Cities, which are the primary economic engine and emission source in China, accounted for 70% of the country’s total energy-related CO
2
emissions in 2010. The development of low-carbon cities has ...become the first priority of policymakers. Low-carbon cities enhance competition in the long run but also inevitably impose costs in the short term. To investigate the associated abatement costs of CO
2
toward low-carbon cities, we apply the directional distance function on panel data covering 104 Chinese prefecture-level and above cities from 2001 to 2014. Our results show that, on average, the cost to control one ton of CO
2
is 1070 CNY, or equivalent to 129 US $. This cost shows great individual heterogeneity and time variation; the year 2011 witnesses a significant reversal of the marginal abatement cost of CO
2
. It is because China begins implementing a mandatory CO
2
intensity reduction target for the 12th Five-Year Plan (FYP). We establish a four-quadrant matrix framework to identify low-carbon cities and track the low-carbon transition path based on emission indicators (total emissions, per capita emissions, and emission intensity) and abatement cost pairs. Among the four types of emission-cost patterns, more cities are scattered in the "low emission-level and high abatement-cost" quadrant, and eight cities are clarified as low-carbon cities in 2014. In terms of per capita emissions and abatement costs, the “high-per-capita-emission and low-abatement-cost” club include five cities in 2001, while this number rises to seven members in 2014. Most cities are also located in the “low-emission-intensity and low-abatement-cost” zone when the relationship between CO
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intensity and abatement cost is considered. Our results call for policymakers' attention to hot spots and emission-based, per capita emission-based, or intensity-based city-level decarbonizing policies.
This paper investigates the technical inefficiency, shadow price and substitution elasticity of
CO
2
emissions of China based on a provincial panel for 2001–2010. Using linear programming to ...calculate a quadratic parameterized directional output distance function, we show that China’s technical inefficiency increases over the period implying further scope for
CO
2
emissions reduction in the medium and longer term at best by 4.5 and 4.9 % respectively. Our results (notwithstanding regional differences) highlight increases in the shadow price of
CO
2
abatement (1,000 Yuan/ton in 2001 to 2,100 Yuan/ton in 2010). Additionally, increasingly steep substitution elasticity highlights the difficult reality of reducing China’s
CO
2
emissions.
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•MMWCNTs adsorbent was prepared and used to treat TC-contaminated water for the first time.•MMWCNTs had efficient TC adsorption over a broad range of pH (2–10).•MMWCNTs showed ...excellent magnetic separation performance.•MMWCNTs showed an excellent regeneration performance after six cycles.•MMWCNTs effectively removed pollutants in simulated and real wastewater.
The challenges encountered in solid–liquid separation hinder the wide applications of carbon nanotube adsorbents. To overcome this problem, MnFe2O4/multiwalled carbon nanotubes (MMWCNTs) that combined the satisfactory adsorption properties of multiwalled carbon nanotubes (MWCNTs) with the magnetic separation of nanoparticles (MnFe2O4) was developed. MMWCNTs with a size of 10–50 nm exhibited remarkable magnetic separability (10.8 emu/g) and high adsorption capacity (qm = 494.91 mg/g, 308 K). Batch experiments to study the effect of pH on tetracycline (TC) adsorption showed that when the TC concentration was less than 80 mg L−1, the MMWCNTs could effectively adsorb TC in the pH range of 2–10, with a removal efficiency greater than 80%. The well fitted pseudo-second-order dynamic adsorption model and Langmuir isotherm indicated that the TC adsorption onto MMWCNTs mainly involved chemical and monolayer adsorption. Since the TC adsorption process was endothermic, increasing temperature could favor TC removal. Besides, after six cycles of regeneration with the NaOH solution, the removal efficiency could be maintained at 70% of the original, which indicated that the MMWCNTs had an excellent regeneration performance. At the same time, the results of our research showed that MMCWNT could not only be used as a good adsorbent for TC treatment, but also could be applied to other types of wastewater treatment.
