Near‐infrared spectroscopy of a hydroecological indicator: new tool for determining sustainable yield for Floridan aquifer system

Pond‐cypress (Taxodium ascendens Brong.) is a dominant canopy species in depressional wetlands of the south‐eastern Coastal Plain. Unsustainable withdrawals from the karst Floridan aquifer system have caused premature decline and death of pond‐cypress trees, presumably owing to altered hydroperiods (which alter the flow of water and nutrients in trees). There has been no scientifically based means to determine sustainable yield from this regional aquifer system or to detect early stages of physical/ecological damage associated with groundwater mining and aquifer storage and recovery (ASR, which also can alter natural hydroperiods). In this study, the relationship between visual symptoms (indicators) of stress or premature decline, and spectral reflectance was evaluated using dried, milled branch tips collected from natural stands of mature pond‐cypress. Depressional systems evaluated represented four of the six aquifer system subregions where subsurface perturbations from groundwater mining: (i) were presumed not to be occurring (reference wetlands); (ii) may be occurring but are not documented; and (iii) have been confirmed. Sampled trees were assigned to one of three stress classes (1, no/minimal; 2, moderate; 3, severe) based on the visual indicators. Partial least squares–linear discriminant analysis of second derivative spectral transformations in the visible/shortwave near‐infrared (NIR) region (400–1100 nm) and the NIR region (1100–2500 nm) was used to evaluate the samples in assigned classes. Class 1 samples were discriminated from combined class 2 and 3 samples in the NIR region with 100% and 97% accuracy for consecutive winter sample periods (before bud‐break). The percentage of correctly classified samples in this spectral region was lower (85%) for summer samples (full leaf‐out). Second‐derivative models for the NIR region developed from the winter data sets predicted assigned classes for alternate winter's samples with an accuracy of 97% and 100%. High correlation between spectral reflectance of dried, milled branch tips collected from mature pond‐cypress in winter and visual indicators of premature decline suggests in situ pond‐cypress are hydroecological indicators of anthropogenic subsurface hydroperiod perturbations. This approach provides objective means for early detection of unsustainable aquifer yield and adverse impacts from ASR activities in the south‐eastern Coastal Plain. Used in conjunction with hydrological monitoring and modelling, the hydroecological indicators should provide the means with which sustainable yield in the south‐eastern Coastal Plain can be achieved and maintained. Copyright © 2003 John Wiley & Sons, Ltd.     

四川拉拉铜矿尾矿中重金属资源和环境意义

尾矿中高含量重金属具有潜在的资源和环境意义。通过分析拉拉铜矿尾矿中的重金属含量及其赋存形式,讨论了尾矿中有价元素的回收利用可能性,并评价了尾矿中重金属的生态风险。结果表明,拉拉铜矿各期尾矿中仅Ⅲ期尾矿的铁、铜、钴具有综合利用价值;各期尾矿中多种重金属元素潜在的生态危害程度轻微,但是各期尾矿中汞的生态危害程度中等,Ⅲ期尾矿中铜的生态危害程度中等。因此,矿区不仅要注意各期尾矿汞对环境的潜在污染,同时也应注意Ⅲ期尾矿铜对环境污染的生态风险。     

Lunar impact breccias: petrology,crater setting,and bombardment history of the Moon

Two general classes of lunar impact breccias have been recognised: fragmental breccias and melt breccias. Fragmental breccias are composed of clastic-rock debris in a finely comminuted grain-supported matrix of mineral and lithic fragments. Impact melt breccias have crystalline to glassy matrices that formed by cooling of a silicate melt. Most lunar impact breccias in our collection probably sample ejecta from large complex craters or multi-ring basins, although linking individual breccias to specific impact events has proven surprisingly difficult. A long-standing problem in lunar science has been distinguishing clast-poor impact melt breccias from igneous rocks produced by melting of the lunar interior. Concentrations and relative abundances of highly siderophile elements derived from the meteoritic impactor provide a useful discriminant, especially when combined with petrologic and geochemical evidence for mechanical mixing. Most lunar impact melt breccias have crystallisation ages of 4.0?–?3.8 Ga, corresponding to an episode of intensive crustal metamorphism recorded by whole-rock U?–?Pb isotopic compositions of lunar anorthosites. This may reflect a short-lived spike in the cratering rate, although other explanations are possible. The question of whether or not a cataclysmic bombardment struck the Earth and Moon at ca 3.9 Ga remains open and the subject of continuing investigations.     

