Microplastics (MPs) in the environment have become an issue worldwide. However, data about MPs in freshwater systems are still limited so far. This study investigated sources, fate, and seasonal and spatial distribution of MPs in the main stream Pearl River and its tributaries, as well as in the Pearl River Estuary (PRE), China. MPs were widely detected in the river water, river bed sediment, and estuarine sediment, with abundances of 0.57 ± 0.71 items L⁻¹, 685 ± 342 items kg⁻¹ dry weight (dw), and 258 ± 133 items kg⁻¹ dw, respectively. Sheet, fragmental, and fibrous polyethylene, polypropylene, and ethylene-propylene copolymers were predominant, suggesting that MPs in the Pearl River catchment be mainly derived from fragmentation of discarded plastic wastes. In addition, municipal wastewater was also an important MPs source, especially for polyethylene terephthalate (PET) fibers. Polymers of higher density, such as PET and polyvinyl alcohol were relatively more abundant in the sediment than in the river water, especially in the estuarine sediment. Upward increase of the MP abundance was observed in the sedimentary core, probably indicating increasing release of plastic wastes due to growing production and uses of plastic products. On the other hand, percentage of finer MPs increased with increasing depth. The results revealed persistence and potential downward dispersion of the fine MPs. The MPs abundance was positively related with population density and gross domestic product, demonstrating impacts of human activities and economic development on the MPs contamination. Higher MPs abundance was detected in dry season than in wet season in the river water, suggesting dilution effect of precipitation. It's estimated that 15963 tons of MPs could be released annually into the PRE from the main stream Pearl River and its tributaries.

The adsorption of polycyclic aromatic hydrocarbons (PAHs) by components such as elemental carbon (EC), total organic carbon (TOC), and particles is different, and EC and PAHs are good materials for reconstructing historical human activity patterns and pollution conditions. In this study, the effects of EC (soot and char), TOC and particles of different grain size on PAHs in surface sediments were quantitatively analysed, and their historical concentrations in a sediment core from western Taihu Lake were reconstructed. The contents of soot, TOC, clay, EC and char explained 57.2%, 27.6%, 26.0%, 24.0% and 16.4%, respectively, of the PAH concentrations in surface sediments. The correlation between the soot and PAH levels was significantly higher than that between the char, TOC, and clay contents and PAH levels, and PAHs were mainly affected by the local economic development and human activity, as indicated by metrics of population, highway mileage, coal burning, and industrial output. With the development of the economy of the Taihu Lake Basin, the composition of PAHs in the sediments has changed: the proportion of low-molecular-weight PAHs decreased from 42.4% to 17.5%, and that of high-molecular-weight PAHs increased from 58.7% to 82.5%. The concentration of PAHs in pore water from Taihu Lake over the past 100 years was reconstructed and ranged from 43.1 to 961.2 μg L−1, with an average of 180.7 μg L−1. After China's reform and opening up, the concentrations of various PAHs in Taihu Lake changed from safe to chronic pollution levels. The ratios of lead (Pb) isotopes and the diagnostic ratios of PAHs showed that the main sources of PAHs in western Taihu Lake sediments were human activities such as coal and petroleum combustion.

Nanotechnology and use of nanomaterials (NMs) improve life quality, economic growth and environmental health. However, the increasing production and use of NMs in commercial products has led to concerns about their potential toxicity on human and environment health, as well as its toxicological classification and regulation. In this context, there is an urgent need to standardize and validate procedures for nanotoxicity testing. Since the zebrafish embryotoxicity test (ZET) has been indicated as a suitable approach for the toxicity assessment of traditional and emergent pollutants, the aim of this review is to summarize the existing literature on embryotoxic and teratogenic effects of NMs on zebrafish. In addition, morphological changes in zebrafish embryos induced by NMs were classified in four reaction models, allowing classification of the mode of action and toxicity of different types of NM. Revised data showed that the interaction and bioaccumulation of NMs on zebrafish embryos were associated to several toxic effects, while the detoxification process was limited. In general, NMs induced delayed hatching, circulatory changes, pigmentation and tegumentary alterations, musculoskeletal disorders and yolk sac alterations on zebrafish embryos. Recommendations for nanotoxicological tests are given, including guidance for future research. This review reinforces the use of the ZET as a suitable approach to assess the health risks of NM exposure.

