Carbon sequestration within millet phytoliths from dry-farming of crops in China

Phytoliths are noncrystalline minerals that form inside cells and cell walls of different parts of plants. Organic carbon in living cells can be occluded in phytoliths during plant growth. It has been documented that the occluded carbon within phytoliths is an important long-term terrestrial carbon reservoir that has a major role in the global carbon cycle. Common millet and foxtail millet have become typical dry-farming crops in China since the Neolithic Age. The study of carbon conservation within phytoliths in these crops could provide insights into anthropogenic influences on the carbon cycle. In this study, we analyzed the carbon content in phytoliths of common millet and foxtail millet. The results indicated that (1) common millet and foxtail millet contained 0.136% ± 0.070% and 0.129% ± 0.085% phytolith-occluded carbon (PhytOC) on a dry mass basis, respectively; (2) based on the mean annual production of common millet and foxtail millet in the last 10 years, the phytolith occluded carbon accumulation rate of common millet and foxtail millet was approximately 0.023 ± 0.015 and 0.020 ± 0.010 t CO 2 ha 1 a 1 , respectively; (3) assuming a similar phytolith occluded carbon accumulation rate as for common millet (the highest accumulation rate was 0.038 t CO 2 ha 1 a 1 ), this could result in the sequestration of 2.37 × 10 6 t CO 2 per year for the 62.4 × 10 6 ha dry-farming crops in China. Although there was a decline in the annual production rate and planting area of foxtail millet during 1949 to 2008, the total phytolith carbon sequestration rate was 7×10 6 t CO 2 within the 60-year period. However, phytolith occluded carbon has not yet been fully considered as a global carbon sink. Also, this carbon fraction is probably one of the best candidates for the missing carbon sink.     

Response of phytoliths in Leymus chinensis to the simulation of elevated global CO2 concentrations in Songnen Grassland, China

Measuring the response of terrestrial ecosystems to elevated CO₂ concentrations is very important for understanding the effects of global change. In this study, OTC (open top chambers) were used to simulate elevated CO₂ concentrations in the Songnen Grassland. As well, phytoliths in Leymus chinensis were extracted to study the relationships between phytoliths and CO₂ concentration. The results show the rondel is abundant in Leymus chinensis, while the trapeziform polylobate is rare. When phytolith production is increased, the rondel phytoliths grow bigger and the proportions of the different phytolith types changes under high CO2 con-centration. These types include elongate hollow, acicular hair cell, square and laminate and are only observed in samples grown under high CO₂ concentrations. All this evidence demonstrates that phytoliths in Leymus chinensis are sensitive to CO₂ concentration, and indicate that phytolith analysis may have potential use in the study of global change, identifying different ecotypes of Leymus chinensis and for the reconstruction of paleoatmospheric CO₂ concentrations.     

Techno-economic evaluation of oxy-combustion coal-fired power plants

Increasing attention is being paid to the oxycombustion technique of coal-fired power plants because CO 2 produced from fossil fuel combustion can be captured and sequestrated by it. However, there are many questions about the economic properties of the oxy-combustion technique. In this paper, a detailed techno-economic evaluation study was performed on three typical power plants (2 × 300 MW subcritical, 2 × 600 MW supercritical, 2 × 1000 MW ultra supercritical), as conventional air fired and oxycombustion options in China, by utilizing the authoritative data published in 2010 for the design of coal-fired power plants. Techno-economic evaluation models were set up and costs of electricity generation, CO 2 avoidance costs as well as CO 2 capture costs, were calculated. Moreover, the effects of CO 2 tax and CO 2 sale price on the economic characteristics of oxycombustion power plants were also considered. Finally, a sensitivity analysis for parameters such as coal sample, coal price, air separation unit price, flue gas treatment unit price, CO 2 capture efficiency, as well as the air excess factor was conducted. The results revealed that: (1) because the oxy-combustion technique has advantages in thermal efficiency, desulfurization efficiency and denitration efficiency, oxy-combustion power plants will reach the economic properties of conventional air fired power plants if, (a) the CO 2 emission is taxed and the high purity CO 2 product can be sold, or (b) there are some policy preferences in financing and coal price for oxy-combustion power plants, or (c) the power consumption and cost of air separation units and flue gas treatment units can be reduced; (2) from subcritical plants to supercritical and finally ultra-supercritical plants, the economics are improving, regardless of whether they are conventional air fired power plants or oxy-combustion power plants.     

