## 2 Bioavailability Assessment of Heavy Metals in the Soil Using DGT
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Element** & **Species/Soils** & **Findings** & **Binding Phase Material** & **Ref.** \\ \hline Cd, Zn, Pb & Contaminated agricultural soil & The C\({}_{\text{DGT}}\) value for Cd and Zn decreased with an increase in the soil temperature, but the C DGT values for Pb were unexpectedly high. & Chelex-100 & [51] \\ \hline Cd, Cu, Ni, Pb, Zn & Agricultural soils & DGT can assess the available concentrations of metals in soil. & Unknown & [44] \\ \hline Cd & Phenanthrene-contaminated & DGT flux can be most easily interpreted as a measure of Cd resupply from the soil solid phase to the solution phase. & Chelex-100 & [52] \\ \hline As, Pb & Spiked soils & DGT measurements reflected both non-specifically and specifically adsorbed As and exchangeable Pb in spiked soil. & Ferrihydrite; Chelex-100 & [53] \\ \hline Cd & Hyperaccumulator (_Sedum plumbizincicola_) & DGT-extractable Cd showed good correlations with Cd\({}_{\text{shoot}}\). DGT was the best method for assessing Cd bioavailability. & Chelex-100 & [56] \\ \hline Cd, Ni & _Nocaea caerulescens_; _Thlasi goesingense_ & DGT measurements combined with the DIFS (DGT induced fluxes in soils) model are more useful than other chemical methods for assessing & Chelex-100 & [57] \\ \hline Cd, Zn & Hyperaccumulator (_Sedum plumbizincicola_) & The dynamic DIFS model of the soil–DGT system was used to obtain information on the changes in metal desorption kinetics during & Chelex-100 & [58] \\ \hline As & Fern (_Pteris vittata_ L.) & The decrease in As flux measured by DGT suggested that As hyperaccumulating ferns are promising for phytoremediation of As-contaminated soils. & Fe-oxide & [54] \\ \hline As & Paddy soils & DGT was used to assess the porewater and solid-phase As. & Fe-oxide & [42] \\ \hline As & Paddy rice rhizosphere soil & DGT can measure the bioavailable As in rice rhizosphere soil and obtain the dynamic curve of soil bioavailable As. & Zr-oxide & [55] \\ \hline Cd, Fe (II), Mn (II), S (-II) & Paddy soils & LDHs-DGT can extract labile Cd, Fe (II), Mn (II), and S (-II) at the same time. & DTPA-modified LDHs nanomaterials & [59] \\ \hline Cd & Rice (_Oryza sativa_ L.) & DGT-labile Cd levels were highly correlated with rice grain Cd levels, which showed a slight or no positive correlation with conventionally extracted Cd. & Chelex-100 & [60] \\ \hline Cd & Rice (_Oryza sativa_ L.) & Cd measurements obtained by DGT had a higher correlation with the Cd in rice grains. DGT technique was a reliable method for the assessment of Cd bioavailability in soils. & Mg-Al-DTPA-LDHs & [61] \\ \hline Cd & Maize & DGT measured bioavailable Cd well correlated with Cd in maize grains. & Chelex-100 & [62] \\ \hline Mo, Cr, Zn, Cu, Co, As & Bean (_P. vulgaris_) & The intensity of exposure to trace elements in soil was assessed by DGT probes. & Chelex-100 & [43] \\ \hline As, Cu & _Lupinus albus_ L. & The distribution of As, Cu, P, and Fe in the lupin rhizosphere was evaluated with chemical images obtained by laser ablation-ICP-MS analysis of DGT gels. & Zirconium hydroxide and iminodiacetate & [63] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._