大亚湾沉积物中重金属元素背景值研究

根据大亚湾的自然条件认为,大亚湾沉积物的物质来源是其周围集水区的岩石风化壳,并计算了其风化壳中重金属元素的平均丰度值;又根据沉积物的粒度和深层沉积物重金属元素的含量资料,列方程计算出湾内沉积物中重金属元素的平均含量,根据这两组数据,确定该区域内重金属元素的平均背景值。再通过粒度关系,计算得出大亚湾内各站沉积物中重金属元素的背景值。应用此结果和大亚湾沉积物重金属元素实测结果,计算了由人为影响带入沉积物中的重金属元素含量,了解其受污染的程度。     

长江和黄河入海沉积物不同粒级组分中稀土元素的比较

为探索区分黄、东海陆架沉积物中来自长江和黄河源的有效替代性指标,从长江和黄河河口区各取3个沉积物样品作为长江和黄河入海沉积物的端元样品。研究结果表明:长江和黄河沉积物不同粒级组分中REE的变化范围分别为145.49~256.77 μg/g和121.22~135.56 μg/g,随粒度由细变粗分别呈下倾的"双峰"型分布和倒"S"型分布;长江沉积物中REE约为黄河的1.5倍,最低值比黄河的最高值高出20%;8~16 μm和2~4 μm是凸显长江和黄河沉积物稀土元素差异的敏感粒级,REE、LREE/HREE和(La/Yb)n等稀土元素特征参数在这两个粒级组分中差异明显。本次实验结果大幅度地提高了两条河流REE差异的灵敏度和可信度,为建立区分长江与黄河入海沉积物物源实用的有效指标提供了可能。     

长江口外缺氧区沉积物中元素分布的氧化还原环境效应

对取自长江口外缺氧区及其邻近海域表层沉积物样品进行了粒度组成和元素(主要包括氧化还原敏感性元素和亲碎屑元素)丰度的分析与测试,对长江口外缺氧区缺氧环境对元素分布的影响进行了探讨,提出了长江口外缺氧区沉积物中氧化还原敏感性元素(Redox sensitive elements,简称RSE)分布的氧化还原环境效应。亲碎屑元素丰度的分布显示出明显的粒控效应,而氧化还原敏感元素的分布受粒度效应的制约很弱,主要受离岸缺氧区还原环境的制约,具有在缺氧区富集的特点。缺氧环境对RSE分布的影响超过了元素的粒控效应,从而使研究区RSE的分布呈现出典型的氧化还原环境效应。     

Rare earth elements in suspended and bottom sediments of the Mandovi estuary, central west coast of India: Influence of mining

Rare earth elements (REEs) in the suspended particulate matter (SPM) of the Mandovi estuary indicated that the mean total-REEs (∑REE) and light REE to heavy REE ratios are lower than that of the average suspended sediment in World Rivers and Post-Archean average Australian shale. High ∑REE were associated with high SPM/low salinity and also with high SPM/high salinity. Although the ∑REE broadly agree with SPM levels at each station, their seasonal distributions along transect are different. SPM increased seaward in the estuary both during the monsoon and pre-monsoon, but consistently low at all stations during the post-monsoon. The mean ∑REE decreased marginally seaward and was <25% at sea-end station than at river-end station. Spatial variations in ∑REE are maximum (64%) during the pre-monsoon. Strong to moderate correlation of ∑REE with Al, Fe and Mn in all seasons indicates adsorption and co-precipitation of REEs with aluminosilicate phases and Fe, Mn-oxyhydroxides. The ratio of mean ∑REE in sediment/SPM is low during the monsoon (1.27), followed by pre-monsoon (1.5) and post-monsoon (1.62). The middle REE- and heavy REE-enriched patterns with positive Ce and Eu anomalies are characteristic at every station and season, both in SPM and sediment. They also exhibit tetrad effect with distinct third and fourth tetrads. Fe-Mn ore dust is the most dominant source for REEs. However, the seasonal changes in the supply of detrital silicates, Fe-Mn ore dust and particulates resuspended from bottom sediments diluted the overall effect of salinity on fractionation and distribution of REEs in the estuary.     

A novel method to estimate mineral compositions of mudrocks: A case study for the Canadian unconventional petroleum systems

The mineral composition of mudrocks is an essential attribute in controlling the reservoir quality of unconventional petroleum systems. The present study introduces a semi-quantitative method to estimate mineral phases of mudrocks in various Canadian unconventional hydrocarbon systems using total elemental analysis (inductively coupled plasma-mass spectrometry (ICP-MS)) and Rock-Eval data (total organic carbon (TOC) and mineral carbon (MinC)).This method involves statistical analysis based on a sound knowledge of hydrocarbon source rock inorganic geochemistry. The workflow can be divided into four steps: (i) converting major elements (Si, Al, Fe, K, Na, Ca, Mg, Ti, and P) to their oxides, (ii) inferring modes of occurrence of elements using statistical analysis of geochemical data (major elements, TOC, and MinC), (iii) identifying the mineral types (oxide, aluminosilicates, carbonates, sulfide, and phosphate) according to elemental occurrences and calculating mineral phase concentrations, and (iv) verifying the results by comparing to XRD data on selected samples. The results, especially for brittle minerals such as quartz, carbonates (e.g. calcite, dolomite, and ankerite), and pyrite, show that the estimated mineral compositions correspond closely and consistently with measured mineralogy obtained from XRD. This method takes advantage of bulk geochemical data already available for hydrocarbon potential and chemostratigraphic studies, without devoting additional samples and cost for XRD analysis.     