Response of leaf dark respiration of winter wheat to changes in CO2 concentration and temperature

Accurate evaluation of dark respiration of plants is important for estimation of the plant carbon budget.The response of leaf dark respiration of winter wheat to changes in CO 2 concentration and temperature was studied,using an open top chamber during 2011-2012,to understand how leaf dark respiration of winter wheat will respond to climate change.The results indicated that leaf dark respiration decreased linearly with increased CO2 concentration.Dark respiration decreased by about 11% under 560 μmol mol-1 CO2 compared with that under 390 μmol mol-1 CO2.Leaf dark respiration showed an exponential relationship with temperature,and the temperature constant(Q10) was close to 2.Moreover,the responses of leaf dark respiration to CO concentration and temperature were independent.A leaf dark respiration model based on CO2 concentration and temperature responses was developed.This model provides a method for estimation of the leaf dark respiration rate of winter wheat under future climate change and guidance for establishment of crop carbon countermeasures.     

尾巨桉人工林主要生态效应研究

为揭示尾巨桉(Eucalyptus urophylla×E. grandis)人工林与生态环境的互作关系，客观评价尾巨桉人工林的生态功能，本研究依托南宁桉树森林生态系统广西野外科学观测研究站和湛江桉树森林生态系统国家定位观测研究站，以尾巨桉人工林为研究对象，观测单木蒸腾耗水量、林分蒸散耗水量和根系吸水来源；分析枯落物量及分解归还特征，并探讨尾巨桉纯林改培混交林对土壤质量的影响；解析林下植物多样性变化规律；评估碳储量和固碳效率。结果发现：尾巨桉单木日均蒸腾耗水量1.32 mm，年蒸腾耗水量349 mm，占当年降水量的27%；尾巨桉林年蒸散耗水量占当年降水量的82%；尾巨桉林的凋落物养分归还以氮元素为主，归还总量随林龄增长而逐渐增加，延长尾巨桉培育周期有助于凋落物分解、养分还土；纯林改培套种灰木莲(Magnoliaceae glance)的混交林能够显著改善土壤质量；广西的尾巨桉林中有维管植物120科369属584种，其中包括灌木201种、草本186种；明确中龄尾巨桉人工林白天为碳汇、夜间为碳源，其中夏季和秋季吸收固定CO₂的能力最强，每日净吸收固定CO₂约为11.0 g·m^-2,转化为每年净固定碳约为10.9 t·hm^-2。阶段性观测研究表明尾巨桉生长未吸收消耗大量水分，纯林改培为混交林可显著提升土壤质量，林下植物物种多样性随林龄增长而增加；桉树的碳汇功能强于其他主要造林树种，该结论为客观认知桉树人工林与生态环境的互作关系提供了基础资料，为优化桉树人工林经营方案提供了参考。     

The impacts of “05.6” extreme flood event on riverine carbon fluxes in Xijiang River

An extreme flood event with a frequency of nearly 200 year occurred in June of 2005 in the Xijiang River, the main trunk stream of the Zhujlang River. Samples were systematically collected during the flood event, and water quality parameters, including total suspended sediment （TSS）, dissolved inorganic carbon （DIC）, dissolved organic carbon （DOC）, and particulate organic carbon （POC） were analyzed, and riverine carbon concentrations associated with its changing pattern through the flood process were discussed. These parameters reflect the changes in basin surface flow and subsurface flow during the flood. This flood event influenced annual flux estimations of POC, DOC, and DIC to great extents. Based on carbon flux estimations for the year 2005 and the flood event （June 21-28） in the Xijiang River, it was found that DIC, DOC, and POC fluxes during ＇05.6＇ flood event are 1.52×10^6g.km^-2.a^-1, 0.24×10^6 g.km^-2.a^-1, and 0.54×10^6 g.km^-2.a^-1, and account for 14.87%, 24.75% and 44.89% of the annual fluxes in 2005, respectively. The results suggested that carbon exports during extreme flood events had great contributions to the total carbon fluxes and composition of various carbon components, being important for accurate estimates of annual carbon fluxes in rivers with frequent floods.     

