Showing papers in "Environmental Science and Pollution Research in 2018"

Ecotoxicological effects of microplastics on biota: a review.

Abstract: The ubiquitous presence of microplastics in the environment has drawn the attention of ecotoxicologists on its safety and toxicity. Sources of microplastics in the environment include disintegration of larger plastic items (secondary microplastics), personal care products like liquid soap, exfoliating scrubbers, and cleaning supplies etc. Indiscriminate usage of plastics and its poor waste disposal management pose serious concern on ecosystem quality at global level. The present review focused on the ecological impact of microplastics on biota at different trophic levels, its uptake, accumulation, and excretion etc., and its plausible mechanistic toxicity with risk assessment approaches. Existing scientific evidence shows that microplastics exposure triggers a wide variety of toxic insult from feeding disruption to reproductive performance, physical ingestion, disturbances in energy metabolism, changes in liver physiology, synergistic and/ or antagonistic action of other hydrophobic organic contaminants etc. from lower to higher trophics. Thus, microplastic accumulation and its associated adverse effects make it mandatory to go in for risk assessment and legislative action. Subsequent research priorities, agenda, and key issues to be addressed are also acknowledged in the present review.

Analyzing the environmental Kuznets curve for the EU countries: the role of ecological footprint.

Abstract: A great majority of the environmental Kuznets curve (EKC) literature use CO2 emissions to proxy for environmental degradation. However, this is an important shortage in application of the EKC concept because environmental degradation cannot be captured by CO2 emissions only. By using a broader proxy, ecological footprint, this study aims to investigate the presence of environmental Kuznets curve hypothesis for the EU countries. The annual data from 1980 to 2013 is examined with second generation panel data methodologies which take into account the cross-sectional dependence among countries. The results show that there is U-shaped relationship between the real income and ecological footprint. In addition, non-renewable energy increases the environmental degradation while renewable energy and trade openness decrease the environmental degradation in the EU countries. Policy implications are further discussed.

Financial development, globalization, and CO 2 emission in the presence of EKC: evidence from BRICS countries

Abstract: This study examines the impact of energy consumption, financial development, globalization, economic growth, and urbanization on carbon dioxide emissions in the presence of Environmental Kuznets Curve (EKC) model for BRICS economies, by using a family of econometric techniques robust to heterogeneity and cross-sectional dependence Results from LM test, CIPS and CADF unit root test, Westerlund Cointegration test, the Dynamic seemingly unrelated regression (DSUR), and Dumitrescu-Hurlin Granger causality test show that (i) the data is cross sectionally dependent and heterogeneous; (ii) carbon dioxide emissions, energy consumption, financial development, globalization, economic growth, square of GDP and urbanization have integration of order one; (iii) the examined variables are co-integrated; (iv) energy consumption and financial development contribute to the carbon dioxide emissions whereas globalization and urbanization have negative but insignificant relationship with carbon dioxide emissions; (v) supports the EKC hypothesis in BRICS economies; (vi) bidirectional causality exists among energy consumption, financial development, economic growth and square of GDP with carbon dioxide emissions whereas globalization and urbanization have unidirectional relationship with carbon dioxide emissions Since these panel techniques account for heterogeneity and cross-sectional dependence in their estimation procedure, the empirical results are robust and reliable for policy recommendations Furthermore, this study also uses time series tests (ADF, P-P, and FMOLS) to find the empirical results for each of the country and finds mixed results Empirical findings directed towards some important policy implications

Biodegradation of plastics: current scenario and future prospects for environmental safety.

Abstract: Plastic is a general term used for a wide range of high molecular weight organic polymers obtained mostly from the various hydrocarbon and petroleum derivatives. There is an ever-increasing trend towards the production and consumption of plastics due to their extensive industrial and domestic applications. However, a wide spectrum of these polymers is non-biodegradable with few exceptions. The extensive use of plastics, lack of waste management, and casual community behavior towards their proper disposal pose a significant threat to the environment. This has raised growing concerns among various stakeholders to devise policies and innovative strategies for plastic waste management, use of biodegradable polymers especially in packaging, and educating people for their proper disposal. Current polymer degradation strategies rely on chemical, thermal, photo, and biological procedures. In the presence of proper waste management strategies coupled with industrially controlled biodegradation facilities, the use of biodegradable plastics for some applications such as packaging or health industry is a promising and attractive option for economic, environmental, and health benefits. This review highlights the classification of plastics with special emphasis on biodegradable plastics and their rational use, the identified mechanisms of plastic biodegradation, the microorganisms involved in biodegradation, and the current insights into the research on biodegradable plastics. The review has also identified the research gaps in plastic biodegradation followed by future research directions.

