Variation in the rate of land subsidence induced by groundwater extraction and its effect on the response pattern of soil microbial communities     

Neda Mohseni  Roland Bol 《地球表面变化过程与地形》2021,46(10):1898-1908

Excessive extraction of groundwater leads to (irreversible) changes in the physical soil properties, causing land subsidence associated with soil compaction to occur. Using a combined image processing and field approach, we examined: (1) how variation in the land subsidence rate induces different soil compaction degrees; and (2) the response patterns of microbial communities to such variations. By using Sentinel Synthetic Aperture Radar image processing, we selected three locations that exhibited different land subsidence rates, including high (HSR), moderate (MSR), and low (LSR). Then, soil sampling was undertaken within these representative locations. Indicators of soil compaction, including total porosity, air-filled porosity, water-filled porosity, and bulk density, were measured. The soil microbial community was determined using qPCR and sequencing. The highest and lowest values for bulk density were observed in the HSR–MSR and LSR zones, respectively. The greatest values of total porosity and macropore volume were displayed in the LSR zone compared to other zones. Bacterial abundance in the LSR zone was significantly greater than that in the HSR and MSR zones. The relative abundances of bacterial taxa indirectly demonstrated that the anaerobic phyla were significantly increased (by 10–13%), and the aerobic phyla decreased (by 30–40%) in the HSR zone compared to the LSR zone. This result demonstrates that the aerobes declined as larger volumes of the soil became more anaerobic. Indeed, the increased abundance of anaerobes was not able to compensate for the larger decrease in the abundance of aerobes. Our work showed that at the increased rates of land subsidence, the abundance distribution of the microbial community critically declined. These findings highlight the critical impacts of increasing the land subsidence rate on the emergence of high soil compaction degrees, which can significantly affect the resilience thresholds of the microbial communities in dryland soils.  相似文献   

Condensation water in heritage touristic caves: Isotopic and hydrochemical data and a new approach for its quantification through image analysis     

Cristina Liñán  José Benavente  Yolanda del Rosal  Iñaki Vadillo  Lucía Ojeda  Francisco Carrasco 《水文研究》2021,35(5):e14083

Condensation water is a major factor in the conservation of heritage caves. It can cause dissolution of the rock substrate (and the pigments of rock art drawn on it) or covering thereof with mineral components, depending on the chemical saturation degree of the condensation water. In show caves, visitors act as a source of CO₂ and thus modify the microclimate, favouring negative processes that affect the conservation of the caves. In spite of their interest, studies of the chemical composition of this type of water are scarce and not very detailed. In this work we present research on the condensation water in the Nerja Cave, one of the main heritage and tourist caves in Europe. The joint analysis of isotopic, hydrochemical, mineralogical and microbiological data and the use of image analysis have allowed us to advance in the knowledge of this risk factor for the conservation of heritage caves, and to demonstrate the usefulness of image analysis to quantify the scope of the possible corrosion condensation process that the condensation water could be producing on the bedrock, speleothem and rock art. To our knowledge, this application of image analysis (relative to the condensation water in caves) is the first one of this type that has been documented.  相似文献   

Sheath fold morphology in simple shear     

《Journal of Structural Geology》2013

Sheath folds are highly non-cylindrical structures often associated with shear zones. We investigate the formation of sheath folds around a weak inclusion acting as a slip surface in simple shear by means of an analytical model. We present results for different slip surface orientations and shapes. Cross-sections perpendicular to the shear direction through the sheath fold display closed contours, so called eye-structures. The aspect ratio of the outermost closed contour is strongly dependent on the initial slip surface configuration. The center of the eye-structure is subject to change in height with respect to the upper edge of the outermost closed contour for different cross-sections perpendicular to the shear direction. This results in a large variability in layer thickness across the sheath fold length, questioning the usefulness of eye-structures as shear sense indicators. The location of the center of the eye structure is largely invariant to the initial configurations of the slip surface as well as to strain. The values of the aspect ratios of the closed contours within the eye-pattern are dependent on the strain and the cross-section location. The ratio (R′) of the aspect ratios of the outermost closed contour (R_yz) and the innermost closed contour (R_y′z′) shows values above and below 1. R′ shows dependence on the slip surface shape and orientation but not on the number of involved contours. Using R′ measurements to deduce the bulk strain type may be erroneous.  相似文献   

西昆仑叶尔羌河上游地区Au元素分布特征及找矿标志     

周勇  高树静  韩玉信 《西北地质》2014,(4):269-276

利用1∶50万区域地球化学资料,对新疆西昆仑叶尔羌河上游地区主要地层及侵入岩中的Au元素在时间和空间上的分布规律,以及Au元素在不同地层中的成矿性进行了研究,通过Au元素异常查证及矿点资料,总结出了金矿的找矿标志。  相似文献   

河北省隆化县杨树沟金矿地质特征及找矿标志     

赵迎磊 《地质与资源》2014,23(Z1)

杨树沟金矿为中低温热液型,呈不规则脉状产出,严格受断裂构造控制.控矿断裂主要为北东向、北西向两组,断裂性质以压性为主,可以作为本区寻找新矿体的构造标志.  相似文献   