The voltammetric behavior of concanavalin a at bare silver electrode and analytical application

The voltammetric behavior of concanavalin A at the bare silver electrode is described. Cyclic voltammograms show a pair of well-defined redox peaks for concanavalin A in the medium of phosphate buffer(pH=7.0) with electrochemical reaction rate constant ofK ₂=0.053 s^?1 and electron transfer number ofn=2. Moreover, both the oxidation currents and the reduction currents have linear relationship with concanavalin A concentrations in the range of 1.0×10^?6～2.0×10^?5 mol/L, which can be used as an analytical method for determining concanavalin A concentration.     

Spatial concentration, congener profiles and inhalation risk assessment of PCDD/Fs and PCBs in the atmosphere of Tianjin, China

Polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) were monitored in a seasonal passive sampling scheme during June 2008 and January 2009 to investigate the spatial concentration, congener profiles and evaluate the potential inhalation risk in different functional areas in Tianjin, China. The spatial air concentrations and I-TEQs ranged 1.08×10²–8.19×10³ fg m^?3 (average 2.63×10³ fg m^?3) and 4.08–325 fg I-TEQ m^?3 (average 91.4 fg I-TEQ m^?3) respectively for PCDD/Fs. The concentration and I-TEQs of PCBs were 3.08×10⁴–3.01×10⁵ fg m^?3 (average 1.39×10⁵ fg m^?3) and 1.72–49.6 fg I-TEQ m^?3 (average 18.5 fg I-TEQ m^?3). It is obvious that PCB concentrations were several hundred times higher than the PCDD/Fs. However, the ambient air PCDD/Fs contributed a major part to the total toxicity equivalents, varying from 72.7% to 89.0% (average 81.8%). The atmospheric PCDD/F levels were observed to be higher in winter for most of sampling sites in the downtown. Besides, inhalation risk assessment showed that local residents might suffer more risk near the point sources than those in living area, industrial zones and background area in Tianjin City. However, the total daily dioxin intake was approximately several to hundreds of times lower than the WHO criteria, showing relatively low exposure risks from the impact of industry point sources in Tianjin City.     

长效及普通碳铵在土壤中的渗透转化特性

碳铵肥料施入土壤后的渗透转化特性是决定以碳铵为载体实现土壤中CO_2固定的重要基础;采用土柱淋溶模拟试验,对比研究施用长效碳铵、普通碳铵后HCO_3~-、CO_3~(2-)在土壤中的渗透转化特性,结果表明施用长效碳铵HCO_3~-、CO_3~(2-)在土壤中的含量、贮存时间以及渗透距离均明显高于相应的普通碳铵;由此可推测以长效碳铵为载体固碳性能优于普通碳铵。     

Pollen record and environmental evolution of Caotanhu wetland in Xinjiang since 4550 cal. a BP

This paper presents a multi-proxy reconstruction of the climate change in Caotanhu wetland using pollen, phytolith and charcoal records, and the data of loss of ignition （LOI）, grain size analysis, and susceptibility. Results reveal that between 4550 and 2500 cal. a BP, a dry climatic condition was not favorable for the accumulation of peat. Since 2500 cal. a BP, the climate became humid and the wetland developed with abundant freshwater aquatic plants, which contributed to peat accumulation. Never-theless, alternate periods of rain and dry climate occurred during that period. Between 2500 and 1810 cal. a BP （550 BC-140 AD）, the climate was more humid than at present. A lot of emerged plants, such as Phragmites, Typha and Sparganium, and freshwater green algae grew in the wetland which was sur-rounded by desert-steppe vegetation composed mainly of Chenopodiaceae, Artemisia, Compositae and Thalictrum. However, from 1810 to 1160 cal. a BP （140--790 AD）, the water level started to decrease and hydrophyte species reduced greatly, but some Phragmites still grew in the wetland and around it was desert vegetation with high proportion of Chenopodiaceae and Artemisia. Then from 1160 to 650 a BP （790--1300 AD）, it entered a period of desert-steppe with abundant mesic and xerophytic plants. And a lot of aquatic plants prevailed in the wetland. Here, what is noticeable is that percentages of arboreal pollen, consisting mainly of Betula and Picea, increased greatly and reached a maximal value of 27.2%, in which, Betula percentages rose to 23.2%. Hence, it is reasonable to conclude that Betula grew in the highland of the wetland, or Picea timberline shifted downward resulting in the increase of percentages of Betula and Picea pollen, which were transported into the wetland by flood or wind. But since 650 cal. a BP, desert vegetation prevailed around the wetland again with dominant Chenopodiaceae and Artemisia, and the climate was similar to modern one. Despite some aquatic plants still growing in the wetland at     