Quantifying shedding of synthetic fibers from textiles; a source of microplastics released into the environment

Abstract: Microplastics in the environment are a subject of intense research as they pose a potential threat to marine organisms. Plastic fibers from textiles have been indicated as a major source of this type of contaminant, entering the oceans via wastewater and diverse non-point sources. Their presence is also documented in terrestrial samples. In this study, the amount of microfibers shedding from synthetic textiles was measured for three materials (acrylic, nylon, polyester), knit using different gauges and techniques. All textiles were found to shed, but polyester fleece fabrics shed the greatest amounts, averaging 7360 fibers/m−2/L−1 in one wash, compared with polyester fabrics which shed 87 fibers/m−2/L−1. We found that loose textile constructions shed more, as did worn fabrics, and high twist yarns are to be preferred for shed reduction. Since fiber from clothing is a potentially important source of microplastics, we suggest that smarter textile construction, prewashing and vacuum exhaustion at production sites, and use of more efficient filters in household washing machines could help mitigate this problem.

The effect of ICT, financial development, growth, and trade openness on CO2 emissions: an empirical analysis.

Abstract: This study investigates the impact of Internet use, financial development, economic growth, and trade openness on carbon dioxide (CO2) emissions in selected European Union (EU) countries. To this end, pooled mean group (PMG) estimator is utilized for panel data from 2001 to 2014. Empirical findings suggest that Internet use has long-run relationship with CO2 emissions and lowering the environmental quality in EU countries. Also, the electricity consumption has a positive and significant effect on CO2 emissions. Moreover, interestingly, economic growth and financial development have a diminishing negative impact on CO2 emission. Heterogeneous panel Granger causality results suggest unidirectional causality running from Internet use to CO2 emissions. The finding implies that the European Union countries did not achieve the level of green information and telecommunication (ICTs) consumption. Overall, the innovative findings indicate that Internet use is raising the threat to the sustainable development. Thus, to curb and mitigate CO2 emissions from Internet use and electricity consumption is the need of time to maintain the sustainable development in EU countries.

The effect of innovation on CO2 emissions of OCED countries from 1990 to 2014.

Abstract: Human activities are accelerating CO2 emissions all over the world most especially in high-income nations, spurring the rise in greenhouse gas emissions. For decades, technologies have been developed and patented in response to the environmental problems. There is an outcry for innovative ways to combat the environmental menace. This attests to the enormity of research being done, in recent years, to investigate how innovation can help mitigate CO2 emissions. This research aims at investigating into the effect of innovation on CO2 emissions in 28 OCED countries at an individual level for the recent period 1990 to 2014. The source of data for our utilized variables is the World Bank Indicators. Our study employed three key models based on the STIRPAT model, the economic-EKC growth model, and the innovation-EKC model. The findings of our study revealed that innovation plays a key role towards mitigation of CO2 emissions in most OECD countries. Its impact, however, varies across the countries, depending on some key factors and channels elucidated in this paper. Additionally, our study asserts that improvement in GDP per capita leads to the rise in CO2 in most OECD economies, although mitigate emissions in few OECDs; hence, the economic-EKC model is not valid for most economies. Non-renewable energy accelerates emissions whiles renewable energy sources mitigate emissions. Research and development (RD hence, governments and policy makers should invest and promote innovative renewable energy sources.

The effects of ozone on human health

Abstract: Ozone is a highly reactive, oxidative gas associated with adverse health outcome, including mortality and morbidity. Data from monitoring sites worldwide show levels of ozone often exceeding EU legislation threshold and the more restrictive WHO guidelines for the protection of human health. Well-established evidence has been produced for short-term effects, especially on respiratory and cardiovascular systems, associated to ozone exposure. Less conclusive is the evidence for long-term effects, reporting suggestive associations with respiratory mortality, new-onset asthma in children and increased respiratory symptom effects in asthmatics. The growing epidemiological evidence and the increasing availability of routinely collected data on air pollutant concentrations and health statistics allow to produce robust estimates in health impact assessment routine. Most recent estimates indicate that in 2013 in EU-28, 16,000 premature deaths, equivalent to 192,000 years of life lost, are attributable to ozone exposure. Italy shows very high health impact estimates among EU countries, reporting 3380 premature deaths and 61 years of life lost (per 100,000 inhabitants) attributable to ozone exposure.

