A pot trial was conducted to assess the effectiveness of sepiolite, bentonite, and phosphate on the immobilization remediation of cadmium (Cd)-contaminated soils using a set of variables, namely, ...physiological traits, sequential extraction procedure, plant growth and Cd concentration, and soil enzymatic activities and microbial population. Results showed that superoxide dismutase and peroxidase activities in the leaves of Oryza sativa L. and catalase activities in soils were stimulated after applying the amendments. However, soluble protein contents in leaves and urease and invertase activities in soils were reduced from 7.1% to 31.7%, 1.0%–23.3%, and 21.1%–62.5%, respectively, compared with the control. Results of the sequence extraction procedures revealed that the exchangeable fraction of Cd in soils was mostly converted into carbonated-associated forms. The water soluble plus exchangeable fraction (SE) of Cd in soil decreased when treated with single and compound materials of sepiolite, bentonite and phosphate, which resulted in 13.2%–69.2% reduction compared with that of CK (control test). The amendments led to decreased Cd concentrations in roots, stems, leaves, brown rice, and rice hull by 16.2%–54.5%, 16.6%–42.8%, 19.6%–59.6%, 5.0%–68.2%, and 6.2%–20.4%, respectively. Higher bacterial and actinomycete amount indicated that remediation measures improved soil environmental quality. Composite amendments could be more efficiently used for the stabilization remediation of Cd contaminated soils with low Cd uptake and translocation in the plants and available contents of Cd in soil.
•The effect of sepiolite, bentonite and phosphate on Cd immobilisation is studied.•The amendments are effective in immobilizing Cd in soils.•The remediation measures improve soil quality.
The reduction of Cd and Pb accumulation in wheat grains grown on Cd and Pb contaminated alkaline soils is a pressing issue that needs to be solved. In this study, ferromanganese functionalized ...biochar (FM-BC) was used to remediate Cd and Pb contaminated alkaline soils and mitigate Cd and Pb accumulation in wheat grains. The immobilization capacity and mechanism of FM-BC were investigated by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) characterization and chemical analysis. Fe and Mn loaded on FM-BC improved the removal efficiencies of DTPA-Cd and DTPA-Pb in soil with DTPA-Cd removal of 22.99%− 52.04% (JM22) and 25.54%− 53.32 (AK58) and DTPA-Pb removal of 11.39%− 22.36% (JM22) and 5.38%− 13.00% (AK58). The FT-IR and XRD results indicated that the complexation and precipitation of Cd and Pb with the Fe-Mn oxides and the oxygen-containing functional groups on biochar surface stabilized the Cd and Pb in soil for the observation of Cd2Mn3O8, PbHPO4, CdCO3, and PbO2 on FM-BC isolated from contaminated soils. FM-BC with excellent adsorption capacity reduced the available Cd and Pb in the soil, therefore, thereby inhibiting the Cd and Pb accumulation in wheat. In the 3% FM-BC treatment, Cd and Pb contents in wheat grains were lower than 0.10 mg/kg and 0.20 mg/kg, respectively, reaching the national safety standards. And FM-BC increased the Fe, Mn, Na and Zn contents in wheat grains, and improved the growth and yield of wheat. These findings suggest that FM-BC can be considered a prospective and effective material for remediation of alkaline soils contaminated with Cd and Pb.
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•Fe-Mn oxides loaded on biochar enhanced the remediation of Cd and Pb in soil.•Mn oxides and CO32- on FM-BC formed stable complexes with Cd.•The oxygen-containing group on biochar effectively stabilized Pb to form PbO2.•FM-BC promoted Fe-Mn transport and reduced Cd and Pb content in wheat grains.
The current study investigated the remediation effects of sepiolite on soils artificially polluted with cadmium (Cd) using a set of variables (soil pH, available Cd content, plant Cd concentration, ...soil enzyme activities, and microorganisms). Results showed that increasing pH after the application of sepiolite favored the stabilization of Cd as well as displayed a significant negative correlation between soil pH and extractable Cd concentration (P<0.05). Sepiolite addition (0.5%–5%) significantly inhibited Cd absorption in spinach shoots, resulting in from 28.0% to 63.7%, from 29.4% to 67.8%, and from 17.2% to 72.1% reductions, respectively, when compared with unamended soil. At 1.25mgkg−1 Cd contamination, the concentrations of Cd in the edible portions of spinach at 1% sepiolite amendment were lower than 0.2mgkg−1 fresh weight, the maximum permissible concentration (MPC) for Cd in vegetables. MPC was met at higher concentrations of Cd (2.5 and 5mgkg−1) when the treatment of sepiolite was up to 5%. The changes in soil enzymatic activities and microbial numbers proved that certain metabolic recovery occurred after the application of sepiolite. Sepiolite-assisted remediation was shown to reduce successfully, on a field scale, Cd entry into the food chain.
