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11.
Apatite-biotite-carbonatite (short form: carbonatite) rock powder originating from Lillebukt alkaline complex, N-Norway is a potential liming and multi-nutrient fertilizer. However, the elevated contents of potentially bio-toxic barium (Ba) (up to 5.5 g kg−1) is a matter of concern. A pot experiment was conducted in order to investigate the geochemistry of Ba in a sandy peat-containing growth media treated with carbonatite, with special focus on Ba-speciation in the pore water. These results were correlated with Ba uptake in Trifolium repens L. (white clover) and Fesctua arundinácea L. (tall fescue). The Ba-speciation and bioavailability as affected by treatment and plant growth was conducted using WHAM/Model VI version 7.0.4 and the diffusive gradients in thin films (DGT) technique, respectively. The increasing cation exchange capacity (CEC) in the growth media, and colloidal fulvic acids (FA) decreased the Ba2+ concentration in pore water. Both the Ba detected in DGT (Badgt), and exchangeable Ba (Baexc) were higher in pots containing rock powder. A strong relationship between Baexc and diffusively bound Ba to FA (Badfa) with plant uptake was evident. The latter was likely initiated by organic material mobilization of Ba from carbonatite. The mobilized Ba bound to FA (Bafa) in pore water was mainly bound diffusively, and the Badfa fraction was thus made available to plants. Finally, the Badgt was increased in pots grown with white clover compared to tall fescue. Further investigation is required to determine if this is related to increased rhizosphere activity by plants or to the nitrogen fixating plant-microbe relationship. 相似文献
12.
Callum J. Hetherington Mattias Lundmark Stefan Graeser Reto Gieré 《International Journal of Earth Sciences》2008,97(1):51-69
The petrographic and geochemical features of two zoisite–celsian gneiss outcrops from the Berisal Complex, characterised by
a syn-kinematic mineral assemblage that contains celsian and barium white micas and a maximum whole-rock BaO content of 8.36 wt%,
are described. The outcrops are enclosed in a larger body of garnet-bearing two-mica augen-gneiss, which has intrusive contacts
with the surrounding garnet–biotite–muscovite paragneiss, and also contains small outcrops of two-mica clinozoisite gneiss.
The zoisite–celsian gneisses are strongly enriched in all alkaline-earth elements, are depleted in the alkali elements, and
have high Zr/Hf and Nb/Ta ratios compared with the surrounding gneisses. The zoisite–celsian, two-mica clinozoisite, and garnet-bearing
two-mica augen-gneisses have Al/CNK molar ratios >1, and the zoisite–celsian gneisses are also enriched in Zr, Y, and Nb.
Chondrite-normalised patterns for the rare earth elements (REE) show light REE enrichment, with a negative Eu anomaly. On
the basis of field and geochemical data it is argued that the barium anomalies in the Berisal complex are the result of igneous
fractionation of barium into anorthosite-dominated cognate inclusions within a larger volume of calc-alkaline peraluminous
melt. On the basis of U–Pb zircon ages, a conservative estimate for the age of magma crystallisation is placed at 460 ± 10 Ma,
and thus was related to significant late Ordovician granitoid magmatism in Gondwana-derived microcontinents during collision
between Avalonia-Cadomia and Gondwana. 相似文献
13.
桂林地区岩溶水中Ba元素的水文地球化学特征 总被引：5，自引：1，他引：4
钡是岩石圈上部最丰富的微量元素之一,与镁、钙、锶同属碱土金属族元素,它们的化学性质比较接近,但在不同的岩石中它们的含量却有显著区别,所以不同类型岩溶水Ba2+含量有较大差别。对桂林地区不同类型岩溶水Ba2+含量分析,可以发现如下一些特点: 桂林地区各种岩溶水中的Ba2+浓度普遍不高,其浓度介于4. 08× 10- 6～ 28. 12× 10- 6 g /l之间。Ba2+ 浓度随着Sr2+和Ca2+浓度增大而减小,随着Mg2+浓度增大而增大。不同岩层地下水的Ba2+浓度有明显差别,灰岩表层岩溶带水中Ba2+浓度明显低于白云岩表层岩溶带水中的Ba2+浓度;三条地下河中,毛村地下河的Ba2+浓度最高,其次为浪石地下河,最后是丫吉地下河。可见,钡在河水中的含量与其补给径流区的岩石组分有关,是较好的天然示踪剂。 相似文献
14.
We discuss geochemical proxies, reflecting processes of primary productivity, CaCO3 dissolution, and sediment redistribution in a piston core (RNDB 74P) from the Ontong Java Plateau. Due to the shallow water
depth, biogenic carbonate is well preserved and a very goodδ
18O stratigraphy is available down to isotopic stage 11.230Thex gives evidence that the sediment accumulation pattern is driven mainly by processes of sediment focusing or winnowing. Due
to the constant production of230Th in the water column, the bulk sediment accumulation rates could be corrected for the particle rain deriving from the water
column above. The230Thex
0/CaCO3 ratio reflects the well-known Pacific CaCO3 preservation pattern with ice growth dissolution spikes and deglacial preservation spikes. The record of the grain size fraction
>63 μm supports these results. The downcore concentrations and accumulation rates of barium (Ba) are on a higher level during
interglacials and show several peaks. Normalization of Ba with230Thex
0 delivers a more uniform level of the Ba accumulation rates throughout the core. This pattern suggests a constantly higher
biological productivity (nearly tenfold) in this area throughout the past 200 kyr compared with an open ocean environment.
