Incorporation of uranium in modern corals

Uranium occurs in corals at three sites: 1, in organic matter; 2, adsorbed on the surfaces of skeletal aragonite; and 3, in the aragonite lattice. Organic matter incorporates from sea water by chelation 40–70 ppm uranium; skeletal aragonite incorporates only 3 ppm. However, as the organic fraction is low (0·1%), its high concentration of uranium does not significantly affect the total concentration of uranium in the coral. A negligible concentration of uranium, 40–60 ppb, is adsorbed on skeletal aragonite from which it is readily leached or exchanged. This low concentration of adsorbed uranium (<2% of the total uranium in skeletal aragonite) is related to the very small specific surface area (1·5–1·8 m²/g of the corals.     

和村-孙庄盆地富锶矿泉水赋存地质条件

和村-孙庄盆地锶矿泉水属低钠低矿化度含锶重碳酸钙镁型中性低温矿泉水。通过对盆地构造、岩溶发育、地下水动态等特征的分析与研究认为,奥陶系中统峰峰组二、三段岩溶裂隙含水层为盆地内的主要富锶矿泉水地层,锶元素来源于碳酸盐和岩浆岩,矿泉水中氚浓度（33．86±3．44TU）含量表明,该矿泉水形成年龄为10～20a,具有远源补给、深层循环特征。     

巴布亚新几内亚合恩半岛晚第四纪上升珊瑚礁造礁珊瑚的成岩历史

更新世以来,剧烈的构造运动已将巴布亚新几内亚合恩半岛东北海岸的晚第四纪珊瑚礁阶地抬升上千米.阶地中造礁珊瑚的成岩变化和成岩产物的组构特征反映了该礁的成岩历史,充分体现该区快速构造上升的影响.海水潜流带和淡水渗流带为上升礁的主要成岩环境.生物钻孔、生物碎屑填隙、珊瑚文石针粗化、珊瑚骨骼的溶解和新生变形转化,以及其不同矿物成分和组构的种种胶结物的胶结作用是造礁珊瑚经历的主要成岩作用.地球化学资料表明其成岩变化发生于开放的化学体系之中.     

Behavior of major and minor elements in a temperate river estuary to the coastal sea

Water samples were collected for 23 different stations along a cross section profile of an estuary extending over to adjacent sea. The collected water samples were filtered and analyzed for major?Cminor ions and strontium isotope using the standard procedure to understand the geochemical behaviors of major and minor elements. The normalized values indicated that all riverine elements were entering to adjacent coastal sea with some significant variations at the estuary. The seawater dilution and regression lines explain about the overall patterns for seven elements. Removal processes were detected on calcium, magnesium, strontium and sulfate in the estuarine region. No significant mineral precipitation observed to release magnesium with respect to calcium. Minor variations of strontium and sulfate ions could be attributed to the presence of organic matter in the study area. Comparing seven elements with total suspended matters revealed that the total suspended matters played crucial role in either adsorption or absorption of all the elements in estuary before it reaches to coastal sea. Mixing patterns of strontium isotope showed minimal non-conservative with an evidence of active geochemical process in the estuary.     

电感耦合等离子体法测定灰岩中的钙镁钾钠铝钛铁锰

灰岩样品的主要成分为碳酸钙,而镁、钾、钠、铝、钛、铁、锰的含量非常低,测试的灵敏度要求很高。该文采用一次溶矿电感耦合等离子体法直接测试灰岩中的镁、钾、钠、铝、钛、铁、锰。实验表明：在5％的盐酸介质中测试镁、钾、钠、铝、钛、铁、锰能取得很好的效果。通过测试国家标准样品,与国家标准值相比较,分析结果基本一致,准确度和精密度均令人满意,镁、钾、钠、铝、钛、铁、锰元素的相对标准偏差≤0．07％。钙元素的标准偏差≤0．15％。     

Holocene carbonate sedimentation in Lake Manitoba, Canada

The carbonate mineral suite of the modern offshore bottom sediment of the South Basin of Lake Manitoba consists mainly of high magnesian calcite and dolomite with minor amounts of low-Mg calcite and aragonite. The high-Mg calcite is derived from inorganic precipitation within the water column in response to supersaturation brought about by high levels of organic productivity in the basin. Both dolomite and pure calcite are detrital in origin, derived from erosion of the surrounding carbonate-rich glacial deposits. Aragonite, present only in trace amounts in the offshore sediments, is bioclastic in origin. The upward increase in the amount of magnesian calcite in the post-glacial sediment record is attributed to increasing photosynthetic utilization of CO₂ in the lake. Stratigraphic variation in the amount of magnesium incorporated into the calcite lattice is interpreted as reflecting a variable magnesium input to the lake from ground water and surface runoff, and possibly variable calcium removal in the precipitating lake water. The effects of long-term chemical weathering at the source and size segregation explain the changes in dolomite content throughout the section.     

