A Redox Fuel Cell That Operates with Methane as Fuel at 120{degrees}C

Platinum black efficiently catalyzes the oxidation of methane by iron(III) to generate carbon dioxide and eight equivalents of iron(II) in solutions of sulfuric acid in water. The rate of oxidation increases over 4 hours to reach approximately 4.83 x 10(-2) moles of iron(II) per gram atom of surface platinum per second. A redox fuel cell was assembled that used this reaction in a liquid reformer to generate soluble reducing equivalents of iron(II) from methane, which was electrochemically oxidized to iron(III) in the cell. A vanadium(V)-(IV)-nitric acid-O(2) redox system catalyzed the electrochemical reduction of O(2). The open-circuit voltage of the cell was 0.48 volt, and the maximum power output of the cell was 8.1 milliwatts per cubic centimeter of graphite felt electrode.     

Water, hydrogen, deuterium, carbon, carbon-13, and oxygen-18 content of selected lunar material

The water content of the breccia is 150 to 455 ppm, with a deltaD from-580 to -870 per mil. Hydrogen gas content is 40 to 53 ppm with a deltaD of -830 to -970 per mil. The CO(2) is 290 to 418 ppm with delta (13)C = + 2.3 to + 5.1 per mil and delta(18)O = 14.2 to 19.1 per mil. Non-CO(2) carbon is 22 to 100 ppm, delta(13)C = -6.4 to -23.2 per mil. Lunar dust is 810 ppm H(2)O (D = 80 ppm) and 188 ppm total carbon(delta(13)C = -17.6 per mil). The (18)O analyses of whole rocks range from 5.8 to 6.2 per mil. The temperature of crystallization of type B rocks is 1100 degrees to 1300 degrees C, based on the oxygen isotope fractionation between coexisting plagioclase and ilmenite.     

Oxygen isotope ratios in trees reflect mean annual temperature and humidity

Values of the oxygen isotope ratios (delta(18)O) in tree-ring cellulose closely reflect the delta(18)O values in atmospheric precipitation and hence mean annual temperature. The change in delta(18)O in cellulose is 0.41 per mil per degree Celsius for selected near-coastal stations. The values of delta(18)O in precipitation and cellulose also change with altitude, as demonstrated for Mount Rainier, Washington. A temperature lapse rate of 5.2 degrees +/- 0.5 degrees C per 1000 meters calculated from cellulose delta(18)O values agrees with the accepted mean annual lapse rate of 5 degrees C per 1000 meters for this region. Cellulose delta(18)O values and delta(18)O values of carbon dioxide equilibrated with leaf water differ by a fixed 16 per mil.     

A mercury-catalyzed, high-yield system for the oxidation of methane to methanol

A homogeneous system for the selective, catalytic oxidation of methane to methanol via methyl bisulfate is reported. The net reaction catalyzed by mercuric ions, Hg(II), is the oxidation of methane by concentrated sulfuric acid to produce methyl bisulfate, water, and sulfur dioxide. The reaction is efficient. At a methane conversion of 50 percent, 85 percent selectivity to methyl bisulfate ( approximately 43 percent yield; the major side product is carbon dioxide) was achieved at a molar productivity of 10(-7) mole per cubic centimeter per second and Hg(II) turnover frequency of 10(-3) per second. Separate hydrolysis of methyl bisulfate and reoxidation of the sulfur dioxide with air provides a potentially practical scheme for the oxidation of methane to methanol with molecular oxygen. The primary steps of the Hg(II)-catalyzed reaction were individually examined and the essential elements of the mechanism were identified. The Hg(II) ion reacts with methane by an electrophilic displacement mechanism to produce an observable species, CH(3)HgOSO(3)H, 1. Under the reaction conditions, 1 readily decomposes to CH(3)OSO(3)H and the reduced mercurous species, Hg(2)(2+) The catalytic cycle is completed by the reoxidation of Hg(2)(2+) with H(2)SO(4) to regenerate Hg(II) and byproducts SO(2) and H(2)O. Thallium(III), palladium(II), and the cations of platinum and gold also oxidize methane to methyl bisulfate in sulfuric acid.     

