Relationship between charge transfer energies of Yb3+ and Sm3+ and crystal environmental factor

Relationship between charge transfer energies E-CT of Yb3+ and Sm3+ and environmental factors h(e) in various crystals was investigated using a dielectric chemical bond method. Both results show that they have an exponential relation E-CT = A+B exp(-kh(e)), but the exponential factors are different, which indicates that the interaction between the rare earth ions and environment is connected with the kind of rare earth ion. This result provides a method of determining charge transfer energies of Yb3+ and Sm3+ from a crystal structure.

内蒙古羊草草原碳通量观测及其驱动机制分析

植被与大气间CO2通量的长期观测能够使人们加深对陆地生态系统在全球碳循环中科学地位的理解。在生态系统水平上，涡度相关技术是评价植被/大气间净生态系统CO2交换量的主要手段。本研究以内蒙古羊草草原通量站为试验平台，以涡度相关技术为主要技术手段，以内蒙古草原生态系统定位研究站羊草草原围封样地2003～2005年开路涡度相关系统观测的CO2通量数据为基础，深入探讨了内蒙古羊草草原生态系统CO2通量不同时间尺度上的变化特征及其驱动机制。 在建立生态系统尺度CO2通量观测基本方法论的前提下，集中探讨了不同时间尺度内蒙古羊草草原生态系统净生态系统碳交换、呼吸作用以及碳吸收的季节变异特征及其控制机制，初步建立了内蒙古羊草草原净生态系统CO2交换量估算的基本方法，可为生态系统过程模拟与模型预测提供科学依据和技术支撑。主要结果包括以下几个方面： 1. 功率谱和协谱分析表明，开路涡度相关系统对高频湍流信号的响应能力可以满足内蒙古草原生态系统实际观测要求。与闭路涡度相关系统和常规气象系统对比分析表明，开路涡度相关系统在CO2通量长期观测中仪器性能稳定，可以满足CO2通量长期观测的客观需要。坐标旋转校正是复杂地形条件下CO2通量测定理想的倾斜校正途径。能量平衡闭合的测试仅可以作为数据质量评价的参考标准之一，而不能作为CO2通量数据质量评价的绝对标准并用于数据校正。 2. 按照CO2通量吸收的高峰特征划分，正常降水年，内蒙古羊草草原CO2通量同时具有一个吸收高峰和两个吸收高峰的特征。而极端干旱年蒙古羊草草原的CO2通量具有两个吸收高峰的特征。在严重干旱胁迫条件下，2005年内蒙古羊草草原生态系统净生态系统交换出现显著下降的趋势。净生态系统交换下降主要是降雨量减少的影响。 3. 通过分析不同时间尺度上CO2通量和环境因子的关系，发现小时尺度上，内蒙古羊草草原生态系统的净生态系统交换主要由光合有效辐射控制，而饱和水汽压差和土壤含水量是影响生态系统光合作用的另外两个关键因素。在更大的时间尺度上降雨量和物候相的变化是调节生态系统碳通量大小的主要因素。最大的生物量和LAI出现的时间和最大的NEE出现的时间相吻合，但是降雨量的变化可以改变这种关系。 4. 在内蒙古羊草草原区>3mm的降雨被认为是对生态系统有效的。土壤含水量(0~20cm)在一次有效降雨事件发生后，约1~2天后才会发生响应， 2003年和2004年，NEE在 >3mm的降雨事件发生后，NEE开始增加，4~6天后达到高峰。随着降雨的结束，NEE在达到高峰后开始降低，10天后达到初始值的60~70%。 5. 在生态系统水平上，温度和土壤水分条件的季节动态是控制生态系统呼吸季节变化模式的重要环境要素，在干旱胁迫的条件下，水分条件也可能成为生态系统呼吸的主导因素，生态系统呼吸在干旱条件降低。

Modeling of cyanobacterial blooms in hypereutrophic Lake Dianchi, China

Compared with other approaches for modeling and predicting, artificial neural networks are more effective in describing complex and non-linear systems. The occurrence of cyanobacterial blooms has been a continuous and serious problem over the past decades in hypereutrophic Lake Dianchi. Yet, the main factor(s) initiating these blooms remain(s) unclear. During 2001-2002 at 40 sampling sites in Lake Dianchi, physicochemical parameters possibly relating to the blooms were measured. Parameters directly or indirectly relating to the cyanobacterial blooms were used as driving factors in a back-propagation network to model the concentration of chlorophyll a. According to sensitivity analysis, chemical oxygen demand was identified as a very significant environmental factor for algal growth in Lake Dianchi.