Occurrence, sources, human health impacts and mitigation of microplastic pollution.

Abstract: The presence and accumulation of plastic and microplastic (MP) debris in the natural environment is of increasing concern and has become the focus of attention for many researchers. Plastic debris is a prolific, long-lived pollutant that is highly resistant to environmental degradation, readily adheres hydrophobic persistent organic pollutants and is linked to morbidity and mortality in numerous aquatic organisms. The prevalence of MPs within the natural environment is a symptom of continuous and rapid growth in synthetic plastic production and mismanagement of plastic waste. Many terrestrial and marine-based processes, including domestic and industrial drainage, maritime activities agricultural runoff and wastewater treatment plants (WWTPs) effluent, contribute to MP pollution in aquatic environments. MPs have been identified in food consumed by human and in air samples, and exposure to MPs via ingestion or inhalation could lead to adverse human health effects. Regulations in many countries have already been established or will soon be implemented to reduce MPs in aquatic environments. This review focuses on the occurrence, sources, and transport of MPs in terrestrial and aquatic environments to highlight potential human health effects, and applicable regulations to mitigate impacts of MPs. This study also highlights the importance of personality traits and cognitive ability in reducing the entry of MPs into the environment.

Phytohormones enhanced drought tolerance in plants: a coping strategy.

Abstract: Drought stress is a severe environmental constraint among the emerging problems. Plants are highly vulnerable to drought stress and a severe decrease in yield was recorded in the last few decades. So, it is highly desirable to understand the mechanism of drought tolerance in plants and consequently enhance the tolerance against drought stress. Phytohormones are known to play vital roles in regulating various phenomenons in plants to acclimatize to varying drought environment. Abscisic acid (ABA) is considered the main hormone which intensifies drought tolerance in plants through various morpho-physiological and molecular processes including stomata regulation, root development, and initiation of ABA-dependent pathway. In addition, jasmonic acid (JA), salicylic acid (SA) ethylene (ET), auxins (IAA), gibberellins (GAs), cytokinins (CKs), and brassinosteroids (BRs) are also very important phytohormones to congregate the challenges of drought stress. However, these hormones are usually cross talk with each other to increase the survival of plants in drought conditions. On the other hand, the transgenic approach is currently the most accepted technique to engineer the genes responsible for the synthesis of phytohormones in drought stress response. Our present review highlights the regulatory circuits of phytohormones in drought tolerance mechanism.

The invisible hand and EKC hypothesis: what are the drivers of environmental degradation and pollution in Africa?

Abstract: This study examined the drivers of environmental degradation and pollution in 17 countries in Africa from 1971 to 2013. The empirical study was analyzed with Westerlund error-correction model and panel cointegration tests with 1000 bootstrapping samples, U-shape test, fixed and random effect estimators, and panel causality test. The investigation of the nexus between environmental pollution economic growth in Africa confirms the validity of the EKC hypothesis in Africa at a turning point of US$ 5702 GDP per capita. However, the nexus between environmental degradation and economic growth reveals a U shape at a lower bound GDP of US$ 101/capita and upper bound GDP of US$ 8050/capita, at a turning point of US$ 7958 GDP per capita, confirming the scale effect hypothesis. The empirical findings revealed that energy consumption, food production, economic growth, permanent crop, agricultural land, birth rate, and fertility rate play a major role in environmental degradation and pollution in Africa, thus supporting the global indicators for achieving the sustainable development goals by 2030.

The N-shaped environmental Kuznets curve: an empirical evaluation using a panel quantile regression approach

Abstract: We evaluate the N-shaped environmental Kuznets curve (EKC) using panel quantile regression analysis. We investigate the relationship between CO2 emissions and GDP per capita for 74 countries over the period of 1994-2012. We include additional explanatory variables, such as renewable energy consumption, technological development, trade, and institutional quality. We find evidence for the N-shaped EKC in all income groups, except for the upper-middle-income countries. Heterogeneous characteristics are, however, observed over the N-shaped EKC. Finally, we find a negative relationship between renewable energy consumption and CO2 emissions, which highlights the importance of promoting greener energy in order to combat global warming.

