New perspectives on radium behavior within a subterranean estuary

Over the past decade, radium isotopes have been frequently applied as tracers of submarine groundwater discharge (SGD). The unique radium signature of SGD is acquired within the subterranean estuary, a mixing zone between fresh groundwater and seawater in coastal aquifers, yet little is known about what controls Ra cycling in this system. The focus of this study was to examine controls on sediment and groundwater radium activities within permeable aquifer sands (Waquoit Bay, MA, USA) through a combination of field and laboratory studies. In the field, a series of sediment cores and corresponding groundwater profiles were collected for analysis of the four radium isotopes, as well as dissolved and sediment associated manganese, iron, and barium. We found that in addition to greater desorption at increasing salinity, radium was also closely tied to manganese and iron redox cycling within these sediments. A series of laboratory adsorption/desorption experiments helped elucidate the importance of 1) contact time between sediment and water, 2) salinity of water in contact with sediment, 3) redox conditions of water in contact with sediment, and 4) the chemical characteristics of sediment on radium adsorption/desorption. We found that these reactions are rapid (on the order of hours), desorption increases with increasing salinity and decreasing pH, and the presence of Fe and Mn (hydr)oxides on the sediment inhibit the release of radium. These sediments have a large capacity to sorb radium from fresh water. Combined with these experimental results, we present evidence from time series groundwater sampling that within this subterranean estuary there are cyclic periods of Ra accumulation and release controlled by changing salinity and redox conditions.     

Cobalt, manganese, and iron near the Hawaiian Islands: A potential concentrating mechanism for cobalt within a cyclonic eddy and implications for the hybrid-type trace metals

The vertical distributions of cobalt, iron, and manganese in the water column were studied during the E-Flux Program (E-Flux II and III), which focused on the biogeochemistry of cold-core cyclonic eddies that form in the lee of the Hawaiian Islands. During E-Flux II (January 2005) and E-Flux III (March 2005), 17 stations were sampled for cobalt (n=147), all of which demonstrated nutrient-like depletion in surface waters. During E-Flux III, two depth profiles collected from within a mesoscale cold-core eddy, Cyclone Opal, revealed small distinct maxima in cobalt at 100 m depth and a larger inventory of cobalt within the eddy. We hypothesize that this was due to a cobalt concentrating effect within the eddy, where upwelled cobalt was subsequently associated with sinking particulate organic carbon (POC) via biological activity and was released at a depth coincident with nearly complete POC remineralization [Benitez-Nelson, C., Bidigare, R.R., Dickey, T.D., Landry, M.R., Leonard, C.L., Brown, S.L., Nencioli, F., Rii, Y.M., Maiti, K., Becker, J.W., Bibby, T.S., Black, W., Cai, W.J., Carlson, C.A., Chen, F., Kuwahara, V.S., Mahaffey, C., McAndrew, P.M., Quay, P.D., Rappe, M.S., Selph, K.E., Simmons, M.P., Yang, E.J., 2007. Mesoscale eddies drive increased silica export in the subtropical Pacific Ocean. Science 316, 1017–1020]. There is also evidence for the formation of a correlation between cobalt and soluble reactive phosphorus during E-Flux III relative to the E-Flux II cruise that we suggest is due to increased productivity, implying a minimum threshold of primary production below which cobalt–phosphate coupling does not occur. Dissolved iron was measured in E-Flux II and found in somewhat elevated concentrations (0.5 nM) in surface waters relative to the iron depleted waters of the surrounding Pacific [Fitzwater, S.E., Coale, K.H., Gordon, M.R., Johnson, K.S., Ondrusek, M.E., 1996. Iron deficiency and phytoplankton growth in the equatorial Pacific. Deep-Sea Research II 43 (4–6), 995–1015], possibly due to island effects associated with the iron-rich volcanic soil from the Hawaiian Islands and/or anthropogenic inputs. Distinct depth maxima in total dissolved cobalt were observed at 400–600 m depth, suggestive of the release of metals from the shelf area of comparable depth that surrounds these islands.     

