Soil Organic Carbon Contents and Stocks in Coastal Salt Marshes with Spartina alterniflora Following an Invasion Chronosequence in the Yellow River Delta,China

Plant invasion alters the fundamental structure and function of native ecosystems by affecting the biogeochemical pools and fluxes of materials and energy. Native(Suaeda salsa) and invasive(Spartina alterniflora) salt marshes were selected to study the effects of Spartina alterniflora invasion on soil organic carbon(SOC) contents and stocks in the Yellow River Delta. Results showed that the SOC contents(g/kg) and stocks(kg/m^2) were significantly increased(P < 0.05) after Spartina alterniflora invasion of seven years, especially for the surface soil layer(0–20 cm). The SOC contents exhibited an even distribution along the soil profiles in native salt marshes, while the SOC contents were gradually decreased with depth after Spartina alterniflora invasion of seven years. The natural ln response ratios(Ln RR) were applied to identify the effects of short-term Spartina alterniflora invasion on the SOC stocks. We also found that Spartina alterniflora invasion might cause soil organic carbon losses in a short-term phase(2–4 years in this study) due to the negative Ln RR values, especially for 20–60 cm depth. And the SOCD in surface layer(0–20 cm) do not increase linearly with the invasive age. Spearman correlation analysis revealed that silt + clay content was exponentially related with SOC in surface layer(Adjusted R^2 = 0.43, P < 0.001), suggesting that soil texture could play a key role in SOC sequestration of coastal salt marshes.

Experimental Design Technique on Removal of Hydrogen Sulfide using CaO-eggshells Dispersed onto Palm Kernel Shell Activated Carbon：Experiment,Optimization,Equilibrium and Kinetic Studies

This study presents the use of chicken eggshells waste utilizing palm kernel shell based activated carbon（PKSAC） through the modification of their surface to enhance the adsorption capacity of H2S. Response surface methodology technique was used to optimize the process conditions and they were found to be： 500 mg/L for H2S initial concentration, 540 min for contact time and 1 g for adsorbent mass. The impacts of three arrangement factors（calcination temperature of impregnated activated carbon（IAC）, the calcium solution concentration and contact time of calcination） on the H2S removal efficiency and impregnated AC yield were investigated. Both responses IAC yield（IACY, %） and removal efficiency（RE, %） were maximized to optimize the IAC preparation conditions. The optimum preparation conditions for IACY and RE were found as follows： calcination temperature of IAC of 880 ℃, calcium solution concentration of 49.3% and calcination contact time of 57.6 min, which resulted in 35.8% of IACY and 98.2% RE. In addition, the equilibrium and kinetics of the process were investigated. The adsorbent was characterized using TGA, XRD, FTIR, SEM/EDX, and BET. The maximum monolayer adsorption capacity was found to be 543.47 mg/g. The results recommended that the composite of PKSAC and Ca O could be a useful material for H2S containing wastewater treatment.

Carbon compensation and carbon neutrality:Regional variations based on net carbon transfer of trade in China

Inter-provincial carbon compensation is an important means for a country to realize regional environmental protection and achieve coordinated regional development and realize the carbon neutral goal.It is easier to realize inter-provincial carbon compensation compared with the national level.Based on the multi-regional input-output model and the input-output data of 30 provinces in China,this study measured the carbon transfer in,carbon transfer out and net carbon transfer of each province,and based on the undesirable slacks-based measurement model under the common frontier,the provinces were given the shadow price of carbon emission in line with the situation of the local economic development,resource endowment,and industrial structure,and based on which,the amount of carbon compensation of each province was measured.The results show that:China's provinces and regions have a larger share of trade-implied carbon emissions;the net carbon transfer in areas mainly concentrated in the traditional energy provinces,which provide industrial products for other regions and undertake the transfer of carbon emissions,and become the main carbon compensation recipient areas;the net carbon transfer out is mainly concentrated in the economically developed and densely populated areas such as Beijing-Tianjin region and the eastern and southern coasts,which satisfy the end-consumption by purchasing a large number of industrial products and generate a large amount of carbon emissions.Transfer out;becoming the main carbon offset payment area.Based on the results of this study,it is proposed to improve the national provincial carbon offset mechanism and implement a differentiated and synergistic carbon emission reduction cooperation approach.The research program of this study can provide a reference for the development of inter-regional carbon offset programs.

Ultrasonic Pulse Signal Resonance Features in Layered CFRP Within Voids

The ultrasonic pulse signal resonance features in layered carbon fiber reinforced plastic（CFRP） within voids were researched. The frequency domain model of acoustic wave propagation in multilayered medium was established. Then the reflection coefficient of multilayered CFRP within voids was numerically calculated. The results are as follows. When the CFRP laminate is tested by ultrasonic whose center frequency is close to the CFRP inherent resonant frequency, the ultrasonic may generate resonance phenomenon in CFRP. If CFRP contains evenly distributed voids, the frequency of resonant signal and its amplitude all decrease with the increase of porosity. For the thick section CFRP within local concentrated voids, the local concentrated voids near testing surface will cause signal frequency reduction and the decrease of its amplitude. But the voids which exist in layers far away from testing surface almost have no influence on signal resonance. The ultrasonic pulse echo testing was conducted for thick section CFRP specimen. The analysis results of testing signals were in accordance with the results of the numerical calculation, showing that the reflection coefficient frequency response model can effectively explain the ultrasonic resonance phenomenon in layered CFRP within voids.