A review of methods for measuring microplastics in aquatic environments

Abstract: An increasing number of reports have been published concerning microplastic (MP) pollution in aquatic environments. Methods used in these studies continue to be updated and lack standardization, so that an up-to-date review pertaining methods for MP research is needed. This critical review examines the analytical methods, including sampling, identification, and quantitation, for MP research. Samples are generally collected from water, sediment, and biota gastrointestinal tract. Manta nets or trawls are prevalently used in surface water sampling, while direct shoveling or box-corer grab are commonly applied in sediment sampling. Microplastics in biota are generally obtained by dissecting organisms and separating livers, gills, and guts. Density separation is frequently chosen to separate MPs from sample matrices. Chemical digestion can dissolve other organic materials and isolate MPs for further identification. Visual sorting should be combined with chemical composition analysis to better identify the polymer type. Pyrolysis or thermal decomposition gas chromatography coupled with mass spectrometry, Fourier transform infrared spectroscopy, and Raman spectroscopy are currently the main technologies for MP identification. Units prevalently used to express MP abundance in water, sediment, and biota are “particles per m3,” “particles per m2,” and “particles per individual,” respectively. As MP abundances often varied with the methods used, we recommend that analytical protocols of MPs should better be standardized and optimized. Despite the important progress in analysis of MPs, detection technologies for identifying nano-sized plastic particles are still lacking, and therefore should be developed swiftly.

Impact of economic growth, nonrenewable and renewable energy consumption, and urbanization on carbon emissions in Sub-Saharan Africa.

Abstract: The present study explores the impact of economic growth; urban expansion; and consumption of fossil fuels, solid fuels, and renewable energy on environmental degradation in developing economies of Sub-Saharan Africa. To demonstrate its findings in detail, the study adopts a system generalized method of moment (GMM) on a panel of 34 emerging economies for the period from 1995 to 2015. The results describe that the consumption of fossil and solid fuels for cooking and expansion of urban areas are significantly contributing to carbon dioxide emissions, on one end, and stimulating air pollution, on the other. The results also exhibit an inverted U-shape relationship between per capita economic growth and carbon emissions. This relation confirms the existence of an environmental Kuznets curve (EKC) in middle- and low-income economies of Sub-Saharan Africa. Furthermore, the findings reveal that the use of renewable energy alternatives improves air quality by controlling carbon emissions and lowering the direct interaction of households with toxic gases. Thus, the use of renewable energy alternatives helps the economies to achieve sustainable development targets.

Hydrogel applications for adsorption of contaminants in water and wastewater treatment

Abstract: During the last decade, hydrogels have been used as potential adsorbents for removal of contaminants from aqueous solution. To improve the adsorption efficiency, there are numerous different particles that can be chosen to encapsulate into hydrogels and each particle has their respective advantages. Depending on the type of pollutants and approaching method, the particles will be used to prepare hydrogels. The hydrogels commonly applied in water/wastewater treatment was mainly classified into three classes according to their shape included hydrogel beads, hydrogel films, and hydrogel nanocomposites. In review of many recently research papers, we take a closer look at hydrogels and their applications for removal of contaminants, such as heavy metal ion, dyes, and radionuclides from water/wastewater in order to elucidate the reactions between contaminants and particles and potential for recycling and regeneration of the post-treatment hydrogels. Graphical abstract ᅟ.

The effect of ICT on CO2 emissions in emerging economies: does the level of income matters?

Abstract: In the modern era of globalization, the rapid increase in information and telecommunication technologies (ICTs) contributes in various sectors of an economy; however, the environmental consequences of ICTs cannot be ignored. Therefore, the study investigates the nexus between ICTs, economic growth, financial development, and environmental quality in emerging economies. The novel feature of the study is that the interaction term of ICT is introduced with economic growth and financial development. The empirical findings of the study are based on panel mean group (MG) and augmented mean group (AMG) estimation methods from 1990 to 2015. The following empirical results are established: first the ICTs significantly affect CO2 emissions. Second, the moderating effect of ICT and financial development stimulate the level of CO2 emissions. Third, economic growth contributes CO2 emission; however, the interaction between ICT and GDP mitigates the level of pollution. Policy thresholds with the R&D in ICT sector are required to mitigate the level of CO2 emission. Introduction of green ICTs projects in the financial sector is a better choice to improve the energy efficiency.