Estimate of carbonate production by scleractinian corals at Luhuitou fringing reef, Sanya, China

Carbonate production by scleractinian corals not only maintains coral reef growth, but also represents an important source of atmospheric carbon dioxide. In this paper the carbonate production by scler-actinian corals at Luhuitou fringing reef, Sanya, Hainan Island, China, is investigated with an ecological census-based method. Averaged carbonate production is 1.16 ± 0.55 kg·m-2·a-1 and 3.52 ± 1.32 kg·m-2·a-1 on the reef flat and reef slope, respectively, depending on the composition and distribution of cor...     

Investigation of nanocrystalline structure in selected carbonaceous materials

The structural parameters of nine Indian coals were determined by X-ray diffraction (XRD) and Raman spectroscopy. The study revealed that the coals contain crystalline carbon of turbostratic structure with amorphous carbon. The stacking height (L_c) and interlayer spacing (d₀₀₂) of the crystallite structure of the coals ranged from 1.986 to 2.373 nm and from 0.334 to 0.340 nm, respectively. The degree of graphitization was calculated to range from 42% to 99%, thereby confirming the ordering of the carbon layers with the increase in coal rank. An exponential correlation was observed among the aromaticity (f_a), the lateral size (L_a), and the rank (I₂₀/I₂₆), suggesting that the coal crystallites are nanocrystalline in nature. A very strong correlation was observed between the structural parameters (f_a, d₀₀₂, L_c, the H/C ratio, and I₂₀/I₂₆), the volatile matter content, and the elemental carbon content, indicating the structures of coals are controlled by the degree of contact metamorphism. The Raman spectra exhibited two prominent bands: the graphitic band (G) and the first-order characteristic defect band (D). The deconvolution resulted in five peaks: G, D1, D2, D3, and D4. The intense D1 band, which appeared at ~1350 cm?1, corresponds to a lattice vibration mode with A_1g symmetry. The D2 mode, which appeared at ~1610 cm?1, arises from the structural disorder as a shoulder on the G band.     

Comparative analysis of the dissolution kinetics of galena in binary solutions of HCl/FeCl<Subscript>3</Subscript> and HCl/H<Subscript>2</Subscript>O<Subscript>2</Subscript>

A comparative study of the dissolution kinetics of galena ore in binary solutions of FeCl₃/HCl and H₂O₂/HCl has been undertaken. The dissolution kinetics of the galena was found to depend on leachant concentration, reaction temperature, stirring speed, solid-to-liquid ratio, and particle diameter. The dissolution rate of galena ore increases with the increase of leachant concentration, reaction temperature, and stirring speed, while it decreases with the increase of solid-to-liquid ratio and particle diameter. The activation energy (E _a) of 26.5 kJ/mol was obtained for galena ore dissolution in 0.3 M FeCl₃/8.06 M HCl, and it suggests the surface diffusion model for the leaching reaction, while the E _a value of 40.6 kJ/mol was obtained for its dissolution in 8.06 M H₂O₂/8.06 M HCl, which suggests the surface chemical reaction model for the leaching reaction. Furthermore, the linear relationship between rate constants and the reciprocal of particle radius supports the fact that dissolution is controlled by the surface reaction in the two cases. Finally, the rate of reaction based on the reaction-controlled process has been described by a semiempirical mathematical model. The Arrhenius and reaction constants of 11.023 s⁻¹, 1.25×10⁴ and 3.65×10² s⁻¹, 8.02×10⁶ were calculated for the 0.3 M FeCl₃/8.06 M HCl and 8.06 M H₂O₂/8.06 M HCl binary solutions, respectively.     

