In the past decades, renewable energy consumption has grown considerably because of environmental degradation caused by non-renewable energy consumption. This research aims to find the causal link between renewable and non-renewable energy consumption, human capital, and non-renewable energy price for the 53 most renewable energy-consuming countries worldwide (hydroelectric) during the period 1990–2017. We use data collected from the World Bank (http://data.worldbank.org/data-catalog/world-development-indicators , 2018) and Statistical Review of World Energy (https://www.bp.com/ , 2018). We test simultaneously two types of regressions in order to measure the degree of elasticity of the two types of energy by using econometric techniques for panel data. The results of the GLS models indicate that human capital has a stronger significant effect on renewable energy consumption at the global level, in the middle high-income countries and low-middle income countries, compared with non-renewable energy consumption. Besides, at the global level, there is a positive and statistically significant relationship between the non-renewable energy price and the two types of energy consumption. There is a long-run consumption of both types of energy. On the other hand, the one-way relationship between human capital and non-renewable energy price and renewable energy consumption is stronger than the relationship with non-renewable energy consumption. The policy implications derived from this study should be designed to promote human capital development in order to promote renewable energy consumption and increase the investment in renewable energy sources to guarantee their access to lower prices that reduce non-renewable energy consumption.

Due to the potential of reducing negative outcomes of brownfields on environment and contribution to urban sustainability, brownfield redevelopment (BR) gained considerable recognition in the more recent era. Comprehensive literature shows that many studies proposed strategies to promote BR in developed nations; however, studies focusing on developing economies are scarce. Therefore, this study intends to identify significant strategies to promote BR in developing countries by taking the case of Pakistan. A comprehensive literature review and expert opinion were commenced to identify potential strategies. Data were collected from the main stakeholders involved in BR process through an empirical questionnaire. The findings revealed that “Low-interest loans and subsidies with the collaboration of government and financial institutions,” “Standardized definition, guidelines, and simplified brownfield process,” “Development of technical and infrastructure support,” “Create investors interest,” “Strengthening remediation technologies R&D” were the five most important strategies to promote BR in Pakistan. Theoretically, the novelty of the current study is to highlight the key strategies to promote BR in developing countries. Practically, the study facilitates governments, urban policymakers, environmentalists, and stakeholders to propose and implement appropriate strategies for promoting BR. Future studies can consider modeling the interactions between strategies and their impact on BR adoption.

A field experiment in Yangtze River delta of China was conducted to investigate the effects of four treatments (conventional chemical fertilizers (CF), chemical fertilizers incorporated with wheat straw (CF-WS), slow-release urea fertilizer incorporated with wheat straw (SCF-WS), and no fertilizers (Non-F)) on methane emission, rice grain yield, and straw biomass in three (2013, 2014, and 2015) consecutive growing seasons. Similar air temperature and precipitation were recorded in 2014 and 2015 normal seasons; however, the 2013 season with a 2.1–2.3 °C higher mean air temperature and a 61–64% lower precipitation than the normal seasons was considered as a warm-and-dry season.No significant differences in seasonal total methane emissions across all treatments were observed in 2014 and 2015 seasons. Seasonal total methane emissions were 58–294% higher in 2013 season compared to 2014 and 2015 seasons, which suggests that higher ambient temperatures increase methane emissions from paddy fields. The enhanced methane emission was seen mainly during the mid-to-late growth stages after mid-season drainage. CF-WS and SCF-WS significantly increased methane emissions before mid-season drainage relative to CF, and thereby enhanced methane emissions in both normal and warm-and-dry seasons in a seasonal scale.While rice grain yield in each treatment in 2013 season was close to or lower than that in 2014 and 2015 seasons, straw biomass in CF, CF-WS, and SCF-WS in 2013 season were significantly higher than those in 2014 and 2015 seasons, by both 29%, 33–41%, and 15–16%, respectively. Enhancements in methane emissions at higher air temperatures were significantly correlated to its greater straw biomass. Furthermore, combination of slow-release urea fertilizer and straw by ploughing can significantly increase above-ground biomass yields and nitrogen use efficiency in both normal and warm-and-dry seasons.

