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Alkaline extraction: An optimal approach for extracting methylmercury from paddy soils
Wenli Tang1, Junru Chu1, Huan Zhong2
1School of the Environment, Nanjing University, State Key Laboratory of Pollution Control and Resource Reuse, Nanjing 210023, China.
The Science of the Total Environment
|May 6, 2023
Summary
Alkaline extraction is optimal for measuring methylmercury (MeHg) in paddy soils, showing high efficiency and minimal artifact formation. Acid extraction methods are less suitable for these critical MeHg production sites.
Area of Science:
- Environmental Chemistry
- Analytical Chemistry
- Soil Science
Background:
- Methylmercury (MeHg) concentration measurement is vital for mercury research.
- Analytical methods for MeHg are not validated for paddy soils, key sites of MeHg production.
Purpose of the Study:
- To compare two common extraction methods for MeHg in paddy soils: acid and alkaline extraction.
- To determine the optimal method for accurate MeHg measurement in paddy soils.
Main Methods:
- Compared CuSO4/KBr/H2SO4-CH2Cl2 (acid) and KOH-CH3OH (alkaline) extraction methods.
- Evaluated MeHg artifact formation using Hg isotope amendments.
- Quantified extraction efficiency using standard spikes in 14 paddy soils.
Main Results:
- Alkaline extraction demonstrated negligible MeHg artifact (0.62-8.11% of background MeHg).
- Alkaline extraction showed consistently high efficiency (81.4-114.6%).
- Acid extraction exhibited lower efficiency (21.3-70.8%) and was less suitable for paddy soils.
Conclusions:
- Alkaline extraction is the preferred method for measuring MeHg in paddy soils.
- Proper sample pretreatment and quality control are crucial for accurate MeHg concentration measurements.
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