This study aims to examine the impact of renewable and non-renewable energy consumption on the agriculture, industry, services, and overall economic activities (GDP) across a panel of G20 nations. The study makes use of annual data from 1980 to 2012 on 17 countries of the G20. To achieve the study objectives, we apply several robust panel econometric models which account for cross-sectional dependence and heterogeneity in the analysis. The empirical findings confirm the significant long-run equilibrium relationship among the variables. The long-run elasticities indicate that both renewable and non-renewable energy consumptions have significant positive effect on the economic activities across the sectors and also on the overall economic output. These results also imply that the impact is more from renewable energy on economic activities than that of non-renewable energy. Given that, our results offer significant policy implications. We suggest that the policy makers should aim to initiate effective policies to turn domestic and foreign investments into renewable energy projects. This eventually ensures low carbon emissions and sustainable economic development across the G20 nations.

Phytolith-occluded organic carbon (PhytOC) is considered one of the most promising terrestrial carbon (C) sinks. Different methods are used for phytolith extraction from wet-ashing techniques and the subsequent determination of PhytOC content from soil. This is in order to optimize the wet-ashing techniques and to improve estimation accuracy of C sequestration potential of phytoliths from soil. Results show that the organic matter removal and carbonate removal protocol, applying sonication, has a significant effect on phytolith extraction. Namely, the sequential removal of first organic matter and then carbonates applied to such methods could eliminate greater than 17.14, 46.68, and 26.17% extraneous material compared to other methods. Moreover, phytoliths extracted using methods that apply sonication eliminated 7.49, 42.70, and 17.57% more extraneous material than methods that did not. Additionally, the procedure associated with the second oxidation step significantly influenced the determination of PhytOC content, that is, 29.34, 33.75, 26.41, and 64.64% of excess organic C were oxidized during this step. The upgraded optimal method we recommend for phytolith extraction in association with wet-ashing techniques and the subsequent determination of PhytOC content is therefore to first apply sonication, then the second oxidation step, and finally the removal of organic matter. Using this optimal upgraded method, we estimated the C sequestration potential of phytoliths from the soil of slash pine in China at 0.51 Mt. C. Furthermore, using this upgraded optimal method increased the precision of the carbon sequestration potential of phytoliths from soil by up to 63.83%.

In this paper, reduced graphenoxide/attapulgite (rGO/APT)-supported nanoscale zero-valent iron (nZVI) composites (rGO/APT-nZVI) were synthesized to remove acid red 18 (AR18) and other organic dyes from aqueous solutions. The structure of synthetic rGO/APT-nZVI composite was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray diffraction (XRD), and the removal properties of rGO/APT-nZVI on AR18 were investigated. The factors of various experimental parameters (ratio, pH, initial concentration, temperature, and time) impacting on removal of AR18 were studied as well. Comparison experiment of different materials showed that 93.5% of AR18 was removed using rGO/APT-nZVI, while only 7.9% and 64.8% of AR18 were removed using rGO/APT-nZVI after reacting for 30 min with an initial AR18 concentration of 100 mg L⁻¹, respectively. Moreover, kinetic and thermodynamic analyses were used to study the reduction process, and possible mechanism of AR18 removal was discussed. The results show that the rGO/APT-nZVI composites can effectively degrade AR18 over a wide range of pH and keep degradation activity in a long storage. In addition, the superior behaviors for other organic dyes removal highlight the great potential as an efficient adsorbent for water pollution.

With increasing graphene oxide (GO) applications in industry and biomedicine, effects of GO on microorganisms, animals, and human health have been frequently studied; however, direct and indirect effects of GO on plants are seldom concerned. In this study, effects of GO and/or Cd²⁺ on seed germination, seedling growth, and uptake to Cd²⁺ were investigated in solution culture. The results showed that GO could quickly adsorb Cd²⁺ in solution, and the higher the GO concentration was, the lower the residual Cd²⁺ concentration was in solution. Rice seed germination, seminal root length, and bud length decreased with increasing GO and Cd²⁺ concentrations respectively, while the presence of GO could alleviate the inhibitive effects of Cd²⁺ on seminal root and bud growth compared with the single Cd²⁺ treatment. In maize seedling, fresh weights of shoot and root showed similar responses to the presence of Cd²⁺ and/or GO. Compared with the single Cd²⁺ treatment, root Cd concentrations were generally increased by GO in high Cd²⁺ solution (20 mg/L), while were slightly affected by GO in low Cd²⁺ solution (5 mg/L) independent of GO concentrations except for 100 mg/L GO. Shoot Cd concentrations were decreased by low GO (100 mg/L) while were increased by high GO (> 500 mg/L) independent of Cd²⁺ concentrations in solution. Moreover, significant interactive effects of GO and Cd²⁺ on root and shoot Cd concentrations were observed. This study indicates that GO can change the effects of Cd²⁺ on seed germination, seedling growth, and uptake to Cd²⁺ in solution through its adsorption on Cd²⁺.

The aim of the study was to get a picture of the geographical variations of N deposition in the snowpack over the French Alps. Using a collaborative research approach, we sampled 139 snow cores along 27 altitudinal gradients between 1100 and 3300 m a.s.l. in the end of February 2013, at maximum snowpack accumulation. Comparing the snowpack composition at a fixed elevation (2000 m), we observed a clear gradient of increasing nitrate concentrations from the south to the north of the massif. This gradient was less marked for NH₄. Mineral N loads were 100–500 g ha⁻¹ in the south and 100–1000 g ha⁻¹ in the north. For several massifs of the Northern Alps, nitrate and ammonium concentrations decreased as elevation increased. This altitudinal variation was not observed (or less) in the south. The weighted average inorganic N concentrations measured in bulk precipitation during the same winter at three monitoring sites at medium altitude (1000–1300 m) were about twice higher than the measured concentrations in the snowpack at 2000 m. We suggest that these altitudinal and latitudinal gradients should be taken into account to model the deposition of N at high altitude and to analyze the relative effects of N deposition on remote alpine ecosystems.

