In this study, 1-year greenhouse pot experiments were conducted to investigate the effect of Phyllobacterium myrsinacearum strain RC6b on the growth and phytoextraction efficiency of heavy metals by a Zn/Cd hyperaccumulator (Sedum alfredii) and alfalfa (Medicago sativa L.) in a co-cropping system. The treated soil sample was collected from a land reclamation site of Pb/Zn mine tailings in Hanzhong City, Shaanxi Province, China. Results showed that, with the inoculation of RC6b, shoot biomass yields of plants were significantly increased by 15.9–20.2 % and 17.2–19.9 % for alfalfa and S. alfredii, respectively, compared to the non-inoculated plants. Biomass yield of alfalfa was higher than that of S. alfredii. RC6b inoculation increased metal concentrations by 18.6–31.2 % (Pb), 23.8–37.5 % (Cd), and 26.4–38.3 % (Zn) in S. alfredii shoots, and by 13.8–24.7 % (Pb), 15.8–26.6 % (Cd), and 24.8–35.6 % (Zn) in alfalfa shoots, respectively. After six consecutive harvests of shoots, RC6b inoculation increased the phytoextraction efficiencies of Pb, Cd, and Zn by shoots of the co-planting system by 16.9, 46.3, and 60.9 %, respectively. Nevertheless, phytoextraction of Cu was not improved by RC6b inoculation. In the co-planting/inoculation system, the percentage removals of metals from soil by the plant shoots were 6.09, 30.97, 11.10, and 1.68 % for Pb, Cd, Zn, and Cu, respectively, after six harvests of shoots. Inoculation with RC6b significantly increased the soil microbial activity and the carbon utilization ability of the soil microbial community.

The impact of Fe₂O₃and TiO₂nanoparticles (NPs) on the removal of trichloroethylene (TCE) in a granular activated carbon (GAC)-fixed bed adsorber was investigated in the presence of humic acid (HA). The surface charges of GAC and NPs were obtained in the presence and absence of HA with the NPs behaving similarly. Isotherm and column studies were conducted in the presence and absence of the NPs and HA. NPs had no effect on TCE adsorption during isotherm studies. However, in the column studies conducted with organic-free water, the presence of NPs resulted in a reduction in TCE capacity most likely due to pore blockage by aggregating NPs. This effect was completely mitigated in the presence of HAs that prevented an association between the GAC and the NPs, and between NPs. The presence of HA provided a high negative charge on the GAC and on the nanoparticles resulting in repulsive forces between the GAC and the NPs, and between NPs, thereby preventing pore blockage. Both Fe₂O₃and TiO₂NPs demonstrated that charge characteristics are more important than chemical characteristics. Pore-size distribution of the fresh and the spent GAC confirmed the adsorption data but points to some HA and NP interaction with the carbon.

A 1D reactive model is developed to simulate the EDTA chelating process in a lead (Pb)-contaminated saturated soil. The model is implemented using a multistep numerical approach in order to avoid numerical diffusion assuring at the same time the algorithm stability. The model takes into account first-order reactions where the lead species are splitted into three fractions: C₁(easily mobilized lead), C₂(lead associated with iron and manganese oxides), and C₃(lead bound to organic matter and in the residual fraction). Two different mobilization kinetics (“slow” and “fast”) are considered for each fraction. The model was therefore calibrated and validated using laboratory experimental data. A sequential extraction procedure was conducted to evaluate the lead mobilization due to the EDTA flushing through the column and to take into account the different soil fraction at which the metal is bound. Several remediation scenarios are used to show the suitability of the model to provide information and knowledge of the best EDTA feed and flux conditions for the lead extraction from soil. The model can therefore be considered as a tool to know in advance the performances of a remediation treatment and to optimize the extraction process minimizing the chelating agent costs and its effects on the soil.

The development of nanotechnology has increased the amount of nanoparticles in the environment inducing pollution. In view of increasing amounts, their toxicity assessment becomes important. Aluminum oxide nanoparticles (Al₂O₃ NPs) have a wide range of applications in industry. The present study aims to reveal the time-dependent (24, 48, 72, 96 h) and dose-dependent (0, 5, 25, 50 mg/ml) effects of 13-nm-sized Al₂O₃ NPs on an agronomic plant wheat (Triticum aestivum L.) roots correlating with the appearance of various cellular stress responses. Al₂O₃ NPs reduced the root elongation by 40.2 % in 5 mg/ml, 50.6 % in 25 mg/ml, and 54.5 % in 50 mg/ml after 96 h. Histochemical analysis revealed lignin accumulation, callose deposition, and cellular damage in root cortex cells correlating the root elongation inhibition. Although the nanoparticle application decreased the total protein content with respect to control after 96 h, the peroxidase activity increased significantly which is considered to be one of the oxidative stress factors. Moreover, agarose gel results revealed that Al₂O₃ NPs induced DNA fragmentation being one of the important markers of programmed cell death. In conclusion, direct exposure to Al₂O₃ NPs leads to phytotoxicity significantly in wheat roots culminating in morphological, cellular, and molecular alterations.

Road dust organic matter plays a vital role in mobilization of contaminants. This study investigated and characterized organic matter (OM) presents in road dust particles of various sizes. Road dust samples were collected from an industrialized city of Ulsan, Republic of Korea and fractionated into four groups: <75, 75–180, 180–850, and 850–2000 μm. OM extracted from the four fractions was characterized by excitation-emission matrix fluorescence and analyzed by parallel factor analysis (PARAFAC). The PARAFAC identified four major fluorophore components (C1–C4). These components were related to microbial humic-like, anthropogenic organic, fulvic-like, and low molecular weight OM contributed by anthropogenic activity, respectively. There were subtle changes in specific OM composition with change in particle size. The finest fraction contained more microbial humic-like substances whereas the coarse fraction was enriched with fulvic acid. The OM in two fractions (75–180 and 180–800 μm) showed dual characteristics. Our findings demonstrated that PARAFAC approach can assist to assess the accumulation of pollutants in road dust.

