基于223Ra和224Ra的桑沟湾海底地下水排放通量

海底地下水排放（SGD）是陆地向海洋输送水量和营养物质的重要通道之一,对沿海物质通量及其生物地球化学循环有重要的影响,对生态环境起着不可忽视的作用。本文运用天然放射性同位素223Ra和224Ra示踪估算了我国北方典型养殖基地桑沟湾的海底地下水排放通量。结果表明,海底地下水样尤其是间隙水中Ra活度[224Ra=（968±31）dpm/（100 L）,223Ra=（31.4±4.9）dpm/（100 L）,n=9]远高于表层海水[224Ra=（38.7±2.0）dpm/（100 L）,223Ra=（1.70±0.50）dpm/（100 L）, n=21]。假设稳态条件下,考虑Ra的各源、汇项,利用Ra平衡模型,估算出桑沟湾SGD排放通量为（0.23~1.03）×107 m3/d。潮周期内的观测结果显示,涨潮时,水力梯度较小,SGD排放变弱,落潮时,水力梯度较大,导致了相对较多的SGD排放。在一个潮周期间,基于223Ra和224Ra得到的SGD排放通量平均为0.39×107 m3/d。潮汐动力下的SGD排放平均占总SGD排放的61%,因此桑沟湾沿岸的地下水排放主要受潮汐动力的影响,并对海水组成及海陆间物质交换有显著贡献。     

小冰期福建海岸沙丘的沉积环境

选取福建东南沿海典型海岸沙丘——东海沙丘,运用GPR（Ground Penetrating Radar）技术探测海岸沙丘内部构造,辅助天然剖面和人工探槽观测,进行系统的年代采样与OSL（Optically Stimulated Luminescence）测年,并选择物理意义明确的粒度参数作为主要环境代用指标,获得了亚热带季风区砂质海岸带典型海岸沙丘的沉积年代和沉积结构。结果表明：（1）东海沙丘是由若干灌丛沙丘组成的横向沙丘,0～6 m主要是～0.45 ka BP以来形成的海岸风成沙丘,可以划分为～0.45 ka BP和0.22～0.12 ka BP两个阶段。（2）东海沙丘沉积过程是多因素共同作用的结果,冷干的气候环境是沙丘发育的适宜条件,入境台风频率增加可能加快了风沙的沉积过程。对比历史文献资料发现,气候异常期往往与社会动荡期、重要历史事件相对应。     

Quantifying the rate and depth dependence of bioturbation based on optically‐stimulated luminescence (OSL) dates and meteoric 10Be

Both the rate and the vertical distribution of soil disturbance modify soil properties such as porosity, particle size, chemical composition and age structure; all of which play an important role in a soil's biogeochemical functioning. Whereas rates of mixing have been previously quantified, the nature of bioturbation's depth dependence remains poorly constrained. Here we constrain, for the first time, the relationship between mixing rate and depth in a bioturbated soil in northeast Queensland, Australia using a novel method combining OSL (optically‐stimulated luminescence) ages and meteoric beryllium‐10 (¹⁰Be) inventories. We find that the best fit mixing rate decreases non‐linearly with increasing soil depth in this soil and the characteristic length scale of 0.28 m over which the mixing coefficient decays is comparable to reported rooting depth coefficients. In addition we show that estimates of surface mixing rates from OSL data are highly dependent on erosion rate and that erosion rate must be constrained if accurate mixing rates are to be quantified. We calculate surface diffusion‐like mixing coefficients of 1.8 × 10^?4 and 2.1 × 10^?4 m² yr^?1 for the studied soil for two different estimates of soil erosion. © 2014 The Authors. Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd.     

抽水对银川台伸缩仪观测资料干扰的探讨与分析

通过对银川台伸缩仪观测资料的综合对比分析,系统地论述了抽水对银川台伸缩仪观测资料的干扰机制,并提出了消除干扰的方法。     

Analytical Theory for One-Dimensional Consolidation of Soil Induced by Time-Dependent Pumping and Loading

Analytical solutions are derived for one-dimensional consolidation induced by time-dependent pumping and loading, in which both the effects of different pumping types and loading conditions are considered, i.e., step pumping, cyclic pumping, constant loading, and step loading. Based on the solutions obtained, some diagrams are prepared and the relevant consolidation behavior of soil is discussed in detail. It has been shown that the consolidation behavior is greatly influenced by pumping velocity, loading pressure, pumping and loading type.     