► Stabilization is a valuable alternative technique for remediation of heavy metal polluted soils. ► Sepiolite is effective in immobilizing Cd in soils. ► Sepiolite has potential for success on a field scale decreasing Cd entry into the food chain.
Phytoextraction and in situ immobilisation are two of the most commonly used remediation techniques for Cd-contaminated farmland. In theory, phytoextraction followed by immobilisation can reduce the ...total Cd and available Cd contents of the soil, making it suitable for the remediation of heavily Cd-contaminated alkaline soil. However, the real remediation efficiency is uncertain, and it is also unknown whether phytoextraction affects subsequent wheat Cd accumulation. In this study, two seasonal pot experiments were conducted to determine the effects of S,S-ethylenediamine disuccinic acid (EDDS)-assisted Tagetes patula L. (T. patula) extraction, mercapto-palygorskite (MPAL) immobilisation, and the combination thereof on subsequent Cd accumulation in wheat. EDDS application significantly increased the Cd content in the subsequent-soil solution, but the EDDS-activated Cd could not be absorbed by wheat roots. T. patula extraction decreased the subsequent soil pH value by 0.1–0.2 pH units, increased the available Cd content by 0.19 mg/kg, but had no effect on subsequent wheat Cd accumulation. The Cd absorption capacity of wheat roots and the Cd translocation capacity of wheat stems to grains of high-Cd wheat were higher than that of low-Cd wheat cultivar. The application of MPAL had no effect on soil pH value, but significantly decreased soil available Cd and exchangeable Cd contents by 17.78–36.76% and 21.13–52.63%; it also increased the Fe/Mn oxide-bound Cd fraction by 14.02–64.00%. MPAL application decreased the wheat grain Cd concentrations from 0.51 to 0.13 mg/kg (high-Cd wheat) and 0.35 to 0.05 mg/kg (low-Cd wheat), but had no negative effect on Fe, Mn, Cu, and Zn elements. Compared with the single MPAL application treatments, the combination treatments had no inhibition effect on Cd accumulation in wheat. MPAL is an efficient amendment, and considering the remediation efficiency, stability, and time of these methods, the combination of MPAL application with a low-Cd accumulation wheat cultivar represents a suitable proposal to ensure the safe production of wheat in Cd-contaminated alkaline soil.
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•One season of phytoextraction did not reduce the Cd absorption of subsequent wheat.•The inhibition of wheat Cd uptake by immobilization was higher than phytoextraction.•Mercapto-palygorskite reduced the soil available Cd content without changing soil pH.•Mercapto-palygorskite can ensure the low-Cd wheat safe production in alkaline soil.
► Sepiolite was functionalized by nanotexturization in aqueous sepiolite gel and grafting in toluene with mercapto silane. ►
29Si NMR indicated that the chemical bonding took place between Si–OH ...within sepiolite and the methoxy group of silane. ► Nanotexturization produced a continuous coating on individual fibers compared with part coating in toluene. ► The surface modification can obviously increase the sorption capacities for Pb(II) and Cd(II).
In order to improve the sorption performance of sepiolite for heavy metals, sepiolite was functionalized by nanotexturization in aqueous sepiolite gel and surface grafting in toluene with mercaptopropyltrimethoxysilane. The pristine sepiolite and mercapto functionalized samples were characterized through XRD, FT-IR, SEM, TEM, TG, surface area analysis, solid state
29Si CP/MAS NMR. The chemical bonding took place between the silanol group within sepiolite and the methoxy group of mercaptopropyltrimethoxysilane. The reaction in aqueous gel produced a continuous coating of individual fibers of sepiolite compared with part grafting on the external surface in toluene. After surface modification, the surface areas decreased due to the bulk size of the mercapto ligand, but the crystal structure did not change obviously, and the stretching of mercapto could be detected by FT-IR. The sorption of Pb(II) and Cd(II) on the samples were studied in batch experiments and it was found that the surface modification can obviously increase the sorption capacities for Pb(II) and Cd(II). The mercapto functionalized sepiolite could provide a potential remedy for heavy metal contamination in soils and water.
