Diffusive gradient in thin films with open and restricted gels for predicting mercury uptake by plants
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The presence of mercury (Hg) in the environment is a major concern because mercury is toxic for living organisms. Estimating the Hg toxicity of environmental samples is difficult because contaminants occur in pools of various bioavailabilities, and thus, measuring the total concentration of a contaminant rarely reflects the real toxicity and risk. There is therefore a need to design advanced methods to measure the bioavailable fraction of the contaminants. Here, we used the diffusive gradient in thin films (DGT) method to determine the bioavailability of Hg in agricultural soils containing 0.02 and 0.64 mg kg−1 of Hg. Specifically, we used homemade manufactured open and restricted diffusive layers to distinguish between inorganic and organic bioavailable Hg species in soil. The findings demonstrate for the first time the successful use of restricted gel for the determination of inorganic Hg species in soil. Moreover, a model program has been used to calculate the effective concentration for predicting Hg concentration uptake by plants. For this purpose, lettuces were planted in soils to assess Hg soil-to-plant transfer. Concentrations of Hg obtained by DGT measurements in soils matched the Hg concentration found in lettuce roots, thus confirming the effectiveness of this technique in predicting Hg uptake by plants.
KeywordsHg Soil Lettuce DGT Open diffusive gel Restricted diffusive gel
The authors gratefully acknowledge the financial support of the Spanish Ministry of Economy, Industry and Competitiveness (MEIC) through projects AGL2017-89518-R and CTM2016-78798-C2-2-P (AEI/FEDER/UE).
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