Thermal stability is one of the most important indexes determining the practical applications of selective catalytic reduction (SCR) catalysts. The influence of typical alkali element on the thermal stability of industrial V₂O₅-WO₃/TiO₂ catalyst is first reported in this work. The activity of the sample is measured, and physicochemical properties are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectrum, field emission scanning electron microscope (FE-SEM), N₂ adsorption-desorption, temperature programmed desorption of NH₃ (NH₃-TPD), and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). The sintering and anatase-to-rutile phase transformation at high temperature will cause deactivation of SCR catalyst, and low concentration of K can increase the thermal stability. Under the same thermal treatment, the activity (380 °C) of sample deposited by K is more than three times higher than that of the fresh sample without K. Aggregation of vanadia in conventional SCR catalyst favors the sintering and anatase-to-rutile phase transformation of catalysts. Incorporation of K can modify the structure of partial V-OH and form V-OK, which hinders the aggregation of vanadia species and further increases the thermal stability of catalysts.

Panax notoginseng is a well-known phytomedicine used all over the world. In recent years, a certain As contamination of the herb appeared in its planting area due to elevated soil As concentration. We investigated the feasibility of intercropping with Pteris vittata, an As hyperaccumulator, on the reduction of As accumulation in Panax notoginseng and As transfer and transformation in soil-plant system. Results showed that, intercropping could decrease the As concentrations of Panax notoginseng by 9.1–54.3 and 30.9–54.3% and increase the biomasses by 40.7–211.6 and 2.1–153.3 %, respectively, in the H-As (soil As 400.4 mg/kg) and M-As (soil As 85.3 mg/kg) treatments. Compared to the monoculture, the ratio of the nonspecifically adsorbed As in soil was decreased by 17.8 and 34.3 %, and the As transfer factor of Panax notoginseng was increased by 22.2 and 66.3 %, respectively, in H-As and M-As treatments. For As speciation, As(III) and As(V) could be detected at the same time only in root and xylem sap of Panax notoginseng in the H-As treatment, and intercropping could increase the ratios of As(III) by 97.8 and 72.4 %, respectively. In summary, intercropping with Pteris vittata is an applicable approach to reduce the As accumulation in Panax notoginseng.

In this work, metal sorption onto grape stalks waste structural compounds and extractives has been studied for determining their role in Cr(VI), Cu(II) and Ni(II) metal sorption. For this purpose, a sequential extraction of extractives and other compounds from the lignocellulosic material has been carried out. The resulting solid samples obtained in the different extraction processes were used as sorbents of Cr(VI), Cu(II) and Ni(II). Sorption results were discussed taking into account the elemental composition and polarity of the solid extracts. Results indicated that tannins and polyphenols are involved in chromium reduction and sorption. Lignin and celluloses are involved in chromium, Cu(II) and Ni(II) sorption. FTIR analysis confirmed the involvement of lignin moieties in the studied metal ions sorption by grape stalks waste. This study presents a new approach on metal sorption field as the knowledge of the role of the sorbent chemical compounds is essential to determine the key sorbent compounds in the sorption process.

The Rio Santiago in the Cordillera Negra of Peru is severely contaminated by acid mine drainage in its headwaters. In a strongly acid stream, at about 3800 m above sea level (masl), microterraces were found with terrace walls built up of dead moss, with encrustations and interstitial fine, creamy sediment. The stream water was turbid due to the presence of similar suspended sediment, which also occurred as a thin basal layer in inter-rim basins. The moss was identified as the rare bryophyte Anomobryum prostratum (Müll. Hal.) Besch. Chemical and mineralogical analyses show that green, living parts of the moss are gradually coated by Al/Fe (hydr)oxides, inducing their senescence and death. The necromass is covered by creamy crusts through precipitation of schwertmannite-type material from the stream water and simultaneous ‘capture’ of fine sediment. The latter consists of a mixture of precipitate and fine detrital primary minerals. These processes are held responsible for the formation of the microterraces, which regarding their composition and environment seem to be unique. Remarkable is the high As content of the creamy crusts and sediment, attributed to strong sorption of As, whereas its solute concentration is relatively low. This calls for more attention to suspended fine sediment in the assessment of environmental risks of stream water use. Lastly, the results raise serious doubts about the use of aquatic bryophytes as bioindicator for chemical pollution in acid mine drainage-polluted streams.

This study investigates the removal of Cu(II) from aqueous solutions by biosorption-flotation as a function of several parameters, such as collector type, pH, molar ratio, air pressure, time, and initial metal concentration. Dissolved air flotation was applied as a polishing technique for the additional purification of the effluent resulted after biosorption. The obtained results were supported by the physicochemical characteristics of the surfactants used as flotation reagents and suggested that cetylpyridinium bromide (CPB) was the optimum collector for Cu(II) ion removal. Cu(II) removal efficiency exhibited a maximum of 97.09 % in the following operating conditions: biosorption pH 4.5, Cu(II) initial concentration 250 mg/L, biosorbent dosage 0.5 % w/v, agitation rate 200 rpm, temperature 20 °C, biosorption time 30 min, flotation pH 9, air pressure 4.5 × 10⁵ Pa, dilution ratio 3:1, flotation time 10 min, collector CPB 0.01 M, and molar ratio collector/Cu(II) 5 × 10⁻¹:1. The experimental data confirmed that the flotation stage contributed to the optimization of the overall separation process.