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Wetland plants play a crucial role in regulating soil geochemistry, influencing heavy metal (HM) speciation, bioavailability, and uptake, thus impacting phytoremediation potential. We hypothesized that variations in HM biogeochemistry within estuarine soils are controlled by distinct estuarine plant species. We evaluated the soils (pH, redox potential, rhizosphere pH, HM total concentration, and geochemical fractionation), plant parts (shoot and root), and iron plaques of three plants growing in an estuary affected by Fe-rich mine tailings. Though the integration of multiple plant and soil analysis, this work emphasizes the importance of considering geochemical pools of HM for predicting their fate. Apart from the predominance of HM associated with Fe oxides, Typha domingensis accumulated the highest Cr and Ni contents in their shoots (> 100 mg kg -1 ). In contrast, Hibiscus tiliaceus accumulated more Cu and Pb in their roots (> 50 mg kg -1 ). The differences in rhizosphere soil conditions and root bioturbation explained the different potentials between the plants by altering the soil dynamics and HM's bioavailability, ultimately affecting their uptake. This study suggests that Eleocharis acutangula is not suitable for phytoextraction or phytostabilization, whereas Typha domingensis shows potential for Cr and Ni phytoextraction. In addition, we first showed Hibiscus tiliaceus as a promising wood species for Cu and Pb phytostabilization., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

Due to its abundance and role as a micronutrient for plants iron (Fe) is rarely perceived as a contaminant. However, in redox active environments, Fe bioavailability increases sharply representing an environmental risk. In this study, a recent catastrophic mining dam failure is used as a field framework to evaluate the role of wetland plants on Fe biogeochemistry and assess their potential for phytoremediation programs. To achieve these objectives, a Fe geochemical partitioning and the concentration of Fe in different plant compartments (iron plaque on root surfaces, roots, and leaves) were determined in two sites vegetated by different wetland species. Soils exhibited contrasting Fe biogeochemical dynamics. Lower pseudo-total contents and more reactive Fe oxides were observed in the soil vegetated by Typha domingensis. Iron plaque was present on both species but more concentrated in Fe in T. domingensis. T. domingensis showed Fe shoot concentrations (3874 mg kg -1 ) 10-fold higher than in Hibiscus tiliaceus, which prevented Fe absorption through iron plaque formation and root accumulation. In conclusion, contrasting biogeochemical effects on Fe (e.g., rhizosphere acidification) lead to different phytoremediation abilities. T. domingensis showed a high potential for Fe phytoremediation on sites affected by Fe-enriched wastes and should be tested in assisted phytoremediation approaches., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The management of initial planting density can be a strategy to increase barium phytoextraction from soil, reducing the time required for soil decontamination. To delimit the ideal planting density for barium (Ba) phytoremediation using Typha domingensis, we conducted a 300-day experiment in an area accidentally contaminated with barite. Four initial planting densities were tested: 4, 8, 12, and 16 plantsm -2 (D4, D8, D12, and D16 treatments, respectively). Plant development was evaluated periodically, and the phytoextraction efficiency was determined at the end of the trial. The initial planting density affected Ba phytoremediation by T. domingensis monoculture. Phytoextraction potential was better represented by the mass-based translocation factor (mTF) than the concentration-based translocation factor. D16 promoted the highest final number of plants and biomass production, but the mass of Ba in the aerial part did not differ among D8, D12, and D16. D4 resulted in more Ba accumulated belowground than aboveground (6.3 times higher), whereas D12 and D16 achieved the greatest mTFs. Higher absorption of Ba from soil can be achieved using less T. domingensis individuals at the beginning of the treatment (D4 and D8) but with high accumulation in belowground tissues. We conclude that the D8 density is considered the most appropriate if considering the phytoextraction potential and field management facilitated using fewer plants., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Barite (BaSO 4 ) is a component of drilling fluids used in the oil and gas industry and may cause barium (Ba) contamination if it is spilled onto flooded soils. Under anoxic soil conditions and low redox potential, sulfate can be reduced to a more soluble form (sulfide), and Ba can be made available. To design a solution for such environmental issues, a field study was conducted in a Ba-contaminated flooded area in Brazil, in which we induced Ba phytoextraction from the management of the planting density of two intercropped macrophytes. Typha domingensis and Eleocharis acutangula were grown in four initial planting densities: "Ld" (low density: 4 and 32 plants m -2 ); "Md" (medium density: 8 and 64 plants m -2 ); "Hd" (high density: 12 and 128 plants m -2 ); "Vhd" (very high density: 16 and 256 plants m -2 ). Vhd produced the largest number of plants after 300 days. However, the treatments did not differ in terms of the amount of biomass. The increments in the initial planting density did not increase the Ba concentration in the aerial part. The greatest Ba phytoextraction (aerial part + root) was achieved by Ld treatment, which removed approximately 3 kg of Ba ha -1 . Md and Vhd treatments had the highest Ba translocation factors. Because more plants per area did not result in greater Ba phytoextraction, a lower planting density was recommended for the intercropping of T. domingensis and E. acutangula to promote the phytoextraction of barium, due to possible lower implementation costs in contaminated flooded environments., Competing Interests: Declaration of Competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

