Quantitative analysis of the driving forces causing declines in marsh wetland landscapes in the Honghe region, northeast China, from 1975 to 2006

The Sanjiang Plain has the most representative and largest concentration of inland freshwater wetlands in China, most of which have been degraded or have disappeared as a result of agricultural development and climatic change since the 1950s. To better understand the spatial and temporal variation and driving forces of marsh reduction, this study investigated variations of marsh reduction in the Honghe region of the Sanjiang Plain, Northeast China over a 30-year period, and analyzed the role of the different driving forces separately and their combined effect on marsh reduction and identified what driving forces have played key roles on the reduction in different periods. Nine natural and anthropogenic variables from remote sensing, GIS data and field surveys, such as precipitation, temperature, precipitation anomaly, population density, agricultural population density, per capita GDP, distance to road, distance to canal and distance to settlement, were evaluated on their impact on observed variations of marsh reduction between 1975 and 2006. The results show that all of these driving forces have significant influences on the decline of the marsh area, and the combination of driving forces that has crucial impacts on marsh reduction varied largely from 1975 to 2006. During 1975–1989, it was the construction of canal and road networks in farms and changes in average annual precipitation that led to marsh reduction. After 1989, the reduction was mainly related to increases in agricultural population, per capita GDP and settlements. These findings may help understand the declines or degradation of marsh areas and provide an empirical and theoretical base for managers, who design and implement wetland management and planning.     

Effects of salt solutions on the hydro-mechanical behavior of compacted GMZ01 Bentonite

In this study, the effects of salinity of infiltrating solutions on the swelling strain, compressibility, and hydraulic conductivity of compacted GMZ01 Bentonite were investigated. After swelling under vertical load using either distilled water or NaCl solutions with concentrations of 0.1, 0.5 M, and 1 M, laboratory oedometer tests were conducted on the compacted GMZ01 Bentonite. Based on the oedometer test results, hydraulic conductivity was determined using the Casagrande’s method. Results show that the swelling strain of highly compacted GMZ01 Bentonite decreases as the concentration of NaCl solution increases. The compression index C _c ^* increases and then turns to decrease with an increase in the vertical stress or a decrease in the void ratio for different solutions, and the C _c ^* decreases as the concentration of NaCl solution increases. The secondary consolidation coefficient C _α increases linearly with the increase of the compression index C _c ^* . Furthermore, a bi-linear relationship between the swelling index C _s ^* and the secondary consolidation coefficient C _α can be characterized clearly. The hydraulic conductivity increases as the concentration of NaCl solution increases, however, this increase can be prevented if a high confining stress is applied.     

Identification and geochemical significance of polarized macromolecular compounds in lacustrine and marine oils

Polarized macromolecular compounds in typical lacustrine and marine shale oils collected from the Ordos Basin and Tarim Basin of China were analyzed by FT-ICR-MS. Maturity was taken into consideration by diagenesis physical simulation experiments on shale oils, which had been collected at various temperature and pressure stages. The results showed that similar components existed in non-hydrocarbon and asphaltenes and the main peak compound classes of Nl and 02 were potential parameters for identifying typical marine oil and lacustrine oil in China. Nitrogen compounds/（nitrogen compounds and oxygen compounds）, such as Nl/（O2＋Nt）, NL/（Oa＋Nt）, Ni/（NiO1＋N1O2） are the maturity indicators, which are related with C-N and C-O bond energy. Differences in molecular components and weights between marine and lacustrine oils are the effective index to identify source maturity and sedimentary environment.     

陕西镇安县太白庙一带金矿地质特征及控矿因素

镇安县太白庙一带金矿以显微金与明金颗粒为特征,矿床由三个近东西向展布的含金石英脉体密集带构成,由南向北可划分为Ⅰ、Ⅱ、Ⅲ三个含矿带。赋矿地层为泥盆系星红铺组,金矿矿(化)体分布受地层、构造双重控制。     

扬子北缘黄陵地区晚中生代盆地演化及其构造意义

扬子北缘黄陵地区古构造应力场于晚中生代经历发生了重大转变,是扬子板块与华北板块在三叠纪碰撞造山之后陆内构造变形的体现。由黄陵背斜周缘晚中生代盆地充填记录所反映出这一变革的起始时间为中侏罗世晚期。早侏罗世-中侏罗世早期,盆地内沉积了以桐竹园组为代表的河流-湖泊相岩层,由沉积碎屑成分和古水流统计所得出的物源区为北部的秦岭地区,黄陵背斜上部可能也接受了碎屑沉积;中侏罗世晚期-晚侏罗世,沉积中心发生了改变,表现为仅仅在黄陵背斜西侧的秭归盆地内有所保存,沉积环境以曲流河到辫状河流和三角洲为主,物源区则局限于黄陵背斜;早白垩世初期,周坪盆地和宜昌盆地为沉积中心,近缘冲积扇和辫状河流体系占据主体,物源区依然为黄陵地区,两盆地在黄陵背斜南缘可能相连,黄陵背斜上部的原下侏罗统被剥蚀;早白垩世晚期-晚白垩世,远安盆地逐渐发育,盆地西缘为冲积扇-辫状河流体系,中、 东部则以曲流河-湖泊沉积环境为主体,并间有干旱沙漠环境。原型盆地再造结果显示,早侏罗世-中侏罗世早期盆地展布具有近东西向特点,古地貌总体呈现出北部为山脉、 南部为盆地的格局;中侏罗世晚期以来,盆地呈近南北向,黄陵背斜逐渐形成山脉,盆地位于其东西两侧。两期盆地沉积特征反映了扬子北缘古构造应力场由近南北向转变为近东西向的过程。     