植物胶泥浆在复杂地层钻进取心中的应用研究

在室内实验的基础上,植物胶泥浆在苏州大阳山隧道工程勘察、常州金坛矿山资源勘查、句容铜山勘探中进行了试验应用研究。试验研究结果表明,植物胶泥浆在复杂地层的钻探施工中,在确保取心质量的前提下,可大幅提高钻进生产效率,降低施工成本。     

月球钻探取心特种钻头研制与试验

对月壤形成过程和物质组成进行了介绍,并将实际月壤基本物理力学指标与CUG-1型模拟月壤和普通干砂进行对比,认为在月球钻探取样过程中可能遇到具有一定胶结强度的硬质团块。为保证钻探取样顺利进行,需要研制月球钻探用特种取心PDC钻头。基于PDC钻头的碎岩机理,对钻头的负前角、旁通角、出露高度、钻头保径和PDC切削齿的钎焊工艺分别进行了设计,并对钻杆和钻头装配体在钻进过程中的受力过程进行有限元分析。最后,采用所设计的特种取心PDC钻头进行岩石干钻试验,试验结果表明,该钻头能钻进可钻性级别小于或等于6级的岩石,能满足月球钻探需要。     

空气反循环取样钻探岩心采取率的计算方法探讨

介绍了RC钻探岩矿心采取率计算的国内现状,对质量采取率和体积采取率的计算方法进行了探讨,并对比了它们的优缺点。建议采用体积采取率作为RC钻孔的质量考核指标。     

绳索取心液动锤在中国岩金勘查第一深钻的应用和最新进展

在中国岩金勘查第一深钻ZK96—5钻孔的深部施工中,应用绳索取心液动锤技术在破碎复杂地层中钻进,增加回次进尺,提高时效,延长钻头寿命;在比较完整地层中提高钻速,减少辅助时间,体现了绳索取心液动锤技术的优越性,目前3911．34m的使用深度创造了绳索取心液动锤适应孔深的最新记录。对绳索取心液动锤在深部钻进的优势和易出现的问题进行了分析总结。     

Study of preexisting shear surfaces of reactivated landslides from a strength recovery perspective

Residual shear strength is generally considered in the design of preventive measures for slopes consisting of preexisting shear surfaces of large-scale landslides. Recent research suggests that the preexisting shear surface of a reactivated landslide can regain strength with the passage of time, which might also be considered in designing the slope stability measures. In this study, three reactivated landslide soils were tested in a ring shear apparatus for the discontinued shear periods of 1, 3, 7, 15, and 30 days with the following main objectives: (i) to understand the strength recovery behavior of landslide soils in a residual state of shear after as long as 30 days of discontinued shear, (ii) to understand the comparative pattern of strength recovery in highly plastic and less plastic soils, and (iii) to understand the mechanism involved in strength recovery at a residual state of shear. The results indicate that recovered strength measured in the laboratory is hardly noticeable after a rest period of 3 days, but recovered strength is lost after a small shear displacement. This paper primarily focuses on the effect of strength recovery from residual strength on preexisting shear surface soils and the mechanisms behind it.     

Effects of salt and alkali stress on Reaumuria soongorica germination

Seed germination and early seedling growth are crucial stages for plant establishment. Two neutral (NaCl and Na₂SO₄) and two alkali (NaHCO₃ and Na₂CO₃) salts were selected to investigate their effects on germination and recovery responses in Reaumuria soongorica. Results show that both salt types significantly reduced germination and radicle elongation. The rate of germination and emergence of R. soongorica seeds continuously decreased as salinity increased, and the time to achieve maximum germination rate was delayed. The speed of seed germination dropped rapidly as salt concentration increased. Alkaline salts restricted the germination rate of R. soongorica seeds, and stresses resulting from alkaline salts and high concentrations of neutral salts resulted in many deformed seedlings. The length of the radicle and germ decreased with increasing salt concentration, but certain concentrations of salt and increased pH promoted germ growth. The results of regression analysis show that salt concentration was the dominant factor inhibiting R. soongorica seed germination rate. Salinity, buffering capacity, and pH all affected embryo growth, but salinity had the most pronounced effect. Seed viability under highly saline conditions appears to be a better indicator of adaptation to saline environments than seed germination under saline conditions.