Effects of calcium and magnesium on strontium distribution coefficients

 The effects of calcium and magnesium on the distribution of strontium between a surficial sediment and simulated wastewater solutions were measured as part of an investigation to determine strontium transport properties of surficial sediment at the Idaho National Engineering Laboratory (INEL), Idaho. The investigation was conducted by the U.S. Geological Survey and Idaho State University, in cooperation with the U.S. Department of Energy. Batch experimental techniques were used to determine strontium linear sorption isotherms and distribution coefficients (K _d's) using simulated wastewater solutions prepared at pH 8.0±0.1 with variable concentrations of calcium and magnesium. Strontium linear sorption isotherm K _d's ranged from 12±1 to 85±3 ml/g, increasing as the concentration of calcium and magnesium decreased. The concentration of sorbed strontium and the percentage of strontium retained by the sediment were correlated to aqueous concentrations of strontium, calcium, and magnesium. The effect of these cation concentrations on strontium sorption was quantified using multivariate least-squares regression techniques. Analysis of data from these experiments indicates that increased concentrations of calcium and magnesium in wastewater discharged to waste disposal ponds at the INEL increases the availability of strontium for transport beneath the ponds by decreasing strontium sorption to the surficial sediment. Received: 8 November 1996 · Accepted: 6 January 1997     

Diagenesis of aragonite from Upper Cretaceous ammonites: a geochemical case-study

Shell aragonite from ammonites collected in the Upper Cretaceous of West Greenland was investigated by means of macroscopic/microscopic visual evaluation, analyses of calcite/aragonite ratios, carbon and oxygen isotopic compositions and Sr and Mg concentrations of shell carbonate and of amino acid compositions of organic matrices. The results are: (1) Material visually classified as well preserved may have suffered diagenetic modifications of mineralogical and chemical composition. (2) Of the chemical and mineralogical parameters studied, amino acid composition, calcite/aragonite ratios and magnesium concentrations were found to be most sensitive to post-depositional modifications, while oxygen isotope composition and strontium concentrations showed detectable diagenetic modifications only after more pronounced alterations. (3) Based on the Mg/Ca ratios and calcite concentrations of the shell aragonite, a diagenetic classification has been proposed grouping the material into well preserved, moderately preserved and poorly preserved. (4) The chemical and mineralogical composition of the best preserved material suggests that the Upper Cretaceous ammonites had a shell composition similar to that of modern Nautilus and other aragonite-shelled molluscs.     

Classification of mineral water types and comparison with drinking water standards

In a study of 291 mineral waters from 41 different countries, 9–20% exceeded the Dutch drinking water standards for chloride, calcium, magnesium, potassium, sodium, sulphate, and fluorine. The mineral water quality cannot be qualified as bad because the standards for these compounds (with the exception of fluorine) are not based on health issues, but matters regarding undesirable taste and possible adverse effects on the water supply system. For the mineral water data set, the amount of dissolved compounds, hardness, and chloride content appear to be the most distinctive criteria. A mineral water type classification based on these criteria will offer consumers a tool for assessing mineral water on the basis of the chemical composition data on the bottle label. In terms of the criteria mentioned, average Dutch tap water strongly resembles the Belgian and Dutch mineral waters. This similarity does not extend to the price, since Dutch tap water is about 500 times cheaper.     