Radium-226 and radon-222: concentration in atlantic and pacific oceans

Measurements of radon-222 in seawater suggest the following. The radium-226 content of surface water in both the Atlantic and Pacific oceans is uniformly close to about 4 x 10(-14) gram per liter. The deep Pacific has a concentration of radium-226 that is four times higher and the deep Atlantic a concentration twice as high as that of the surface. These distribution profiles can be explained by the same particle-settling rate for radium-226 from surface to depth for the two oceans and by a threefold longer residence time of water in the deep Pacific than in the deep Atlantic. The vertical distribution of the deficiency of radon-222 in the surface water of the northwest Pacific Ocean suggests a coefficient of vertical eddy diffusion as high as 120 square centimeters per second and a gas-exchange rate for carbon dioxide in surface water between 14 and 60 moles per square meter per year. Vertical profiles of the excess of radon-222 in near-bottom water of the South Atlantic give coefficients of vertical eddy diffusion ranging from 1.5 to more than 50 square centimeters per second.     

Rate constants for the reactions of hydroxyl and hydroperoxyl radicals with ozone

Chain decomposition of ozone by hydroxyl and hydroperoxyl radicals has been observed. The rate constant at 3000 degrees K for OH + O(3)-->HO(2) + O(2) is 8 x 10(-14) cubic centimeters per second. The rate constant for HO(2) + O(3)--> OH + 2O(2), is 3 x 10(-15) cubic centimeters per second. These results have implications concerning stratospheric ozone.     

荒漠植物沙拐枣群体光合作用及土壤呼吸研究

为了探讨荒漠植物群体光合作用和干旱荒漠区碳源汇特征,联合利用改进同化箱和LI鄄8100 土壤CO2 通量自 动测量系统,选择高温强光和适宜环境期,连续2 年进行了观测研究。结果表明:沙拐枣群体光合速率(CAP)在不 同年份、不同月份差异较大,土壤水分改善可显著提高群体光合能力,高温强光期和适宜环境期日平均(08:00— 18:00)CAP 分别为1郾82 和2郾89 滋mol / (m2·s);用同化枝水平光合速率(Pn )计算群体水平光合速率时,高温强光 期和适宜环境期分别用公式CAP = 0.12Pn + 0.39 (r = 0.86, P 0.000 1)和CAP = 0.18Pn + 0.28 (r = 0.92, P 0.000 1)。沙拐枣生长期植冠下土壤CO2 释放速率平均为0.29 滋mol/ (m2·s),荒漠裸地为0.15 μmol / (m2·s)。沙 拐枣群体生长期固定碳为3.82 g/ (m2·a);相应时期植冠下土壤释放碳为1.03 g/ (m2·a),荒漠裸地为0.53 g/ (m2· a)。研究表明:在水分短缺的荒漠地区,荒漠植物沙拐枣群体光合速率提高幅度超过根系主要分布层土壤水分提 高幅度,适宜环境期可提高近1 倍。荒漠生态系统土壤呼吸速率较低,荒漠裸地土壤呼吸速率约为植冠下的50%。 荒漠植物沙拐枣种群区为弱碳源      

A large terrestrial carbon sink in north america implied by atmospheric and oceanic carbon dioxide data and models

Atmospheric carbon dioxide increased at a rate of 2.8 petagrams of carbon per year (Pg C year-1) during 1988 to 1992 (1 Pg = 10(15) grams). Given estimates of fossil carbon dioxide emissions, and net oceanic uptake, this implies a global terrestrial uptake of 1.0 to 2. 2 Pg C year-1. The spatial distribution of the terrestrial carbon dioxide uptake is estimated by means of the observed spatial patterns of the greatly increased atmospheric carbon dioxide data set available from 1988 onward, together with two atmospheric transport models, two estimates of the sea-air flux, and an estimate of the spatial distribution of fossil carbon dioxide emissions. North America is the best constrained continent, with a mean uptake of 1.7 +/- 0.5 Pg C year-1, mostly south of 51 degrees north. Eurasia-North Africa is relatively weakly constrained, with a mean uptake of 0.1 +/- 0.6 Pg C year-1. The rest of the world's land surface is poorly constrained, with a mean source of 0.2 +/- 0.9 Pg C year-1.     

