positive stomatal conductance values and null values during nocturnal hours. The main factors involved in desorption were stomatal conductance and temperature, but other factors may need to be considered. The absorption process only involved total gaseous Hg, stomatal conductance and relative humidity. A net balance of the two experiments provided data on the amount of Hg transferred per unit leaf area (167 ng m-2 for desorption and 9213 ng m-2 for absorption), which implies total amounts of 23 ng of Hg desorbed and 1280 ng absorbed during the whole experiment. Finally, the reversible/non-reversible nature of the Hg exchange process must be reconsidered bearing in mind that Hg within the leaf can be emitted if changes in ambient conditions are appropriate to favour this process.
R. Naharro J. M. Esbrı´ (&) P. L. Higueras Instituto de Geologı´a Aplicada, Escuela de Ingenierı´a Minera e Industrial de Almade´n (EIMIA), Universidad de Castilla-La Mancha, Plaza Manuel Meca, 1, 13400 Almade´n, Ciudad Real, Spain e-mail: [email protected]
Introduction and background
R. Naharro J. A. Amoro´s Instituto de Geologı´a Aplicada, Escuela Te´cnica Superior de Ingenieros Agro´nomos de Ciudad Real, Universidad de Castilla-La Mancha, Ciudad Real, Ciudad Real, Spain
Keywords Mercury Plant–atmosphere Stomatal conductance Epipremnum aureum Gas exchange
Mercury (Hg) is an element that is present in the environment, and it exists in the three states of matter: liquid (rarely), solid and gas. The ability to transform this element from the solid or liquid to the gaseous state leads to very complex global cycling processes, in which the important aspects to consider are flows
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Environ Geochem Health
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