Removal of Perchloroethylene from a Layered Soil System by Steam Flushing

Steam flushing experiments were concluded in a two-dimensional chamber containing two layers of F75 silica sand separated by a layer of finer F10 silica sand. Perchloroelhylene (PCE), which had spilled into the chamber under water-saturated conditions, formed a pool on the F110 sand layer. Steam was injected above the F110 sand layer. Temperatures, moisture content, and PCE concentrations in the chamber were monitored. Samples, taken from the various locations in the sand chamber, indicated that complete removal of PCE from the steam zone was achieved, with an 84% overall recovery. Some downward displacement of PCE-contaminated water through the F110 sand layer was observed and a small amount of gravity override occurred. Channeling of steam was minimal. The experiment indicates that steam flushing may be used successfully for removal of PCE from relatively homogeneous soils. Issues of gravity override and downward mobilization of contaminants must be considered in applying steam flushing at the field scale.     

基于GIS和模型库的土地整治三维规划设计

为探索在现有技术条件下实现土地整治三维规划设计,提高规划设计质量和效率,本研究结合无人机航测遥感技术、GIS以及三维模型库等相关技术,构建一套实用的土地整治三维规划设计技术方案。以湖北省红安县高桥镇高标准基本农田土地整治项目为例,利用无人机航测并处理得到的基础数据,构建研究区现状三维景观,在GIS中利用空间分析进行辅助规划设计,运用模型库的方法构建土地整治单体模型,并完成规划三维景观构建,将土地整治规划设计由二维转向三维,促进土地整治事业的发展。     

The luminescence dating chronology of a deep core from Bosten Lake (NW China) in arid central Asia reveals lake evolution over the last 220 ka

The lacustrine deposits of lakes in arid central Asia (ACA) potentially record palaeoclimatic changes on orbital and suborbital time scales, but such changes are still poorly understood due to the lack of reliable chronologies. Bosten Lake, the largest freshwater inland lake in China, is located in the southern Tianshan Mountains in central ACA. A 51.6‐m‐deep lacustrine succession was retrieved from the lake and 30 samples from the succession were used for luminescence dating to establish a chronology based on multi‐grain quartz OSL and K‐feldspar post‐IR IRSL (pIRIR₂₉₀) dating. Quartz OSL ages were only used for samples from the upper part of the core. The K‐feldspar luminescence characteristics (dose recovery test, anomalous fading test, first IR stimulation temperature plateau test) are satisfactory and from the relationship amongst the quartz OSL, IR₅₀ and pIRIR₂₉₀ doses we infer that the feldspar signals are likely to be well bleached at deposition. Bacon age‐depth modelling was used to derive a chronology spanning the last c. 220 ka. The chronology, lithology and grain‐size proxy record indicate that Bosten Lake formed at least c. 220 ka ago and that lake levels fluctuated frequently thereafter. A stable deep lake occurred at c. 220, 210–180, c. 165, 70–60, 40–30 and 20–5 ka, while shallow levels occurred at c. 215, 180–165, 100–70, 60–40 and 30–20 ka. Bosten Lake levels decreased by at least ~29 m and possibly the lake even dried up between c. 160 and c. 100 ka. We suggest that the water‐level fluctuations in the lakes of ACA may not respond directly to climatic changes and may be affected by a number of complex factors.     

塔里木河中游近200年的温度序列和变化

本文利用塔里木河中游的胡杨年表,重建了该区沙雅气象站近200年胡杨生长季的温度序列,分析表明,它可作为塔里木河中游近百年冷暖变化的参考依据。     

A collaborative study on temperature diurnal tide in the midlatitude mesopause region (41°N, 105°W) with Na lidar and TIMED/SABER observations

The na lidar-observed temperature diurnal tidal perturbations, based on full-diurnal-cycle observations from 2002 to 2008, are compared with tidal wave measurements by the TIMED/SABER instrument to elucidate the nature of diurnal tidal-period perturbations observed locally. The diurnal amplitude and phase profiles deduced by the two instruments are in very good agreement most of the year. However, the lidar-observed diurnal amplitudes during winter months and early spring are considerably larger than SABER observations, leading to the existence of a significant amplitude maximum of 12 K near 90 km in February and a different seasonal structure of temperature diurnal amplitude from the two instruments. The lidar-observed diurnal phase shows propagating wave characteristics during equinoctial months, but exhibit “evanescent wave” behavior in winter months, whereas SABER diurnal tidal phase exhibits propagating diurnal tidal character all year long with small seasonal variation. This anomalous tidal characteristic from the lidar observations repeats almost every winter. The exact mechanism behind this tidal feature is not fully understood, therefore further investigation and more experimental observations are necessary.     

