A temporospatial assessment of environmental quality in urbanizing Ethiopia.

Global environmental quality has been negatively affected by urbanization, particularly vulnerable in the Sub-Saharan Africa. Therefore, understanding the underlying mechanism and driving forces for the change of environmental quality with urbanization process is essential to improve the environmental sustainability. In this study, the compounded night light index (CNLI) and remote sensing ecological index (RSEI) were used respectively to evaluate the urbanization level and environmental quality in Ethiopia from 2010 to 2020. On this basis, a temporospatial assessment framework was proposed, followed by methods of coupling coordination degree, spatial autocorrelation, elasticity, and decomposition. The results showed that 63 out of 690 woredas experienced environmental deterioration. Socioeconomic effect, carbon intensity, and climate change were decomposed as drivers to environmental quality, with socioeconomic effects contributing >68% of environmental improvement, while carbon intensity and climate change were responsible for >51% and >58% of environmental deterioration from 2010 values. Continuous increase in impervious surfaces resulted in a six-fold increase in surface runoff, which raised the flooding risk in sub areas and rural landscapes. This demands reforms of climate strategies and proper livestock management.

Impact of subsidies on innovations of environmental protection and circular economy in China.

Technological innovations in China's energy conservation and environmental protection industry (EEPI) are capital-intensive and useful to mitigate environmental externality, thus they need policy support and government subsidies (GSs) at the emerging stage. Nevertheless, research is limited on the influence of GSs onto innovation performance of China's EEPI, with particular to the effect of GSs from enterprise level. This study investigated 62 listed energy conservation and environmental protection enterprises (EEPEs) in China's market in 2013-2018. The innovation performance of these enterprises was quantitatively evaluated, and multivariate regression models were devised to examine GSs and other potential drivers that might influence the innovation. Key findings include (1) EEPEs' investment in R&D and protection of intellectual properties played a positive intermediary and regulatory role between GSs and enterprise innovation performance (correlation at the significance level of 0.05 (p = 0.045; p = 0.036)). (2) There is a significant positive correlation at the significance level of 0.05 (p = 0.011), which indicates that the strongest positive relation between GSs and innovation performance was identified in an environment of low external regulation and high internal regulation, and the effects were more significant for non-state-owned EEPEs(correlation at the significance level of 0.05 (p = 0.018)). (3) The promotion of GSs to innovation was found less effective in the three most developed regions in China, i.e., the Yangtze River Delta, the Pearl River Delta, and the Beijing-Tianjin-Hebei Area. Nonetheless it was more effective for enterprise engaged in the circular economy and resource recycling (correlation at a significant level of 0.05 (P = 0.048)). These findings may shed lights on decision making of green technology development for environmental conservation and circular economy.

Tracking the carbon flows in municipal waste management in China.

Municipal solid waste (MSW), a carbon-intensive waste stream, may create both instant and indirect impacts onto environmental and climate management. Despite multiple studies made for greenhouse gases (GHGs) emissions of municipal waste, this research aims to achieve a comprehensive assessment for the carbon cycle by exploring evolution of waste composition and temporal-spatial disparities in waste management. Carbon flows embodied in MSW have been estimated across 31 provinces in Mainland China in the period 2000-2018. This improved estimation could be 15-40% smaller than the conventional estimation employing a constant waste composition. Aggregately some 578 ± 117 megatonnes carbon (MtC) were contained in MSW, including 239 ± 60 Mt of fossil carbon and 339 ± 58 Mt of degradable organic carbon. After treatment, 299 ± 66 MtC were possibly deposited in landfills and dumps. 279 ± 51 MtC were released to the atmosphere, creating net GHGs emissions equivalent to1870 ± 334 megatonnes of CO2 (MtCO2e). MSW generation in China nearly doubled during the period, net GHGs emissions increased by 1.8×, whereas fossil carbon grew by a factor of 3.5, mainly propelled by an increasing content of waste plastic in MSW. More rapid growth was witnessed in provinces in southern China than in northern. Distinct spatial-temporal evolution of waste and carbon metabolism was driven by increment, composition, and management effects. In the long run, the increment and composition effects may drop off. Enhanced practices of waste management integrating the circular economy are needed to fully recycle carbon flows, minimize emissions, and manage carbon deposits in aging landfills and dumps.