黄土沟壑区小流域不同地形下土壤微量元素分布特征

研究了黄土沟壑区小流域塬面、坡地、梯田和沟道土壤微量元素的剖面分布特征,以揭示不同地形条件下微量元素的有效性及地球化学特性.结果表明,不同土层土壤全量微量元素的变异系数均小于15%,为小变异土壤性质,有效态和吸附态铁和锰的变异系数均高于36%,为高度变异土壤性质;有效态和吸附态锌和铜属于中到高度变异.全量铁、锰和铜以沟道土壤较高,全锌、有效态和吸附态微量元素含量以塬面土壤较高.不同形态微量元素的剖面分布趋势取决于地形条件.不同地形下成土过程及不同地形条件所对应的土地利用方式造成了全量微量元素的差异,而土壤有机质含量的差异是不同地形条件下有效态和吸附态微量元素剖面分布特征不同的主要原因.

川西北高寒草甸土壤呼吸研究：季节动态和放牧效应

除植被冠层的光合作用之外，土壤的呼吸作用是陆地生态系统碳收支中最大的通量。土壤呼吸即使发生较小的变化也能显著地减缓或加剧大气中CO2浓度的增加，从而明显影响到全球气候变化。土壤呼吸速率变化与否以及变化的方向可以反映生态系统对环境变化的敏感程度和响应模式。尽管如此，土壤呼吸仍是一个为人们了解不多的生态系统过程。 草地生态系统是陆地生态系统的一个重要组成部分。针对草地土壤呼吸进行野外实验研究和相应方法论的探讨将对区域乃至全球碳源汇性质的准确估算具有重要的科学意义。然而，近几年来关于草地土壤呼吸的主要研究工作都集中在温带草原和部分热带草原，而针对高寒草甸生态系统土壤呼吸的研究报道还很少。 2008年4月至2009年4月期间，我分别在2008年6、8、10、12月和2009年2月和4月分6次对川西北的典型高寒草甸群落的土壤呼吸进行观测，分析了不同类型高寒草甸群落土壤呼吸的季节变化特征以及环境因子和放牧模式对其影响。主要研究结果如下： 1）该地区高寒草甸生态系统在生长季（6月～8月）土壤呼吸速率较大（6.07～9.30μmolCO2¡m-2¡s-1 ） ， 在非生长季（ 12 月～ 2 月） 较小（ 0.16 ～0.49μmolCO2¡m-2¡s-1 ） 。土壤CO2 年累积最大释放量为3963 ～ 5730gCO2¡m-2¡yr-1，其中，生长季土壤CO2的释放量占年总释放量的85%～90%。非生长季占10%～15%。非生长季所占比例略小于冬季积雪覆盖地区的冬季土壤呼吸占年土壤呼吸量的比例（14%～30%）。温度，尤其地温，是影响该地区高寒草甸生态系统土壤呼吸速率的最主要环境因子。土壤呼吸速率与地上生物量和土壤水分之间没有显著相关性，但是土壤含水量过大会导致土壤呼吸速率下降。 2）在观测期内，草丘区的土壤呼吸显著高于对照区的土壤呼吸，其最大土壤呼吸速率为16.77μmolCO2¡m-2¡s-1，土壤CO2 年累积最大释放量为8145gCO2¡m-2¡yr-1，是对照区的近2 倍。由于草丘在高寒草甸中占有较大的面积比例（近30%），因此，它将对高寒草甸生态系统的碳循环起着重要的作用。 3）放牧模式不仅可以影响高寒草甸群落的土壤CO2 排放，而且还可以改变土壤呼吸的温度敏感性（Q10）。本研究表明，在生长季有长期放牧活动干扰时将会增加土壤向大气中释放二氧化碳的速度，促使土壤碳库中碳的流失。禁牧样地的土壤呼吸速率在刚禁牧时先迅速增大，随着禁牧时间的延长土壤呼吸速率将会下降。此外，与其它放牧模式相比，冬季放牧将高寒草甸群落土壤呼吸速率在生长季达到最大值的时间明显向后推迟。不同放牧模式下高寒草甸群落土壤呼吸的Q10 值大小顺序为：禁牧一年群落>冬季放牧群落>禁牧三年群落>夏季放牧群落>自由放牧群落。 4）基于呼吸室技术的观测方法中，测量前的剪草处理可以明显改变该地区高寒草甸群落的土壤温度和土壤呼吸速率。在生长季，剪草处理将使土壤呼吸速率的瞬时响应增加90%左右。由于剪草处理明显增加了剪草样方白天的土壤温度，而土壤温度与土壤呼吸之间存在着极显著的指数相关关系，因而剪草处理导致土壤呼吸速率迅速增加。因此，在高寒地区基于呼吸室技术观测的土壤呼吸应当进行校正。 综上所述，川西北高寒草甸生态系统土壤呼吸速率在生长季较高，而在非生长季较低。土壤温度是影响该地区土壤呼吸的最主要环境因子。在实验观测期，草丘区土壤呼吸速率显著高于对照区的，是对照区土壤呼吸速率的近2倍。由于测量前的剪草处理可以明显改变待测点的土壤呼吸速率，因此，应对在高寒地区基于呼吸室技术观测的土壤呼吸进行校正。 Soil respiration is the second largest component (less than plant phtotosynthesis) of carbon dioxide flux between terrestrial ecosystems and the atmosphere. A minor change in soil respiration rate can significantly slow down or accelerate the increase of atmospheric CO2 concentration that is closely related to global climatic change. In turn, the change in the flux direction and rate of soil respiration may indicate the elasticity and stability of ecosystems to global changes and human disturbance. However, soil respiration is still an ecosystem process that has been poorly understood. Grassland ecosystem is an important component of the terrestrial ecosystem. Accurately estimating the CO2 flux from soil to atmosphere in situ is the key to evaluating the carbon resource and sink regionally or globally. Despite of extensive studies on the temperate and tropic grasslands, the soil respiration of alpine meadows has not substantially been measured. In the current study, soil respiration was measured for an annual cycle from April, 2008 to April, 2009 for the alpine meadow in northwestern Sichuan Province of China to determine the seasonal variation of soil respiration for the typical