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Soil lead (Pb) contamination is one of the environmental problems facing the modern world. Sources of Pb in soil include industrial activities such as mining and smelting processes, agricultural activities such as application of insecticide and municipal sewage sludges, and urban activities such as use of lead in gasoline, paints, and other materials. Phytoremediation is the direct use of living green plants and is an effective, cheap, non-invasive, and environmentally friendly technique used to transfer or stabilize all the toxic metals and environmental pollutants in polluted soil or groundwater. Current work in this area is invested in elucidatingmechanisms that underpin toxic-metal tolerance and detoxification mechanisms. The present study aims to gain insight into themechanisms of Pb tolerance in T. qataranse by comparative proteomics. MALDI-TOF/MS and in silico proteome analysis showed differential protein expression between treated (50 mg kg-1 Pb) and untreated (0 mg kg-1 Pb) T. qataranse. A total of eighty-six (86) differentially expressed proteins, most of which function in ion and protein binding, antioxidant activity, transport, and abiotic response stress, were identified. In addition, essential stress-regulating metabolic pathways, including glutathione metabolism, cellular response to stress, and regulation of HSF1-mediated heat shock response, were also enriched. Also, at 52- and 49-kDa MW band areas, up to six hypothetical proteins with unknown functions were identified. Of these, protein AXX17_AT2G26660 is highly rich in glycine amino acid residues (up to 76%), suggesting that it is a probable glycine-rich protein (GRP) member. Although GRPs are known to be involved in plant defense against abiotic stress, including salinity and drought, there is no report on their role on Pb tolerance and or detoxification in plants. Further enrichment analysis in the current study reveals that the hypothetical proteins do not interact with known proteins and are not part of any enriched pathway. However, additional research is needed to functionally validate the role of the ident ified proteins in Pb detoxification mechanism. [ABSTRACT FROM AUTHOR]

Toxic elements are present naturally in the environment; however, during the last century, their level has been continuously rising in the air, water, and soil due to anthropogenic activities, including urban runoff, pesticides and fertilizers, industrial effluents, and vehicle emissions. Once released in the environment, they are extremely stable, and therefore humans can get in contact with them through different routes of exposure. In addition, because of their toxicities, they are increasingly threatening human health. Exposure to toxic elements such as heavy metals (HMs) might contribute to the onset of disorders through their ability to generate reactive oxygen species (ROS), which are involved in cell macromolecule injuries. Moreover, several heavy metals (arsenic (As), cadmium (Cd), nickel (Ni), chromium (Cr), and beryllium (Be)) are classified by the International Agency for Research on Cancer as group one carcinogens and can induce different types of cancer through various and heterogeneous mechanisms. Therefore, a better understanding of heavy metals etiopathogenesis in cancer development and the identification of new bioactive products to prevent heavy metal carcinogenicity is warranted. Microalgae, known for their wide range of biological activities, could possess a promising metallo-protective effect against heavy metal-induced carcinogenicity. This protective effect is mainly attributed to their antioxidant and anti-cancer capacities as well as their heavy metal chelating potential. This review discusses the mechanisms implicated in heavy metal carcinogenicity. In addition, a deep understanding of microalgae's mitigating roles and strategies against heavy metal carcinogenicity are reviewed. • Toxic elements are threatening human health through the food chain. • Carcinogenic heavy metals induce different cancers through various mechanisms. • Microalgae bioactives protect and/or prevent toxic metal-induced carcinogenicity. • Microalgae primarily prevent toxic metal-induced carcinogenicity through biosorption. [ABSTRACT FROM AUTHOR]

