Adsorption and Desorption of Phosphate on Calcite and Aragonite in Seawater

The adsorption and desorption of phosphate on calcite and aragonite were investigated as a function of temperature (5–45 °C)and salinity (0–40) in seawater pre-equilibrated with CaCO₃. An increase in temperature increased the equilibrium adsorption; whereas an increase in salinity decreased the adsorption. Adsorption measurements made in NaCl were lower than the results in seawater. The higher values in seawater were due to the presence of Mg²⁺ and Ca²⁺ ions. The increase was 5 times greater for Ca²⁺ than Mg²⁺. The effects ofCa²⁺ and Mg²⁺ are diminished with the addition of SO₄ ^2- apparently due to the formation of MgSO₄ and CaSO₄ complexes in solution and/or SO₄ ^2- adsorption on the surface of CaCO₃. The adsorbed Ca²⁺ and Mg²⁺ on CaCO₃ (at carbonate sites) may act as bridges to PO₄ ^3- ions. The bridging effect of Ca²⁺is greater than Mg²⁺ apparently due to the stronger interactions of Ca²⁺ with PO₄ ^3-.The apparent effect of salinity on the adsorption of PO₄ was largely due to changes in the concentration of HCO₃ ^- in the solutions. An increase in the concentration of HCO₃ ^- caused the adsorption of phosphate to decrease, especially at low salinities. The adsorption at the same level of HCO₃ ^- (2 mM) was nearly independent of salinity. All of the adsorption measurements were modeled empirically using a Langmuir-type adsorption isotherm[ [PO₄]_ad = K_mC_m[PO₄]_T/(1 +K_m [PO₄]_T) , ]where [PO₄]_ad and [PO₄]_T are the adsorbed and total dissolved phosphate concentrations, respectively. The values of C_m (the maximum monolayer adsorption capacity, (mol/g) and K_m (the adsorption equilibrium constant, g/(mol) over the entire temperature (t, °C) and salinity (S) range were fitted to[ C_m = 17.067 + 0.1707t - 0.4693S + 0.0082S² ( = 0.7) ][ ln K_m = - 2.412 + 0.0165t - 0.0004St - 0.0008S² ( = 0.1) ]These empirical equations reproduce all of our measurements of[PO₄]_ad up to 14 mol/g and within ±0.7 mol/g.The kinetic data showed that the phosphate uptake on carbonate minerals appears to be a multi-step process. Both the adsorption and desorption were quite fast in the first stage (less than 30 min) followed by a much slower process (lasting more than 1 week). Our results indicate that within 24 hours aragonite has a higher sorption capacity than calcite. The differences between calcite and aragonite become smaller with time. Consequently, the mineral composition of the sediments may affect the short-term phosphate adsorption and desorption on calcium carbonate. Up to 80 % of the adsorbed phosphate is released from calcium carbonate over one day. The amount of PO₄ left on the CaCO₃ is close to the equilibrium adsorption. The release of PO₄ from calcite is faster than from aragonite. Measurements with Florida Bay sediments produced results between those for calcite and aragonite. Our results indicate that the calcium carbonate can be both a sink and source of phosphate in natural waters.     

蚀变超基性岩金（镍）矿床中的贵金属元素──以云南墨江金矿和陕西煎茶岭金矿为例

云南墨江金矿和陕西煎茶岭金矿中Ａｇ、Ａｕ和ＰＧＥ（铂族元素）的丰度和共生状况如下：（１）两矿床中的Ａｇ－Ａｕ关系呈三种情况：硅质岩型矿石和其他类型低品位金矿石中Ａｇ－Ａｕ基本上不具相关关系；石英脉型矿石中Ａｇ－Ａｕ呈明显的正相关关系；氧化矿石中Ａｇ－Ａｕ呈负相关关系。（２）所有样品中的ＰＧＥ均低于７１×１０（－６），其ＰＧＥ的特征是Ｐｔ≥Ｐｄ和Ｒｕ＞Ｏｓ、Ｉｒ、Ｒｈ。（３）这些样品的地幔标准化ＰＧＥ分布模式是以Ｒｈ为峰的上凸曲线，而墨江样品又具Ｉｒ的负异常。与一般超基性岩的情况不同，这些样品的模式曲线中Ｐｄ－Ａｕ部分呈陡弯折，它表明矿化元素金可能主要由区域成矿流体提供。     