plant communities. The results are shown as follows: 1) Large seasonal variation of soil respiration was observed in the alpine meadow. The rate of soil respiration was the greatest (6.07～9.30μmolCO2¡m-2¡s-1) in June and the smallest (0.16 ～ 0.49μmolCO2¡m-2¡s-1) occurred from December to February in the non-growing season. The total emission of soil CO2 was estimated as 3963～5730 gCO2¡m-2¡yr-1, 85%~90% of which was released during the growing season, and 10%~15% during the non-growing season which was slightly less than the ratio of winter and annual CO2 flux from soil. Temperature, particularly the soil temperature, was the major environmental factor regulating the soil respiration. Significant and positive relationships were not found between soil respiration and soil moisture and between soil respiration and plant above-ground biomass, but excessive soil water content would decrease in the rate of soil respiration. 2) The rate of soil respiration in grass hummock communities was up to 16.77μmolCO2¡m-2¡s-1, which was about twice as great as in the controls (communities located in low and even sites). Considering the large proportion (about 30% on average) of hummock area in the meadow, it can be concluded that the hummocks played an important role in the carbon cycling of the study ecosystem. 3) Grazing patterns affected the flux of CO2 emission and the temperature sensitivity of soil respiration (Q10) in the alpine meadow. Grazing during growing season increased the rate of soil respiration. The rate of soil respiration increased significantly immediately after the alpine meadow being fenced, but thereafter decreased. In addition, grazing in winter delayed the peak respiration rate relative to the non-grazing mode. The Q10 value was the largest in the non-grazed area for one year, and next came the area with grazing in winter, followed by the non-grazed area for three years, the area with grazing in summer, and the non-limited grazed area. 4) In the chamber-based techniques, clipping manipulation before each measurement increased the transient rate of soil respiration by about 90% in the summer of the alpine meadow. As increase in soil temperature at daytime in the clipped plots by clipping and the exponential relationship between soil respiration and temperature, clipping manipulation led to increase in the rate of soil respiration. This suggested that a correction should be done for the techniques if employed in alpine and cold regions. In summary, the rate of soil respiration in the alpine meadow was the greatest in June and the smallest occurred from ecember to February in the non-growing season. Soil temperature was the major environmental factor regulating the soil respiration. The rate of soil respiration in grass hummock communities was up to 16.77μmolCO2¡m-2¡s-1, which was about twice as great as in the controls. A correction should be done for the techniques if employed in alpine and cold regions, because of the effect of clipping manipulation on soil temperature and respiration.