New insights on the green synthesis of metallic nanoparticles using plant and waste biomaterials: current knowledge, their agricultural and environmental applications.

Abstract: Nanotechnology is a rapidly growing scientific field and has attracted a great interest over the last few years because of its abundant applications. Green nanotechnology is a multidisciplinary field that has emerged as a rapidly developing research area, serving as an important technique that emphasize on making the procedure which are clean, non-hazardous, and especially environmentally friendly, in contrast with chemical and physical methods currently employed for nanosynthesis. The biogenic routes could be termed green as these do not involve the use of highly toxic chemicals or elevated energy inputs during the synthesis. Differences in the bio-reducing agents employed for nanosynthesis can lead to the production of nanoparticles (NPs) having distinct shapes, sizes, and bioactivity. The exquitiveness of the green fabricated NPs have capacitated their potential applications in various sectors such as biomedicine, pharmacology, food science, agriculture, and environmental engineering. The present review summarizes current knowledge on various biogenic synthesis methods, relying on plants, waste biomass, and biopolymers and their reducing and stabilizing agents to fabricate nanomaterials. The main emphasis has been given on the current status and future challenges related to the wide-scale fabrication of nanoparticles for environmental remediation, pathogenicity, and agricultural applications.

Wetlands for wastewater treatment and subsequent recycling of treated effluent: a review

Abstract: Due to water scarcity challenges around the world, it is essential to think about non-conventional water resources to address the increased demand in clean freshwater. Environmental and public health problems may result from insufficient provision of sanitation and wastewater disposal facilities. Because of this, wastewater treatment and recycling methods will be vital to provide sufficient freshwater in the coming decades, since water resources are limited and more than 70% of water are consumed for irrigation purposes. Therefore, the application of treated wastewater for agricultural irrigation has much potential, especially when incorporating the reuse of nutrients like nitrogen and phosphorous, which are essential for plant production. Among the current treatment technologies applied in urban wastewater reuse for irrigation, wetlands were concluded to be the one of the most suitable ones in terms of pollutant removal and have advantages due to both low maintenance costs and required energy. Wetland behavior and efficiency concerning wastewater treatment is mainly linked to macrophyte composition, substrate, hydrology, surface loading rate, influent feeding mode, microorganism availability, and temperature. Constructed wetlands are very effective in removing organics and suspended solids, whereas the removal of nitrogen is relatively low, but could be improved by using a combination of various types of constructed wetlands meeting the irrigation reuse standards. The removal of phosphorus is usually low, unless special media with high sorption capacity are used. Pathogen removal from wetland effluent to meet irrigation reuse standards is a challenge unless supplementary lagoons or hybrid wetland systems are used.

The impact of internet use on air pollution: Evidence from emerging countries.

Abstract: The goal of this study is to analyze the impact of Internet use, employed as a proxy for information and communications technologies (ICTs), on CO2 emissions. Using a panel of 20 emerging economies spanning the period 1990 to 2015, this paper finds that increased Internet access results in lower levels of air pollution. Moreover, panel causality test results highlight a unidirectional causality running from Internet use to CO2 emissions. This result also has crucial policy implications for the governments in emerging markets. For instance, increased investment in the ICT sector could be a plausible channel to reduce air pollution level.

Panel estimation for renewable and non-renewable energy consumption, economic growth, CO 2 emissions, the composite trade intensity, and financial openness of the commonwealth of independent states

Abstract: This article investigates the long-run and causal linkages between economic growth, CO2 emissions, renewable and non-renewable (fossil fuels) energy consumption, the Composite Trade Intensity (CTI) as a proxy for trade openness, and the Chinn-Ito index as a proxy for financial openness for a panel of the Commonwealth of Independent States (CIS) region including Armenia, Azerbaijan, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Moldova, Russia, Tajikistan, Turkmenistan, Ukraine, and Uzbekistan over the period of 1992-2015. It is the first time that CTI and the Chinn-Ito indexes are used in an economic-pollution model. Employing three panel unit root tests, panel cointegration estimation methods (DOLS and FMOLS), and two panel causality tests, the main empirical results provided evidence for the bidirectional long-run relationship between all the variables in all 12 sampled countries except for economic growth-renewable energy use linkage. The findings of causality tests indicated that there is a unidirectional short-run panel causality running from economic growth, financial openness, and trade openness to CO2 emissions and from fossil fuel energy consumption to renewable energy use.