古里雅冰帽8米浅冰芯的化学成分组成特征及其来源

对古里雅冰帽８ｍ浅冰芯的８０个雪冰样品化学分析结果表明，化学成分主要来自陆源物质，陆源冰芯样品叶弱碱性，明显不同于一般的大气降水及南北极冰雪样品。     

水热条件下黄铁矿片、板状晶体的微结构

利用透射电子显微镜(TEM)系统观测了黄铁矿片、板状晶体的微结构,发现在水热条件下生成的黄铁矿片、板状晶体具有正方形、矩形等多种形貌。其中,正方形较多,矩形次之,另可见到一些其他不规则形状。黄铁矿片、板状晶生长完好,未见缺陷。经测定多数四边形片状黄铁矿的两组边分别平行(010)和(100),其生长晶面为(001);个别四边形片状黄铁矿的两组边分别平行(010)和(101),其生长晶面为(101),矩形片状黄铁矿长轴生长方向为001。在水热条件下黄铁矿以多形貌出现,黄铁矿的片、板状晶体多数是沿(001)面生长的结果,(001)为黄铁矿片、板状晶体的主要二维生长面,并沿001方向扩展,构成了二维晶体。     

热带土壤发育过程的定量研究—以海南岛北部为例

海南岛北部不同时期喷发的玄武岩上发育的土壤构成一个成土年代系列, 由此可以定量地探讨发育过程中土壤性质随风化成土年龄增加的变化规律.研究表明土体厚度、B层厚度、RR指数、w(REE)、w(Ba)/w(Nb)、w(Fe_d)/w(Fe_t)、w(Fe_d)、w(Fe_o)/w(Fe_d)、土壤硅铝率、土壤硅铁铝率、频率磁化率等土壤性质与风化成土年龄具有确定的相应关系.根据土壤发生学原则, 得出土壤性质与风化成土年龄两者间的统计方程.对于成土环境相同或相近地区可从这些方程由土壤性质推断相对风化成土年龄和发育程度, 也可由风化成土年龄估计土壤特性, 研究成土速率      

长江流域矿产资源特征及成矿规律

长江流域分布着我国很多重要的矿产资源基地。在长江流域不搞大开发的前提下，如何合理地开发利用矿产资源以保障国家的能源资源安全，同时又要保护生态环境，达到人类与环境和谐共赢的目的，是当前迫切需要研究的新课题。本文系统梳理了长江流域已发现的128种矿产、14683处矿产地信息，总结了长江流域矿产资源分布特征，系统分析了长江领域矿产资源的时空演化规律。长江流域矿产种类较齐全，能源矿产总体不发育但页岩气有潜力，金属矿产以铁、有色金属为主，矿物类和岩石类非金属矿产都比较发育，水气矿产潜力很大。时间上，成矿历史悠久，按构造演化时段，可分为太古宙、元古宙、晚古生代、早古生代、中生代、新生代6个时段，以中生代和晚古生代为主要成矿期；空间上，可划分八大资源集中区，上游矿产地数量较多，但下游成矿密度更大。只要合理布局，科学谋划，加强法制，严格管控，通过矿产资源的高端开发利用，不但可以为社会经济的高质量发展提供资源保障，也可以为环境保护作出新的贡献。     

Geology, Geochemistry and Tectonic Significance of Mafic-ultramafic Rocks of Mesoproterozoic Phulad Ophiolite Suite of South Delhi Fold Belt, NW Indian Shield

A thick sequence of mafic-ultramafic rocks, occurs along a major shear zone (Phulad lineament), running across the length of Aravalli Mountain Range for about 300 kms. It has been suggested, that this sequence may represent a fragment of ophiolite or a rift related metavolcanic suite made up of basalts and fractionated ultramafics. The geological and tectonic significance of the complex is assessed using field relationships, petrography and geochemistry. Structurally, the lowest part of the complex comprises a discontinuous band of plastically deformed harzburgite (mantle component) followed by layered cumulus gabbroic rocks (crustal component). A complex of non-cumulus rocks comprising hornblende schists, gabbros, sheeted dykes and pillowed basalts structurally overlies layered gabbros. Huge bodies of diorite intrude volcanics.

Geochemical classification suggests that all non-cumulus mafic rocks are sub-alkaline basalts except one variety of dykes which shows mildly alkaline character. The sub-alkaline rocks are tholeiite to calc-alkaline with boninite affinity. Tectono-magmatic variation diagrams and MORB normalised patterns suggest a fore arc tectonic regime for the eruption of these rocks.