黄土高原沟壑区小流域不同地形下土壤性质分布特征

地形条件是影响黄土高原地区土壤性质分布的主要因素,研究不同地形条件下土壤性质的分布是合理评价黄土区土壤质量状况的重要前提。论文研究了黄土高原沟壑区小流域地形条件对土壤性质剖面分布的影响,结果表明土壤硝态氮、速效磷、碱性磷酸酶和蔗糖酶为高度变异的土壤性质;pH值和过氧化氢酶为小变异土壤性质。塬面和沟道土壤pH值和过氧化氢酶活性较低,阳离子交换量较高。土壤有机质、全氮、全磷、速效磷、碱性磷酸酶和蔗糖酶活性在土壤剖面随土层深度的增加逐渐降低,且均表现为塬面>梯田>坡地>沟道的趋势。不同地形条件下土壤pH值的变化由地形条件引起的土壤过程及硝态氮在土壤中的累积引起;阳离子交换量的变化由成土过程、pH值和有机质的差异引起;土壤有机质及氮、磷养分的差异由与地形条件对应的土地利用方式引起;土壤酶活性的差异则是有机质的差异引起的。

Crystal structure and charge transfer energy of the vaterite-type orthoborate YBO3:Eu

Ligand-to-metal charge transfer energies of YBO3:Eu have been investigated from the chemical bond viewpoint. The chemical bond parameters, such as the covalency, the polarizability of the chemical bond volume, and the presented charge of the ligands in the chemical bond have been quantitatively determined based on the dielectric theory of complex crystal. We calculated the environmental factor (h(e)), which is the major factor influencing the charge transfer energy in the compounds. The calculated results show that the suitable group space of YBO3 is C2/c. The method provides us with a supplementary tool to judge the proper structure when the structure of the crystal has many uncertain space groups.

Dependence of charge transfer energy on crystal structure and composition in Eu3+-doped compounds

We report a method for estimating the positions of charge transfer (CT) bands in Eu3+-doped complex crystals. The environmental factor ( he) influencing the CT energy is presented. he consists of four chemical bond parameters: the covalency, the bond volume polarization, the presented charge of the ligand in the chemical bond, and the coordination number of the central ion. These parameters are calculated with the dielectric theory of complex crystals. The relationship between the experimental CT energies and calculated environmental factors was established by an empirical formula. The calculated values are in good agreement with the experimental results. Such a relationship was confirmed by detailed analysis. In addition, our method is also useful to predict the charge-transfer position of any other rare earth ion.

Predicting the position of the spin-forbidden band for Tb3+ ions in crystal hosts

The energy difference DeltaE between the spin-allowed and spin-forbidden states of Tb3+ in crystals is studied. The environmental factor he representing the character of the host is redefined by using the chemical band of complex crystals. The relationship between h(e) and DeltaE is found to be a linear relation. The results show that the energy difference between the spin-forbidden and spin-allowed states for Tb3+ ions in crystals can be predicted from the environmental factor.

Chemical bond properties and Mossbauer spectroscopy in REBa2Cu3O7 (RE = Eu, Y)

By using the chemical bond theory of complex crystals, the chemical bond properties of REBa2Cu3O7 (RE = Eu, Y) were calculated. The calculated covalencies for Cu(1)-O and Cu(2)-O bond in REBa2Cu3O7 compounds are 0.41 and 0.28 respectively. Mossbauer isomer shifts of Fe-57 doped, and Sn-119 doped in REBa2Cu3O7-x were calculated by using the chemical environmental factor, h(e), defined by covalency and electronic polarizability. Four valence state tin ion and iron ion sites were identified in Fe-57 and Sn-119 doped REBa2Cu3O7-x superconductors.

