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1.
Erika Sternberg Catherine Jeandel Juan-Carlos Miquel Beat Gasser Marc Souhaut Roseanna Arraes-Mescoff Roger Francois 《Marine Chemistry》2007,105(3-4):281-295
Biogenic barium, mostly in the barite (BaSO4) form, has been proposed as a tracer for export production in the ocean. Here we report on biogenic barium (Baxs) and particulate organic carbon (POC) fluxes from sediment traps deployed at the DYFAMED site in the Northwestern Mediterranean Sea. Baxs fluxes display average values of 37 ± 45 and 50 ± 58 μg/m2/d at 200 and 1000 m respectively, and are linearly correlated to POC fluxes (mean values of 7.9 ± 9.3 and 6.8 ± 6.8 mg C/m2/d at 200 and 1000 m). Export production estimates, calculated using published Baxs- or POC-based algorithms, all fall below or close to the lower limit of potential export values proposed in the literature. This work clearly demonstrates the usefulness of Baxs as a tracer of oceanic export production in the Northwestern Mediterranean Sea. However, development of a quantitative export production proxy requires a clear understanding of the underlying cause(s) for the observed spatial variations in the relationship between Baxs and POC fluxes. The present study confirms that the processes leading to barite formation differ between margin and open-ocean sites and probably account for much of the regional variability in the POC/Baxs ratio. 相似文献
2.
着重解决了以运城盐湖卤水与氯化钡溶液为原料生产硫酸钡的技术难题。目前 ,该技术已被应用到南风集团硫化碱分公司的工业化生产中。 相似文献
3.
This paper demonstrates the importance of advective transport of water through permeable estuarine and salt marsh sediments. This transport delivers significant quantities of radium and barium to the coastal ocean; and, in some cases may remove significant quantities of uranium. These conclusions are based on repeated analyses of seven river–estuarine systems from North Carolina to Florida. Fluxes of radium and barium from these river systems are shown to be inadequate to balance the dissolved inventories of these elements in the South Atlantic Bight. The strong interactions that occur between surface and subsurface waters as these rivers encounter coastal marshes lead us to consider these river mouths as marsh-dominated in terms of their chemical fluxes to the ocean. Such interactions between the river and coastal marsh must be considered when estimating fluxes of material between the land and ocean. 相似文献
4.
The objective of this work is to present an example of environmental impact of barite waste management observed in stream sediments of the western part of the Kupa River drainage basin. It is a significant water resource for Croatia and a part of Slovenia. In addition, it is for both countries a region of tourism, sport and fishing. Sediments (fraction < 63 μm) collected within the whole drainage basin have shown a significant barium anomaly in the western part. The highest concentration of total barium (5790 mg/kg) was determined in Kupica, a tributary of Kupa River. The barium anomaly was traced in Kupa River about 120 km downstream. Looking for the contamination source it was found that the anomaly originates from uncareful waste disposal into an abyss, after barite separation in Homer (Lokve), Gorski Kotar, Croatia. From there barite entered Kupica River subterraneous. Barite and albite were identified by XRD near the source of Kupica River as minor minerals, while quartz and dolomite ferroan were major minerals. This preliminary report does not give yet an answer about barium solubility in river water, about its bioavailability and consequently about barium pollution in the western part of the Kupa River drainage basin, however the possibility is highlighted and discussed. 相似文献
5.
深海沉积物蕴藏了丰富的古海洋环境变化信息.利用沉积物中的某种替代指标,有效地恢复古海洋环境变化历史是海洋地球化学家和古海洋学家致力研究的课题.海洋系统中Ba元素的地球化学行为及其与古海洋环境的关系研究表明,深海沉积物中Ba元素的丰度和变化特征能够很好地揭示古海洋环境变化信息.根据海洋系统中Ba元素地球化学研究的最新进展,系统归纳了深海沉积物中Ba的来源、富集相态及其在早期成岩过程中的行为,并在此基础上,探讨了沉积物中Ba元素丰度变化特征与古生产力和沉积物中甲烷释放通量的关系. 相似文献
6.
Shigeaki Ono 《Physics and Chemistry of Minerals》2007,34(4):215-221
Barium carbonate (BaCO3) was examined in a diamond anvil cell up to a pressure of 73 GPa using an in situ angle-dispersive X-ray diffraction technique. Three new phases of BaCO3 were observed at pressures >10 GPa. From 10 to 24 GPa, BaCO3-IV had a post-aragonite structure with space group Pmmn. There are two molecules in a single unit cell (Z = 2) of the orthorhombic phase, which is same as the high-pressure phases of CaCO3 and SrCO3. The isothermal bulk modulus of BaCO3-IV is K 0 = 84(4) GPa, with V 0 = 129.0(7) Å3 when K 0′ = 4. The c axis of the unit cell parameter is less compressible than the a and b axes. The relative change in volume that accompanies the transformation between BaCO3-III and BaCO3-IV is ～6%. BaCO3-V, which has an orthorhombic symmetry, was synthesized at 50 GPa. As the pressure increases, BaCO3-V is transformed into tetragonal BaCO3-VI. This transformation is likely to be second order, because the diffraction pattern of BaCO3-V is similar to that of BaCO3-VI, and some single peaks in BaCO3-VI become doublets in BaCO3-V. After decompression, the new high-pressure phases transform into BaCO3-II. Our findings resolve a dispute regarding the stable high-pressure phases of BaCO3. 相似文献
7.