水下无人系统发展概念和研究现状

水下无人系统在降低平台全寿命费用、减少高危作业风险与人员伤亡等方面具有先天优势,使其成为当今世界各国争相研究的热点领域。深入分析了美国水下无人系统的发展战略和现状,研究了我国水下无人系统的实际需求,提出了我国水下无人系统的发展概念和思路。     

潜北断层下降盘潭口盐泥隆起塑性变形机制及油气地质意义

江汉盆地潜江凹陷潜北断层下降盘潭口凸起的成因是该区多年关注的问题之一。通过地震剖面解析,认为是由渔洋组—新沟嘴组和荆沙组—潜江组两套多层盐泥侵—底辟刺穿形成的大型盐泥隆起,主要形成于荆河镇组沉积之后,将完整的潜江凹陷分割成3个次洼;盐泥隆的成因是在差异负载和重力滑脱动力作用下潜北断裂下降盘塑性侧向上侵推挤,与上升盘重力滑脱推覆造成南北双向挤压上拱, 形成了以汉水断层面为底板、中部为盐泥隆核、上层盐泥上部膝折—断褶穹窿3层结构;强烈塑性变形使潭口地区潜北断层面中部塑化—揉皱消失, 上部强拱左旋翻转成平卧断层;各个构造层盐泥塑性变形程度和形态差异与构造层盐泥含量、盐泥比有关;盐泥隆是形成各种油藏类型的关键因素,潜三段、潜四上段、新沟嘴组中被盐泥隆和刺穿作用形成的地层、岩性油藏是该区具有勘探潜力的油藏类型,且被近期钻探证实。     

应用贝叶斯方法对有效信息较少的渔业资源进行资源评估-以印度洋长鳍金枪鱼的资源评估为例

众所周知,对有效信息较少的渔业资源进行资源评估面临很大的挑战,而贝叶斯方法在数据数量较少、质量较差的情况下能利用其它种群高质量的数据或已知的先验信息提高资源评估结果的可靠性。由于印度洋长鳍金枪鱼的数据质量较差而数据量有限,长鳍金枪鱼的资源评估结果存在很大的不确定性,为此,本文以印度洋长鳍金枪鱼的资源评估为例,以调查贝叶斯方法在有效信息较少的资源评估中的优势。本文根据不同的先验假设与捕捞数据系列,共构建了8个贝叶斯动态产量模型,以评估长鳍金枪鱼资源。结果表明:(1)分析参数的后验分布能提高捕捞数据系列选择与参数假设的合理性; (2) 利用种群统计学方法为内禀增长率(r)构建有信息先验,能提高资源评估结果的可靠性。与传统方法相比,当基于贝叶斯框架时,能将已知的知识表示为先验信息并能分析参数的后验分布,从而在数据较少或数据质量较差的情况下,能利用各种信息提高参数估计的合理性与资源评估的可靠性。因此,对数据量较少或数据质量较差情况下的渔业资源评估而言,贝叶斯方法非常有效,如本文所示的印度洋长鳍金枪鱼的资源评估。     

分形在下庄铀矿田中的应用

本文运用分形理论对下庄地区铀矿床(矿点)的空间分布进行了研究。结果表明,铀矿床(矿点)的空间分布具有统计自相似性的分形特征,分数维可以用来定量描述铀矿床(矿点)的分布规律;应用盒计维数的统计方法计算了铀矿床(矿点)空间分布的分数维D值,并对西、中、东成矿活动区的分数维D值进行了比较,探讨了分数维D值的地质意义。实际资料计算结果显示网格数与标度之间具很好的相关性,其相关系数均达0.98以上。     

Paleozoic Tectonic Switch in the North Qinling Orogenic Belt: Constraints from the Paleozoic Granites from the Northern Qinling Migmatite Terrane

The variations in source rocks and melting conditions of granites can provide essential clues for the crustal magmatic response in orogenic process. Based on geochronology, whole-rock and mineral chemistry, this paper reveals two different granites in the Northern Qinling migmatite complex, which reveal obvious differences in source region and melting condition. The older granodiorite (402 ± 0.8 Ma) displays typical Na-rich adakite affinity, i.e., high Na2O/K2O (2.04 to 2.64) and Sr/Y (96 to 117) ratios, they have relative evolved isotopic compositions (εNd(t) = ?0.52 to ?0.04; zircon εHf(t) = ?0.06 to +7.78). The younger leucogranite (371 ± 2 Ma) displays higher SiO2 (72.32 to 73.45 wt%), lower (TFeO + MgO + CaO + TiO2) contents (<2 wt%) and depleted Sr-Nd-Hf isotopic compositions (i.e., εNd(t) = +2.6 to +3.0; zircon εHf(t) = +5.94 to +14.12), as well as high 10000 × Ga/Al and TFeO/MgO ratios, indicating that they represent highly fractionated I-type granites that derived from melting of juvenile crust. The variations in source rocks and melting condition of the two granites indicating a tectonic switch from compression to extension in 400 to 370 Ma, this switch is later than that in the eastern section of the North Qinling, indicating a scissor collision process between the South Qinling and North China Craton (NCC) in Devonian era.