Plants are particularly sensitive to climate change in alpine ecosystem of the Tibetan Plateau. The various mountain micro-climates provide a natural gradient for space-for-time substitution research ...that plant responses to climate change. In this study, we surveyed the plant community in term of species composition, diversity and biomass across 189 sites on a hill of the Tibetan Plateau and analysed the individual and integrated effects of soil temperature and moisture on the plant community. The results showed that, at the quadrat scale, there were decrease in richness of 1.08 species for every 1 °C increase in soil temperature and 3.56 species for every 10% decrease in soil moisture. The integrated effects of increasing soil temperature and decreasing moisture are expected to lead to a rapid decrease in species richness. Biomass had no significant correlation with soil temperature but significantly decreased with soil moisture decreasing (p < 0.01). Biomass would decrease when soil moisture was below 20%, no matter how the change of soil temperature. We also found that gramineae and perennial forbs were sensitive to climate change. With soil temperature increased, the proportion of gramineae increased, whereas the proportion of perennial forbs decreased. The integrated effects of soil temperature increasing and moisture decreasing caused a shift from sedge-controlled to gramineae-controlled communities in alpine meadow. This study not only enhances our understanding of mountain plant community dynamics under climate change, but also predicts the shift of vegetation response to climate change on high-elevation alpine meadow.
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•Using “space-for-time substitution” to study plant responses to climate warming•Plant diversity significantly decreases with climate warming.•Community biomass remains unchanged with climate warming.•The change of community species composition is more dependent on the migratory ability of broadleaf forbs.
Soil cracking is an important process and feature of degradation in terrestrial ecosystems. However, the patterns and causes of cracks related to alpine rangeland overgrazing have not been reported. ...In this study, we used a multiscale approach to investigate the distribution of soil‐cracking areas at a landscape scale (217 survey sites), selected the grazing‐induced parameter that was closely related to the cracks at a small scale (2013–2017), and evaluated the water infiltration due to mosaic cracking at a microscale. The results showed that cracks only formed in the alpine meadow after overstocking. Soil compaction and water content explained 89.0% of the total variance in the crack characteristics, and soil compaction was closely related to cracking. The initial infiltration rate and steady infiltration rate of the healed cracks were significantly higher than those in the raised areas in the centre of the mosaic crack patches (p < .001). We propose a new model of alpine meadow degradation considering the cracking phenomenon due to overgrazing and provide key and easy‐to‐measure indicators to prevent overgrazing and cracking: a residual biomass greater than 65 g m−2 and a height greater than 6 cm, and the soil compaction should be lower than 1,044.26 ± 188.88 kPa. These safeguard thresholds warn rangeland managers to reduce the stocking rate or improve grazing management. We suggest that the cracking stage of alpine rangelands is the most critical turning point in the process of rangeland degradation and that rangeland managers should pay more attention to crack phenomena to prevent severe degradation.
Defensive behaviors are a response to immediate and potential threats in the environment, including abiotic and biotic threats. Subterranean rodents exhibit morphological and physiological adaptions ...for life underground, and they will seal with mounds and additional plugs when their burrow opened. However, little is known about the factors driving this defensive behavior. In this study, we selected a subterranean rodent, plateau zokor (Myospalax fontanieri), as a species to investigate (both in the laboratory and in the field) the possible factors responsible for burrow-sealing behavior. Our results showed that: (1) In the laboratory, the burrow-sealing frequency of plateau zokor in response to five factors were as follows: oxygen (52.63%) > light (34.58%) > temperature (20.24%) > gas flow (6.48%) > sound/control (0%). Except for light, the burrow-sealing frequency in response to other factors was significantly lower than that in response to oxygen (P < 0.05). (2) Burrow-sealing behavior in response to each treatment did not differ significantly between males and females in the laboratory experiment. (3) In the field, during the animal's active periods in both the cold and warm season, the burrow-sealing frequency under the oxygen treatment was higher than that under the light and temperature treatments. Plateau zokors were found not to be sensitive to these treatments during their inactive periods during both the cold and warm season. (4) The latency to reseal the burrow showed no obvious differences between each treatment both in the laboratory and in the field. In conclusion, the main factor that influences the burrow-sealing behavior of plateau zokors is the variation in oxygen concentration, and this defensive behavior is related to their activity rhythm.
