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Using the ARDL test and Granger approaches, this paper investigates long-term co-integration and causal relationships among nuclear, renewables, GDP and CO2 emissions in China, US, France and Japan. The findings reveal that the long-term coefficient of nuclear energy is smaller than renewable energy, indicating a relative advantage of nuclear power. However, the emission reduction effect of nuclear and renewables in China was not as much as compared to other nations. Moreover, causality from economic growth to nuclear or renewable energy existed in all countries, whereas no causality from nuclear energy to economic growth existed except in Japan. Therefore, giving priority to energy conservation and energy mix optimization is not likely to hurdle economic growth in China. However, greenness of the overall energy production process, augmentation of energy efficiency, technological progress in energy storage and internet, sustainable development of resource-society, and nuclear safety issues should be given priority in order to contribute to low-carbon growth in China.
To explore regulated mechanisms of Brassinosteroids-induced chilling tolerance, we studied the involvement of foliar sprayed 24-epibrassinolide (EBR) in the growth, lipid peroxidation, distribution of absorbed energy and excitation energy, chlorophyll fluorescence characteristics and antioxidant defense system of pepper seedlings under chilling stress. We found that low temperature retarded the growth of pepper seedlings, but foliar spray of EBR solution markedly improved the photoinhibition by increasing maximum quantum efficiency of photosystem II (Fv/Fm), the actual photochemical efficiency of photosystem II, photochemical quenching coefficient and the efficiency of excitation capture of open PSII center (Fv'/Fm'). Likewise, EBR increased the fraction of photochemical efficiency (P) and reduced the fraction of antenna heat dissipation (D) and excess energy (E). Low temperature led the increase in end product of lipid peroxidation and the content of H2O2, O2 - and OH-, and it caused the occurrence of oxidative stress. The activities of antioxidative enzymes including superoxide dismutase, peroxidase, catalase and ascorbate peroxidase, and contents of ascorbic acid and reduced glutathione were significantly improved by EBR during low temperature stress. The application of EBR also markedly increased the contents of proline, soluble sugar and protein under low temperature. EBR significantly reinforced antioxidant defense system, and it can be reflected through the reduced accumulation of harmful reactive oxygen species and MDA in pepper seedlings. Overall, these results suggest that EBR increases the tolerance of pepper seedlings against chilling stress largely by optimizing distribution of absorbed energy and excitation energy and enhancing antioxidant defense system.
Fine particles (PM₂.₅) and particulate matter (PM₁₀) monitoring data from 2015 to 2016 in 18 major cities in the Yangtze River Delta were analyzed to determine the temporal and spatial distribution characteristics of PM₂.₅ and PM₁₀ pollution in the Yangtze River Delta urban agglomeration, China. The results showed that the cities with the most serious PM₂.₅ and PM₁₀ pollution were mainly distributed along the Yangtze River in Jiangsu Province, while the lowest concentrations of PM₂.₅ and PM₁₀ were measured in Zhoushan of Zhejiang Province. The PM₂.₅ and PM₁₀ concentrations in 2016 were lower than those in 2015. In 2015 and 2016, the PM₂.₅ and PM₁₀ concentrations were the highest in winter, followed by spring, and the concentrations were the lowest in summer. In 2015 and 2016 the average annual concentrations of PM₂.₅ and PM₁₀ were lower than the ambient air quality standard of China (Grade II; PM₂.₅: 35 µg/g and PM₁₀: 70 µg/g) in Zhoushan only, but were higher than the particulate pollutant emission limits of the United States and the European Union. The ratios of PM₂.₅/PM₁₀ in the urban agglomeration were greater than 0.5, indicating that the pollution in the atmospheric particulate matter in the Yangtze River Delta was generally less than 2.5 μm.
The adsorption behavior and the adsorption mechanism of the persistent organic pollutant DDT existing extensively in soils around the world are the key to solve the DDT-contaminated soils. Hence, in this paper, selective extraction and batch experimental method were used to examine the adsorption of DDT on farmland soils H and S in Northeast China. Simultaneously, the parameters indicating soil properties and composition such as soil particle, organic matter, and minerals, ect. were analyzed. Results show that the shape and the best fitted model of adsorption isotherm of DDT in both soils were L-type and Freundlich model, respectively. Smaller soil particle had greater adsorption capacity to DDT. The effects of organic matter and minerals on the adsorption of DDT were related to the composition and the origin of organic matter and minerals. Both SiO2 and illite-montmorillorite mixed-layer could hardly adsorb DDT, and the iron oxides could adsorb DDT, while the function of manganese oxides was inhibitory of DDT adsorption. Organic matter had greater adsorption capacity to DDT than iron oxides. The adsorption capacity of the plant residues is the greatest, followed by the aromatic substances from the plant and the products from microbial degradation.
The terrestrial mosses Hypnum hamulosum and Brachythecium brotheri, which could live in water under experimental conditions, were treated with Cd²⁺ at 0, 20, 50, 100, 150, and 200 mg‧L⁻¹, and Cr³⁺ at 0, 10, 20, 30, 50, and 100 mg‧L⁻¹. The Cd²⁺ and Cr³⁺ contents in H. hamulosum and B. brotheri were measured by ICP-AES after they had been submerged in the treatment solution for 7, 14, 21, and 28 days. The results showed: 1) Both moss species have a high ability in absorb Cd and Cr. 2) With the increase of Cd²⁺ (or Cr³⁺) concentration in the culture solution, the Cd (or Cr) contents both in H. hamulosum and B. brotheri increased linearly. 3) With the extension of the treatment time, their Cd and Cr content increased logarithmically. 4) Hyphnum hamulosum and B. brotheri differ in their ability to absorb Cd²⁺ and Cr³⁺; the former has a higher ability to absorb Cd²⁺, but lower ability to absorb Cr³⁺ than the latter.
Plant hormones are trace organic molecules that play important roles in plant growth, development and stress resistance. 24-epibrassinolide (Br24) and strigolactones (Gr24) were reported to alleviate the toxicity of heavy metals and restrict their translocation into plants. In this study, the effects of Br24 and Gr24 with or without iron plaque (IP) induction on the uptake and accumulation of cadmium (Cd) and arsenic (As) were examined in rice seedlings exposed to 6-day treatments of 2 mg L⁻¹ Cd or 5 mg L⁻¹ As in nutrient solution. The results showed that the growth of rice seedlings was decreased by Cd or As treatment, but Br24 or Gr24 with or without IP alleviated this adverse effect. Br24 or Gr24 can improve root length, average diameter, surface area, and volume, and tip the number of roots of rice plants with or without IP. Cadmium contents in rice shoots were significantly reduced by Br24 with IP or Gr24, but Cd accumulation and translocation from root to shoot were not decreased. The interaction of Br24 or Gr24 and IP dramatically increased As contents in rice root, and reduced As translocation from root to shoot. Br24 or Gr24 with IP induction significantly increased Fe content, but decreased the contents of mineral elements (Mn, Cu and Zn) in rice plants. Our results suggested that the exogenous application of Br24 or Gr24 could be advantageous against the toxicity of Cd or As, and a potential way to effectively inhibit Cd or As uptake by rice plants.
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