Role of Ekman transport versus Ekman pumping in driving summer upwelling in the South China Sea

Relative roles of Ekman transport and Ekman pumping in driving summer upwelling in the South China Sea (SCS) are examined using QuikSCAT scatterometer wind data. The major upwelling regions in the SCS are the coastal regions east and southeast of Vietnam (UESEV), east and southeast of Hainan Island (UESEH), and southeast of Guangdong province (USEG). It is shown that the Ekman transport due to alongshore winds and Ekman pumping due to offshore wind stress curl play different roles in the three upwelling systems. In UESEV, Ekman pumping and Ekman transport are equally important in generating upwelling. The Ekman transport increases linearly from 0.49 Sv in May to 1.23 Sv in August, while the Ekman pumping increases from 0.36 to 1.22 Sv during the same period. In UESEH, the mean estimates of Ekman transport and Ekman pumping are 0.14 and 0.07 Sv, respectively, indicating that 33% of the total wind-driven upwelling is due to Ekman pumping. In USEG, the mean Ekman transport is 0.041 Sv with the peak occurring in July, while Ekman pumping is much smaller (0.003 on average), indicating that the upwelling in this area is primarily driven by Ekman transport. In the summers of 2003 and 2007 following El Niño-Southern Oscillation (ENSO) events, both Ekman transport and Ekman pumping decrease in UESEV due to the abnormally weak southwest monsoon. During the same events, however, Ekman transport is slightly enhanced and Ekman pumping is weakened in UESEH and USEG.     

天津王4井抽水观测水汞影响因素的探讨

王4井因受井区地热开发的影响,于2008年12月断流停测。2010年对原观测井口装置进行改造,开始进行抽水观测水汞试验研究。在新的观测方式下,为确保观测数据稳定、可靠,本文从抽水观测的观测条件方面,对不同取样位置和抽水时间对水汞测值的影响进行了试验。试验结果表明,不同抽水时间和不同取样位置抽水观测对水汞测值影响不大,这一结论与水汞本身的化学特性相一致。认为在没有自流井的地区,只要选择灵敏的观测点使用抽水方式采样,固定观测条件,依然可以进行水汞监测。     

Sea surface height variations in the Mindanao Dome region in response to the northern tropical Pacific winds

Sea surface height (SSH) variability in the Mindanao Dome (MD) region is found to be one of the strong variations in the northern Pacific. It is only weaker than that in the Kuroshio Extension area, and is comparable to that in the North Pacific Subtropical Countercurrent region. Based on a 1.5-layer reduced gravity model, we analyzed SSH variations in this region and their responses to northern tropical Pacific winds. The average SSH anomaly in the region varies mainly on a seasonal scale, with significant periods of 0.5 and 1 year, ENSO time scale2-7years, and time scale in excess of 8 years. Annual and long-term variabilities are comparably stronger. These variations are essentially a response to the northern tropical Pacific winds. On seasonal and ENSO time scales, they are mainly caused by wind anomalies east of the region, which generate westward-propagating, long Rossby waves. On time scales longer than 8 years, they are mostly induced by local Ekman pumping. Long-term SSH variations in the MD region and their responses to local winds are examined and discussed for the first time .     

内蒙古扎鲁特旗地区更新世地层划分

根据孢粉组合特征及光释光测年结果,对分布在内蒙古东南部的第四系更新统做了进一步的划分和研究。研究结果表明,主要分布在内蒙古东南部的中更新统风积物,岩性为黄色亚砂土,含钙质结核,发育柱状节理,区域上称乌尔吉组,含Artemisia-Ephedra-Pinus孢粉组合,光释光测年结果为(40.4±1.9)~(110.0±7.5)ka; 下更新统沉积物,岩性为红褐色亚砂土及亚黏土,含钙质结核、砂砾透镜体,区域上称为赤峰黄土,含Artemisia-Polygonum-Betula孢粉组合,光释光测年结果为（200.9±9.6）~（220.4±13.2）ka。上述2套地层在内蒙古东南部广泛分布,更新世地层的划分为内蒙古东南部地区的第四系地层划分对比研究提供了基础地质资料。     

Optimizing layout of pumping well in irrigation district for groundwater sustainable use in northwest China

Optimizing layout of pumping well plays a vital role in curbing the groundwater level decline. A novel optimization model is presented in this study. First, the optimal well number is obtained by taking into account factors of local economy and environment based on nonlinear programming model. Then, the well spatial layout assessment model is attained based on information entropy weight and technique for order preference by similarity to ideal solution (TOPSIS). After that, the relative closeness to positive ideal solution of alternative (c_i) on the rationality of well spatial layout in cultivated land is calculated, and a set of alternatives are ranked according to the descending order of c_i. Finally, the well optimization layout is obtained by combining the optimal well number with well spatial layout assessment result based on the GIS data of pumping wells. As a case study, this method was applied in Yongchang Irrigation District of Shiyang River Basin, the arid region of northwest China. Results show that under the conditions of sustainable use of water resources, the irrigation district needed 724 wells for irrigation, with a decrease of 31.0% when compared with the existing number of wells. The wells with low flow rate and operating efficiency distributed in high density where groundwater is over‐exploitation were recommended to be closed. This well optimization layout method is expected to play a significant role in helping make plans for exploiting groundwater at more sustainable level, curbing the groundwater level decline trend, and improving the local ecological environment. Copyright © 2015 John Wiley & Sons, Ltd.