The importance of presoaking to improve the efficiency of MgCl2-modified and non-modified biochar in the adsorption of cadmium.

Investigating the effect of presoaking, as one of the most important physical factors affecting the adsorption behavior of biochar, on the adsorption of heavy metals by modified or non-modified biochar and presoaking mechanism is still an open issue. In this study, the water presoaking effect on the kinetics of cadmium (Cd) adsorption by rice husk biochar (produced at 450 °C, B1, and at 600 °C, B2) and the rice husk biochar modified with magnesium chloride (B1 modified with MgCl2, MB1, and B2 modified with MgCl2, MB2) was investigated. Furthermore, the effect of pH (2, 5, and 6), temperature (15, 25, and 35 °C), and biochar particle size (100 and 500 µm) on the kinetics of Cd adsorption was also investigated. Results revealed that the content of Cd adsorbed by the presoaked biochar was significantly higher than that by the non-presoaked biochar. The highest Cd adsorption capacity of MB2 and MB1 was 98.4 and 97.6 mg g-1, respectively, which was much better than that of B1 (7.6 mg g-1) and B2 (7.5 mg g-1). The modeling of kinetics results showed that in all cases pseudo-second-order model was well-fitted (R2>0.99) with Cd adsorption data. The results also indicated that the highest Cd adsorption values were observed at pH 6 in presoaked MB1 with size of 100 µm as well as at the temperature of 35 °C in presoaked MB2, indicating the optimum conditions for this process. The presoaking process was not affected by biochar size and pH, and the difference in adsorbed Cd content between presoaked biochars and non-presoaked ones was also similar. However, the temperature had a negative effect on presoaking. The presoaking process decreased micropores (<10 µm) in the biochars but had no effect on biochar hydrophobicity. Therefore, presoaking, which could significantly increase Cd adsorption and reduce equilibrium time by reducing the micropores of biochars, is suggested as an effective strategy for improving the efficiency of modified biochars or non-modified ones in the adsorption of contaminants (Cd) from aquatic media.

Insight into the role of magnetic nutrient solution on leaf morphology and biochemical attributes of Rasha grapevine (Vitis vinifera L.).

The growth, development, and morphology of plants are extremely affected by many internal and external factors. In this regard, plant nourishing solutions take the most impact. Nowadays, the magnetization of nutrient solutions has been recommended as a promising eco-friendly approach for improving the growth and development of plants. This study was designed to explore the potential of magnetic nutrient solutions in altering morphometric characteristics as well as some physiological and nutritional attributes of Rasha grapevines. Magnetic treatments included magnetized nutrient solution (MagS) and pre-magnetized water completed with nutrients (MagW + S) at magnetic field intensities (0.1 and 0.2 T). According to the results, the most considerable changes in leaf shape and size as well as fresh and dry weights were observed in the plants treated with MagS at 0.2 T. Also, MagS 0.2 had a significant effect on increasing photosynthetic pigments, content of total soluble carbohydrates and protein, and activity of antioxidant enzymes. The content of TNK, K, P, Fe, and Cu was considerably amplified by MagW + S 0.2. Overall, the magnetic solutions had favorable influences on physiological, nutritional state, and leaf morphology of grapevines possibly through alerting water and solution properties, mineral solubility, and phytohormones signalling.

Digital mapping of potentially toxic elements enrichment in soils of Urmia Lake due to water level decline.

Anthropogenic activities, in addition to climate change caused the drying of Urmia Lake in Iran, since 2005. Dust storms blown from the dried lakebed have created serious environmental hazards in adjacent areas. These crises would jeopardise achieving United Nations Sustainable Development Goals (UN SDGs) and emphasise the need for evaluating the spatial distribution of soil enrichment of potentially toxic elements (PTEs) (As, Cr, Cu, Ni, Pb and Zn). Conventional assessment would require a costly sampling method to map potentially polluted areas. Digital soil mapping (DSM) has proved to be a cost-efficient method for soil mapping, however its application in mapping enrichment of PTEs in soil is still lacking. This study aims to map and project the potential pollution of PTEs in the Urmia Lake area using digital mapping techniques and Landsat-8 OLI satellite images. A total of 129 surficial soil samples were collected as ground control. Enrichment factors (EFs) of PTEs and the Modified Pollution Index (MPI) were spatially predicted using two machine learning models. Covariates were derived from a suite of Landsat-8 spectral indices. The bootstrapping method was used to analyse the uncertainties. The results showed that Random Forests performed well in estimating EFs of several PTEs. Spectral indices using NIR and SWIR bands were key to predict these PTEs and MPI. The digital maps demonstrated that the study area was enriched with As, Cu and Pb at moderate to significant levels. Regions under the lower ecological level (elevation <-1274 m) had significantly larger enrichment than those of higher elevation. Based on MPI, 43% of the area was categorised as moderately polluted, and 31% of the area was moderately-heavily polluted. Possible sources of PTEs were discharges from farmlands, landfills, and industries. Our results revealed that the Urmia Lake desiccating has caused severe environmental challenges and needs immediate restoration.

