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Soil plays an important role in controlling the biogeochemical cycling of nutrients and contaminants in the environment. Reliable analytical techniques are critical to better understand their transformation in soils. Diffusive Gradients in Thin-films technique (DGT) is one of such techniques, which has become increasingly popular in soil research since 1998. Undeniably, DGT attracts increasing attentions from multidisciplinary researchers worldwide. This is mainly due to its inherent merits, including ease of use, in situ measurement, and biomimetic applications. Further, four important aspects of DGT applications in soil research were summarized. They include: 1) chemical speciation, 2) bioavailability measurement, 3) desorption kinetic modeling, and 4) interfacial process mapping of nutrients and contaminants, with main focus on the progresses achieved during the past five years. In short, DGT is effective in studying the biochemical behaviors of nutrients (e.g., phosphate and nitrate), trace elements (e.g., Cd, Ni, Zn, Cu, Pb, and As), and polar organic compounds (e.g., antibiotics, pesticides, and bisphenols) in soils. Toward the end, we proposed several aspects of applying DGT as a versatile tool in soil research. [ABSTRACT FROM AUTHOR]

The behaviors of antimony (Sb) and arsenic (As) in plants are different, though they are chemical analogs. Here, we examined the Sb uptake and speciation in two As-hyperaccumulators P. vittata and P. cretica , which were exposed to 0.5 or 5 mg L-1 antimonate (SbV) or antimonite (SbIII) under hydroponics for 7 d. Both plants grew better under Sb exposure, especially for P. cretica. The biomass of P. cretica roots increased by 29–46% after exposing to SbV, possibly due to increased S. Further, the Sb content in P. vittata was 17–93% greater than P. cretica , with 2–3 times more SbIII than SbV in both plants and > 92% Sb being concentrated in the roots, showing limited translocation. Under SbV exposure, SbV was dominant in P. vittata roots at 86–94%, while SbIII was predominant in P. cretica roots at 36–95%. P. cretica 's stronger reducing ability than P. vittata may be due to arsenate reductases HAC1 and ACR2 , which were upregulated in both plants. In short, while effective in Sb accumulation, it is mostly concentrated in the roots for both plants. The differences in their accumulation and speciation may help to better understand Sb behaviors in other plants. [Display omitted] • P. vittata & P. cretica grew better under Sb exposure probably due to increased S uptake. • As-hyperaccumulator P. vittata accumulates 17–93% more Sb than P. cretica. • 36–95% SbIII was in P. cretica roots while 86–94% SbV was in P. vittata roots. • SbV was reduced to SbIII in P. cretica roots via upregulating arsenate reductases. [ABSTRACT FROM AUTHOR]

Arsenic-hyperaccumulator Pteris vittata exhibits remarkable absorption ability for chromium (Cr) while beneficial element selenium (Se) helps to reduce Cr-induced stress in plants. However, the effects of Se on the Cr uptake and the associated mechanisms in P. vittata are unclear, which were investigated in this study. P. vittata plants were grown for 14 days in 0.2-strength Hoagland solution containing 10 (Cr 10) or 100 μM (Cr 100) chromate (CrVI) and 1 μM selenate (Se 1). The plant biomass, malondialdehyde contents, total Cr and Se contents, Cr speciation, expression of genes associated with Cr uptake, and Cr subcellular distribution in P. vittata were determined. P. vittata effectively accumulated Cr by concentrating 96–99% in the roots under Cr 100 treatment. Further, Se substantially increased its Cr contents by 98% to 11,596 mg kg−1 in the roots, which may result from Se's role in reducing its oxidative stress as supported by 27–62% reduction in the malondialdehyde contents. Though supplied with CrVI, up to 98% of the Cr in the roots was reduced to insoluble chromite (CrIII), with 83–89% being distributed on root cell walls. Neither Cr nor Se upregulated the expression of sulfate transporters PvSultr1;1 − 1;2 or phosphate transporter PvPht1;4 , indicating their limited role in Cr uptake. P. vittata effectively accumulates Cr in the roots mainly as CrIII on cell walls and Se effectively enhances its Cr uptake by reducing its oxidative stress. Our study suggests that Se can be used to enhance P. vittata Cr uptake and reduce its oxidative stress, which may have application in phytostabilization of Cr-contaminated soils. [Display omitted] • P. vittata effectively accumulates Cr by concentrating 96–99 % in the roots at 100 μM CrVI. • Selenate promotes Cr uptake by 98% to 11,596 mg kg-1 in the roots at 100 μM CrVI. • Selenate reduces its oxidative stress as evidenced by 27–62% decrease in its MDA. • 94–99% CrVI is reduced to CrIII in the roots, with 83–89% on cell walls. [ABSTRACT FROM AUTHOR]