Incorporation of strontium into reef coral skeletal carbonate

Two thousand and twenty well-characterized coral specimens from 17 localities have been analyzed for Sr. Seventy-three genera and subgenera, mostly hermatypic scleractinians, are represented. For some genera, specimens living in surface reef environments are compared with those from 18.3 m depths on the same reefs. Growth rates for some species have also been measured at these depths at one of the sampling sites. Skeletal strontium for a given genus decreases with increasing water temperature, a relationship which previously eluded detection. Aragonite deposited by corals living on the reef at a depth of 18.3 m contains more strontium than the skeletal aragonite of the same coral genera from shallow-water, surface environments. Quantitative treatment of the data for Acropora, one of the most abundant and widely distributed of the reef-building corals, suggests that the observed strontium variations may reflect variations in the rate of skeletal calcification, rather than direct dependence upon temperature or water depth. There is evidence for ‘species effects’, apparently unrelated to growth rate differences, in that certain coral genera are consistently enriched or depleted in skeletal strontium content relative to other genera living in the same reef environments under identical ambient conditions. Temperature, salinity, water depth, seawater composition, and/or other such parameters may in part determine the levels of trace element concentration in carbonates deposited by corals and other marine invertebrates, but it would appear that these variables more directly affect physiological processes which in turn control skeletal chemistry.     

Economic potential of brines of Sabkha Jayb Uwayyid, Eastern Saudi Arabia

Sabkha Jayb Uwayyid is part of extensive sabkhas covering wide areas of eastern Saudi Arabia. Other than the production of salt for industrial and domestic purposes, no other economic utilization of sabkha brines is known in the region. Analyses from water samples collected in more than 20 shallow wells in Sabkha Jayb Uwayyid were used to estimate the concentrations and total mass of magnesium, potassium, calcium, and sodium. The total mass of each ion is calculated by multiplying the volume of water within the sabkha sands and the ion concentrations. The volume of water is the product of the saturated sabkha sediment thickness and the specific yield. The study shows that Sabkha Jayb Uwayyid brines are rich in some salts that exist in concentrations higher than that in seawater. The results show that Sabkha Jayb Uwayyid contains about 1.4, 0.4, 0.9, and 9.9 million metric tons of magnesium, potassium, calcium, and sodium, respectively. These amounts and probably more in other sabkhas potentially represent a significant untapped mineral resource in the eastern province of Saudi Arabia based on the current world production and market prices. The total mass estimates represent full extraction of brine from the sabkha and are based on a conservative specific yield estimate. Total recovery is unlikely and the actual amount will be limited by various logistical and climatic factors. Some uncertainty exists in the estimation of some parameters used in the calculations, including depth to the bedrock and hydraulic parameters.     

Preservation of organic matter in mound-forming coral skeletons

This study demonstrates that intracrystalline organic matter in coral skeletons is well preserved over century timescales. The extent of preservation of organic matter in coral skeletons was investigated by measuring total organic carbon (TOC), total hydrolyzable amino acid (THAA), chloropigment, and lipid concentrations in 0-300 year old annual growth bands from Montastraea annularis (Florida Keys) and Porites lutea (Red Sea). Organic matter intrinsic to the calcium carbonate mineral (intracrystalline) was analyzed separately from total skeletal organic matter. The Red Sea coral had less TOC (0.02-0.04 wt%) than the Florida Keys coral (0.04-0.11 wt%), but a higher percent of intracrystalline organic matter in all annual bands measured. Carbon in the form of THAA, most likely from mineral-precipitating proteins, contributed 30-45% of the TOC in both corals. Carbon in lipids represented about 3% of the TOC in the coral skeletons. Chlorophyll-a and b were present in annual bands where endolithic algae were present, but these compounds were minor contributors to TOC. The distribution of specific organic compounds showed that organic matter was well preserved throughout the time period sampled in both the total and intracrystalline pools. Variations in THAA were not correlated with TOC over time, suggesting that organic matter that is involved in biomineralization, like amino acids, may be deposited in response to different environmental factors than are other components of skeletal organic matter. Differences in the quantity and composition of organic matter between the two corals investigated here were assessed using principal components analysis and suggest that location, species and skeletal structure may all influence organic matter content and possibly the degree of physical protection of organic matter by the coral skeleton. Further, our study suggests that intracrystalline organic matter may be better protected from diagenesis than non-intracrystalline organic matter and may therefore be a more reliable source of organic matter for paleoceanographic studies than total skeletal organic matter.     