Biogenic methane, hydrogen escape, and the irreversible oxidation of early Earth

The low O2 content of the Archean atmosphere implies that methane should have been present at levels approximately 10(2) to 10(3) parts per million volume (ppmv) (compared with 1.7 ppmv today) given a plausible biogenic source. CH4 is favored as the greenhouse gas that countered the lower luminosity of the early Sun. But abundant CH4 implies that hydrogen escapes to space (upward arrow space) orders of magnitude faster than today. Such reductant loss oxidizes the Earth. Photosynthesis splits water into O2 and H, and methanogenesis transfers the H into CH4. Hydrogen escape after CH4 photolysis, therefore, causes a net gain of oxygen [CO2 + 2H2O --> CH4 + 2O2 --> CO2 + O2 + 4H(upward arrow space)]. Expected irreversible oxidation (approximately 10(12) to 10(13) moles oxygen per year) may help explain how Earth's surface environment became irreversibly oxidized.     

Reaction of plutonium dioxide with water: formation and properties of PuO(2+x)

Results show that PuO(2+x), a high-composition (x 相似文献   

Carbon tunneling from a single quantum state

We observed ring expansion of 1-methylcyclobutylfluorocarbene at 8 kelvin, a reaction that involves carbon tunneling. The measured rate constants were 4.0 x 10(-6) per second in nitrogen and 4 x 10(-5) per second in argon. Calculations indicated that at this temperature the reaction proceeds from a single quantum state of the reactant so that the computed rate constant has achieved a temperature-independent limit. According to calculations, the tunneling contribution to the rate is 152 orders of magnitude greater than the contribution from passage over the barrier. We discuss environmental effects of the solid-state inert-gas matrix on the reaction rate.     

温度和盐度对栉江珧耗氧率和排氨率的影响

[目的]探讨温度和盐度对栉江珧耗氧率（OR）和排氨率（NR）的影响。[方法]设置5个温度梯度和5个盐度梯度,测定温度和盐度对栉江珧OR和NR的影响。[结果]在18～34℃范围内,栉江珧单位体重OR和NR均随温度升高而增加,分别为260．82～585．90μg/（g·h）和26．32～42．19μg/（g·h）,OR和NR与温度的相关方程分别为：ORT=-16．14lt^2＋197．58t＋89．29l（R^2=0．9738）;NRT=-0．6981t^2＋8．4677t＋17．792（R^2=0．9733）：在21～41盐度范围内,栉江珧单位体重OR和NR先随盐度增加而降低,在盐度31时达最小值,然后随盐度增加而升高,其变化分别为：575．82～734．40μg/（g·h）和36．78～54．45μg/（g·h）,0R和NR与盐度之间的相关方程分别为：ORs=37．929s^2一214．27s＋867．6（R^2=0．9872）;NRs=3．5442s^2-19．748s＋62．08（R^2=0．9461）;表明在正常盐度下,贝体能量消耗较低。[结论]温度和盐度对栉江珧OR和NR均有显著影响,     