Testing EKC hypothesis with energy and sustainable development challenges: a fresh evidence from belt and road initiative economies.

Abstract: Diverse impact of greenhouse gasses (GHGs) over the landscape of environment is generally believed in literature. As CO2 emission acutely leads to GHGs is a major contributor for global warming, it creates a serious pressure on natural resources and ecological settings. Similarly, low-carbon (CO2) economy, plenty of energy resources, and sustainable growth are a big ask for worldwide economies in this era of mechanization. This paper analyzes the Environmental Kuznets Curve (EKC) hypothesis, for Belt and Road Initiative (BRI) economies, to contend the role of mega projects in BRI as an attribute for ecological detriments. The on-hand study engages fresh data information ranging from 1981 to 2016 holding with heterogeneity and cross-sectional dependence as a special deliberation. The calculated outcomes expose that, mean group estimator provides strong evidence and favor the existence of EKC approximately in every region. The long-run influence is measured by pooled mean group estimators, which shows significant outcomes in every region; additionally, the EKC hypothesis affirmed in the long run especially for developed economies. Mega projects, i.e., BRI requisite immense energy sources to accomplishing the enclosed projects efficiently and effectively. The positive association between carbon emission and energy consumption troubled the governments to make policies for restraining the magnitude of carbon emission and controls energy usage for enduring environment to its original position. Next, the valuations depicted the dense recommendations for state administrations in capacity of rigorous level supremacy, trash managing campaigns, renewable energy reliance, and advance for desirable judgments to sterilize the atmosphere.

Toxicity evaluation of textile effluents and role of native soil bacterium in biodegradation of a textile dye.

Abstract: Water pollution caused by the discharge of hazardous textile effluents is a serious environmental problem worldwide. In order to assess the pollution level of the textile effluents, various physico-chemical parameters were analyzed in the textile wastewater and agricultural soil irrigated with the wastewater (contaminated soil) using atomic absorption spectrophotometer and gas chromatography-mass spectrometry (GC-MS) analysis that demonstrated the presence of several toxic heavy metals (Ni, Cu, Cr, Pb, Cd, and Zn) and a large number of organic compounds. Further, in order to get a comprehensive idea about the toxicity exerted by the textile effluent, mung bean seed germination test was performed that indicated the reduction in percent seed germination and radicle-plumule growth. The culturable microbial populations were also enumerated and found to be significantly lower in the wastewater and contaminated soil than the ground water irrigated soil, thus indicating the biotic homogenization of indigenous microflora. Therefore, the study was aimed to develop a cost effective and ecofriendly method of textile waste treatment using native soil bacterium, identified as Arthrobacter soli BS5 by 16S rDNA sequencing that showed remarkable ability to degrade a textile dye reactive black 5 with maximum degradation of 98% at 37 °C and pH in the range of 5–9 after 120 h of incubation.

Mode of action of nanoparticles against insects

Abstract: The employment of nanoparticles obtained through various synthesis routes as novel pesticides recently attracted high research attention. An impressive number of studies have been conducted to test their toxic potential against a wide number of arthropod pests and vectors, with major emphasis on mosquitoes and ticks. However, precise information on the mechanisms of action of nanoparticles against insects and mites are limited, with the noteworthy exception of silica, alumina, silver, and graphene oxide nanoparticles on insects, while no information is available for mites. Here, I summarize current knowledge about the mechanisms of action of nanoparticles against insects. Both silver and graphene oxide nanoparticles have a significant impact on insect antioxidant and detoxifying enzymes, leading to oxidative stress and cell death. Ag nanoparticles also reduced acetylcholinesterase activity, while polystyrene nanoparticles inhibited CYP450 isoenzymes. Au nanoparticles can act as trypsin inhibitors and disrupt development and reproduction. Metal nanoparticles can bind to S and P in proteins and nucleic acids, respectively, leading to a decrease in membrane permeability, therefore to organelle and enzyme denaturation, followed by cell death. Besides, Ag nanoparticles up- and downregulate key insect genes, reducing protein synthesis and gonadotrophin release, leading to developmental damages and reproductive failure. The toxicity of SiO2 and Al2O3 nanoparticles is due to their binding to the insect cuticle, followed by physico-sorption of waxes and lipids, leading to insect dehydration. In the final section, insect nanotoxicology research trends are critically discussed, outlining major challenges to predict the ecotoxicological consequences arising from the real-world use of nanoparticles as pesticides.