The dominant Co locus controls the columnar growth phenotype of apple (Malus × domestica) trees. Candidate gene MdCo31, encoding 2-oxoglutarate-dependent dioxygenase, causes dwarf growth with short ...internodes in transgenic plants by reducing the abundance of biologically active gibberellin. However, the pathway regulating MdCo31 in the dwarfism of apple trees remains unclear. In this study, expression of MdCo31 was proved to be negatively correlated with internode length in F1 populations created by crossing columnar parents, and with dwarfism in transgenic apple plantlets. Yeast (Saccharomyces cerevisiae) two-hybrid screening identified the RNA polymerase II transcription subunit MdMED32 as putative interactor of MdCo31. Bimolecular fluorescence complementation, co-immunoprecipitation, and dual-luciferase reporter assays confirmed this interaction both in vivo and in vitro. Ectopic expression of MdMED32 in Nicotiana tabacum led to a dwarf phenotype, similar to that of MdCo31 transgenic apple plants. Expression of GA2ox1 and GA20ox1, encoding key enzymes of gibberellin metabolism, was upregulated in transgenic plants. Transient transcriptional activity demonstrated that MdMED32 functioned as an activator, promoting expression of MdGA2ox1 and MdGA20ox1. These findings indicate that the interaction between MdCo31 and MdMED32 functions in the regulation of internode length in columnar apple.
•MdCo31 expression is negatively correlated with internode length in columnar apple.•MdCo31 and MdMED32 cause dwarf growth with short internodes in transgenic plants.•MdCo31 interacts with MdMED32.•MdMED32 is an activator, promoting expression of MdGA2ox1 and MdGA20ox1.
Molecular motion provides a way for biomolecules to mix and interact in living systems. Quantifying their motion is critical to the understanding of how biomolecules perform its function. However, it ...has been a challenged task to spatially map the fast diffusion of unbound proteins in the heterogenous intracellular environment. Here we reported a new imaging technique named cumulative area based on single-molecule diffusivity mapping (CA-SMdM). The strategy is based on the comparison of single-molecule images between a shorter and longer exposure time. With longer exposure time, molecules will travel further, thus giving more blurred single-molecule images, hence implying its local diffusion rates. We validated our technique through measuring the fast diffusion rates (10–40 µm
2
/s) of fluorescent dye in glycerol-water mixture, and found the values fit well with Stokes-Einstein equation. We further showed that the spatially mapping of diffusivity in live cells is plausible through CA-SMdM, and it faithfully reported the local diffusivity heterogeneity in cytosol and nucleus. CA-SMdM provides an efficient way to mapping the local molecular motion, and therefore will have profound applications in probing the biomolecular interactions for living systems.
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In this paper, pure BiOCl was prepared using a simple solvothermal method, followed by modification of BiOCl by doping with magnesium and characterisation of the material using SEM, ...TEM, XRD, EDS and DRS. The characterisation results illustrate that the magnesium was successfully doped in BiOCl and that the doping was relatively homogeneous. The photocatalytic degradation of RhB was carried out under visible light irradiation and the results showed that the photocatalytic performance of the magnesium-doped BiOCl was significantly enhanced, with a degradation rate of 99.3 % after 25 min. The doping of magnesium increased the specific surface area of BiOCl, broadened the photoresponse range and suppressed the photogenerated electron-hole complexation rate.
A facile route was developed for the large-scale preparation of core–shell CuO nanostructures based on a solvothermal route with subsequent calcination. The CuO nanostructures show core–shell shape ...and are composed of numerous nanoparticles with high porosity resulting from the thermal decomposition of the Cu2O precursors. A possible growth mechanism of the CuO core–shell nanostructures was proposed. The novel core–shell structure enlarges the range of absorbed light and enhances the absorption intensity of light. The as-obtained CuO core–shell nanospheres were evaluated for the degradation of hazardous organic contaminants in water such as phenol and methylene blue (MB) under visible light irradiation. Compared with other CuO products, the as-prepared CuO core–shell nanosphere possesses superior property on photocatalytic decomposition of phenol and MB. It is believed that the efficient photocatalytic property of the as-prepared CuO core–shell nanosphere is originated from its unique openly core–shell nanostructure, which is highly beneficial to the reagent diffusion, mass transportation and the light reflection and absorption inside the CuO nanostructure.
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•CuO core–shell nanostructures were prepared via a mild chemical solution method.•The possible growth mechanism of core–shell nanostructures was proposed.•CuO core–shell nanostructures showed high photocatalytic performance.
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