Summary: In this study, styrene‐butadiene‐styrene (SBS) was used to develop a novel functionalized electrospun membrane for the effective treatment of heavy metals in direct contact membrane distillation (DCMD) applications. Functionalization was achieved by the addition (doping) of the super hydrophobic Al2O3 nanoparticles (Al NPs) within the matrix of the membrane during electrospinning. Neat (pristine nondoped) and doped SBS membranes were tested. The performance of the SBS membranes were also compared with fabricated polyvinylidene fluoride membranes with and without doping with Al NPs. The membrane characteristics were tested via Fourier transform infrared, scanning electron microscopy, pore size, and porosity investigations. The wettability of the membranes was investigated with respect to the liquid entry pressure (LEP) and contact angle. The performance of the membranes was tested in a DCMD setting for its ability to treat water containing salt (NaCl) and heavy metals (Cr (VI), Cd, Pb) in various concentration in a single and multicomponent systems. The SBS member exhibited excellent hydrophobicity characteristics such as a high LEP (16.87 psi) and contact angle (141° ± 2°). It also had superior permeate flux rate compared to the other prepared membranes (54.4 LMH). The addition of the Al2O3 nanoparticles enhance the performance of the membranes substantially. Slight decline in the flux was observed after 14 hours of continuous operating time that could be attributed to agglomeration, adsorption, or temperature polarization effects. The SBS AL NPs membranes also demonstrated excellent flux for saline solutions of varied concentrations with 99% salt rejection. [ABSTRACT FROM AUTHOR]

Anthropogenic activities leads to increase in toxic metals in the environment. The toxicity of Cd, Cr and Pb to P. juliflora were tested in agar media; Seeds germinated in 25, 50 and 100 mg/L Pb; 5, 10 and 20 mg/ 10 L Cd; and 10 mg/L Cr were mostly unaffected. At 20 and 40 mg/L, Cr inhibited germination. Similarly, Cd and Cr treatments but not Pb disturbed seedlings development. Up to 3366.3 mg/kg and 1228.6 mg/kg of Pb accumulates in the root and shoot. The bioconcentration factor for both tissues ranged from 27.8 to 115.4 and 11.4 to 45.7, respectively. The translocation factor ranged from approximately 0.4 to 0.5, suggesting that it preferentially accumulates Pb in the root. Fourier Transformed Infrared Spectroscopy confirms Pb ions complexation with functional groups on the plant dry tissue biomass. These findings therefore, suggest that P. juliflora is suitable for Pb phytostabilization in metalliferous soil. Abbreviations: ICP-OES: Inductively Coupled Plasma Optical Emission Spectrometry; FTIR: Fourier Transform Infrared Spectroscopy; BCF: Bioconcentration Factor; TF: Translocation Factor. [ABSTRACT FROM AUTHOR]

This study evaluated biosolid quality over time and the efficiency of using amounts (5 and 7 kg/m2) of municipal class A biosolids in Qatar to fertilize tomato plants (Solanum lycopersicum). Random samples were subjected to physical and chemical analysis, which revealed excellent particle uniformity and stability with minor odor defects. The analysis confirmed the product was nutrient-rich while pollutant levels were below the international standards. The nominated rates were used to fertilize tomato plants in pots grown in a greenhouse for four months with a control treatment of manure and Peat-Moss, before measuring the plant biological characteristics. Plants were examined via chemical analysis of nutrients and pollutants both for the whole plant and for stems, fruits, and leaves. Results indicated that both experimental treatments enhanced plant growth and development as compared to the control treatment. However, the chemical analyses also revealed levels of zinc, copper, and manganese in the plant fruits that were well in excess of the maximum acceptable levels, as defined by international health organizations. This study found that while the application of class A biosolids as organic fertilizer for tomato plants greatly enhanced the overall plant growth, the plant fruits contained toxic levels of trace heavy metals. [ABSTRACT FROM AUTHOR]

Computerised flow injection coupled with potentiometric stripping analysis (FIPSA) was employed for examination of the adsorption behaviour of Pb(II), Cd(II) and Zn(II) ions onto diatomite modified with manganese oxides. Signal optimisation was undertaken with respect to flow rate, deposition time, deposition potential, oxidising agent concentration, thickness of mercury film, solution pH and metal ion concentration. Examination of the column adsorption characteristics was facilitated by introduction of an adsorption microcolumn, as a complementary component of the flow injection system. The resulting breakthrough curves were employed to calculate parameters including adsorption capacity and adsorption rate constant, taking into consideration initial ion concentration, flow rate, mass and particle size of adsorbent, and column internal diameter. Adsorption capacities, determined using the Thomas mathematical model, showed that manganese modified Jordanian diatomite had an efficiency towards the removal of heavy metal ions from aqueous solutions; Cd(II)>Zn(II)≉Pb(II). The relative adsorption rates of the ions followed the order: Pb(II)>Zn(II)≉Cd(II). [Copyright &y& Elsevier]