Leverage of resource efficiency over environmental emissions: Case of a megacity in China.

Material metabolism in a Chinese megacity, Shanghai, was investigated with an integrated approach. Production-based raw material input, city-wide waste output and carbon emissions were compiled for the period 1995-2020, by computing hundreds of products and by-products. Decoupling of these resource and environmental flows from economic development was assessed, and the socio-economic and technical drivers were decomposed. The research demonstrated a hypothesis that flows of primary resources, waste, and carbon emissions displayed a certain level of synchronicity in the past decades. An order effect was seen with waste indicators usually performing better than carbon indicators, and carbon indicators are better than resource indicators in terms of material/environmental intensity and decoupling. There might be a resource leverage leading to the synchronicity of environmental emissions. Improvement in resource efficiency was decomposed as the most significant driver to urban metabolism, bringing about >33 % of resource reduction, 32 % of carbon mitigation, and 30 % of waste diminution from the 2010 values. A greater extent in emission reduction than resource use was attributed to the decrease of fossil fuels share in total resource use and carbon intensity per energy consumption. Continuous increase in post-use waste flows caused a rebound of waste indicators in the recent five-year period (2016-2020) and broke up the synchronicity. This potentially foresees the shift of material metabolism from production to consumption side in major cities in China and calls for reforms of environmental policies.

Textile Waste-Derived Cobalt Nanoparticles Embedded in Active Carbon Fiber for Efficient Activation of Peroxymonosulfate to Remove Organic Pollutants.

Burning and dumping textile wastes have caused serious damage to the environment and are a huge waste of resources. In this work, cobalt nanoparticles embedded in active carbon fiber (Co/ACF) were prepared from bio-based fabric wastes, including cotton, flax and viscose. The obtained Co/ACF was applied as a catalyst for the heterogeneous activation of peroxymonosulfate (PMS) to remove bisphenol A (BPA) from an aqueous solution. The results showed that cotton-, flax- and viscose-derived Co/ACF all exhibited excellent performance for BPA degradation; over ~97.0% of BPA was removed within 8 min. The Co/ACF/PMS system exhibited a wide operating pH range, with a low consumption of the catalyst (0.1 g L-1) and PMS (0.14 g L-1). The high specific surface area (342 m2/g) and mesoporous structure of Co/ACF allowed the efficient adsorption of pollutants as well as provided more accessible active sites for PMS activation. This study provided an example of using textile wastes to produce a valuable and recyclable catalyst for environmental remediation.

Simultaneous Cr(VI) reduction and Cr(III) sequestration in a wide pH range by using magnetic chitosan-based biopolymer.

The simultaneous reduction of Cr(VI) and sequestration of the resulting Cr(III) in one process is highly desirable as a cost-effective and environmental-friendly approach for the decontamination of Cr(VI)-polluted wastewater. However, most of the existing adsorptive materials are only effective in low pH environments (pH = 1-3), severely restricting the adsorption efficiency and cost effectiveness. Herein, we proposed a chitosan-based magnetic porous microsphere (PPy@PMCS) for simultaneous Cr(VI) reduction and Cr(III) sequestration in a wide pH range. Benefiting from its abundant interaction sites, Cr(VI) was effectively adsorbed on the surface and then immediately reduced to Cr(III) with much lower toxicity. Most importantly, the resulting Cr(III) was in-situ sequestrated by the complexation of chitosan matrix. As a result, PPy@PMCS exhibited a maximum Cr(VI) adsorption capacity of 330.42 mg/g at pH 2.0 and an adsorption capacity of 167.82 mg/g even at near neutral pH (6.0), which is superior to most reported adsorbents. Furthermore, the exhausted PPy@PMCS can be rapidly separated from solutions under an external magnetic field and facilely regenerated. The proposed novel biopolymer-based material shows great application potentials in wastewater treatment.