Indigenous benefits and carbon offset schemes: An Australian case study

The nexus between human rights and the environment is a key issue for climate policymakers and Indigenous peoples around the world. We combine national spatial, social and biological datasets from Australia to describe where Indigenous carbon projects are happening, why Indigenous people are participating, and how effective these schemes might be at marrying Indigenous co-benefit, biodiversity and carbon emission mitigation goals. Our study shows that many Indigenous people engage in carbon offset schemes as part of their broader cultural responsibility for landscapes, and that they seek to grow the relationship between social and ecological benefits. It also highlights the challenges associated with designing carbon offset schemes that address the impacts of climate change and respond to Indigenous peoples’ world views about what is required to sustain cultural-social-ecological systems.     

Elevated CO2 facilitates C and N accumulation in a rice paddy ecosystem

Elevated CO2 can stimulate wetland carbon(C) and nitrogen(N) exports through gaseous and dissolved pathways, however, the consequent influences on the C and N pools are still not fully known. Therefore, we set up a free-air CO2 enrichment experiment in a paddy field in Eastern China. After five year fumigation, we studied C and N in the plant–water–soil system. The results showed:(1) elevated CO2 stimulated rice aboveground biomass and N accumulations by 19.1% and 12.5%, respectively.(2) Elevated CO2 significantly increased paddy soil TOC and TN contents by 12.5% and 15.5%, respectively in the 0–15 cm layer, and22.7% and 26.0% in the 15–30 cm soil layer.(3) Averaged across the rice growing period,elevated CO2 greatly increased TOC and TN contents in the surface water by 7.6% and 11.4%,respectively.(4) The TOC/TN ratio and natural δ15N value in the surface soil showed a decreasing trend under elevated CO2. The above results indicate that elevated CO2 can benefit C and N accumulation in paddy fields. Given the similarity between the paddies and natural wetlands, our results also suggest a great potential for long-term C and N accumulation in natural wetlands under future climate patterns.     

二氧化碳水合物生成过程的强化方法研究进展

二氧化碳水合物是一种潜在的新能源,随着环境问题的日益突出,国内外科学家愈加重视二氧化碳水合物的研究,本文主要对二氧化碳水合物的强化方法进行了总结,对比了几种方法对水合物生成的影响。     

Reducing the risk level for pipelines transporting carbon dioxide and hydrogen by means of optimal safety valves spacing

In many countries where electricity generation is based on their natural resources of fossil fuels a need arises to implement new power engineering technologies that allow carbon dioxide capture. Simultaneously, efforts are made to find new energy carriers which, if fired, do not involve carbon dioxide emissions. Hydrogen is one of such fuels with this future potential which is now becoming increasingly popular. Obviously, this means that the two gases mentioned above – carbon dioxide and hydrogen – will be produced in large quantities in future, which in many cases will necessitate their transport over considerable distances. If a pipeline failure occurs, the transport of the gases may pose a serious hazard to people in the immediate vicinity of the leakage site. This paper presents an analysis of the possibility of reducing the level of risk related to pipelines transporting CO₂ and H₂ by means of safety valves. It is shown that for a 50 km long and a 0.4 m diameter pipeline transporting gas with the pressure of 15 MPa the individual risk level can be reduced from 1·10⁻⁴ to 6.5·10⁻⁷ for CO₂ and from 1·10⁻⁶ to 6·10⁻¹⁰ for H₂. The social risk can be diminished in similar proportions.     

Enhanced U(VI) bioreduction by alginate-immobilized uranium-reducing bacteria in the presence of carbon nanotubes and anthraquinone-2,6-disulfonate

Uranium-reducing bacteria were immobilized with sodium alginate, anthraquinone-2, 6-disulfonate (AQDS), and carbon nanotubes (CNTs). The effects of different AQDS-CNTs contents, U(IV) concentrations, and metal ions on U(IV) reduction by immobilized beads were examined. Over 97.5% U(VI) (20 mg/L) was removed in 8 hr when the beads were added to 0.7% AQDS-CNTs, which was higher than that without AQDS-CNTs. This result may be attributed to the enhanced electron transfer by AQDS and CNTs. The reduction of U(VI) occurred at initial U(VI) concentrations of 10 to 100 mg/L and increased with increasing AQDS-CNT content from 0.1% to 1%. The presence of Fe(III), Cu(II) and Mn(II) slightly increased U(VI) reduction, whereas Cr(VI), Ni(II), Pb(II), and Zn(II) significantly inhibited U(VI) reduction. After eight successive incubation-washing cycles or 8 hr of retention time (HRT) for 48 hr of continuous operation, the removal efficiency of uranium was above 90% and 92%, respectively. The results indicate that the AQDS-CNT/AL/cell beads are suitable for the treatment of uranium-containing wastewaters.     