Environmental exposure to cadmium—a risk for health of the general population in industrialized countries and preventive strategies

Abstract: Cadmium (Cd) is a heavy metal belonging to the group of the main chemical pollutants of the natural and occupational environment in economically developed countries. The forecasts indicate that contamination of the environment with this toxic metal, and thus the exposure of the general population, will increase. Food (particularly plant products) is the main source of the general population exposure to this element. Moreover, an important, and often the main, source of intoxication with Cd is habitual tobacco smoking. Recent epidemiological studies have provided numerous evidence that even low-level environmental exposure to this toxic metal, nowadays occurring in numerous economically developed countries, creates a risk for health of the general population. The low-level lifetime exposure to this metal may lead to the damage to the kidneys, liver, skeletal system, and cardiovascular system, as well as to the deterioration of the sight and hearing. Moreover, it has been suggested that environmental exposure to this xenobiotic may contribute to the development of cancer of the lung, breast, prostate, pancreas, urinary bladder, and nasopharynx. Taking the above into account, the aim of this review article is to draw more attention to Cd as an environmental risk factor for the health of the general population and the need to undertake preventive actions allowing to reduce the risk of health damage due to a lifetime exposure to this toxic metal.

An enhancement of antimicrobial efficacy of biogenic and ceftriaxone-conjugated silver nanoparticles: green approach.

Abstract: Of the various methods explored for the synthesis of nanoparticles, biogenesis of silver nanoparticles (AgNPs) received great attention due to their versatile properties. In this report, Daucus carota extract was used for the synthesis of AgNPs and ceftriaxone was conjugated with AgNPs to enhance their antimicrobial efficacy. The conjugated and unconjugated AgNPs were characterized by adopting UV-Vis spectroscopy, FTIR, AFM, DLS, and TEM, which revealed the SPR peak at 420 nm and spherical shaped nanoparticles of 20 nm size, respectively. The antimicrobial efficacies of the unconjugated AgNPs and ceftriaxone-conjugated AgNPs were tested against ceftriaxone-resistant human pathogens, Bacillus cereus, Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The ceftriaxone-conjugated AgNPs showed high inhibitory action (23 mm) than the unconjugated AgNPs (18 mm) at the concentration of 50 μg/mL. Both the unconjugated and ceftriaxone-conjugated AgNPs were found to be non-toxic on EAC cells at 50 μg/mL. The dose-dependent cytotoxic activities were observed on increasing the concentration of the AgNPs. The ceftriaxone-conjugated AgNPs showed high activity than the unconjugated AgNPs. The enhanced activity could be useful to treat ceftriaxone-resistant human pathogens.

Determination of point of zero charge of natural organic materials.

Abstract: This study evaluates different methods to determine points of zero charge (PZCs) on five organic materials, namely maple sawdust, wood ash, peat moss, compost, and brown algae, used for the passive treatment of contaminated neutral drainage effluents. The PZC provides important information about metal sorption mechanisms. Three methods were used: (1) the salt addition method, measuring the PZC; (2) the zeta potential method, measuring the isoelectric point (IEP); (3) the ion adsorption method, measuring the point of zero net charge (PZNC). Natural kaolinite and synthetic goethite were also tested with both the salt addition and the ion adsorption methods in order to validate experimental protocols. Results obtained from the salt addition method in 0.05 M NaNO3 were the following: 4.72 ± 0.06 (maple sawdust), 9.50 ± 0.07 (wood ash), 3.42 ± 0.03 (peat moss), 7.68 ± 0.01 (green compost), and 6.06 ± 0.11 (brown algae). Both the ion adsorption and the zeta potential methods failed to give points of zero charge for these substrates. The PZC of kaolinite (3.01 ± 0.03) was similar to the PZNC (2.9-3.4) and fell within the range of values reported in the literature (2.7-4.1). As for the goethite, the PZC (10.9 ± 0.05) was slightly higher than the PZNC (9.0-9.4). The salt addition method has been found appropriate and convenient to determine the PZC of natural organic substrates.