Transcriptome response of wheat Norin 10 to long-term elevated CO_2 under high yield field condition

The increasing atmospheric carbon dioxide concentration, caused by fossil fuel combustion and deforestation, plays an important role in plant growth and development. Wheat, as a major staple crop, adapts to climate change by tuning its inherent molecular mechanism, which is not well understood. The present study employed the RNA-Seq method to generate transcriptome profiles of the wheat Norin 10 in response to elevated CO_2 in comparison with ambient CO_2. The 10 895 787 high-quality clean reads of Norin 10 were assembled de novo using Trinity（without a reference genome） resulting in a total of 18 206 candidate transcripts with significant BLAST matches. GO enrichment analysis of Norin 10 at different CO_2 concentrations showed that some functional genes related to plastids, precursor metabolites, and energy, thylakoid and photosynthesis were apparently enriched at elevated CO_2（550 μmol mol^–1） in contrast to that at ambient CO_2（400 μmol mol^–1）; these findings were further confirmed by RT-PCR analysis. The findings demonstrated the specific effects of elevated CO_2 during long-term period in free air CO_2 enrichment（FACE） on transcriptome response of the high yielding wheat variety, Norin 10, which has a large spike.

Iron-mediated soil carbon response to water-table decline in an alpine wetland

With the support by the National Natural Science Foundation of China and the Ministry of Science and Technology of China,a collaborative study by the research groups led by Prof.Feng Xiaojuan(冯晓娟)from the Institute of Botany,Chinese Academy of Sciences and Prof.He Jinsheng(贺金生)from Peking University demonstrates the under-investigated role of iron(Fe)in mediating soil enzyme activity

Effects of Doubled Carbon Dioxide on Rainfall Responses to Radiative Processes of Water Clouds

The effects of doubled carbon dioxide on rainfall responses to radiative processes of water clouds are investigated in this study.Two groups of two-dimensional cloud-resolving model sensitivity experiments with regard to pre-summer heavy rainfall around the summer solstice and tropical rainfall around the winter solstice are conducted and their five-day averages over the model domain are analyzed.In the presence of radiative effects of ice clouds,doubled carbon dioxide changes pre-summer rainfall from the decrease associated with the enhanced atmospheric cooling to the increase associated with the enhanced infrared cooling as a result of the exclusion of radiative effects of water clouds.Doubled carbon dioxide leads to the reduction in tropical rainfall,caused by the removal of radiative effects of water clouds through the suppressed infrared cooling.In the absence of radiative effects of ice clouds,doubled carbon dioxide changes pre-summer rainfall from the increase associated with the strengthened atmospheric warming to the decrease associated with the weakened release of latent heat caused by the elimination of radiative effects of water clouds.The exclusion of radiative effects of water clouds increases tropical rainfall through the strengthened infrared cooling,which is insensitive to the change in carbon dioxide.

Wastewater-nitrogen removal using polylactic acid/starch as carbon source： Optimization of operating parameters using response surface methodology

Nitrogen removal from ammonium-containing wastewater was conducted using polylactic acid （PLA）/ starch blends as carbon source and carrier for fimctional bacteria. The exclusive and interactive influences of operating parameters （i.e., temperature, pH, stirring rate, and PLA-to-starch ratio （PLA proportion）） on nitrification （Y1）, denitrification （Y2）, and COD release rates （Y3） were investigated through response surface methodology. Experimental results indicated that nitrogen removal could be successfully achieved in the PLA/starch blends through simultaneous mtnncatlon anti clenltnncatlon. The carbon release rate of the blends was controllable. The sensitivity of Y1, Y2, and Y3 to different operating parameters also differed. The sequence for each response was as follows： for Y1, pH 〉 stirring rate 〉 PLA proportion 〉 temperature; for Y2, PH 〉 PLA proportion 〉.temperature.〉 stirring rate; and for Y3, stirring rate 〉pH 〉 PLA proportion 〉 temperature. In this study, the following optimum conditions were observed： temperature, 32.0℃; pH 7.7; stirring rate, 200.0 r · min^-1 and PLA proportion 0.4. Under these conditions Y1 Y2 and Y3 were 134.0 μg-N·g-blend^-1·h^-1, 160.9μg-N-g-blend^-1·h^-1, and 7.6 × 10^3 μg-O·g-blend^-1·h^-1, respectively. These results suggested that the PLA/starch blends may be an ideal packing material for nitrogen removal.