内蒙古额仁陶勒盖银矿区火成岩岩石地球化学特征及锆石SHRIMPU-Pb同位素定年

通过对额仁陶勒盖银矿区的塔木兰沟组中酸性火山岩详细的岩石地球化学特征研究表明,该套火山岩具高硅(SiO₂>57%)、高铝(Al₂O₃>16%)、富碱尤其富钾(K₂O>3%)特征,属HKCA系列;稀土含量中等(187×10^-6~240×10^-6),(La/Yb)_N在18.6~27.9,Yb<1.90×10^-6,Y<18.0×10^-6,δEu=0.85~0.96,轻重稀土分馏强烈,明显亏损重稀土,无或略具负铕异常;微量元素相对富集Rb、Ba、Th、U、K等大离子亲石元素(LILE),亏损高场强元素Nb、Ta、Ti、HREE,与活动陆缘火成岩的微量元素特征一致.塔木兰沟组安山质火山岩特征表明,安山质岩浆来源较深(>50km),起源于加厚地壳底部,源区残留为石榴石、单斜辉石及角闪石,岩浆在部分熔融及后期演化过程中不曾与斜长石平衡过,可能是蒙古-鄂霍茨克洋闭合后进入碰撞后松弛阶段,钙碱性或高钾钙碱性的中基性变火成岩的部分熔融形成.对与额仁陶勒盖银矿关系密切的石英斑岩(脉)测年,获得SHRIMP U-Pb年龄138.6±2.3Ma,为石英斑岩的成岩年龄,进一步限定该银矿床形成于早白垩世早期.对塔木兰沟组安山岩与石英斑岩成岩年龄、矿床成矿特征等方面进行探讨了,认为该银矿床为岩浆热液成因.     

Sudden surface collapse disasters caused by shallow partial mining in Datong coalfield,China

Numerous sudden surface collapses induced by shallow partial mining in the Datong Jurassic coal seam have caused fatalities, significant property losses and brought about harmful results to the environment. By introducing efficient pillar widths and using the Voronoi diagram, irregular pillar stability can be estimated rationally. Theoretical analysis and numerical simulation demonstrate that the failure of a single pillar increases the load on surrounding pillars. If the magnitude of the transferred load is sufficiently high, the adjoining pillars will also fail in a chain reaction. This can be interpreted by the merger of inner stress arches combined with the external stress arch. In this paper, the evolution mode of sudden surface collapse caused by shallow partial mining is proposed and has been verified by ‘similar material simulation.’ Finally, the potential of sudden surface collapse is determined and an example of collapse prediction and prevention of surface building damage with relocation is given.     

CPT-Based estimation of undrained shear strength of fine-grained soils in the Huanghe River Delta

The Huanghe River（Yellow River） Delta has a wide distribution of fine-grained soils. Fluvial alluviation, erosion,and wave loads affect the shoal area, resulting complex physical and mechanical properties to sensitive fine-grained soil located at the river-sea boundary. The cone penetration test（CPT） is a convenient and effective in situ testing method which can accurately identify various soil parameters. Studies on undrained shear strength only roughly determine the fine content（FC） without ma...     

福岛第一核电站事故及核污水排海进入中国海路径及其影响

自2011年3月日本福岛第一核电站事故发生以来,其对中国海的影响一直备受国内高度关注。基于近10年的研究成果,本文综述了福岛第一核电站事故释放的放射性核素进入中国海的海洋传输路径主要为表层环流和模态水(亚热带模态水和中央模态水),经表层环流和模态水到达中国海的时间尺度分别在10—15年和2—3年之间。对比分析福岛第一核电站事故前后可知:南海¹³⁷Cs活度持平,黄海¹³⁷Cs活度稍有降低,但东海¹³⁷Cs活度有所升高。鉴于目前有限的监测站位和短期的观测时间,福岛第一核电站事故对中国海的影响程度大小还有待于长期监测和进一步的评估。同时针对日本政府宣布福岛第一核电站核污水排海计划,分析了其潜在的风险和指出了未来的研究方向。     

汾河流域城市化与水资源耦合协调关系研究

通过构建汾河流域城市化与水资源系统指标体系,利用综合评价法对2010—2019年汾河流域城市化和水资源综合水平的变化趋势进行分析,在此基础上构建耦合协调度模型,分析汾河流域城市化与水资源的耦合协调关系。结果表明：汾河流域城市化综合指数整体呈上升趋势,城市化子系统重要程度表现为经济城市化>社会城市化>空间城市化>人口城市化;水资源综合指数呈波动上升趋势,水资源子系统重要程度呈现出水资源利用>水资源水平>水资源保护,水资源环境不断优化,2013年出现短期下降,主要受水资源量和用水量等要素的影响;从时间上看,2010—2019年汾河流域城市化与水资源耦合协调度不断提高,经历了从2010年低水平轻度失调到2019年高水平协调发展过程;空间上,2010—2019年汾河流域六市城市化与水资源耦合协调度不断提升,吕梁、太原、忻州达到良好协调水平,临汾、运城处于勉强协调水平,而晋中则处于磨合阶段的濒临失调水平。