Nexus between financial development and CO 2 emissions in Saudi Arabia: analyzing the role of globalization

Abstract: This study examines the contribution of financial development to environmental degradation in Saudi Arabia in the period from 1971 to 2016, controlling the model for globalization and electricity consumption. The autoregressive distributive lag (ARDL) and vector error correction methods (VECM) are applied to the long-run and causal relationship, respectively. Empirical results indicate that financial development contributes to CO2 emissions and degrades environmental quality. The results also show that the role of globalization in environmental degradation is insignificant and that electricity consumption is the main culprit behind the growing CO2 emissions in Saudi Arabia. In addition, bidirectional causality exists between globalization and CO2 emissions in the long run, and financial development and CO2 emissions Granger-cause each other. Insights from the study help policymakers to understand the roles of financial development and globalization in environmental degradation and to comply with global mandate for the reduction of CO2 emissions.

Influence of foreign direct investment on indicators of environmental degradation

Abstract: This study aims to contribute to the existing literature by looking at the influence of foreign direct investment on carbon dioxide emissions, carbon footprint, and ecological footprint. In order to realize the aim of this study, we have utilized the augmented mean group estimator, which is supported by common correlated effect mean group estimator in the analysis for 20 countries. The panel results reveal that foreign direct investment has no effect on environmental degradation indicators. The panel results further reveal that gross domestic product, energy consumption, and urbanization are the main contributors to environmental degradation. The results at country level show that foreign direct investment and urbanization increase pollution in the developing countries while they mitigate pollution in the developed countries. Moreover, gross domestic product and energy consumption increase pollution for both developed and developing countries, which includes China and the USA. The negative impact of foreign direct investment on environmental degradation in the developed countries can be explained on the basis that these countries have strong environmental regulations, which makes it almost impossible for dirty foreign industries to invest therein. From the output of this research, several policy recommendations are enumerated for the investigated countries.

The impact of economic growth, energy consumption, trade openness, and financial development on carbon emissions: empirical evidence from Turkey

Abstract: This study examines the impact of economic growth, energy consumption, trade openness, financial development on carbon emissions for the case of Turkey by using annual time series data for the period of 1960-2013. The Lee and Strazicich test suggests that the variables are suitable for applying the bounds testing approach to cointegration. The cointegration analysis reveals that there exists a long-run relationship between the per capita real income, per capita energy consumption, trade openness, financial development, and per capita carbon emissions in the presence of structural breaks. The results show that in the long run, carbon emissions are mainly determined by economic growth, energy consumption, trade openness, and financial development. The VECM Granger causality analysis indicates a long-run unidirectional causality running from economic growth, energy consumption, trade openness, and financial development to carbon emissions. The findings also show that the EKC hypothesis is valid for Turkey both in the long run and short run. The study provides some implications for policy makers to decrease carbon emissions in Turkey.

A review on pesticide removal through different processes.

Abstract: The main organic pollutants worldwide are pesticides, persistent chemicals that are of concern owing to their prevalence in various ecosystems. In nature, pesticide remainders are subjected to the chemical, physical, and biochemical degradation process, but because of its elevated stability and some cases water solubility, the pesticide residues persist in the ecosystem. The removal of pesticides has been performed through several techniques classified under biological, chemical, physical, and physicochemical process of remediation from different types of matrices, such as water and soil. This review provides a description of older and newer techniques and materials developed to remove specific pesticides according to previous classification, which range from bioremediation with microorganisms, clay, activated carbon, and polymer materials to chemical treatment based on oxidation processes. Some types of pesticides that have been removed successfully to large and small scale include, organophosphorus, carbamates, organochlorines, chlorophenols, and synthetic pyrethroids, among others. The most important characteristics, advantages, and disadvantages of techniques and materials for removing pesticides are described in this work.