水流对三疣梭子蟹幼蟹运动行为和代谢的影响

在实验室条件下,观察了水流刺激对不同体重（小、中、大3种规格的体重分别为13．348g±1．751g、21．71g±1．247g、30．308g±3．009g）的三疣梭子蟹Portunus trituberculatus幼蟹运动行为的影响,研究了幼蟹在水流刺激（23cm／s）1h及恢复12、24h时的耗氧率、氨氮排泄率、氧氮比和血蓝蛋白含量的变化。结果表明：小、中、大3种规格幼蟹最大耐流流速分别为23．0、26．7、31．0cm／s,水流刺激对幼蟹的运动行为影响显著。当流速为23．0cm／s时,3种规格的幼蟹均在水槽底部顶流爬动;流速高于23cm／s时,小规格组幼蟹趴于拦网区不动。幼蟹的耗氧率和氨氮排泄率随体重增大而降低,在水流刺激1h后,3种规格幼蟹的耗氧率、氨氮排泄率和血蓝蛋白含量均下降,而氧氮比升高;静水中恢复12h,其氧氮比恢复至正常,耗氧率、氨氮排泄率和血蓝蛋白含量升高,至24h恢复到正常水平;与对照组相比,水流刺激1h后和恢复12h时幼蟹的耗氧率、氨氮排泄率差异显著（P〈0．05）,恢复24h后无显著差异（P〉0．05）。     

Decadal variation of the surface water PCO2 in the western and central equatorial Pacific

The equatorial Pacific Ocean is one of the most important yet highly variable oceanic source areas for atmospheric carbon dioxide (CO2). Here, we used the partial pressure of CO2 (PCO2), measured in surface waters from 1979 through early 2001, to examine the effect on the equatorial Pacific CO2 chemistry of the Pacific Decadal Oscillation phase shift, which occurred around 1988 to 1992. During the decade before the shift, the surface water PCO2 (corrected for temperature changes and atmospheric CO2 uptake) in the central and western equatorial Pacific decreased at a mean rate of about -20 microatm per decade, whereas after the shift, it increased at about +15 microatm per decade. These changes altered the CO2 sink and source flux of the equatorial Pacific significantly.     

Effects of Water Regime and Straw Application in Paddy Rice Season on N2O Emission from Following Wheat Growing Season

A split-plot experiment in a rice-winter wheat rotation system was performed to study theeffects of water regime and wheat straw application in rice-growing season on N2O emission from followingwheat growing season. Water regime in the rice-growing season was designed as the conventional irrigation(flooding/drainage cycle) and the permanent flooding. Wheat straw was incorporated with three rates of 0,225 and 450 g m-2 into the paddy soil for each water regime just before rice was transplanted. N2O emissionwas measured by static chamber-gas chromatograph method. Results from the variance analysis indicated thatthe permanent flooding in rice-growing season markedly enhanced N2O emission in following wheat growingseason (P=0. 003), and that the effect of straw application on N2O emission was distinguished between twowater regimes. Under the conventional irrigation, incoporation of wheat straw reduced N2O emission in thefollowing wheat growing season, while there were no significant differences in the emission for the straw appli-cation rates of 225 and 450 g m-2. No significant differences in N2 O emissions were observed among the threerates of straw application for the permanent flooding regime. In addition, the seasonal variation of N2O emis-sion was regulated by soil temperature and moisture. The daily N2O flux (Y, mgm-2 d-1) can be quantitativelydescribed by soil temperature (T, ℃ ) and moisture (W, WFPS %) as Y=A0+A1T+A2W+A3 W2 (n=23, R2≥0. 4159** )or Y=C0 +C1W+C2W2 (n=23, R2 ≥0. 4074**). Compared with the effect of soil temperature onN2O emission, soil moisture was an important factor regulating the seasonal pattern of N2O emission.     

Surface oxidation: a major sink for water on Mars

Surface oxidation irreversibly removes both oxygen and hydrogen from the martian atmosphere at a rate of 10(8) to 10(11) per square centimeter per second. This rate corresponds to a net loss of 10(25) to 10(28) per square centimeter (10(2) to 10(5) grams per square centimeter) of H(2)O, if it is assumed that the loss rate is uniform over geologic time. Heretofore, exospheric escape was considered to be the principal irreversible sink for H(2)O, but the loss rate was estimated to be only 10(8) per square centimeter per second. It is possible that surface oxidation may have had a minor effect on the supply of H(2)O in the regolith and polar caps.     