Highlights: [•] The uptake capacity order was: Pb2+ >Cu2+ >Ni2+. [•] The thermodynamic constants were endothermic and spontaneous for Pb2+ and Cu2+. [•] The thermodynamic constants were exothermic and non-spontaneous for Ni2+. [•] The adsorption mechanisms are affected by metal ion hydration and other factors. [•] Different functional groups are responsible on the metals binding. [Copyright &y& Elsevier]

Gas-to-liquid (GTL) sludge is a specific wastewater treatment by-product, which is generated during the industrial process of natural gas conversion to transportation fuels. This least studied sludge is pathogen-free and rich in organic carbon and plant nutrients. Therefore, it can be reused for soil enhancement as a sustainable management strategy to mitigate landfill gas emissions. In this field study, we compared the performance of soil treatments with GTL sludge to the more conventional chemical fertilizers and cow manure compost for the cultivation of cotton under hyperarid conditions. After a complete growing season, GTL sludge application resulted in the enhancement of soil properties and plant growth compared to conventional inputs. As such, there was a significant dose-dependent increase of soil organic matter (4.01% and 4.54%), phosphorus (534 and 1090 mg kg−1), and cumulative lint yield (4.68 and 5.67 t ha−1) for GTL sludge application rates of 1.5% and 3%, respectively. The produced fiber quality was adequate for an upland cotton variety (Gossypium hirsutum var. MAY 344) and appeared more dependent on the prevailing climate conditions than soil treatments. On the other hand, the adverse effects generally related to industrial sludge reuse were not significant and did not affect the designed agro-environmental system. Accordingly, plants grown on GTL sludge-amended soils showed lower antioxidant activity despite significant salinity increase. In addition, the concentrations of detected heavy metals in soil were within the standards' limits, which did not pose environmental issues under the described experimental conditions. Leachate analysis revealed no risks for groundwater contamination with phytotoxic metals, which were mostly retained by the soil matrix. Therefore, recycling GTL sludge as an organic amendment can be a sustainable solution to improve soil quality and lower carbon footprint. To reduce any environmental concerns, an application rate of 1.5% could be provisionally recommended since a two-fold increase in sludge dose did not result in a significant yield improvement. [Display omitted] • Gas-to-liquid sludge is a carbon-rich by-product of GTL wastewater treatment. • GTL sludge land application mitigates the risks of landfill gas emissions. • GTL sludge improves soil and plant properties under hyperarid conditions. [ABSTRACT FROM AUTHOR]

Abstract: Unlike coal fly ash, fly ash of heavy fuel oil has received much less attention in the literature. In this work, detailed physicochemical characterization of heavy fuel oil fly ash (FA) is provided. The ash has a carbonaceous matrix and contains V, Ni, Zn, Cr, Cu, and Pb with variable amounts. V was the most abundant heavy metal with enrichment factor of 277 in the FA. The presence of V in the FA is attributed to the formation of Mg3V2O8 oxides at high combustion temperature as confirmed by XRD. Particle size distribution showed that the mean particle diameter of the FA was 70.5μm. Extraction recovery up to 85% of metals was achieved using 1.0M HNO3 and at room temperature. Standard metal-leaching tests confirmed that the elution of the toxic metals and the level of eluted Zn were much higher than the regulated value for the solid residues. Five stable geopolymers GPs containing 41.7wt.% FA were prepared. All GPs showed high compressive strength and low water absorption which support their application as lightweight construction composites. Most importantly, adding FA to GP had significantly reduced metal migration into the environment as confirmed by the synthetic precipitation leaching procedure. [Copyright &y& Elsevier]