Eutrophication of an under-ice river-lake system in Canada has been modeled using the Water Quality Analysis Simulation Program (WASP7). The model was used to assess the potential effect on water quality of increasing inter-basin transfer of water from an upstream reservoir into the Qu’Appelle River system. Although water is currently transferred, the need for increased transfer is a possibility under future water management scenarios to meet water demands in the region. Output from the model indicated that flow augmentation could decrease total ammonia and orthophosphate concentrations especially at Buffalo Pound Lake throughout the year. This is because the water being transferred has lower concentrations of these nutrients than the Qu’Appelle River system, although there is complex interplay between the more dilute chemistry, and the potential to increase loads by increasing flows. A global sensitivity analysis indicated that the model output for the lake component was more sensitive to input parameters than was the model output of the river component. Sensitive parameters included dissolved organic nitrogen mineralization rate, phytoplankton nitrogen to carbon ratio, phosphorus-to-carbon ratio, maximum phytoplankton growth rate, and phytoplankton death rate. Parameter sensitivities on output variables for the lake component were similar for both summer (open water) and winter (ice-covered), whereas those for the river component were different. The complex interplay of water quality, ice behaviors, and hydrodynamics of the chained river-lake system was all coupled in WASP7. Mean absolute error varied from 0.03–0.08 NH₄-N/L for ammonium to 0.5 to1.7 mg/L for oxygen, and 0.04–0.13 NO₃-N/L for nitrate.

Several chemical compounds are being studied for their capacities to cause imbalances in several biological systems. Some of those are able to affect the endocrine system and are known as endocrine disruptors. Many negative effects can be induced in the organisms by the action of these chemicals, highlighting the capacity to cause a decrease in the fertility rate, sex inversion, and problems in embryonic development and even cancer in humans. Those contaminants can be found in different environmental conditions, in groundwater, sediments, residual waters, sludges, and even in drinking water. The purpose of this review is to provide a general overview of the main estrogenic endocrine disruptors and their effects on living organisms, showing the most frequently used tools to detect these contaminants in environmental matrices. According to the data found, there is a need to develop more studies and improve the techniques, in order to effectively determine the mechanism of action of these contaminants and, thus, establish appropriate strategies for their removal from the environment and reduce their actions on living beings.

In this study, we prepared a homogeneous dispersion of CaO-SiO₂ sorbent with advanced nanostructures as an efficient solid-reducing agent for the elimination of hazardous chemicals. The hydrophobic properties of SiO₂ ceramic particles are of interest for reducing the limitations and enhancing the chemical properties of highly hygroscopic materials. Nano-sized SiO₂ is introduced and composited with CaO through a facile synthetic route. The structural and microstructural characteristics and elemental compositional analyses confirm the uniform distribution of the CaO-SiO₂ nanocomposite. The as-prepared nanocomposites have particle sizes in the range of ~ 20–100 nm. Optimization of the composition reveals that the 60 wt% CaO-SiO₂ can be considered as an efficient solid-reducing agent for the hydrogen fluoride (HF) removal process. In order to identify the catalytic effect and binder ratio, the specific surface area and HF removal performance was investigated and compared to CaO-SiO₂ nanostructures with individual CaO catalyst. The higher amount of HF concentration was absorbed by CaO-SiO₂ catalyst than the CaO only. In the first 2.5-h reaction, the outlet HF concentration is rapidly increased to 380 ppm by using CaO catalyst as a HF sorbent. However, the outlet HF concentration is sluggishly increased up to 180 ppm, when nanostructured CaO-SiO₂ catalyst used as a sorbent in RE-RCS. It has been found that the addition of hydrophobic properties of SiO₂ has prevented the reaction between water/moisture and CaO in CaO-SiO₂ catalyst system, which is a major reason for enhancement in HF removal process. Furthermore, the CaF₂ byproduct can be effectively used in the ceramic industry and building material applications.

Lead is known to be a highly toxic metal; it is often found in soils with the potential to be incorporated by plants. Here, the bioaccumulation of lead by rapeseed (Brassica napus) from a soil with Pb(II) added just before sowing is studied. The effect on plant organs is also studied at the ontogenetic stages of flowering and physiological maturity. Moreover, the chemical fractionation of Pb in the rhizosphere and bulk soil portions is investigated and related to Pb accumulation in plant organs. B. napus are found to accumulate Pb in its organs: 1.5–19.6 mg kg⁻¹ in roots, 3.3–15.6 mg kg⁻¹ in stems, 0.5–8.6 mg kg⁻¹ in leaves in all treatments, and in grains 1.45 mg kg⁻¹ at physiological maturity and only for the highest Pb dose (200 mg kg⁻¹). Plant biomass reduction was observed to be about 20% at the flowering stage and only for the highest Pb dose. The analysis of metal fractionation in soil shows Pb migration from the bulk soil to the rhizosphere, attributed to concentration gradients created by root intake. Along the time period studied, lead chemical fractionation in soil evolved toward the most stable fractions, which coupled to plant uptake depleted the soluble/exchangeable one (assumed bioavailable).