屋顶绿地碳固定潜力的研究

屋顶绿化因为能减轻城市内涝、热岛效应和空气污染等一系列城市化带来的负面影响,在很多国家和地区已经得到推广和应用。通过野外调查对10个用草坪草建植的简单式屋顶绿地的碳固定潜力进行评价,并探讨影响其碳固定能力的各种因子。同化箱试验的结果表明,屋顶绿地在白天可以通过吸收和固定CO2,降低其周围空气中的CO2含量。在多云清冷的上午,由朝鲜结缕草或狗牙根为主建植而成的屋顶植被在1 h内吸收的CO2可达0.46 g·m-2,在5 min内同化箱里CO2体积分数的降低幅度可达42%(162×10-6);地上部分碳储量试验的结果表明,以草坪草为主建成的屋顶绿地植被的地上部平均固定的有机碳为92.55 g/m2。故屋顶绿地是城市内小型碳库,具有一定的固碳作用。同时,基质厚度与草坪草地上部分的有机碳含量呈显著的正相关,也说明基质厚度可能是影响屋顶绿地碳固定潜力的重要因素。     

A new estimate of global soil respiration from 1970 to 2008

Soil respiration(Rs)is one of the key processes that underline our understanding of carbon cycle in terrestrial ecosystems.Great uncertainty remains in the previous global Rs estimates with a difference of 70 Pg C a 1between the highest and lowest estimates.Thus,the present study aimed to estimate the global annual Rs and investigate the interannual and spatial variability in global annual Rs using a semi-mechanistic,empirically-based model which included climatic factors(temperature and precipitation)and topsoil(0–20 cm)organic carbon storage.About 657 published studies of annual Rs from 147 measurement sites were included in this meta-analysis.The global data sets from 1970 to 2008 on climate,surface air temperature,and soil properties were collected.The Monte Carlo method was used to propagate the simulation errors to global Rs.The results indicated that the mean annual global Rs was 94.4 Pg C a 1,increasing at roughly 0.04 Pg C a 1(~0.04%a 1)from 1970 to 2008.The Rs rate increased from colder,drier and less soil carbon-rich regions to warmer,moister and more carbon-rich regions.Highest Rs rates appeared in the tropical forest,while the lowest ones were in polar and desert regions.The annual Rs correlated directly with global temperature anomalies,suggesting that the interannual variability in temperature was responsible for the interannual variations in predicted global Rs.The global Rs increased from high-latitude zones to low-latitude zones.Further studies are recommended to explore the relationship between soil respiration and vegetation characters.     

星载CO2探测频率步进扫描IPDA激光雷达回波信号反演及误差分析

设计了星载CO₂探测频率步进扫描积分路径差分吸收（IPDA）激光雷达,弥补了欧洲航天局A-SCOPE项目单波长CO₂探测IPDA激光雷达对波长依赖性较强等不足.仿真计算了一个扫描周期内的激光雷达回波信号和系统的相对随机误差、大气压强不确定性误差以及频率不稳定性误差.当频率步进扫描到on-line波长为6 361.235 0 cm-1时,在海面反射率为0.035 sr-1、大气压强不确定性为0.001以及激光频率不稳定性为0.3 MHz条件下,系统综合相对误差为0.084 2%.结果表明,采用频率步进扫描方法结合IPDA激光雷达技术探测大气CO₂浓度不仅可以观察到相对误差随on-line波长变化的关系,而且可以有效地减小测量误差,使其小于0.5×10-6.      

