Comparing chemical extraction and a piecewise function with diffusive gradients in thin films for accurate estimation of soil zinc bioavailability to Sedum plumbizincicola

Abstract

Summary Accurate evaluation of metal bioavailability to hyperaccumulators is necessary for prediction of metal uptake and estimation of phytoextraction potential. Sedum plumbizincicola X.H. Guo et S.B. Zhou ex L.H. Wu (Crassulaceae), a hyperaccumulator of cadmium (Cd) and zinc (Zn), was grown in a pot experiment in 108 agricultural soils representing a wide range of typical Chinese soil types. The contribution of soil properties to Zn uptake was assessed quantitatively. Soil total Zn, soluble Zn, CaCl2‐extractable Zn and (DGT)‐extractable Zn concentrations (Zntotal, Znsoln, ZnCaCl2 and ZnDGT, respectively) were compared to predict shoot Zn concentration (Znshoot) using a piecewise equation. This showed a logarithmic increase with increasing Zntotal from 100–1000 mg kg−1 but plateaued outside this range. The optimum soil pH for Zn removal was ~ 5.5 and further acidification was unnecessary because Znshoot increased significantly with a decrease in pH from 7.5 to 5.5 and rarely changed at pH < 5.5. Sedum plumbizincicola grown in loamy or clay loam soils had larger Znshoot than in sandy or clay soils. The ZnCaCl2 was superior to other methods in estimating Zn bioavailability across all the data. At pH < 5.5, ZnCaCl2 showed much stronger correlation with Znshoot than Zntotal, Znsoln or ZnDGT. Piecewise equations (single linear regression equations at different intervals of soil properties) versus Zntotal and ZnCaCl2 at different pH ranges considerably increased the accuracy of prediction of Znshoot compared with the global equations derived from all data. Estimation of the potential of S. plumbizincicola for Zn phytoextraction in the field indicated that it is feasible to decontaminate acid‐polluted soils with Zntotal ≤ 500 mg kg−1 with S. plumbizincicola. Highlights Zn bioavailability to hyperaccumulators needs to be estimated over a wide range of soil types. Piecewise equations considerably improved the prediction of shoot Zn concentration. CaCl2 extraction was more suitable than DGT for the estimation of Zn bioavailability. Decontamination with S. plumbizincicola is feasible for acid soils with Zntotal ≤ 500 mg kg−1.

Use of diffusive gradients in thin-film technique to predict the mobility and transfer of nutrients and toxic elements from agricultural soil to crops—an overview of recent studies

“…A new type of resin gel combined with layered double hydroxide nanoparticles changed with diethylenetriaminepentaacetic acid was created for the use of DGT tools to measure eight anions and cations in waters and soils (Wang et al 2023b ). A hyperaccumulator plant of Cd and Zn, Sedum plumbizincicola , was grown in a pot experiment (Zhou et al 2019 ). Soil total Zn and water soluble, CaCl 2 -extractable, and C DGT Zn concentrations were measured and used to predict the shoot Zn concentration.…”

Editorial for special issue on “Recent innovations in soil physical, chemical and biological analysis” (2nd National Symposium on soil analysis)

“…Using liquid chromatography coupled to high-resolution mass spectrometry (LC-QTOF-MS), Brock et al (2020) developed a novel method for non-target screening of leaf litter-derived dissolved organic matter. CaCl 2 extraction was shown to be more appropriate than diffusive gradients in thin films (DGT) for estimating zinc (Zn) bioavailability to Sedum plumbizincicola when comparing chemical extraction and DGT techniques (Zhou et al, 2019). Laser-induced breakdown spectroscopy (LIBS) and partial least squares regression (PLSR) were used for rapid, on-site quantitative analysis of potentially toxic metals in wet soil samples, and the results showed that LIBS technology can detect these metals with high sensitivity and specificity (Xu et al, 2022).…”