Bonding and Mossbauer isomer shifts in (Tl, Pb)-1223 cuprate

By using the clinical bond theory of dielectric description, the chemical bond parameters of (Tl.Pb) - 1223 was calculated. The results show that the Sr-O, Tl-O, and Ca-O types of bond have higher ionic character and the Cu-O types of bond have more covalent, character. Mossbauer isomer shifts of Fe-57 and Sn-119 doped in (Tl, Pb) -1223 were calculated by using the chemical environmental factor, h, defined by covalency and electronic polarizability. Four valence state tin and three valence iron sites were identified ill Fe-57, and Sn-119 doped (Tl, Pb) -1223 superconductor. We conclude that all of' the Fe atoms substitute the Cu at square planar Cu (H site, whereas Sn prefers to Substitute the square pyramidal Cu (2) site.

栉孔扇贝大规模死亡病原学研究

用平板画线法从患病栉孔扇贝（Chlamys farreri）体内分离到了一种原核生物（简称QDP）。QDP可以在改进的液体培养基MEM（含2.2%NaCl，5%小牛血清）和脑心浸液（含2.2% NaCl）中生长；菌落在显微镜下（150×）为无色、透明的小点状；革兰氏染色阴性；菌体为圆形或近似圆形。QDP在发育过程中有两种状态，一种为未成熟阶段，直径小于100nm；另一种为成熟阶段，直径变化很大，最小约60nm，最大可达4µm以上。较小的个体有拟核、核糖体和新月状的空泡，未见细胞壁；较大的个体有细胞壁，胞内大部分被空泡充满，未见拟核和核糖体。栉孔扇贝组织超簿切片电镜观查证实QDP的存在。QDP的密度随着生长发育时间的不同而有所变化，繁殖高峰期密度较大。 建立了密度梯度离心结合滤膜过滤分离技术，优化人工培养条件。最适生长温度为23℃，最适生长pH值为7.4，最适生长盐度相当于细胞培养液所需的盐浓度（0.85%NaCl）。 提取的QDP核酸能被RNase A 降解，且没有检测到DNA。以PCR、RT-PCR扩增其16SrRNA基因序列片段，PCR反应没有扩增出扩增子，而RT-PCR则扩增出了16S rRNA基因序列片段，经测定其序列全长度为1430bp，经与GENEBANK中的16S rRNA片段比较分析，与6种不同科的微生物的同源率最高的为95%-95.47%。 采用温度梯度和病原浓度梯度回归感染实验方法，较为系统地研究了QDP的致病性。研究结果表明：QDP对栉孔扇贝有强烈的致病作用，高温（23℃以上）是其致病的必要条件，证实DQP是栉孔扇贝大规模死亡的病原体之一。

Size-fractionated phytoplankton biomass in autumn of the Changjiang (Yangtze) River Estuary and its adjacent waters after the Three Gorges Dam construction

A cruise was undertaken from 3rd to 8th November 2004 in Changjiang (Yangtze) River Estuary and its adjacent waters to investigate the spatial biomass distribution and size composition of phytoplankton. Chlorophyll-a (Chl-a) concentration ranged 0.42-1.17 mu g L-1 and 0.41-10.43 mu g L-1 inside and outside the river mouth, with the mean value 0.73 mu g L-1 and 1.86 mu g L-1, respectively. Compared with the Chl-a concentration in summer of 2004, the mean value was much lower inside, and a little higher outside the river mouth. The maximal Chl-a was 10.43 mu g L-1 at station 18 (122.67 degrees E, 31.25 degrees N), and the region of high Chl-a concentration was observed in the central survey area between 122.5 degrees E and 123.0 degrees E. In the stations located east of 122.5 degrees E, Chl-a concentration was generally high in the upper layers above 5 m due to water stratification. In the survey area, the average Chl-a in sizes of > 20 mu m and < 20 mu m was 0.28 mu g L-1 and 1.40 mu g L-1, respectively. High Chl-a concentration of < 20 mu m size-fraction indicated that the nanophytoplankton and picophytoplankton contributed the most to the biomass of phytoplankton. Skeletonema costatum, Prorocentrum micans and Scrippsiella trochoidea were the dominant species in surface water. The spatial distribution of cell abundance of phytoplankton was patchy and did not agree well with that of Chl-a, as the cell abundance could not distinguish the differences in shape and size of phytoplankton cells. Nitrate and silicate behaved conservatively, but the former could probably be the limitation factor to algal biomass at offshore stations. The distribution of phosphate scattered considerably, and its relation to the phytoplankton biomass was complicated.