The effects of immobilization remediation of Cd-contaminated soils using sepiolite on soil pH, enzyme activities and microbial communities, TCLP-Cd （toxicity characteristic leaching procedure-Cd） ...concentration, and spinach （Spinacia oleracea） growth and Cd uptake and accumulation were investigated. Results showed that the addition of sepiolite could increase soil pH, while the TCLP-Cd concentration in soil was decreased with increasing sepiolite. The changes of soil enzyme activities and bacteria number indicated that a certain metabolic recovery occurred after the sepiolite treatments, and spinach shoot biomass increased by 58.5%-65.5% in comparison with the control group when the concentration of sepiolite was ~ 10 g/kg. However, the Cd concentrations in the shoots and roots of spinach decreased with an increase in the rate of sepiolite, experiencing 38.4%-59.1% and 12.6%--43.6% reduction, respectively, in contrast to the control. The results indicated that sepiolite has the potential for success on a field scale in reducing Cd entry into the food chain.
Mg
2Al layered double hydroxide (Mg
2Al LDH) samples intercalated with diethylenetriaminepentaacetic acid (DTPA) (Mg
2Al–DTPA LDH in short) were prepared by co-precipitation and well characterized by ...XRD, SEM, TEM, IR and XPS. The sorption behaviors and mechanisms of Pb
2+ on the samples were studied in detail while Mg
2Al–Cl LDH as a reference. The maximum sorption amounts were about 170 and 40
mg/g for Mg
2Al–DTPA LDH and Mg
2Al–Cl LDH, respectively. Langmuir isotherm was proved to describe the sorption data better and pseudo-second order kinetic model could fit the sorption kinetic processes better for both LDHs samples. The mechanisms of Pb
2+ sorption on Mg
2Al–DTPA LDH can be explained by Pb–DTPA chelating while that for Mg
2Al–Cl LDH is primary surface-induced precipitation. The Mg
2Al–DTPA LDH could provide a potential remedy for heavy metal contamination in soils and water.
Since the National Fitness has become a national strategy, people’s enthusiasm for fitness has also been increasing. When winter comes, the outdoor temperature becomes unsuitable for people to carry ...out exercise activities. Therefore, more community residents choose underground garages as a place for fitness activities. Due to the frequently entry and exit of vehicles and ventilation restrictions in the underground garage, whether the internal air quality in an underground garage meets the requirements of personnel activities remains to be studied. In this study, an underground garage in a residential area of Jinan was tested. The parameters involved CO
2
, CO, PM2.5, temperature and relative humidity. Select areas where people often gather for measurement. According to the test results, the distribution of CO
2
, CO, PM2.5, temperature and relative humidity in the underground garage were quantitatively analyzed. It is found that the air quality in some areas of the underground garage is poor, and long-term activities in this environment will affect people’s health. To solve this problem, in this study, the area with relatively good air quality in the underground garage is found to provide personnel activities, and the optimization measu.res of winter ventilation in the underground garage were put forward.
The coordinated development of higher education and the industrial economy is global, relevant, comprehensive, and practical. The scientific understanding and accurate evaluation of the coordinated ...development of higher education and industrial economy are related to the government's macro‐layout of educational structure and the macro‐guidance of industrial structure. Starting from the strategic height of the development of industrial economic structure and higher education structural system, this article, with the aid of the Internet of Things analysis platform, draws lessons from the research results of the coordinated development of education and industry at home and abroad, puts forward an evaluation model of the coordinated development of higher education and industrial economy based on fuzzy neural network, and reveals the structure of higher education and industrial economy through evaluation and prediction. Comprehensive theoretical prediction and fuzzy analysis of the general and special relations and mechanisms of the coordinated development of higher education and industrial economic structure make the cooperative model of higher education and local industry more transparent and provide theoretical guidance for the coordinated development of higher education and local industrial structure.
From the strategic height of the development of industrial economic structure and higher education structure system, this paper builds an information collection system with the help of the Internet of things analysis platform. Based on the data, an evaluation model of coordinated development of higher education and industrial economy based on fuzzy neural network is proposed. Comprehensive theoretical prediction and fuzzy analysis of the general and special relations and mechanisms of the coordinated development of higher education and industrial economic structure make the cooperative model of higher education and local industry more transparent and provide theoretical guidance for the coordinated development of higher education and local industrial structure.
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