三轴压力下水与砂岩反应的实验研究

通过饱水砂岩的三轴压缩实验, 研究了含水层砂岩的破裂过程及其伴随的水化学变化, 并探讨了砂岩在蠕变和剪切破裂过程中地震水化异常现象的形成机理。 用离子色谱仪(IC)和等离子原子发射光谱仪(ICP-OES)测定了不同压力条件下实验溶液的F^-、 Cl^-、 NO^-₃、 SO^2-₄、 Ca²⁺、 Mg²⁺、 Na⁺浓度。 饱水砂岩在差应力作用下, 随着蠕变时间延长和剪切作用的强化实验, 溶液中主要离子的浓度均有不同程度的增大, 仅Mg²⁺浓度是降低的。 F^-和Cl^-浓度变化最明显, 在2~12小时的蠕变时间内分别增大约10倍和4倍, 而随剪切作用的强化分别增大约5倍和3倍。 这种变化主要与矿物的溶解和流体包裹体的混入有关。 实验结果表明, F^-、 Cl^-和Ca²⁺可作为砂岩含水层地震水化前兆监测的灵敏组分。     

雪冰中生物有机酸的测试分析方法研究

生物有机酸是构成酸雨的组分类别，对地表环境有着重要影响，由于其来源与生物界关系密切，因此，对其在雪冰中记录的研究是从历史的角度认识C，H，O等生源元素生物地球化学循环，认识过去生态和环境变化的途径之一，但是，由于其含量较低，易遭受污染等原因，雪冰中有机酸含量的定量测定一直是困扰研究人员的一个问题，在对目前有机酸测试分析现状，测试分析的难点和问题调研的基础上，文章提出了一种利用DX－300离子色谱测试山地冰川雪冰中生物有机酸含量的方法，该方法利用AS4A分析柱，AG4A保护柱，TAC－2样品富集柱和ATC－1阴离子捕集柱，以梯度淋洗方式，在14min内可分离检测出甲酸，乙酸，丙酮酸，甲烷磺酸，草酸等有机酸根离子及氟，氯，亚硝酸，硝酸，溴，磷酸和硫酸等常见无机阴离子，上述有机，无机离子的测试分析相对标准误差分别为：氟（2．0％），乙酸（4．5％），甲酸（2．0％），甲烷磺酸（16．9％），氯（3．1％），亚硝酸（3．9％），硝酸（2．2％），溴（4．9％）和硫酸（2．4％）。     

The depositional environment and mineralogical and chemical compositions of high ash brown coal resting on early Tertiary saprock (Schirnding Coal Basin, SE Germany)

The late Tertiary high ash brown coal (R_r=0.26%) of the Schirnding Seam Zone is mainly composed of huminite. The seam is underlain by a thick saprock (mica saprockkaolinite-mica saprock) some tens of meters thick which gradually developed from phyllitic basement rocks and a thin Footwall Series of coarse-grained clastic sediments which, however, occur only in a few places. The roof rocks ‘ Hanging Wall Series' abruptly appear on top of the seam and consist of massive gray mudstones and arenites, intercalated with some tuffites. These Tertiary series were studied in open-pit mines operated for coal and clay and in bore holes. Chemical investigation involved the analyses of TOC, TSC, Ni, Co, Pb, Zn, Ga, Be, V, Cr, U, Th, P, Zr, REE and organic compounds of extracted organic matter (=OM). Early Tertiary chemical weathering was responsible for the monotonous kaolinite-mica-goethite mineral assemblage in the saprock and the footwall series. In the coal-bearing basin a more variegated mineral association including, pyrite, kaolinite, illite, smectite, illite-smectite mixed layers and siderite was brought about by volcanic processes, intrastratal solution set free in course of coalification and early diagenesis and by meteoric waters infiltrating the coal-bearing series from uplifted parts of the basin, which underwent strong oxidation. The environment of deposition is interpreted in terms of peatswamps that were fed by small streams and crevasse splays of a meandering drainage system grading towards the basin margin into a braided stream system on an alluvial fan plain. Strongly fluctuating water levels were responsible for the pronounced cyclicity to be encountered across the coal-bearing series. The processes of element redeposition and element migration in the Schirnding Basin are operative across the interface coal-saprolite (detrital influx of heavy minerals and intrastratal solution, hydrocarbon infiltration and redistribution of organic matter, reworking of duricrusts), in the saprolite proper (weathering leachats) and across the redox boundaries between the Schirnding Seam Zone and the Hanging Wall Series (input of physils and diagenetic alteration) as well as its strongly oxidized stratigraphic equivalents at the basin edge (volcanic influx, intrastratal solutions). Chemical and mineralogical variations across the coal basin which are directly controlled by the variation in the environment of deposition, weathering and groundwater movements may be directly correlated to changes in the saprock due to the immediate contact between coal and bedrock.     