Mesoporous carbon adsorbents from melamine-formaldehyde resin using nanocasting technique for CO2 adsorption

Mesoporous carbon adsorbents, having high nitrogen content, were synthesized via nanocasting technique with melamine–formaldehyde resin as precursor and mesoporous silica as template. A series of adsorbents were prepared by varying the carbonization temperature from 400 to 700°C. Adsorbents were characterized thoroughly by nitrogen sorption, X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), thermogravimetric analysis(TGA), elemental(CHN) analysis, Fourier transform infrared(FTIR) spectroscopy and Boehm titration. Carbonization temperature controlled the properties of the synthesized adsorbents ranging from surface area to their nitrogen content, which play major role in their application as adsorbents for CO_2 capture.The nanostructure of these materials was confirmed by XRD and TEM. Their nitrogen content decreased with an increase in carbonization temperature while other properties like surface area, pore volume, thermal stability and surface basicity increased with the carbonization temperature. These materials were evaluated for CO_2 adsorption by fixed-bed column adsorption experiments. Adsorbent synthesized at 700°C was found to have the highest surface area and surface basicity along with maximum CO_2 adsorption capacity among the synthesized adsorbents. Breakthrough time and CO_2 equilibrium adsorption capacity were investigated from the breakthrough curves and were found to decrease with increase in adsorption temperature. Adsorption process for carbon adsorbent–CO_2 system was found to be reversible with stable adsorption capacity over four consecutive adsorption–desorption cycles. From three isotherm models used to analyze the equilibrium data, Temkin isotherm model presented a nearly perfect fit implying the heterogeneous adsorbent surface.     

Vegetation and carbon sequestration and their relation to water resources in an inland river basin of Northwest China

In the Heihe River Basin in the arid inland area of northwest China, the distribution of water resources in vegetation landscape zones controls the ecosystems. The carbon sequestration capacity of vegetation is analyzed in relation to water resources and vegetation growing conditions. During the last 20 years, the vegetation ecosystems have degenerated in the Heihe River Basin. Simulation using the C-FIX model indicates that, at present, the total amount of NPP of vegetation accounts for about 18.16 TgC, and the average value is 106 gC/m(2)/yr over the whole basin. NPP has generally the highest value in the upperstream mountain area, middlestream artificial oases area, downstream river bank area, alluvial fan and the terminal lake depression where vegetation grows relatively well. The lowest value is found in the vast downstream desert and Gobi area. Protection of vegetation ecosystems and enhancement of carbon sequestration require such inland river basins as the Heihe River Basin to be brought under management in a comprehensive way, taking water as a key, to carry out a rational and efficient allocation and utilization of water resources.     

Removal of Se(IV) from aqueous solution using sulphuric acid-treated peanut shell

A carbonaceous sorbent was prepared from peanut shell via sulphuric acid treatment. Se(IV) removal from aqueous solution on the sorbent was studied varying time, pH, Se(IV) concentration, temperature and sorbent status (wet and dry). Se(IV) removal was faster using the wet sorbent than the dry sorbent following a pseudo-first-order model. Se(IV) removal increases at low pH values, and decreases as pH increases until pH 7. Sorption was found to fit the Langmuir equation and sorption capacity for the wet sorbent was higher than that for the dry one. Both sorbents showed an increased selenium sorption by rising the temperature. Redox processes between Se(IV) and the carbon sorbent are involved. Analysis by scanning electron microscope and X-ray powder diffraction for the sorbent after the reaction with acidified Se(IV) confirmed the availability of elemental selenium as particles on the sorbent surface as a result of Se(IV) reduction. Physicochemical tests showed an increase in sorbent acidity, cation exchange capacity (CEC) and surface functionality after the reaction with acidified Se(IV), indicating the oxidation processes occurring on the sorbent surface. Due to its reduction properties, the sorbent seems efficient for Se(IV) removal from aqueous solution.     

Wood carbon content of tree species in Eastern China: interspecific variability and the importance of the volatile fraction

Data on the mass density and carbon content of tree organs, and in particular stem wood, are essential for accurate assessments of forest carbon sequestration. However most available data, including that for East Asia, has neglected the volatile C fraction. Wood samples were collected and assayed for C content from 14 native tree species in Jilin Province, NE China. C content showed statistically significant variation among species, ranging from 48.4% to 51.0%. The volatile C fraction was non-negligible, averaging 2.2%, and showed high variation among species. As found in prior studies, wood C content was appreciably higher in conifer than hardwood (angiosperm) species (50.8+/-0.1% vs. 49.5+/-0.2%, respectively). Wood carbon density (gC/cm(3)) showed very high inter-specific variation, due mainly to differences in wood specific gravity. Our analyses, in conjunction with recently published data from North America, indicate a global mean value of 47.5+/-0.5% wood C content exclusive of volatile C; the widely used 50% figure corresponds more closely to total wood C inclusive of the volatile fraction. Failure to include volatile C or to use species- or higher-taxon-specific C content values in forest C assessments is likely to introduce biases on the order approximately 4-6%. In addition, the stocks and flows of the volatile C fraction in wood are in themselves an important and sorely neglected aspect of forest C processes likely to be strongly impacted by harvests and other management practices.