Photoelectrochemical reduction of CO2 mediated with methylviologen at roughened silver electrodes

The photoelectrocatalytic effect for the reduction of CO2 mediated with methylviologen (MV) was studied at mercury, polished silver and roughened silver electrodes using electrochemical and surface-enhanced Raman scattering (SERS) techniques. A large photoelectrocatalytic effect for the reduction of CO2 in the presence of MV was observed at the roughened silver electrode, whereas there was only a very small photoelectrocatalytic current at a more negative potential on mercury and polished silver electrodes. The SERS spectra of MV in the presence and absence of CO2, along with the electrochemical results, demonstrate that the surface adsorbed complexes, MV+ -Ag and MV0-Ag, played a role as the mediator for photoinduced electron transfer to CO2 in the solution. The results also suggest that the surface plasmon resonance of the nanoscale silver particle contributes to the overall photoelectrocatalytic effect on a roughened silver electrode.

Synthesis, crystal structure and magnetic properties of a series of polymeric lanthanoid-copper complexes [Ln(2)Cu(3){O(CH2-CO2)(2)}(6)].nH(2)O (Ln=La, Nd, n=9; Ln=Er, n=6)

The reaction of diglycolic acid, O(CH2CO2H)(2), with Cu(NO3)(2) . H2O and lanthanoid nitrate hydrate produces a series of novel Ln-Cu mixed metal complexes, [Ln(2)CU(3){O(CH2CO2)(2)}(6)]. nH(2)O (Ln = La, Nd, n = 9; Ln = Er, n = 6), which have been characterized by elemental analysis, i.r. spectroscopy, magnetic measurements and X-ray crystallography. The Ln(3+) and Cu2+ ions are connected by the carboxylate groups of the ligands, resulting in the formation of a complicated network.

Electrochemical investigations of micro-droplets formed on metals during the deliquescence of salt particles in atmosphere

CORROSION; WATER; SPECTROSCOPY; CHLORIDE; ZINC; NUCLEATION; INTERFACE; ELECTRODE; SURFACES; GROWTH

Phenomenon of micro-droplets formation on metals during the deliquescence of salt particles in atmosphere

CORROSION; MECHANISM; WATER; ZINC

A hybrid coupled ocean-atmosphere model and ENSO prediction study

A hybrid coupled ocean-atmosphere model is designed, which consists of a global AGCM and a simple anomaly ocean model in the tropical Pacific. Retroactive experimental predictions initiated in each season from 1979 to 1994 are performed. Analyses indicate that: (1) The overall predictive capability of this model for SSTA over the central-eastern tropical Pacific can reach one year, and the error is not larger than 0.8 degrees C. (2) The prediction skill depends greatly on the season when forecasts start. However, the phenomenon of SPB (spring prediction barrier) is not found in the model. (3) The ensemble forecast method can effectively improve prediction results. A new initialization scheme is discussed.

五种红树植物光合产量模型及对环境因子的响应

以木榄（Bruguiera gymnorriza）、白骨壤（Avicennia marina）、桐花树（Aegiceras corniculata）、秋茄（Kandelia candel）和海漆（Excoecaria agallocha）为对象，以光合作用对环境因子的响应为主线，建立了从叶片水平到群体冠层水平上的光合产量模型，探讨了从器官、个体到群体的光合产量对环境因子响应的定量关系。 将Farquhar提出的单叶片光合作用生理生化模型与气孔导度B-B模型相结合，建立了光合作用－气孔导度耦合模型。模型模拟结果与实际测量结果具有较好的一致性。在温度为25.0℃，光合有效辐射为1000μmol•m-2s-1 的条件下，当外部CO2浓度倍增到720μmol•mol-1时，白骨壤、木榄、桐花树、秋茄、海漆的光合速率分别提高22.56%，17.13%，18.43%，18.63%和18.41%。在大气CO2浓度和光合有效辐射通量密度不变的条件下，光合作用速率对温度的响应呈单峰型曲线，即有一个最适温度，5种红树植物的最适温度值均为26.5℃左右。大气CO2浓度和温度固定不变（分别为350μmol•mol-1和25.0 ℃）时，光合作用对光合有效辐射的响应符合Michaelis-Menten反应曲线，模型在PAR<1800μmol•m-2s-1时模拟精度较高（P<0.01）。 在典型晴天条件下，5种红树植物的光合速率日变化都出现两个极大值（分别在11时和15时左右），中午前后光合速率较低，模型模拟光合速率日变化与实测数值日变化趋势一致。本模型能较好地模拟5种红树植物光合产量以及对环境因子的响应，模拟预测精度较高（P<0.01）。 以Ross和Nilson叶倾角分布模型为基础，分别建立了直接辐射和散射辐射在冠层内传输的子模型。冠层内的消光系数均有明显的日变化，且上午8时之前和下午16时之后随时间变化较大。在典型晴天条件下，单位土地面积日合成干物质总量（折合为CH2O）白骨壤为15.840g•m-2d-1，对于木榄、桐花树、秋茄、海漆其相应的值分别为 22.254 g•m-2d-1， 23.610 g•m-2d-1，24.525 g•m-2d-1和25.996 g•m-2d-1 。