电感耦合等离子体发射光谱法测定西藏日多温泉地热水中11种主次量元素

西藏地热水的矿化度普遍较高,矿物质种类丰富,本文建立了采用电感耦合等离子体发射光谱(ICP-OES)同时测定西藏日多温泉地热水中11种主次量元素(钾钠钙镁硅硼锂锶砷铁和硫酸根)的分析方法。使用双向观测模式可确保不同浓度元素的同时检出,且地热水采用1%硝酸介质保存,在5周时间内11种元素含量的测定值基本稳定。方法检出限为0.0006~0.0162 mg/L,加标回收率为95.5%~105.8%,精密度(RSD,n=10)均小于6%,实际水样的测试结果与传统方法基本吻合。本方法为西藏温泉的水文地球化学研究提供了大量可靠的数据。     

History of the extraglacial zone of the West Siberian Lowland in the Late Cenozoic

A distinction must be drawn between "molar" and "total" basicities of minerals and their components. The "molar" basicity is defined as the degree of ionization of the components. As the acidity of solutions attacking rocks increases, we observe a series of metasomatic reactions with replacement of the components in order of decreasing molar basicity, the reverse picture being observed as the basicity of the solutions increases. The "total basicity" of a mineral is its molar basicity multiplied by its solubility. The molar and total basicities of minerals usually agree. However, as shown by Marakushev (1973), sodium feldspar (albite) has a higher basicity than potassium feldspar, and dolomite has a higher basicity than calcite, although potassium is more electro-positive than sodium, and calcium is more electropositive than magnesium. Calculations reveal that this special case is due to the higher solubility of albite and dolomite, although the molar basicity of potassium feldspar is higher than that of albite, and the molar basicity of calcite is higher than that of dolomite. Correspondingly, an increase in the acidity of the solutions leads to replacement of potassium feldspar by albite, and of calcite by dolomite. Complications are also induced by the markedly different mobilities of the components during mineral formation. Thus owing to the leveling of the CO₂ concentrations in the pore solutions of the rocks during their metamorphism, the presence or absence of CO₂ in the minerals of the rocks has no effect on their relative basicity. —Author.     

CaCO3生物矿化的研究进展——有机质的控制作用

生物CaCO₃是自然界分布最广泛的一类生物矿物,其组成除了无机相的CaCO₃外,还含有少量的有机质,包括水可溶(SM)和水不可溶有机质(IM),SM富含阴离子基团,是控制CaCO₃结晶的重要因素之一。通过有机—无机界面分子识别,有机质选择性地与CaCO₃晶体特定方向的面网相互作用,从而对CaCO₃的生长、形貌、多型及结晶学定向等产生明显的控制作用。有机—无机界面的分子识别机制包括静电、晶格几何匹配和立体化学互补等。仿生矿化的研究为进一步深入了解生物矿化的机理及制造高级复合材料提供了新的方法。     

Suitability of monosaccharides as markers for particle identification in carbonate sediments*†

The identification of the remains of organisms contributing to carbonate sediments by means of scanning electron-microscopy is limited to particles of the 2–20 μm size class. Mineralogy and the content of Mg, Sr and trace elements alone are usually insufficient to solve the problem of identification, especially in the differentiation between algal and coral aragonite. The organic matrix of calcareous organisms consists of stable biopolymers such as polysaccharides and glycoproteins which are intimately associated with the carbonate skeleton. Analysis of these hydrolysed compounds gives rise to characteristic arrays of monosaccharides which provide independent criteria for producer identification. The calcareous green algae Halimeda, Penicillus and Udotea show high xylose and low fucose levels. Xylose and fucose levels are elevated in the red algae Amphiroa but only fucose is prominent in the brown algae Padina. The corals Oculina, Porites, Millipora and Montastrea are relatively rich in fucose and show little or no xylose. In the bivalves Arca, Codakia and in Argopecten mannose may be characteristic. Analysis of artificial and natural sediments demonstrates that coral and algal aragonite can be distinguished on the basis of the total sugar concentration and respective xylose and fucose levels. The applicability of the technique in comparison to geochemical and mineralogical methods has been demonstrated for surface sediments from varying water depths of Harrington Sound, Bermuda.     

Calcium isotope fractionation in modern scleractinian corals

The ⁴⁴Ca/⁴⁰Ca ratios of cultured (Acropora sp.) and open ocean (Pavona clavus, Porites sp.) tropical reef corals are positively correlated with growth temperature. The slope of the temperature-fractionation relation is similar to inorganic aragonite precipitates. However, δ^44/40Ca of the coral aragonite is offset from inorganic and sclerosponge aragonite by about +0.5‰. This offset can neither be explained by the very fast, biologically controlled calcification of scleractinian corals, nor as a consequence of calcification from a partly closed volume of fluid. As corals actively transport calcium through several cell layers to the site of calcification, the most likely explanation for the offset is a biologically induced fractionation. Our results indicate a limited use of Ca isotopes in scleractinian corals as temperature proxy.     