Nonlinear dynamic analysis of deep water risers

The paper presents a theoretical and numerical approach to the dynamical behaviour of risers in deep water which takes into account two types of nonlinearity; that due to viscous drag forces and that due to the large displacements of the riser when submitted to strong axial loads. As the second nonlinearity may have a significant influence upon the behaviour of risers in deep water, a method for automatically updating the structural geometry during the dynamic analysis is given. A computer programme has been written for this purpose.     

云南澜沧老厂铅锌多金属矿床闪锌矿微量元素组成

云南澜沧老厂是三江成矿带南段最重要铅锌多金属矿床之一,通过LA-ICPMS和ICP-MS微量元素组成分析结果表明,矿床中闪锌矿属于铁闪锌矿,形成于中温环境,以富Fe、Mn、Cd和In等元素为特征,其中Fe、Mn、Cd、In等元素以类质同象形式赋存于闪锌矿中,而Pb、Cu 、Sn和Bi等元素含量变化范围较大,以显微包裹体(方铅矿和黄铜矿等)赋存于闪锌矿中。本矿床闪锌矿中Fe和Mn等微量元素组成与VMS矿床类似,但In和Cd的异常富集可能暗示其独特的成矿机制。总体而言,其闪锌矿微量元素组成特征和与燕山-喜山期花岗岩叠加改造作用有关的喷流沉积铅锌矿床(如云南白牛厂和广东大宝山)相似,而明显不同与矽卡岩型矿床(如核桃坪与鲁子园),更不同于MVT型铅锌矿床(牛角塘、会泽和勐兴)和金顶铅锌矿床。结合矿床产出地质特征,笔者认为云南澜沧老厂铅锌多金属矿区经历了古、中、新特提斯期不同程度的拉张与闭合发展演化,使矿床多期同位叠加成矿特征明显,其闪锌矿微量元素组成具喷流沉积成因特征,深部喜山期花岗斑岩与铅锌成矿作用关系不大,但在其侵入过程中叠加改造作用使闪锌矿等硫化物组合及其微量元素组成发生一定程度变化(如局部富集Sn和Sb等元素)。此外,两种测试方法结果对比可以看出,在硫化物单矿物微量元素分析中,LA-ICPMS相对于ICP-MS分析具有更高精度,不仅可以进行硫化物原位分析,并能即时了解微量元素在硫化物中赋存状态,而且克服了ICP-MS分析中由于单矿物选样不纯致使测试误差大等弱点。     

Deterministic sensitivity analysis for a model for flow in porous media

A deterministic method for sensitivity analysis is developed and applied to a mathematical model for the simulation of flow in porous media. The method is based on the singular value decomposition (SVD) of the Jacobian matrix of the model. It is a local approach to sensitivity analysis providing a hierarchical classification of the directions in both the input space and of those in the output space reflecting the degree of sensitiveness of the latter to the former. Its low computational cost, in comparison with that of statistical approaches, allows the study of the variability of the results of the sensitivity analysis due to the variations of the input parameters of the model, and thus it can provide a quality criterion for the validity of more classical probabilistic global approaches. For the example treated here, however, this variability is weak, and deterministic and statistical methods yield similar sensitivity results.     

五家沟矿区5号煤中伴生元素地球化学特征

为了研究大同煤田南部煤中伴生元素的地球化学特征,运用矿物学、煤地球化学以及岩石学等学科的理论和研究方法,利用X射线荧光光谱分析（XRF）、电感耦合等离子质谱分析（ICP-MS）、X射线衍射分析（XRD）、扫描电镜+能谱分析（SEM-EDS）,对五家沟矿区5号煤中伴生元素的含量及赋存特征进行研究。结果表明,五家沟5号煤中常量元素Al、Si、Ca、Fe含量较高,占到灰分总量的95%以上。Al主要以高岭石的形式存在,Si以黏土矿物和石英的形式赋存于煤中,煤中Ca的主要载体是方解石,Fe在煤中主要以黄铁矿的形式存在。煤中微量元素Li富集,Ga、Sr、Zr、Nb、Hf、Ta轻度富集。锂和镓主要赋存于高岭石中;铌和钽赋存于黏土矿物中,部分可能赋存于伊利石中;锆和铪赋存于黏土矿物中,还有部分赋存于金红石内。     

秦岭某钼矿区开发对东川河流域Cd的影响

为了探索矿业活动对河流水质产生的影响,以秦岭某大型钼矿区下游的东川河流域为研究对象,通过现场采样与室内测试的方法,分析了地表水、沉积物、岩矿样品中重金属Cd的含量特征。采用污染超标倍数法、地累积指数法及Hakanson潜在生态风险评价法分别对东川河流域的河水和底泥样品进行了污染现状评价和生态风险程度评价,最后讨论了Cd的来源。结果表明:东川河主沟16个河水采样点位中,有11个点位的Cd含量明显高于未受矿业活动影响的对照区各点位Cd含量值,Cd含量变异系数达到95.65%,并且从上游到下游各点位Cd含量呈偏态分布,说明东川河流域Cd受矿业活动影响显著。东川河主沟16个河水采样点中有15个Cd含量满足地表水Ⅱ类水标准,比重为93.75%,可以判断东川河整体水质较好。仅5号点位超Ⅱ类水质标准,污染超标倍数为1,为轻度污染。地累积指数分析结果表明,东川河主沟11个底泥样品均存在不同程度的污染:污染最严重的10号点位达到中度-强污染级别;污染最轻的8、9、13号点位为无污染-中度污染;大多数点位为中度污染。东川河主沟11件底泥样品重金属Cd的潜在生态危害指数平均值为120.27,表明东川河主沟底泥总体达到强生态风险程度。酸性矿山废水、原生地质背景、底泥释放、大气干湿降尘等是造成东川河流域Cd重金属污染的主要污染源。