Oceanic iron fertilization: one of strategies for sequestration atmospheric CO2

Carbon cycle is connected with the most important environmental issue of Global Change. As one of the major carbon reservoirs, oceans play an important part in the carbon cycle. In recent years, iron seems to give us a good news that oceanic iron fertilization could stimulate biological productivity as CO2 sink of human-produced CO2. Oceanic iron fertilization experiments have verified that adding iron into high nutrient low chlorophyll (HNLC) seawaters can increase phytoplankton production and export organic carbon, and hence increase carbon sink of anthropogenic CO2, to reduce global warming. In sixty days, the export organic carbon could reach 10 000 times for adding iron by model prediction and in situ experiment, i.e. the atmospheric CO2 uptake and inorganic carbon drawdown in upper seawaters also have the same magnitude. Therefore, oceanic iron fertilization is one of the strategies for increasing carbon sink of anthropogenic CO2. The paper is focused on the iron fertilization, especially in situ ocean iron experiments in order that the future research is more efficient.

A comparison of future increased CO2 and temperature effects on sympatric Heterosigma akashiwo and Prorocentrum minimum

Very little is known about how global anthropogenic changes will affect major harmful algal bloom groups. Shifts in the growth and physiology of HAB species like the raphidophyte Heterosigma akashiwo and the dinoflagellate Prorocentrum minimum due to rising CO2 and temperature could alter their relative abundance and environmental impacts in estuaries where both form blooms, such as the Delaware Inland Bays (DIB). We grew semi-continuous cultures of sympatric DIB isolates of these two species under four conditions: (1) 20 degrees C and 375 ppm CO2 (ambient control), (2)20 degrees C and 750 ppm CO2 (high CO2),(3) 24 degrees C and 375 ppm CO2 (high temperature), and (4) 24 degrees C and 750 ppm CO2 (combined). Elevated CO2 alone or in concert with temperature stimulated Heterosigma growth, but had no significant effect on Prorocentrum growth. P-Bmax (the maximum biomass-normalized light-saturated carbon fixation rate) in Heterosigma was increased only by simultaneous CO2 and temperature increases, whereas P-Bmax in Prorocentrum responded significantly to CO2 enrichment, with or without increased temperature. CO2 and temperature affected photosynthetic parameters alpha, Phi(max), E-k, and Delta F/F'(m) in both species. Increased temperature decreased and increased the Chl a content of Heterosigma and M Prorocentrum, respectively. CO2 availability and temperature had pronounced effects on cellular quotas of C and N in Heterosigma, but not in Prorocentrum. Ratios of C:P and N:P increased with elevated carbon dioxide in Heterosigma but not in Prorocentrum. These changes in cellular nutrient quotas and ratios imply that Heterosigma could be more vulnerable to N limitation but less vulnerable to P-limitation than Prorocentrum under future environmental conditions. In general, Heterosigma growth and physiology showed a much greater positive response to elevated CO2 and temperature compared to Prorocentrum, consistent with what is known about their respective carbon acquisition mechanisms. Hence, rising temperature and CO2 either alone or in combination with other limiting factors could significantly alter the relative dominance of these two co-existing HAB species over the next century. (c) 2007 Elsevier B.V. All rights reserved.

pCO(2) and carbon fluxes across sea-air interface in the Changjiang Estuary and Hangzhou Bay

Partial pressure of CO2 (pCO(2)) was investigated in the Changjiang (Yangtze River) Estuary, Hangzhou Bay and their adjacent areas during a cruise in August 2004, China. The data show that pCO(2) in surface waters of the studied area was higher than that in the atmosphere with only exception of a patch east of Zhoushan Archipelago. The pCO(2) varied from 168 to 2 264 mu atm, which fell in the low range compared with those of other estuaries in the world. The calculated sea-air CO2 fluxes decreased offshore and varied from -10.0 to 88.1 mmol m(-2) d(-1) in average of 24.4 +/- 16.5 mmol m(-2) d(-1). Although the area studied was estimated only 2 x 10(4) km(2), it emitted (5.9 +/- 4.0) x 10(3) tons of carbon to the atmosphere every day. The estuaries and their plumes must be further studied for better understanding the role of coastal seas playing in the global oceanic carbon cycle.

青藏高原高寒灌丛暖季CO2地-气交换特征

利用涡度相关技术对青藏高原高寒灌丛CO2通量进行连续观测,并以2003年7、8月份为例,对高寒灌丛暖季CO2通量变化模式及其主要气候影响因子进行了分析.结果表明,7、8月青藏高原高寒灌丛日平均净生态系统CO2交换(NEE)分别为-7.17,-7.26g/(m2•d);最高日NEE分别为-11.00,-12.09g/(m2•d).暖季高寒灌丛生态系统NEE日变化波动极为明显,8:00～19:00为CO2净吸收阶段,峰值一般出现在12:00左右,最大值为-1.72g/(m2•h)(7月份)、-1.63g/(m2•h)(8月份).19:00～次日8:00为CO2净释放,最大值为0.69g/(m2•h)(7月份)、0.86g/(m2•h)(8月份).在主要气候因子中,光合有效辐射(PAR)与NEE变化呈显著正相关,但PAR达到1000μmol/(m2•s)以后,随着PAR进一步升高,NEE有下降趋势.就温度而言,白昼(7:00～20:00)NEE变化与温度无显著关联,而夜间(21:00～次日6:00)温度与NEE变化呈显著正相关.