The mafic rocks of Phulad Ophiolite Suite are zoned across the strike in terms of their distribution from west to east. The hornblende schists and basalts are exposed at the westernmost margin followed by gabbros and dykes. The alkaline dyke occurs at the easternmost part. The rocks of Phulad suite are juxtaposed with shallow water sediments in the east followed by platformal sediments and then continental slope sediments in the further east indicating gradual thickening of the crust from west to east and an eastward subduction. The geochemical interpretation presented in this study, together with discussion of lithological association is used to decipher the tectonic evolution of the Mesoproterozoics of NW Indian shield.     

卫星热红外遥感技术在火山区地热探测中的应用——以内蒙古锡林郭勒火山区为例

能源的全球性短缺以及全球环境问题的日益加剧,使得绿色新能源的研究与开发成为当今世界许多国家的一项重要任务。地热资源作为其中一员其重要性日益凸显。在地热资源的勘查中,传统的地质和地球物理勘探投入高、难度大,而遥感技术具有经济、高效、覆盖范围广等优势,已逐渐成为地热资源探测与调查的一种新技术手段。地热能开发的首选地区往往是新生代火山活动区,因其在相对较小的深度内就能获得很高的温度。本文综述了国内外利用遥感技术探测火山地热的发展历史和研究现状,介绍了这项技术在美国黄石公园、日本阿苏火山以及我国长白山火山和腾冲火山的应用。同时选取内蒙古锡林郭勒盟新生代火山活动构造区作为实例,利用美国NASA陆地卫星Landsat-7 ETM+第6波段的红外遥感数据反演了研究区的地表温度,结合ETM+7-4-1波段组合影像的地质构造解译结果以及其它相关资料对研究区地表温度分布进行了分析。结果表明,区内红外遥感地表温度异常区多位于北东东与北西向构造的交汇处或与环形构造密切相关。本文圈定了7个地表温度异常区作为这一地区下一步地热资源勘查的远景区。     

塔里木盆地西北缘露头区奥陶系古溶洞地质建模

塔里木盆地西北缘奥陶系大型古溶洞广泛出露,为古溶洞露头地质建模提供了优越的条件。综合野外资料和Google Earth影像分析,将大型古溶洞以形态结构特征为依据划分成管道—厅堂连通型溶洞、单一管道孤立型溶洞、流线型溶洞3种类型;以存在形式划分成单一溶洞和溶洞群。其中,管道—厅堂连通型溶洞以潜流带型为主,在平面上沿主方位通过岩溶管道连接厅堂分布,厅堂大小不等,在50～50000m³之间变化;单一管道孤立型溶洞以渗流带型为主,平面上呈现单一管道线条状;流线型溶洞分布在潜流带中,从剖面上看呈近圆形、椭圆形和豆荚状等多种形状,包括顺层和斜交地层2种类型。结合各露头剖面中构造、地层条件及发育溶洞类型,明确管道—厅堂联通型溶洞受不整合面控制,分布在三间房、五道班和西克尔剖面中;单一管道孤立型溶洞受断裂系统控制,分布在一间房和硫磺沟剖面中;流线型溶洞主要分布在西克尔剖面,沿溶蚀沟道两侧分布;多种不同因素的耦合控制了溶洞群的分布。以此建立了综合大型古溶洞特征及其控制因素的古溶洞发育概念地质模型,以溶洞群为主要体积计算单元,通过与塔北奥陶系串珠进行体积对比,明确了地质模型的油气勘探意义。     

A simplified analytical model for run-out prediction of flow slides in municipal solid waste landfills

Flow slides in municipal solid waste (MSW) landfills are common geoenvironmental issues in the urban environment and can pose a serious threat to the surrounding population and infrastructure. Prediction of the maximum run-out distance of flow slides in MSW landfills is therefore an essential part of hazard and risk assessment in engineering design. Based on the framework for simple analysis originally developed by Hungr (1995), we propose a simplified analytical model for calculating dam breaks in a plastic fluid along a single inclined base. In the proposed model, a quarter-elliptical shape is used to describe the approximate configuration of the flow slide. Following this step, the physical laws relating to the conservation of mass and energy are used to calculate the potential flow. Of additional note is a boundary condition in mathematics relating to this simplified analytical model, which is also reported in this study. Taking the obvious mobility characteristics of the MSW at point of failure into consideration, a three-phase simplified model along double inclined bases has been further developed for run-out prediction of the flow slide in MSW landfill. The proposed three-phase model is then applied to estimate the maximum run-out distance of two typical flow failures of landfills located in Sarajevo and Bandung, which demonstrate the capability of the proposed simplified analytical model for use in hazard assessments of landfills.