Coastal heavy metal pollution has become an important topic for seafood safety and marine environmental protection. Unlike toxic heavy metals such as cadmium or chromium, copper is essential for oysters’ growth but can inhibit their immune response to exotic stress when going above normal levels. Oysters with high copper levels can easily accumulate and transfer abnormal amounts of copper to upper trophic levels, and generate health risks for humans. This study investigated the spatiotemporal variability and health risk of copper levels in cultured oysters (Crassostrea rivularis) sampled from 23 harbors, bays, or estuaries along the northern South China Sea during 1989–2015. Overall, oyster copper concentrations in the study area ranged from 0.9 to 1897.0 μg/g wet weight with a mean of 210.0 (± 143.6) μg/g and a median of 89.3 μg/g. Although oyster copper levels in the southern China provinces of Guangdong, Guangxi, and Hainan showed an overall decrease during 1989–2015, they stayed relatively low since 1996 and increased slightly after 2010. Oyster copper levels in Guangdong were significantly higher than in Hainan and Guangxi. In Guangdong, oyster copper levels were highest in the Pearl River Estuary, followed by west Guangdong and east Guangdong. The health risk of copper exposure through oyster consumption increased in 2011–2015 compared with in 2006–2010. It is recommended that the human daily intake of cultured oysters in the study area should be reduced by half to minimize copper exposure. This study suggested that copper is one of the most important heavy metal contaminants in coastal and estuarine ecosystems of the northern South China Sea.

The present study investigated the effects of polyvinyl chloride (PVC) microparticles (MP) on hepatic antioxidant enzymes activities, serum biochemical and liver histology of juvenile Clarias gariepinus. A total of 180 (25.15 g average weight) C. gariepinus were fed PVC MP (95.41 ± 4.23 μm) spiked diets at 0.5, 1.5, 3.0 percentage inclusion levels and a control diet for 45 days of exposure, then followed by 30 days of depuration trials. Fish specimens (9) from each treatment were sampled every 15-day interval for serum biochemical, liver antioxidant enzymes and histopathological assay. Glucose and triglyceride levels increased significantly in PVC-treated groups when compared with the control. Protein levels of 0.5% and 3.0% PVC-treated groups reduced significantly on the 15th and 30th day exposure periods, while serum enzyme activities of all PVC-treated groups increased significantly in a time-dependent manner. Antioxidant enzymes (superoxide dismutase, glutathione peroxidase, catalase) activity in the liver of the treated groups also decreased progressively in a time-dependent manner. A time-dependent elevation in lipid peroxidation levels was observed in PVC MP-treated groups. Histopathological assessment of the fish liver showed mild to severe levels of glycogen depletion, fatty vacuolation and degeneration, hepatocellular necrosis in PVC-treated groups with reference to the control. The present study revealed that PVC microplastic induced oxidative damage and hepatic histopathological alterations in the exposed fish.

The impacts of the increasing human activities mostly through socio-economic and environment interactions have continued to generate more scientific studies and contemporary discussion on issues ranging from the climate change to income and gender gap. Accordingly, the current study employed the cointegration and a two-step (system) SYS-Generalized Method of Moments to examine the environmental sustainability effects of income, international tourism arrivals, and labour force vis-à-vis gender unemployment in the panel of (32) Organization for Economic Development and Corporation (OECD) for the period 1995–2016. The study revealed that income growth in the OECD countries and increase in the inflow of international tourists into the OECD member countries are significant endangering factors for the bloc’s environmental sustainability. More striking is the environmental impact of labour force in the panel countries. Intuitively, a positive labour force-environmental degradation nexus is expected; the negatively desirable labour force-environmental degradation nexus in the current study is a justification of (1) the prevailing gender employment/unemployment classifications in the OECD member countries, and (2) the increasing adoption of more environmental friendlier working conditions or operation among the member countries. Moreover, the current study strongly posits a significant policy framework for the governments and stakeholders of the OECD member countries.

In present study, garlic peel (GP) was modified by loading with Fe(III), Ti(IV), and Ce(III) through a cation exchange process, i.e., nGP-COOH + Mⁿ⁺ = (nGP-COO)-Mⁿ⁺ + nH⁺ (M = Fe, Ce, Ti), which could adsorb tungstate effectively under the weakly acidic conditions. The optimal initial pH for maximum adsorption of W(VI) was determined at 1~3 for Ti-GP, 1~4 for Fe-GP, and 3 for Ce-GP, respectively; and at pH 2.5, the corresponding maximum adsorption capacity for Fe-GP, Ti-GP, and Ce-GP was evaluated as 91.5 mg/g, 83 mg/g, and 84 mg/g tungsten respectively. Coexisting anions like chloride, sulfate, and carbonate showed little effect on tungsten adsorption, while fluoride and phosphate inhibited the adsorption drastically. The column adsorption showed that the breakthrough point for Ce-GP, Ti-GP, and Fe-GP was 180 min, 200 min, and 270 min respectively. And 0.1 mol/L NaOH effectively eluted the adsorbed tungsten, and concentration of the eluted solution had almost 6, 19.9, and 22 factors of the initial tungstate concentration correspondingly.

