Evaluating carbon emission performance of the construction industry is a significant prerequisite for developing regional carbon mitigation plans. Taking environmental and technical heterogeneities into account, this paper employed a meta-frontier method to measure the carbon emission efficiency, carbon mitigation potential, and costs of the construction sector in different regions of China from 2005 to 2016. The empirical results show that substantial disparities in carbon emission efficiency exist in the construction industry. The total carbon mitigation potential of this sector was 206.76 million tons, with the Lower Yellow river area accounting for the largest proportion at 27%. Meanwhile, the carbon mitigation costs of this sector increased from 584.94 to 1273.30 yuan/ton during 2005–2016. The highest mitigation costs occur in the Lower Yangtze River area and the South Coastal area, indicating it was more costly in these areas to conduct additional carbon emissions mitigation. The results could facilitate the policy formulation on regional-oriented carbon emissions mitigation of the construction industry in China.
Urbanization is a dominant component of social and economic development around the world, but this process creates tremendous pressure on the ecological environment. How to achieve coordination between urbanization and conservation of this environment has become a key issue, especially in developing countries. It is necessary to identify the driving factors that affect this coordination. To identify these factors, we chose 290 Chinese prefecture-level cities to analyze the driving factors behind urbanization using spatial regression analysis, and explored the spatial differences among regions in these factors. Our results show that industrial upgrading and technological progress were the main factors that promoted coordinated development, with industrialization having positive effects under government management, but with differences among regions in how the driving forces affected coordinated development. Using technological progress to promote industrial upgrading, creating new employment to absorb surplus rural labor, and providing workers with skills training so they can take advantage of new jobs can promote win–win solutions that coordinate urbanization with conservation of the ecological environment. 相似文献
Rapid urbanization in Beijing stimulates the urban land expansion and diminishes available agricultural land. Monofunctional agricultural land use can not meet the demand of the devel- opment of the multifunctional agriculture and urbanization any more, so multifunctional agricultural land use is going to be promoted in the city. This article proposes the evolvement of the land use change from 1992 to 2004 and discusses some evolvement views. 相似文献
A self-designed experimental device was employed to simulate the pyrolytic dismantling process of selected electronic wastes(E-wastes), including printed wiring boards(PWBs)and plastic casings. The generated particulate matter(PM) of different particle sizes, carbon monoxide(CO) and carbon dioxide(CO_2) were determined, and the corresponding emission factors(EFs) were estimated. Finer particles with particle sizes of 0.4–2.1 μm accounted for78.9% and 89.3% of PM emitted by the pyrolytic processing of PWBs and plastic casings,respectively, and the corresponding EFs were 9.68 ± 4.81 and 18.49 ± 7.2 g/kg, respectively.The EFs of CO and CO_2 from PWBs and plastic casings were 55.9 ± 26.9 and 1182 ± 439 g/kg,and 133.6 ± 34.6 and 2827 ± 276 g/kg, respectively. Compared with other emission sources,such as coal, biomass, and traffic exhaust, the EFs of E-wastes were relatively higher,especially for PM. There were significant positive correlations(p 0.05) of the initial contents of carbon and nitrogen in PWBs with the related EFs of PM, CO, and CO_2, while the correlations for plastic casings were insignificant. The EFs of CO of PWBs were significantly positively correlated with the corresponding EFs of PM and the parent polycyclic aromatic hydrocarbons(PAHs); however, the same result was not observed for plastic casings. 相似文献
La2O3/Bi2O3 photocatalysts were prepared by impregnation of Bi2O3 with an aqueous solution of lanthanum precursor followed by calcination at different temperatures. The composite materials were used for the first time for the photocatalytic removal of Hg0 from a simulated flue gas under UV light irradiation. The results showed that the sample containing 6 wt.% La2O3 and calcined at 500°C has the highest dispersion of the active sites, which was promoted by the strong interaction with the support (i.e., the formation of Bi-O-La species). Since they are fully accessible on the surface, the material also exhibits excellent optical properties while the heterojunction formed in La2O3/Bi2O3 promotes the separation and migration of photoelectron-hole pairs and thus Hg0 oxidation efficiency is enhanced. The effects of the various factors (e.g., the reaction temperature and composition of the simulated flue gas (i.e., O2, NO, H2O, and SO2)) on the efficiency of the Hg0 photocatalytic oxidation were investigated. The results demonstrated that O2 and SO2 enhanced the efficiency of the reaction while the reaction temperature, NO, and H2O had an inhibitory effect. 相似文献
Widespread use of azole fungicides and low removal efficiency in wastewater treatment plants (WWTPs) have led to the elevated concentration of azole fungicides in receiving environment. However, there was limited research about the removal mechanism of azole fungicides in the biological treatment of WWTPs. Imidazole fungicide climbazole and triazole fungicide fluconazole were selected to investigate the biodegradation mechanism of azole fungicides in activated sludge under aerobic conditions. Climbazole was found to be adsorbed to solid sludge and resulted in quick biodegradation. The degradation of climbazole in the aerobic activated sludge system was fitted well by the first-order kinetic model with a half-life of 5.3 days, while fluconazole tended to stay in liquid and had only about 30% of loss within 77 days incubation. Ten biotransformation products of climbazole were identified by high resolution mass spectrometry using suspect and non-target screening method. But no biodegradation products of fluconazole were identified due to its limited removal. The possible biodegradation pathways for climbazole were proposed based on the products identification and pathway prediction system, and involves oxidative dehalogenation, side chain oxidation and azole ring loss. The findings from this study suggest that it should be a concern for the persistence of fluconazole in the environment. 相似文献
Understanding atmospheric mercury (Hg) accumulation in remote montane forests is critical to assess the Hg ecological risk to wildlife and human health. To quantify impacts of vegetation, climatic and topographic factors on Hg accumulation in montane forests, we assessed the Hg distribution and stoichiometric relations among Hg, carbon (C), and nitrogen (N) in four forest types along the elevation of Mt. Gongga. Our results show that Hg concentration in plant tissues follows the descending order of litter > leaf, bark > root > branch > bole wood, indicating the importance of atmospheric Hg uptake by foliage for Hg accumulation in plants. The foliar Hg/C (from 237.0 ± 171.4 to 56.8 ± 27.7 µg/kg) and Hg/N (from 7.5 ± 3.9 to 2.5 ± 1.2 mg/kg) both decrease along the elevation. These elevation gradients are caused by the heterogeneity of vegetation uptake of atmospheric Hg and the variation of atmospheric Hg° concentrations at different altitudes. Organic soil Hg accumulation is controlled by forest types, topographic and climatic factors, with the highest concentration in the mixed forest (244.9 ± 55.7 µg/kg) and the lowest value in the alpine forest (151.9 ± 44.5 µg/kg). Further analysis suggests that soil Hg is positively correlated to C (r2 = 0.66) and N (r2 = 0.57), and Hg/C and Hg/N both increase with the soil depth. These stoichiometric relations highlight the combined effects from environmental and climatic factors which mediating legacy Hg accumulation and selective Hg absorption during processes of organic soil mineralization. 相似文献