Grazing intensity alters soil respiration in an alpine meadow on the Tibetan plateau

Grazing intensity may alter the soil respiration rate in grassland ecosystems. The objectives of our study were to (1) determine the influence of grazing intensity on temporal variations in soil respiration of an alpine meadow on the northeastern Tibetan Plateau; and (2) characterise, the temperature response of soil respiration under different grazing intensities. Diurnal and seasonal soil respiration rates were measured for two alpine meadow sites with different grazing intensities. The light grazing (LG) meadow site had a grazing intensity of 2.55 sheep ha(-1), while the grazing intensity of the heavy grazing (HG) meadow site, 5.35 sheep ha(-1), was approximately twice that of the LG site. Soil respiration measurements - showed that CO2 efflux was almost twice as great at the LG site as at the HG site during the growing season, but the diurnal and seasonal patterns of soil respiration rate were similar for the two sites. Both exhibited the highest annual soil respiration rate in mid-August and the lowest in January. Soil respiration rate was highly dependent on soil temperature. The Q(10) value for annual soil respiration was lower for the HG site (2.75) than for the LG site (3.22). Estimates of net ecosystem CO2 exchange from monthly measurements of biomass and soil respiration revealed that during the period from May 1998 to April 1999, the LG site released 2040 g CO2 m(-2) y(-1) to the atmosphere, which was about one third more than the 1530g CO2 m(-2) y(-1) released at the HG site. The results suggest that (1) grazing intensity alters not only soil respiration rate, but also the temperature dependence of soil CO2 efflux; and (2) soil temperature is the major environmental factor controlling the temporal variation of soil respiration rate in the alpine meadow ecosystem. (C) 2003 Elsevier Ltd. All fights reserved.

层状反倾向结构岩质边坡变形机理及稳定性研究

Toppling is a major failure model in anti-dip layered rock slopes. Because of the limited by testing means and experimental apparatus, present research on the deformation mechanism and stability analysis are mainly focus on the 2-Dimensional deformation, and the research really based on 3-Dimension is still limited. Therefore, based on the present research station, the article rely on the important hydroelectric project of typical anti-dip layered rock slopes -- The left bank slope of Long-tan hydropower-station in Guang Xi, China, and focused on the influencing factors, deformation mechanism and stability analysis of anti-dip layered rock slopes, three problems as follows are researched in this paper. (1) Deformation influencing factor analysis on ant-dip layered rock slopes Three influencing factors are included: geological factor, engineering factor and environmental factor. It is concluded that the toppling deformation of anti-dip layered rock slopes are more sensitive to geological and engineering factors, but less sensitive to environmental factor. In addition, the sensitivity of various factors to the rock toppling deformation is also arranged sequentially as follows: construction, gravitation, rainfall (underground water) and rock structure intensity, etc. (2) 3D deformation study on the anti-dip layered toppling rock slopes Used 3D Distinct Element Method (3DEC) analyzed the 3D deformation characteristic of anti-dip layered rock slops. It can be seen that the toppling characteristics are obvious when the inter-angle between slope direction and layer striking direction is under 20o, when the inter-angle is over 20o and equal or less than 40o，the toppling deformation characteristics decrease sharply with increase of inter-angle, when the inter-angle is over 40o , the slope deformation is not controlled by joints but influenced by other failure mode. Therefore, in order to quantify the toppling characteristics, a differential value of displacement vector angle between layered rock slope and block rock slope is proposed as a key index to distinguish failure model for anti-dip layered rock slopes, and it was applied to study the toppling of the rock slopes at Guangxi Long-tan hydropower station, China. The results indicated that the index was effective and instructive for analyzing the anti-dip layered rock slopes. (3) Stability analysis methods Because of the imperfection of some present slope analysis methods, based on slope failure mode and those three influencing factors, “slope stability entropy” method is defined in this paper, which makes good use of the sensitivity of relational matrix to influencing factors on slope stability and the qualification characteristics for information entropy to the irregularity of slope deformation. By this method, not only the randomness of geologic body on the base of dynamic analysis of slope failure mode is fully concerned, but also it makes the analysis time-saving and simple. Finally, the research findings were used to the engineering example successfully, and rational conclusion has been obtained.