热磁技术确定矿床有效指示元素的试验与效果     

胡树起  马生明  刘崇民 《物探化探计算技术》2014,(6):730-735

针对找矿指标的有效性和找矿模型的普适性问题,研究引入热磁技术,以乌努格吐山铜矿和丰山洞铜矿为例,对比分析了土壤热磁组分与岩石、岩石热磁组分与黄铁矿的元素组合。试验表明,在确定成矿指示元素组合方面,土壤热磁组分是一种可行的介质,相比岩石具有更高的元素含量,可以挖掘出更多的异常信息;而岩石热磁组分与黄铁矿则具有一致的元素组合,比较而言,岩石热磁组分具有更宽的适用范围(如风化岩石)。作为一种人工方法分离组分,热磁组分弥补了岩石或黄铁矿等自然介质本身所固有的一些不足,为成矿指示元素的选择提供了一个新的研究平台;对于确定同一类型矿床有效指示元素组合,解决找矿模型的普适性问题,开拓了一种新思路。  相似文献   

Onshore Contribution to the Microbial Communities in the Lakes on the Qing-Tibetan Plateau     

JIANG Hongchen  YANG Jian  DONG Hailiang  MA Li’an  WU Liyou  ZHOU Jizhong 《《地质学报》英文版》2014,88(Z1):77-77

正The inland lakes on the Tibetan Plateau are inhabited by diverse microbial communities,which play a significant role in biogeochemical cycles of biogenic elements(e.g.carbon,nitrogen).Onshore inputs provide essential  相似文献   

湖南省醴陵市正冲金矿地质特征与找矿标志     

骆珊  胡斌 《矿产与地质》2014,(1):46-49

正冲金矿所处区域构造复杂,岩浆活动频繁而强烈,成矿条件十分有利。文章阐述了正冲金矿矿床地质特征及成矿地质条件,总结了找矿标志,且在该区找矿具有重要的指导意义。  相似文献   

内蒙古曹四夭钼矿床地质特征及找矿标志   总被引：2，自引：0，他引：2  

刘永慧  ;马润  ;陈志勇  ;甘云燕  ;贺斐  ;李香资  ;权知心  ;赵清旭  ;阿木古冷 《世界地质》2014,33(2):423-432

曹四夭钼矿床位于华北地台北缘内蒙古台隆凉城断隆东部。钼矿体主要赋存于曹四夭花岗斑岩外接触带的集宁群黄土窑组浅粒岩、变粒岩中,燕山期中酸性岩浆侵入活动与成矿关系密切。初步估算钼金属量为176万t。笔者在分析曹四夭钼矿成矿地质背景、矿体地质特征、物化探异常特征等基础上,提出了该矿床成因为具"二元结构"的斑岩型钼矿床,并进一步总结了找矿标志。  相似文献   

大兴安岭北段岔路口巨型钼(锌铅)矿床脉体特征、产状及其对成矿的指示   总被引：6，自引：0，他引：6  

金露英  秦克章  孟昭君  李光明  宋国学  李真真  吕克鹏  阚学胜  赵超 《矿床地质》2014,33(4):742-760

岔路口斑岩钼(锌铅)矿床是在大兴安岭北段新发现的超大型斑岩钼矿床,伴有一定规模的锌铅矿化,钼矿体呈拉长穹窿状,空间上呈上锌铅下钼的分带特征。钼成矿作用与晚侏罗世细晶斑岩和花岗斑岩的关系最为密切,矿化呈网脉状、脉状和浸染状产出,发育多期_多阶段脉体。根据形成温度、穿插关系、矿物组合和蚀变晕特征可划分出14类脉体,成矿前表现为石英±钾长石±磁铁矿±赤铁矿±硬石膏脉体(共4类),成矿期发育辉钼矿脉、钼铅锌过渡脉以及锌铅脉体(共7类),成矿后发育萤石、石膏和碳酸盐等脉体(共3类)。脉体内萤石的持续发育且早期硬石膏、磁铁矿、赤铁矿等矿物的存在,指示成矿流体具有高氟性质且早期具高氧化特征;脉体两侧蚀变晕从钾长石/黑云母→钾长石+绢云母→绢云母+黄铁矿→绢云母的变化,表明成矿流体具有从碱性向酸性演化的特征。高温脉体穿插低温脉体这类反切脉体的存在,反映岔路口矿床成矿流体具有多期脉动涌入的特征。成矿系统内脉体倾角研究表明,产状较平缓的脉体主要环绕成矿岩体分布在外围,高角度的放射状脉体(倾角60°)主要形成于成矿岩体的顶部;且高角度脉体与高品位矿体密切相关,矿体品位高的区域同时也是脉体集中发育区。脉体_蚀变_矿化的系统研究可指示矿床的剥蚀深度,岔路口矿区地表仅出露黏土化带和青磐岩化带,产出黏土矿物脉、碳酸盐脉等低温脉体,钻孔显示金属矿化自上而下具有Ag—Pb_Zn—Mo的分带,表明岔路口矿床的剥蚀程度较低,保存完整。  相似文献