The Ba/Ca in the growth bands of Montastraea faveolata from the Veracruz Reef System was used to reconstruct the long-term environmental change associated to anthropogenic activity in the Southern Gulf of Mexico (SGM). The 168-yr coral record shows two periods of distinct Ba concentrations: a pre-industrial period (1835-1965: 7.54 μmol/mol) followed by an industrial one (1966-2000: 8.57 μmol/mol). As human population quadrupoled during the latter, sediment load in the fluvial discharge also increased due to changes in land-use, yielding a 14% increase in the Ba-levels. A remarkable finding is that the periods at which the coral Ba/Ca ratio losses its correlation with fluvial discharge coincide exactly with peak periods of high barite consumption (used for oil drilling) in the Northern Gulf of Mexico, and the onset of oil drilling in the SGM. This finding suggests that barite may be one of the dominant sources for dissolved-Ba in the SGM. 相似文献
8.
根据八水氢氧化钡脱水制一水氢氧化钡的反应原理,采用真空加热脱水工艺,对八水氢氧化钡制备一水氢氧化钡工艺进行了研究。通过实验,找出了适宜的工艺条件。该工艺设备、操作简单,条件易于控制,尤其防止产品碳酸化更具有独特的优点。 相似文献
9.
E. Robin C. Rabouille G. Martinez I. Lefevre J. L. Reyss P. van Beek C. Jeandel 《Marine Chemistry》2003,82(3-4):289-306
Barite (BaSO4) in marine sediments is considered as a proxy of surface ocean productivity and is widely used for paleo-productivity reconstructions. However, direct barite determination is not achieved by currently used methods, which rely on the measurement of total barium by inductively coupled plasma–mass spectrometry (ICP-MS) and instrumental neutron activation analysis (INAA) and correction from the allogenic Ba contribution. We report here on a technique that directly counts individual barite crystals using a scanning electron microscope (SEM) coupled to an energy dispersive spectrometer (EDS) equipped with an automated particle counting and classification (ACC) system. We show that barite–Ba concentrations can be deduced from the abundance, shape and size distributions of barite crystals with current precision and sensitivity as high as ±5 wt.% (2σ confidence limit) and 10 ppm, respectively. This technique, coupled with ICP-MS and INAA techniques for total Ba measurements, was applied to sediment samples from the tropical North Atlantic and the Central North Pacific oceans. Results show that: (1) barite and detrital aluminosilicates are the two main carriers of Ba in the investigated sediments; (2) calculated Ba/Al ratios range from 0.005 to 0.008 with an average value around 0.0066, in close agreement with previously reported values; (3) barite might not be the major source for released barium out of sediments and we suggest instead adsorbed barium as a potential source. 相似文献
10.
Hydraulic fracturing is an important technological advance in the extraction of natural gas and petroleum from black shales, but water injected into shale formations in the fracturing process returns with extraordinarily high total-dissolved-solids (TDS) and high concentrations of barium, Ba. It is generally assumed that high TDS comes from the mixing of surface water (injected fluid) with Na–Ca–Cl formation brines containing elevated Ba, but the mechanisms by which such mixing might occur are disputed. Here we show that Ba in water co-produced with gas could originate from water-rock reactions, with Ba levels observed in produced waters reached on a time scale relevant to hydraulic fracturing operations. We examined samples from three drill cores from the Marcellus Shale in Pennsylvania and New York to determine the possible water-rock reactions that release barium during hydraulic fracturing. Two samples, one containing microcrystalline barite (BaSO4) and one without barite, contain elevated concentrations of Ba relative to the crustal average for shale rocks. A third sample is slightly depleted in Ba relative to the crustal average. Micro-XRF measurements and SEM/EDS analysis combined with chemical sequential extraction methods reveal that a majority of the Ba in all samples (55–77 wt.%) is present in clays and can only be leached from the rock by dissolution in hydrofluoric acid. Thus, a majority of barium in our samples is relatively inaccessible to leaching under hydraulic fracturing conditions. However, the balance of Ba in the rocks is contained in phases that are potentially leachable during hydraulic fracturing (e.g., soluble salts, exchangeable sites on clays, carbonates, barite, organics).We next studied how shale reacts with water at elevated temperatures (80 °C), low Eh (−100 to −200 mV), and a range of ionic strengths (IS = 0.85–6.4) that emulate conditions prevalent at depth during hydraulic fracturing. Our experimental results indicate that the amount of Ba released from the bulk rock has a positive correlation with the ionic strength of the reacting fluid. Between 5 and 25% of the total Ba in the rock can be leached from shale under ionic strength conditions and leachate compositions typical of produced waters over a contact time of just 7 days. We suggest that reductive weathering of black shale occurs during hydraulic fracturing due to: 1) Ba2+ in clays exchanging with Na+ and Ca2+ ions that are present in high concentrations in produced water, and 2) increased solubility and dissolution kinetics of barite under high ionic strength conditions. At the low Eh conditions prevalent during hydraulic fracturing the sulfate deficient water allows Ba to be dissolved into the produced water. Based on Ba yields determined from laboratory leaching experiments of Marcellus Shale and a reasonable estimate of the water/rock mass ratio during hydraulic fracturing, we suggest that all of the Ba in produced water can be reconciled with leaching directly from the fractured rock. 相似文献