铂微粒修饰固体石蜡碳糊电极对过氧化氢的电催化特征及分析应用

研究铂微粒修饰的固体石蜡碳糊电极(Pt-SCPE)对H2O2的电催化行为。在pH值4.6的柠檬酸盐-0.03 mol/L硝酸钾溶液中,用该电极H2O2在+0.18V(vs．SCE)可产生灵敏的还原电流,线性范围为1.0×10-1 mol/L～3.0×10-7 mol/L,检出限为7.5×10-8 mol/L。Pt-SCPE与液体石蜡碳糊电极比较,在峰电位、线性响应范围、检出限方面有更好的结果。用该电极测定样品中的过氧化氢,获得满意结果。     

Trend, seasonal and diurnal variations of atmospheric CO2 in Beijing

The concentration of atmospheric CO₂ in Beijing increased rapidly at a mean growth rate of 3.7% · a⁻¹ from 1993 to 1995. After displaying a peak of (409.7±25.9) μmol · mol⁻¹ in 1995, it decreased slowly. Both the almost stable anthropogenic CO₂ source and increasing biotic CO₂ sink contribute to the drop of CO₂ concentration from 1995 to 2000. The seasonal variation of CO₂ concentration exhibits a clear cycle with a maximum in winter, averaging (426.8±20.6) μmol · mol⁻¹, and a minimum in summer, averaging (369.1±6.1) μmol·mol⁻¹. The seasonal variation of CO₂ concentration is mainly controlled by phenology. The mean diurnal variation of atmospheric CO₂ concentration for a year in Beijing is highly clear: daily maximum CO₂ concentration usually occurs at night, but daily minimum CO₂ concentration does in the daytime, with a mean diurnal difference more than 34.7 μmol·mol⁻¹. It has been revealed that the interannual variations of atmospheric CO₂ concentration in winter and autumn regulated the interannual trend of atmospheric CO₂, whereas the interannual variation of CO₂ concentration in summer affected the general tendency of atmospheric CO₂ in a less degree.     

Characteristics of carbon storage in Shanghai’s urban forest

Urban forest has undergone rapid development in China over the last three decades because of the acceleration of urbanization.Urban forest thus plays an increasingly important role in carbon sequestration at a regional and national scale.As one of the most urbanized cities in China,Shanghai showed an increase of forest coverage from 3% in the 1990s to 13% in 2009.Based on CITY-green model and the second soil survey of Shanghai,the forest biomass carbon(FBC) was estimated to be 0.48 Tg in the urban area and,forest soil organic carbon(SOC)(0-100 cm soil depth) is 2.48 Tg in the urban and suburban areas,respectively.These values are relatively within the median and lower level compared with other Chinese megacities,with the FBC of 0.02 Tg in Harbin to 47.29 Tg in Chongqing and the forest SOC of 1.74 Tg in Nanjing to 418.67 Tg in Chongqing.For the different land-use types in Shanghai,the SOC density ranges from 13.8(tidal field) to 38.6 t ha-1(agricultural land).On average,the forest SOC density(31.5 t ha-1) in Shanghai is lower than that in agricultural lands(38.6 t ha-1) and higher than that in lawns(26.5 t ha-1) and gardens(21.3 t ha-1).In Shanghai,the SOC density in newly established urban parks is generally lower than that in older parks.In the northern and southeastern suburban areas(e.g.,Baoshan,Yangpu,and Nanhui districts),greenspace SOC density is higher than that in the central commercial areas(Hongkou,Putuo,Changning,and Zhabei districts) and in newly developed district(Pudong District).Uncertainties still exist in the estimation of urban forest carbon in Shanghai,as well as in other Chinese cities.Thus,future research directions are also discussed in this paper.     

HPLC determination of ascorbic acid using luminol-Cu (II) chemiluminescence-application to the analysis of Juice beverage

The chemiluminescence (CL) of luminol-Cu (II) was applied to HPLC determination of ascorbic acid, which was separated by a C₁₈ reverse-phase column with a mobile phase of 0.25 mol/L HAc. The eluted ascorbic acid was mixed with 0.3 mmol/L luminol and 0.05 mol/L CuSO₄. The light emission from the reaction of Cu(II) oxidized ascorbic acid and luminol was detected by a modified luminometer. The detection limit was 3.6×10⁻⁶ mol/L for ascorbic acid at aS/N ratio of 3, and the linear calibration range was 2×10⁻⁴–2×10⁻³ mol/L. The relative standard deviation for 5 replicate injections of 1×10⁻³ mol/L ascorbic acid was calculated as 4.3%. The method was successfully applied to determination of ascorbic acid in juice beverage. Foundation item: National Natural Science Foundation of China (29605001) Biography: Wu Feng-wu(1963-), male, research direction: analytical chemistry.