Eliciting effects of magnetized solution on physiological and biochemical characteristics and elemental uptake in hydroponically grown grape (Vitis vinifera L. cv. Thompson Seedless).

Hydroponic systems are used as an instrument to solve a wide range of environmental concerns such as climate change, drought, and soil fertility. Effective growing media are vital to the hydroponically plant cultivation system. Plant reaction to the growing media treated by magnetic fields, as an innovative technology, should be investigated since the magnetic field can constitute a non-toxic and non-residual stimulus. In the current study, some physiological and biochemical responses (leaf fresh and dry weight, biomass, leaf area, plant height, stem diameter, photosynthesis pigments, carbohydrates, protein, and proline contents and peroxidase activity (POD)) and elemental uptake of hydroponically grown grapevines to the magnetic solutions (with 0.1 and 0.2 T intensities) were evaluated. The solutions were magnetized in two ways: 1) solutions magnetized after preparing (S 0.1 and S 0.2), and 2) salts were added to the pre-magnetized waters (W + S 0.1 and W + S 0.2). The results revealed that magnetic treatments had effect on increasing of leaf elements uptake including N+, P+, K+, Ca2+, Fe2+, and Zn2+. Magnetic treatments also stimulated chlorophyll content, leaf extension, leaf fresh and dry weight, and biomass accumulation. Carbohydrates content and POD were promoted in grapes treated by S 0.1 and W + S 0.1 than control. W + S 0.1 and S 0.2 increased the proline and protein content, respectively. The findings proposed that solution magnetization application could act as an elicitor agent to mimic the stress condition, but at the lesser level resulting in activation of grape physiological and biochemical processes and elemental state through stress-related responses.

CrVI reductive transformation process by humic acid extracted from bog peat: Effect of variables and multi-response modeling.

The present paper reports the efficiency of bog peat-derived humic acid (HA) in the reductive removal of hexavalent chromium (CrVI) from aqueous solution as affected by solution pH, the dose of FeIII and reaction time (numeric variables) and light irradiation (categorical variable). A three-level Box-Behnken design (BBD) applied to design experimental matrix, model the effects and interactions of variables on four determined responses (residual concentration of dissolved CrVI, dissolved CrIII, dissolved FeII and total CrVI) and optimize the experimental conditions for highest CrVI removal efficiency (CrVI RE). Reaction mechanisms are also well discussed. Regression models were developed and analyzed by the ANOVA test and models determination coefficient R2. Obtained models were significant (F values > 13) and an excellent relationship between experimental and predicted responses (R2: 98.1-99.6%) was observed. The optimum conditions were established corresponding to the residual concentration of dissolved CrVI as an index for CrVI removal efficiency (RE). In the dark system, the highest CrVI RE (98.1%) was obtained under the following conditions: pH = 1, reaction time = 7 d and FeIII dosage = 0.110 mM. In the light-irradiated system, the optimal CrVI RE of 98.3% was observed in pH = 1, reaction time = 5 d and FeIII dosage = 0.075 mM. Almost all reduced CrIII remained in the solution even at high pH value. No adsorption or precipitation of CrIII on the HA surface at pH 5 was confirmed by surface analyses of HA using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM).

Tolerance to heavy metals in filamentous fungi isolated from contaminated mining soils in the Zanjan Province, Iran.

In the present study the population of fungi inhabiting metal contaminated soil samples from lead-zinc mining area was investigated, and their tolerance and biosorption capacity towards Cd, Pb, Zn and Cu were evaluated. Fungal species, including Acremonium persicinum, Penicillium simplicissimum, Seimatosporium pistaciae, Trichoderma harzianum, Alternaria chlamydosporigena and Fusarium verticillioides were isolated. Fungal tolerance was determined by measuring of the "Minimum Inhibitory Concentration", after exposure to increasing concentrations of heavy metal chlorides. Among the test fungi, Trichoderma harzianum was the most tolerant against Cd, Pb and Cu. The Heavy metal content in the fungal biomass was quantified after combustion. The calculated total sorption of heavy metals showed that Acremonium persicinum and Penicillium simplicissimum had the highest accumulation of Zn and Cu, respectively. The data presented in this study should help to use the accumulation potential of some of those fungal species examined for bioremediation of contaminated soils.