Initial stages of effluent plume development, Kinloch water treatment plant (WTP), Kinloch, Taupo, New Zealand

Studies of groundwater following changes to the wastewater treatment plant and disposal field at Kinloch (Taupo area, New Zealand) showed increases in chloride (Cl) after 5 months, followed by increased calcium (Ca) and magnesium (Mg) concentrations arising as a result of cation exchange with sodium (Na) and potassium (K). Sodium (Na) and potassium (K) showed only small increases after 12 months of initial discharge, while phosphorus (P) was still being totally adsorbed by ion exchange in the aquifer.     

Hydrogeological and hydrochemical characterization of the Voltaian Basin: the Afram Plains area,Ghana

In the Afram Plains area, groundwater is the main source of water supply for most uses. The area is underlain by aquifers of the southern Voltaian sedimentary basin, which are predominantly sandstones, mudstones, conglomerates and shale. Ordinary least squares regression analysis using 41 well-test data from aquifers in the Afram Plains portion of the Voltaian system reveals that transmissivity, T, exists in a non-linear relationship with specific capacity, Sc. The analysis reveals that T = 0.769Sc^1.075 with R ² = 0.83 for aquifers in the area. The mudstone/conglomerate aquifer in the area appears to be the most variable in terms of both specific capacity and transmissivity with transmissivity ranging from 0.18 to 197.7 m²/day and 0.5 and 148.5 m³/day/m, respectively. Horizontal fractures and joints resulting from secondary fracturing appear to be the main determinants of both transmissivity and specific capacity in the area. PHREEQC modeling and mineral stability diagrams indicate that groundwater quality in the Afram Plains area is controlled by the incongruent weathering of silicate minerals in the aquifers. These processes concentrate calcium, sodium, magnesium, potassium, bicarbonate ion and quartz, leading to calcite, dolomite and aragonite supersaturation at most locations. Hierarchical cluster analysis performed on the raw chemical data reveals two main water types or facies: the calcium–sodium–chloride–bicarbonate facies, and the magnesium–potassium–sulfate–nitrate facies for the southern and northern sections of the Afram Plains area, respectively.     

Oxygen isotopic signature of the skeletal microstructures in cultured corals: Identification of vital effects

In order to identify vital effect on oxygen isotopic ratio, we analyzed at micrometer size scale skeleton microstructures of a scleractinian coral Acropora, cultured under constant conditions. Measurements focused on the two crystalline units highlighted different isotopic signatures. Massive crystals (centers of calcification: COC) exhibit quasi-constant lowest values whereas fibers, the dominant units exhibit scattered distribution with amplitude of up to 5‰. Fiber oxygen isotopic ratios (δ¹⁸O) range from values similar to instantaneous deposition to equilibrium value. By comparing data obtained on the Acropora specimen and deep-sea corals grown under well constrained conditions, we infer that the scattered δ¹⁸O aragonite fibers indicate precipitation through kinetic precipitation. Thus, we argue for inherent biological feature typical to all coral genera. Modalities of COC formation remain ignored.The different isotopic signature of two mineral microstructures present in close proximity in coral skeleton can only be explained by compartment depositions related to different organic environments. Indeed, multiple secondary electron microscopy (SEM) observations favor interaction between mineral and organic matrix surface. Moreover, atomic forcing microscopy (AFM) investigations demonstrated thermodynamic changes induced by mineralization in presence of organic compounds. The combination of our results with previous published ones from biological studies, allows us proposing a consistent model of fiber skeleton formation. The prerequisite step of mineral growth unit precipitation would be initiated by organic matrix secretion, which defines spatial extension. Specific carriers supply ionic compounds of the crystals to ensure local supersaturation. However, possibly controlled by organic molecules, ionic amount would be limited, implying the supersaturation decline over the time. This could explain the progressive decrease of the coral growth rate. In this case, vital effect should not only bias isotopic fractionation through biological activity but the mechanism of skeleton deposition is imposed by specific chemical and/or physical conditions due to the presence of organic molecules. These conclusions derive from observations performed at high resolution.Therefore, isotopic ratio measured on millimeter scale for paleoclimatic purposes, result of the average of strongly heterogeneous values. It could explain vital effects shown by geochemical time series derived from tropical coral skeleton, including the high species and/or colony variability.