植物生长过程中碳同位素分馏对气候的响应

探讨C4植物的碳同位素组成对气候的响应是碳同位素示踪研究的重要任务。观察了典型的C4植物玉米生长过程的碳同位素效应，结果表明，玉米在其生长季节里碳同位素组成有明显的变化。不同部位的叶片碳同位素组成变化不一样，顶部叶片变化较大，下部叶片变化则相对较小。这种变化受温度、水分和光照强度等多种气候要素的影响。同一株玉米，其顶部的叶片δ^13C值比下部叶片要偏正，而且随着玉米的不断生长，这一现象更加明显，温度和光照强度则是引起这一现象的主要气候因子。     

浅海底层流与沉积物磁组构参数P、Fs对应关系的初步探讨

对海阳湾外侧浅水区域实测水体运动特征及其对应的沉积磁组构参量 ,采用线性回归方法进行统计分析 ,取得的结果是 :EV1 (估算流速 1) =17.372 4- 2 .16 87(P- 1.0 )× 10 0 +10 .890 9(Fs- 1.0 )× 10 0 ,其估计平均误差 (V(实测流速 ) - EV1 ) =0 .2 83;EV2 (估算流速 2 ) =- 886 .1178- 2 87.6 32 1P+1191.1870 Fs,其估计平均误差 (V- EV2 ) =0 .2 98。初步探讨结果表明 ,水体运移小潮期最大涨潮流底层流流速与沉积磁组构参量 P、Fs对应关系研究是可行的。     

Determination of wave energy dissipation factor and numerical simulation of wave height in the surf zone

Based on the time-dependent mild slope equation including the effect of wave energy dissipation, an expression for the energy dissipation factor is derived in conjunction with the wave energy balance equation. The wave height of regular and irregular waves is numerically simulated by use of the parabolic mild slope equation considering the energy dissipation due to wave breaking. Comparison of numerical results with experimental data shows that the expression for the energy dissipation factor is reasonable. The effects of the wave breaking coefficient on the breaking point and the distribution of wave height after breaking are discussed through the study of a specific experimental topography.     

Rediscussion of balmer decrement of broad-line radio-galaxies

On the basis of the erenkov line emission theory in the optically thick case, a new interpretation of intensity ratios H/H and H/H in broad-line radio-galaxies (BLRGs) is reported. Calculation shows that if the theoretical ratio H/H is just taken to be the mean observed value 0.21, equivalently, the parameterX(H)=3.0, then the expected ratio H/H=6.70 is almost the same as the observations. By comparing these values with the previous investigations of QSOs (X(H)=20.9), we conclude that the number density of neutral hydrogen gas in BLRGs is almost one order-of-magnitude smaller than that in the QSOs.Preliminary verification of the erenkov line emission has been obtained by Xuet al. (1981) in the laboratory.     

Spatial variations of throughfall through secondary succession of evergreen broad‐leaved forests in eastern China

Linking spatial variations of throughfall with shifting patterns during forest succession is important for understanding developmental patterns of ecosystem function. However, no such approach has been previously used for the chronosequence of evergreen broad‐leaved forests in subtropical regions. This study was conducted in a chronosequence of secondary forest succession in Tiantong National Forest Park, to determine the optimum number of collectors within certain limits of error. Throughfall was 66, 55 and 77% of gross precipitation in an early‐succession (SS), sub‐climax (SE) and climax (CE) forest, respectively. The coefficient of variations (CV) of throughfall reduced with increasing rainfall amounts. Monte Carlo resampling approach was used to find mean values and 90 and 95% confidence intervals of a variable number of collectors (n) ranging from 2 to 24. During the study period, with nine collectors at SS, five at SE and five at CE, the error in the mean individual throughfall did not exceed 10%, respectively. This error was reduced to 5% when using 16, 10 and 10 collectors at SS, SE and CE, respectively. The CVs decreased greatly with increasing sample size when the sample size was less than 16 for the three successional stages, regardless of rainfall amounts. Based on the Student's t‐value analysis of the mean individual throughfall volumes, a sample size of 16 at SS, five at SE and four at CE would be enough for throughfall estimates at an accepted error of 10% of 95% confidence level, respectively. Therefore, we concluded that the 25 of collectors used in the present study were sufficient to estimate the throughfall value at an accepted error of 10% at 90 and 95% confidence levels, even for those small rainfalls in eastern China. Copyright © 2011 John Wiley & Sons, Ltd.     

On the attribution of changing pan evaporation in a nature reserve in SW China

Negative trends of measured pan evaporation are widely reported. Studies of the factors that underlie this reduction in pan evaporation have not reached a consensus about the controlling factors. Most studies employ statistical analysis (correlation analysis or stepwise regression) to identify the controlling climatic variables; in contrast, few studies have employed physical‐based theories. In addition, observations of pan evaporation and related climatic variables are reported to be influenced by anthropogenic activities. Consequently, the observed trends of climatic variables in a nature reserve would be useful for understanding regional climate change. The present study site is located in Ailaoshan National Nature Reserve, SW China, which is free of anthropogenic activity. In this study, we firstly applied the adjusted PenPan model to estimate the pan evaporation. Then, using this physical‐based model, we identified a positive trend in pan evaporation, with a much larger increase in the dry season than in the wet season. The model results indicate that the change in the aerodynamic component is larger than that in the radiative component. In contrast to the reduction in wind speed and sunshine hours that has been reported in previous studies at various sites, we found that wind speed and sunshine hours have increased in recent decades, thereby explaining the increase of the pan evaporation rate. Wind speed made the greatest contribution to the change in pan evaporation, followed by sunshine duration. This study indicates that the potential evaporation has increased at this site despite the widely reported reduction in measured pan evaporation. During the dry season, the availability of water for agriculture and agroforestry could be threatened. Copyright © 2012 John Wiley & Sons, Ltd.     

页岩气录井技术进展及展望

经过十几年技术攻关,国内页岩气录井技术发展与应用水平不断提高。本文基于地质工程一体化的评价需求,总结了具有特色的页岩气录井技术系列：岩石热解录井和自然伽马能谱录井结合的烃源岩特性评价技术;元素录井和自然伽马能谱录井结合的页岩岩性、脆性评价技术;气测录井和碳同位素录井结合的含气性评价技术;核磁录井为主的页岩物性评价技术。同时,还对页岩气录井技术发展进行了展望,认为现今页岩气录井技术面临水平井目标靶体复杂化、深层页岩气地层温度高、常压页岩气地层压力低的技术难题,需要不断提升录井仪器分辨率,加强多维核磁录井技术等录井新技术创新;为实现页岩气层的立体刻画和精确评价,需要利用大数据资源开发智能化录井工程技术系列,为页岩气高效优质勘探开发提供全面技术支撑。