A global perspective on the biology,impact and management of Chenopodium album and Chenopodium murale: two troublesome agricultural and environmental weeds

Environmental Science and Pollution Research - Chenopodium album and C. murale are cosmopolitan, annual weed species of notable economic importance. Their unique biological features, including high...     

Application of chemical oxidation to remediate HCH-contaminated soil under batch and flow through conditions

This is the first study describing the chemical oxidation of hexachlorocyclohexanes (HCHs) in contaminated soil under water saturated and unsaturated flow through conditions. Soil contaminated with β-HCH (45 mg kg^?1) and γ-HCH (lindane, 25 mg kg^?1) was sampled from former lindane waste storage site. Efficiency of following treatments was tested at circumneutral pH: H₂O₂ alone, H₂O₂/Fe^II, Na₂S₂O₈ alone, Na₂S₂O₈/Fe^II, and KMnO₄. Experimental conditions (oxidant dose, liquid/solid ratio, and soil granulometry) were first optimized in batch experiments. Obtained results revealed that increasing dose of H₂O₂ improved the oxidation efficiency while in Na₂S₂O₈ system, maximum HCHs were removed at 300 mM. However, oxidation efficiency was slightly improved by Fe^II-activation. Increasing the solid/liquid ratio decreased HCH removal in soil samples crushed to 500 μm while an opposite trend was observed for 2-mm samples. Dynamic column experiments showed that oxidation efficiency followed the order KMnO₄ > Na₂S₂O₈/Fe^II > Na₂S₂O₈ whatever the flow condition, whereas the removal extent declined at higher flow rate (e.g., ~50% by KMnO₄ at 0.5 mL/min as compared to ~30% at 2 mL/min). Both HCH removal and oxidant decomposition extents were found higher in saturated columns than the unsaturated ones. While no significant change in relative abundance of soil mineral constituents was observed before and after chemical oxidation, more than 60% of extractable organic matter was lost after chemical oxidation, thereby underscoring the non-selective behavior of chemical oxidation in soil. Due to the complexity of soil system, chemical oxidation has rarely been reported under flow through conditions, and therefore our findings will have promising implications in developing remediation techniques under dynamic conditions closer to field applications.     

Treatment of hydrocarbon contamination under flow through conditions by using magnetite catalyzed chemical oxidation

Soil pollution by hydrocarbons (aromatic and aliphatic hydrocarbons) is a major environmental issue. Various treatments have been used to remove them from contaminated soils. In our previous studies, the ability of magnetite has been successfully explored to catalyze chemical oxidation for hydrocarbon remediation in batch slurry system. In the present laboratory study, column experiments were performed to evaluate the efficiency of magnetite catalyzed Fenton-like (FL) and activated persulfate (AP) oxidation for hydrocarbon degradation. Flow-through column experiments are intended to provide a better representation of field conditions. Organic extracts isolated from three different soils (an oil-contaminated soil from petrochemical industrial site and two soils polluted by polycyclic aromatic hydrocarbon (PAH) originating from coking plant sites) were spiked on sand. After solvent evaporation, spiked sand was packed in column and was subjected to oxidation using magnetite as catalyst. Oxidant solution was injected at a flow rate of 0.1 mL min^?1 under water-saturated conditions. Organic analyses were performed by GC–mass spectrometry, GC–flame ionization detector, and micro-Fourier transform infrared spectroscopy. Significant abatement of both types of hydrocarbons (60–70 %) was achieved after chemical oxidation (FL and AP) of organic extracts. No significant by-products were formed during oxidation experiment, underscoring the complete degradation of hydrocarbons. No selective degradation was observed for FL with almost similar efficiency towards all hydrocarbons. However, AP showed less reactivity towards higher molecular weight PAHs and aromatic oxygenated compounds. Results of this study demonstrated that magnetite-catalyzed chemical oxidation can effectively degrade both aromatic and aliphatic hydrocarbons (enhanced available contaminants) under flow-through conditions.     

Impact of economic capabilities and population agglomeration on PM2.5 emission: empirical evidence from sub-Saharan African countries

Environmental Science and Pollution Research - The utilization of economic capabilities to raise production in the economy enhances the industrial activities and use of transportation. These...     

Heavy-metal fractionation and distribution in soil profiles short-term-irrigated with sewage wastewater

Six soil profiles irrigated and non-irrigated with sewage wastewater were investigated for soil pH, electrical conductivity (EC), organic matter (OM), and CaCO₃. The distributions and chemical fractions of Cu, Zn, Cd, and Pb, and their lability were also studied. The results indicated that pH, EC, OM, and CaCO₃, as well as metal fractionation in soil profiles were affected by wastewater irrigation, especially in the surface layer. The surface layer (0-15 cm) irrigated with wastewater exhibited a 0.6 unit decrease in soil pH, a 40.6% decrease in CaCO₃, and a 200% increase in EC as compared with that of the non-irrigated soil. The soil OM increased from 0.04% to 0.35% in the surface layer. The irrigation of soil with wastewater resulted in transformation of metals from the carbonate fraction (CARB) towards the exchangeable (EXCH), Fe-Mn oxide (ERO), and organic (OM) fraction for Zn, towards the EXCH, the OM, and residual fraction for Cu, and towards the exchangeable (EXCH) fraction for Cd. It was concluded that the use of sewage wastewater led to salt accumulation and an increase in the readily labile fraction of Zn, Cu, and Cd in the surface layer. Therefore, this reason may limit the use of wastewater under arid and semi-arid conditions.     

Correction to: Does globalization affect the green economy and environment? The relationship between energy consumption,carbon dioxide emissions,and economic growth

Environmental Science and Pollution Research - A Correction to this paper has been published: https://doi.org/10.1007/s11356-021-15192-8     

An empirical nexus between economic growth,energy utilization,trade policy,and ecological footprint: a continent-wise comparison in upper-middle-income countries

Environmental Science and Pollution Research - This study investigates the causal connection between economic growth, foreign direct investment, primary and renewable energy utilization, trade...     

Multivariate analysis of accumulation and critical risk analysis of potentially hazardous elements in forage crops

Environmental Monitoring and Assessment - Few estuaries remain unaffected by water management and altered freshwater deliveries. The Caloosahatchee River Estuary is a perfect case study for...     

Effect of clay minerals on extractability of heavy metals and sewage sludge mineralization in soil

An incubation experiment lasting 111 d was carried out to study the effect of the addition of three clay minerals (Na-bentonite, Ca-bentonite, and zeolite) to soil derived from sewage sludge on water-extractable and exchangeable forms of four heavy metals (Zn, Cd, Cu, and Ni), as well as on soil organic matter mineralization, microbial biomass C and the release of inorganic N. The addition of clay minerals led to a significant decrease in water-extractable and exchangeable forms of heavy metals. The extent of decrease ranged from 14 to 75% for the water-extractable heavy metals and from 12 to 42% for the exchangeable form over the incubation time, as compared with untreated soil. The reduction in extractability of heavy metals was greater due to the addition of Na-bentonite and Ca-bentonite than that due to the addition of zeolite. Addition of clay minerals did not affect any of the following microbiological parameters in the soil: microbial biomass C, organic C (C_org) mineralization, and metabolic quotient (qCO₂), and release of inorganic N during the first 3 weeks of incubation. However, as the incubation period increased, these parameters were significantly increased by the addition of clay minerals, especially by the addition of Na-bentonite and Ca-bentonite. This result is explained by a strong reduction in extractability of heavy metals after the addition of Na-bentonite and Ca-bentonite.