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An Isotopic Dilution Approach for Quantifying Mercury Lability in Soils Waleed Hares Shetaya, Stefan Osterwalder, Moritz Bigalke, Adrien Mestrot, Jen-How Huang, and Christine Alewell Environ. Sci. Technol. Lett., Just Accepted Manuscript • DOI: 10.1021/acs.estlett.7b00510 • Publication Date (Web): 29 Nov 2017 Downloaded from http://pubs.acs.org on December 3, 2017
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Environmental Science & Technology Letters
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An Isotopic Dilution Approach for Quantifying Mercury Lability in
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Soils Waleed H. Shetaya1, 2,*, Stefan Osterwalder1, Moritz Bigalke3, Adrien Mestrot3, Jen-How Huang1, Christine Alewell1.
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Environmental Geosciences, University of Basel, Bernoullistrasse 30, 4056 Basel, Switzerland. 1
Air Pollution Department, Environmental Sciences Division, National Research Centre, 33 El-Bohouth St., Dokki, Giza 12622, Egypt. 2
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Institute of Geography, University of Bern, Hallerstrasse 12, 3012 Bern,
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Switzerland.
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*
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[email protected] Corresponding Author:
[email protected],
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ACS Paragon Plus Environment
Environmental Science & Technology Letters
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Abstract
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The accurate estimation of soil mercury lability is crucial for risk assessment. In
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comparison to chemical fractionation and speciation, isotopic dilution (ID) offers precise
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definition of labile mercury fractions while maintaining natural equilibrium. We developed
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and applied an ID protocol with
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exchangeable (labile) pool or HgE using a range of industrially contaminated soils in
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Switzerland. The measured HgE values were consistent for the same soil against different
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spike levels (50, 100 and 200% of native 199Hg) indicating that the spiked and soil isotopes
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achieved required dynamic equilibrium at the soil-water interface. Total soil Hg (THg; mg
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kg-1) was the best predictor of HgE (mg kg-1) and %HgE and accounted for 96 and 63 %
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of the variance, respectively. Nonetheless, despite the wide range of THg (0.37 - 310 mg
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kg-1) in the studied soils, Hg lability spanned across a narrow range (~ 12 – 25 % of THg),
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highlighting the large capacity of soils to sequester Hg in a very stable form. The
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‘exchangeable pool’ of Hg extracted by CH3COONH4 and MgCl2 (