硼特效树脂离子交换法分离B的研究

本文对Amberlite IRA 743 硼特效树脂交换分离B的特征及其影响因素进行了研究。它适用于各种地质样品中B的分离提取，特别是在B同位素地球化学研究时必须进行B纯化的场合。     

水溶液体系的化学平衡模型

概括了化学平衡计算的历史及特点；对在地球化学研究中常用的水溶液体系化学平衡模型作了简要的介绍；讨论了水溶液体系化学平衡模型研究的现状及今后的发展动向。     

X射线荧光光谱分析在我国铁矿石分析中的应用

系统介绍了20世纪90年代以来X射线荧光光谱分析（XRF）在我国铁矿石分析中的应用,包括粉末压片法和熔片法两种最基本的分析手段,主要内容集中在熔片—波长色散X射线荧光光谱分析法在我国铁矿石分析方面的测试技术,重点介绍了熔剂的类型、配比、熔片方法、熔融温度以及钴内标的使用,同时介绍了基体效应校正、谱线重叠校正等方面的内容。     

气相色谱-串联质谱技术分析地质调查植物样品中持久性有机污染物的优势

对于复杂基质的样品,采用气相色谱法、气相色谱-质谱法( GC - MS)不能满足当前痕量水平分析的要求,串联质谱已发展成一种有机分析测试的成熟技术可应用于地质调查样品分析.本文建立了气相色谱-串联质谱技术( GC - MS - MS)分析植物样品中有机氯农药及多氯联苯的方法,通过对植物样品(圆白菜、菠菜、胡萝卜、橘子)分析,系统比较了GC- MS-MS与气相色谱-电子捕获检测器(GC-ECD)和气相色谱-选择离子-质谱( GC - SIS - MS)三种分析技术的检出限、定性定量分析结果,确认了分析方法的适用性.GC- MS-MS方法的检出限为0.03～0.29 ng/g,大部分化合物均低于GC -ECD的检出限,是GC - SIS -MS检出限的0.4倍.GC- MS-MS分析表明,圆白菜不含反式-氯丹,排除了GC-ECD的假阳性检出;检测胡萝卜等基质复杂、净化困难的样品,GC- MS-MS也表现出良好的定性定量能力;检出低含量水平样品菠菜含有0.26 ng/g六氯苯,而气相色谱未检出,表明GC- MS-MS显著提高了分析灵敏度,能够对样品中低含量的化合物进行准确定量.在三种分析技术中,GC- MS-MS在样品的准确定性、复杂基质样品分析灵敏度、低含量水平准确定量等方面都具有独特的优势,同时能够应用于复杂样品检测结果的确证.     

Jovian plasma torus interaction with Europa: 3D hybrid kinetic simulation. First results

The hybrid kinetic model supports comprehensive simulation of the interaction between different spatial and energetic elements of the Europa moon-magnetosphere system with respect to variable upstream magnetic field and flux or density distributions of plasma and energetic ions, electrons, and neutral atoms. This capability is critical for improving the interpretation of the existing Europa flyby measurements from the Galileo orbiter mission, and for planning flyby and orbital measurements (including the surface and atmospheric compositions) for future missions. The simulations are based on recent models of the atmosphere of Europa ( [Cassidy et al., 2007] and [Shematovich et al., 2005]). In contrast to previous approaches with MHD simulations, the hybrid model allows us to fully take into account the finite gyroradius effect and electron pressure, and to correctly estimate the ion velocity distribution and the fluxes along the magnetic field (assuming an initial Maxwellian velocity distribution for upstream background ions). Non-thermal distributions of upstream plasma will be addressed in future work. Photoionization, electron-impact ionization, charge exchange and collisions between the ions and neutrals are also included in our model. We consider two models for background plasma: (a) with O⁺⁺ ions; (b) with O⁺⁺ and S⁺⁺ ions. The majority of O₂ atmosphere is thermal with an extended cold population (Cassidy et al., 2007). A few first simulations already include an induced magnetic dipole; however, several important effects of induced magnetic fields arising from oceanic shell conductivity will be addressed in later work.