Regional specification of PM2.5 pollution characteristics is crucial for pollution control and policymaking. Spatiotemporal variations of six criteria air pollutants and influencing factors in China were studied using hourly concentrations of PM2.5, PM10, SO2, NO2, CO, and O3 from 2015 to 2016. China was categorized into eight regions: north-east, northern coastland, eastern coastland, southern coastland, Yellow River middle reaches, Yangtze River middle reaches, south-west, and north-west. The 29 exemplary cities in China were also researched. It was found that the PM2.5 concentration in the northern coastland (Beijing–Tianjin–Hebei–Shandong) was the highest (72.28 μg.m−3) among the eight regions, particularly in the city of Baoding, Hebei, which had an annual average PM2.5 concentration of 98.53 μg.m−3. Average PM2.5 concentrations in 2015 and 2016 of China were 50.16 μg.m−3 and 46.61 μg.m−3, respectively. Compared with 2015, the PM2.5 concentration decreased by 8.41% in 2016, the decline of PM2.5 in summer was the largest, followed by autumn, spring and winter. The average mean PM2.5 concentrations of the 29 exemplary cities in 2015 and 2016 were 54.66 μg.m−3 and 48.37 μg.m−3, respectively, exceeding the limit for grade 2 of the national standards (35 μg.m−3). National air pollution distribution has exploded geographically with influence of regional economic factors. Gaseous pollutant as well as geographical and socio-economic conditions influenced PM2.5 emissions. Effects of these factors on PM2.5 emissions varied across regions and decreased continuously from the northern region to the south-west and eastern coastland regions. This paper clearly identifies the regional characteristics and distribution of PM2.5, focusing on the effects of gaseous pollutant, geography and socio-economic development. Secondary transformation and vehicle exhaust across regions should be further studied.

Our world is awash with plastic. The massive increase in plastics production, combined with a shift to single-use, disposable plastics and widespread mismanagement of plastic waste, has created a huge “tragedy of the commons” (Hardin, 1968) in our oceans, seas and waterways. Plastics pollution is now a global externality that damages ecosystems, curtails biodiversity and ultimately has the potential to affect everyone on the planet. Although waste output is often modelled separately from environmental pollution in research, in the case of plastics, the waste problem has become one of global pollution. In this paper, we model the relationship between mismanaged plastic waste1 and income per capita for 151 countries, and for the first time find empirical support for the environmental Kuznets curve using plastics pollution data. Further, we find support for the hypothesis that a key instrument for reducing plastics pollution is investment in scientific and technological research. The paper concludes with a discussion of the results, limitations, and implications for future research and practice.

Many recent studies have focused on the influencing factors of the ecological footprint, but less attention has been given to human capital. Human capital, which is based on education and rate of return on education, may reduce the ecological footprint since environmental issues are human-induced. The current study investigates the impact of human capital on the ecological footprint in India for the period 1971 to 2014. The outcomes of the newly developed combined cointegration test of Bayer and Hanck disclose the long-run equilibrium relationship between variables. The findings reveal a significant negative contribution of human capital to the ecological footprint. The results of the causality test show that human capital Granger causes the ecological footprint without any feedback. In addition, energy consumption adds to the ecological footprint, while the relationship between economic growth and ecological footprint follows an inverted U-shaped pattern. The findings unveil the potential to reduce the ecological footprint by developing human capital.

Global trade plays an imperative role in the world economy that yields environmental degradation. Therefore, the current paper’s ambitions are to explore the trade–air pollution nexuses by introducing the value-added trade (VT) concept from a global value chain stance. The value-added trade (VT) indicator is constructed by the World Input-Output (WIOD) classifications database. Owing to scanty data accessibility, the sample set is reduced to 39 countries covering the period from 1995 to 2009. Furthermore, this paper is also contributing by including the eight different pathways of per capita air pollution in terms of ammonia (NH3), carbon monoxide (CO), carbon dioxide (CO₂), methane (CH₄), nitrogen oxides (NOₓ), nitrous oxide (N₂O), sulphur oxides (SOₓ) and non-methane volatile organic compounds (NMVOC) respectively. The valuable outcomes from empirical analysis have been found; Firstly, it explores that the preliminary stage of the development of value-added trade (VT) has a positive impact on air-bonds pollution. However, in the later stage of the economic development, trade improves the environmental quality as the square of value-added trade (VT²) has a negative impact on air pollution. Moreover, it also elaborates that the magnitude impact of trade on carbon monoxide (CO) air pollution is more than the other seven air pollutants. Thirdly, the inverted U-shape in the trade–air pollution Environmental Kuznets Curve (EKC) hypothesis, the non-linear relationship between trade and pollution is also validated in all eight air pollutants indicators. Policy proposals for green economy that underlines the global value chain stance and environmental factors in the growing economy are proposed.