In anoxic environmental conditions and with a drastic reduction of the redox potential, the barium sulphate used in petroleum drilling fluids becomes a hazard to the ecosystem. A field study was conducted in Brazil in an area with a history of accidental Barium (Ba) contamination to evaluate the role of frequent plant cutting on phytoremediation. The plant species Typha domingensis and Eleocharis acutangula, cultivated in a combined plantation, were subjected to four different cut frequencies: every 90 days (four cuts), 120 days (three cuts), 180 days (two cuts), or 360 days (one cut). The total amount of Ba extracted from the soil by the plants was evaluated for each treatment and at different soil depths Overall, total Ba in the soil decreased the most dramatically for cut frequencies of 120 (37.83%) and 180 (47.73%) days at 0-0.2 m below the surface, and with cut frequencies of 120 (51.98%) and 360 (31.79%) at 0.2-0.4 m depth. Further, total Ba in the plant biomass was greatest in the 120 and 360-days frequency groups. Thus, cuts at intervals of 120 days or more are associated with high levels of Ba in the plant tissue and a decrease of soil Ba., (Copyright © 2018 Elsevier B.V. All rights reserved.)

This study evaluated remediation of the herbicide sulfentrazone in soils with three different mineralogies (kaolinite, hematite, and gibbsite) and three remediation sulfentrazone treatments (Canavalia ensiformis L., Crotalaria juncea L., and natural attenuation). This study was conducted in a factorial scheme, in triplicate with randomized block design. Sulfentrazone was applied at 0 and 400 g ha -1 . We analyzed sulfentrazone residue in the soils by high-performance liquid chromatography and confirmed the results with bioassays of Pennisetum glaucum. Herbicide movement was greater in the kaolinitic soil without plant species. The retention of herbicide in the kaolinitic soil occurred in larger quantities in the 0-12 cm layer, with higher levels found in the treatments with plants. In the hematitic soil with C. juncea, all applied herbicides were concentrated in the 0-12 cm layer. In the other hematitic soil treatments, sulfentrazone was not detected by chemical analysis at any soil depth, although in many treatments, it was detected in the bioassay. Phytoremediation was more efficient with C. ensiformis grown in gibbsitic soil, reducing the sulfentrazone load by approximately 27%. Natural attenuation was more efficient than phytoremediation in oxidic soils due to soil pH and texture soils favored microbial degradation of the compound. Highlights The influence of soil mineralogy of herbicide sulfentrazone retention was evaluated. Canavalia ensiformis and Crotalaria juncea were evaluated as phytoremediation plants. Kaolinite soils presented great movement of sulfentrazone in the soil. Natural attenuation is more efficient in oxide soils than phytoremediation.