Thermal barrier coating (TBC) implementations and oxygenated additives are remarkable issues that may decrease the exhaust emissions of engines. This study examines the effect of chromium oxide (Cr₂O₃) coating and the addition of ethylhexyl nitrate (EHN) on exhaust emissions of a diesel engine. In addition, an artificial neural network (ANN) model was designed which estimates exhaust emissions based on engine speed in order to reduce time, labor, and costs lost in experimental studies, and the performance of the ANN was evaluated. Piston crown and valves of engine were processed with Cr₂O₃. The E3, E6, and E9 blends were produced by blending 3%, 6%, and 9% (vol.) ratios of 2-ethylhexyl nitrate with diesel fuel. Engine speed was used as input parameter and carbon monoxide (CO), nitrogen oxide (NOX), hydrocarbon (HC), and smoke density were used as output parameters. To evaluate the performance of ANN, error rates, and regression (R) values were considered. Experimental results revealed that CO, HC, and smoke density decreased in the CE whereas NOX values increased compared with the UE. The addition of EHN reduced NOX emission and smoke density, whereas it increased CO and HC emissions. The result showed that ANN model can predict the exhaust emissions at a high accuracy rate. The lowest regression results were achieved as 0.98395, 0.99047, 0.99268, and 0.98383 for the CO, NOX, smoke density, and HC, respectively. Moreover, the average R values of NOX, HC, CO, and smoke density were obtained as 0.99767, 0.99131, 0.99396, and 0.99741. The maximum error rates of the estimated outcomes were obtained as 5.25% on average. Graphical abstract

Recent developments in the nanotechnology field have created opportunities to design new biomaterials for Staphylococcus aureus biofilm eradication. These biomaterials including disinfectant-loaded nanoparticles could overcome the limitations of conventional disinfectants. The objective of this study was to assess the biocidal activity of five commercial disinfectants (DC&R®, VirkonS®, TH4++, Tek-Trol, and peracetic acid) alone and as with silver and copper nanocomposites on S. aureus biofilm at different concentrations and exposure times. Consequently, 227 samples were collected from two broiler farms, two-layer farms, and three abattoirs at El-Dakahlia Province, Egypt, during summer 2018. The samples were collected from birds as well as the surrounding environment. S. aureus strains were isolated and biofilm producers were phenotypically evaluated by Congo red agar (CRA) test. Besides, 4 biofilm-associated genes including bap, fnbA, cna, and ebps were genotypically detected by PCR technology. Out of 227 collected samples, 141 (62.1%) strains were identified as S. aureus, while 127 strains (90.1%) were S. aureus biofilm producers for all examined samples except for hand swabs of abattoir workers. The prevalence of fnbA and bap genes was 79.5% (101/127) and 20.5% (26/127), respectively but, no strains harbored cna or ebps genes. Tested nanocomposites were prepared using an aqueous solution of metal salts such as copper sulfate and silver nitrate and added to the same amount of disinfectant solution. The obtained nanocomposites were characterized by transmission electron microscopy (TEM) and zeta potential which showed spherical and elongated particles and with a surface charge of disinfectants—silver and copper nanocomposites—of 2.92 and 3.43 mV, respectively. Complete eradication of S. aureus biofilm was observed after treatment with disinfectants loaded onto silver (AgNPs) and copper (CuNPs) nanoparticles in varying concentrations as well as at different exposure times in comparing to disinfectants alone. Our results exhibited the potential applications of disinfectant nanocomposites in complete eradication of S. aureus biofilm in farms and abattoirs without developing of disinfectant resistant bacteria.

As a common environmental problem in China, trace metal accumulation and contamination in soils of greenhouse vegetable production (GVP) may pose significant health risk via oral ingestion, inhalation, and dermal contact to vegetable farmers and children playing in greenhouse fields. Thus, bioaccessibility and health risk of Cr, Ni, Cu, Zn, Cd, and Pb in GVP soils collected from 13 GVP farms or bases near industrial areas of the Yangtze River Delta, China, were investigated as a case study. The results suggested that both GVP and industrial discharges contributed a lot to accumulation or contamination especially of Zn and Cd in soil, which subsequently increased their bioaccessible concentrations. In addition, soil acidification caused by GVP also increased bioaccessible Cr and Ni concentrations in soil of the Anthrosols study area. However, the health risk assessment of metals in GVP soil through inhalation and oral ingestion considering metal bioaccessibility suggested no non-carcinogenic and carcinogenic risks to both farmers and children. In contrast, there was potential carcinogenic risk within acceptable level posed by Cr in GVP soil through dermal contact to farmers and children. This indicates that both GVP and industrial activities had limited effect on health risk of trace metals in GVP soil via ingestion, inhalation, and dermal contact. However, the carcinogenic risk posed by Cr, which mainly originated from natural sources, still cannot be negligible. Overall, the results will provide valuable information for decision-makers to develop reasonable strategies and guidelines for risk management of trace metals in GVP soil.