This study aims to analyze the impact of financial development, foreign direct investment, economic growth, electricity consumption, and trade openness on environmental quality for a panel of 59 Belt and Road Initiative (BRI) countries, over the period of 1980–2016. The presence of the environmental Kuznets curve (EKC) hypothesis is investigated. The cross-sectional augmented Dickey-Fuller (CADF) and cross-sectional Im, Pesaran, and Shin panel unit root test; the Westerlund cointegration test, the dynamic seemingly unrelated regression (DSUR) approach; and the Dumitrescu and Hurlin (Econ Model 29:1450–1460, 2012) panel causality approach are employed. It is found that the analyzed variables are stationary at first differences and are cointegrated. It is also found that an increase in financial development, foreign direct investment, and trade openness enhance environmental quality, while the increase in economic growth and electricity consumption degrade environmental quality. The presence of the EKC hypothesis for the selected panel countries is validated. Furthermore, the Dumitrescu-Hurlin (DH) panel causality test result confirmed the presence of bidirectional causality among economic growth, foreign direct investment, financial development, electricity consumption, and trade openness with environmental quality.

To effectively combat global warming, an enormous reduction in CO₂ emissions is required. Cameroon, which is currently the largest emitter of CO₂ in the CEMAC subregion, has committed to reducing its greenhouse gas emissions by 32% by 2035. However, previous studies in Cameroon have only addressed the relationship between economic growth, energy consumption, and CO₂ emissions without estimating all causal relationships at the same time. Moreover, no study has yet decomposed this country’s CO₂ emissions to date. To fill these research gaps and further assess the determinants of these CO₂ emissions, an extended Kaya identity and the Logarithm Mean Divisia Index (LMDI I) have been applied in this paper to identify, quantify, and explain the main drivers of Cameroon’s CO₂ emissions from 2007 to 2014. Seven effects were measured and the main findings show that carbon intensity and the emission factor increased by 0.57% and 107.50% respectively. Regarding contributions to the increase of CO₂ emissions, the population effect was the most positive followed by the activity effect, whereas the energy intensity, the substitution of fossil fuels and the penetration of renewable energies have contributed to reduce the CO₂ emission. To enable Cameroon to not only achieve the goals of its vision but also develop a low-carbon economy, this paper provides some proposed avenues that should be considered by policymakers.

As an important role in economic development in China, industrial parks have consumed plenty of energy, while emitting enormous air pollutants and discharging large quantities of waste heat. Energy cascade utilization is an effective way to improve the energy efficiency of industrial parks. The objective of this study was to assess the co-benefits of energy cascade utilization, including the energy savings potential, reduction potential of air pollutants, and air quality improvements, in an industrial park in China. Through an energy flow analysis of steam at different pressures and residual gas among various enterprises, this study identified the existing energy cascade utilization network in a baseline scenario and proposed an enhanced scenario. To evaluate the co-benefits of these two scenarios, the CALPUFF model was used to integrate energy savings and air pollutant mitigation for the park in 2017. The results show that energy cascade utilization can result in considerable co-benefits related to energy conservation, air pollutant emission reductions, and air quality improvements. In the enhanced scenario, the total energy savings potential is 11,425 TJ, with emission reductions of 859 tons of SO₂ and 910 tons of NOₓ. Based on the CALPUFF simulations of SO₂ and NOₓ diffusion in the four seasons, the concentrations of SO₂ and NOₓ in the study area considerably decreased in the enhanced scenario compared with those in the baseline scenario. This study demonstrates that the park should focus on the cascade utilization of waste heat and residual gas to improve the energy utilization efficiency and reduce atmospheric pollutant emissions.