平安县三合镇寺台等六村人饮安全工程供水规模核定

供水规模包括生活用水量、牲畜用水量、管网漏失与未预见水量之和。即:Q=Q1+Q2+Q3+Q4+Q5=720m3/d据此,平安县三合镇寺台等六村农村饮水安全工程实际供水规模按Q=720m3/d进行核定。     

猪舍不同发酵床垫料温室气体排放研究

为评价生态养猪过程中不同发酵床垫料组成对温室气体排放的影响,在南京六合发酵床养殖基地,设置3种不同垫料的发酵床处理,其垫料组成分别为木屑(S)、木屑+稻壳(SR)、木屑+稻壳+秸秆段(SRS).在一个试验周期内,连续测定垫料中CO₂、CH₄及N₂O等温室气体的排放,以及pH、含水率、铵态氮和硝态氮的动态变化,同时分析了三种垫料温室气体排放差异的机理.结果表明,垫料排放的温室气体以CO₂和N₂O为主,二者在三种温室气体二氧化碳排放当量中的占比高达99.3%~99.6%;三种垫料N₂O的排放主要集中在猪出栏前一个月,占整个试验期间排放总量的61%~68%;在垫料中添加秸秆段(SRS)对CO₂和N₂O排放总量的影响不显著,但显著增加CH₄的排放,其CH₄排放总量分别是S和SR的2.30倍和2.46倍;SRS的二氧化碳排放当量亦高于S和SR,而S和SR的二氧化碳排放当量相差不大,三种处理间无显著性差异.     

基于Biome-BGC模型的千烟洲森林水分利用效率研究

目的为了探究全球气候变化背景下森林生态系统水分利用效率的影响因子及其对气候变化的响应。方法本文利用经PEST模型参数优化后的Biome-BGC模型,对千烟洲森林生态系统2000—2014（CK）年以及不同气候情景变化模式下的水分利用效率及其影响因子进行了探究。结果（1）千烟洲的年均温和最大叶面积指数同水分利用效率呈显著正相关关系（P < 0.01）,降水同水分利用效率间的相关性不显著（P > 0.05）。（2）千烟洲不同情景模式水分利用效率的取值区间是2.09 ~ 3.71 g/kg、均值2.90 g/kg。（3）同CK（2.18 ~ 2.57 g/kg、均值2.38 g/kg）相比,千烟洲各情景模式下大气CO₂浓度增加情景（2.38 ~ 3.41 g/kg、均值2.90 g/kg）、降水和大气CO₂浓度同时增加情景（2.38 ~ 3.33 g/kg、均值2.86 g/kg）、气温和大气CO₂浓度同时增加情景（2.58 ~ 3.71 g/kg、均值3.15 g/kg）、降水和气温同时增加（2.30 ~ 2.84 g/kg、均值2.57 g/kg）及降水、气温和大气CO₂浓度同时增加情景（2.70 ~ 3.60 g/kg、均值3.15 g/kg）的水分利用效率差异显著。但是,降水增加情景（2.09 ~ 2.68 g/kg、均值2.39 g/kg）和气温增加情景（2.13 ~ 2.81 g/kg、均值2.47 g/kg）对水分利用效率的影响不显著。（4）降水和大气CO₂浓度同时增加情景与大气CO₂浓度增加情景的水分利用效率差异不显著,气温和大气CO₂浓度同时增加情景与大气CO₂浓度增加情景的水分利用效率差异显著。结论（1）千烟洲森林生态系统的水分利用效率受到气温和叶面积指数的影响,情景分析表明水分利用效率能很好的对气候变化做出响应。（2）降水、气温和大气CO₂浓度对水分利用效率的影响存在耦合效应。（3）增温对水分利用效率的影响要大于降水。      

Carbon dioxide hydrate and floods on Mars

Ground ice on Mars probably consists largely of carbon dioxide hydrate, CO(2) . 6H(2)O. This hydrate dissociates upon release of pressure at temperatures between 0 degrees and 10 degrees C. The heat capacity of the ground would be sufficient to produce up to 4 percent (by volume) of water at a rate equal to that at which it can be drained away. Catastrophic dissociation of carbon dioxide hydrate during some past epoch when the near surface temperature was in this range would have produced chaotic terrain and flood channels.