Barium peaks observed at the climatic transitions 2/1 and 6/5 and in stage 5 are in contrast to a predicted reduction of interglacial
productivity at this location. A possible explanation might be the onset of the modern circulation pattern. The transition
from Ba-enriched deep water to lower contents in the Atlantic might have resulted in an enhanced deposition of Ba in the Pacific. 相似文献
15.
Irena Pluta 《Environmental Geology》2001,40(3):345-348
Waters discharged from coal mines in the Upper Silesia in Poland cause contamination of rivers and their sediments. Saline
waters discharged from coal mines of the southern region contain elevated barium and radium. The discharge of these elements
can be reduced by treating these waters with sulphates in mine workings. Sources of sulphate used in treatments include gypsum,
anhydrite and industrial wastes such as: fly ash, slags and flotation tailings. Gypsum and anhydrite are used in the coal
mine workings as components of the fire protection walls. Industrial wastes from power plants are stored in the mine workings
as fire- and methane-protection agents. Sulphates precipitate barium and radium from saline waters inflowing into the mine
workings. The waters can be treated by flowing them through old mine workings. In this case, the source of sulphates is the
natural oxidation of pyrite. Mining activities and the natural process of desulphurisation of the Carboniferous rocks reduce
the amount of barium and radium that is discharged in the southern region of Upper Silesia. The processes for reducing the
environmental impact of toxic discharges from the mines should be monitored.
Received: 3 July 1997 · Accepted: 27 March 2000 相似文献
16.
The temperature (T) evolution of the barium carbonate (BaCO3) structure was studied using Rietveld structure refinements based on synchrotron X-ray diffraction and a powdered synthetic
sample. BaCO3 transforms from an orthorhombic, Pmcn, α phase to a trigonal, R3m, β phase at 811°C. The orthorhombic BaCO3 structure is isotypic with aragonite, CaCO3. In trigonal R3m BaCO3, the CO3 group occupies one orientation and shows no rotational disorder. The average <Ba–O> distances increase while the <C–O> distances
decrease linearly with T in the orthorhombic phase. After the 811°C phase transition, the <Ba–O> distances increase while C–O distances decrease.
There is also a significant volume change of 2.8% at the phase transition. 相似文献
17.
Labile barite contents and dissolved barium concentrations on Blake Ridge: New perspectives on barium cycling above gas hydrate systems 总被引：1，自引：0，他引：1
Blake Ridge hosts an extensive gas hydrate system where escaping CH4 is consumed through anaerobic oxidation of methane (AOM) at a sulfate–methane transition (SMT) in shallow sediment. Previous geochemical work on ridge crest sediment has documented Ba fronts above the SMT, and has suggested that these horizons can be used to constrain the evolution of the SMT and AOM over time. We expand on this concept and further test it by determining the labile Ba contents of sediment and the dissolved Ba2+ concentrations of pore waters at four ODP sites on Blake Ridge (on the crest at Sites 994, 995 and 997, and on the southern flank at Site 1059). Labile Ba contents are fairly low at all four sites (0.44 and 1.32 mmol/kg), except within 3 m above the SMT at Sites 994, 995 and 997, where they typically exceed 1.24 mmol/kg and can reach 11.3 mmol/kg. These Ba fronts have a diagenetic origin, and SEM analyses show them to be composed of microcrystalline barite. Site 1059 lacks a prominent Ba front. The lowest labile Ba contents generally underlie the Ba fronts and correlate to the base of the SMT. Dissolved Ba2+ concentrations are low (< 1–4 μM) from the seafloor to within 2 m above the main Ba front. Below this depth, they rapidly increase at Sites 994, 995, and 1059, reaching peak concentrations (to 57 μM) at the base of the SMT. By contrast, a rapid rise in dissolved Ba2+ is not observed at Site 997. Dissolved Ba2+ concentrations are only moderately high (10–25 μM) below the SMT at all four sites. Collectively, this information supports a diagenetic model where barite passing into the SMT dissolves, and some of the dissolved Ba2+ then migrates up to form an authigenic barite peak. The contrasting signatures at the different sites indicate non-steady-state differences in the overall process. The size of the peaks on the crest of Blake Ridge necessitates that the recycling of Ba across the SMT has been operating at the current sub-bottom depths for > 100 kyr. Thus, CH4 escaping through the AOM has likely been fairly constant over this time. It is possible that the SMT is currently rising toward the seafloor at Site 1059. 相似文献
18.
Michael E. Böttcher Nadja Neubert Peter Escher Katja von Allmen Elias Samankassou Thomas F. Nägler 《Chemie der Erde / Geochemistry》2018,78(2):241-247
Carbonates formed from hyperalkaline aqueous solutions at the Earth?s surface are known to bear the most extreme disequilibrium isotope signatures reported so far in nature. We present here the results for stable carbon (C), oxygen (O), and barium (Ba) isotope fractionation during the precipitation of witherite (BaCO3) induced by the chemical absorption of atmospheric carbon dioxide (CO2) into an aqueous hyper-alkaline solution (at 4° and 21?°C; 1?atm total pressure). Independent from temperature, the barium carbonate formation was associated with a substantial enrichment of the lighter C and O isotopes in the solid compared to the atmosphere (C, O), close to previous results found in experiments and nature. A new approach is introduced to explain oxygen isotope fractionation upon hydroxylation of CO2. With Ba isotope enrichment factors between ?0.45 and ?0.53‰ (138/134ε) or ?0.34 and ?0.40‰ (137/134ε), respectively, the synthesized BaCO3 displays the highest kinetic enrichment of the light Ba isotope in the carbonate solid reported so far. 相似文献
19.
秦巴山区钡矿床分带初步研究 总被引：5，自引：0，他引：5
秦巴山区钡资源丰富,钡矿床（重晶石、毒重石）分３ 带：南带为毒重石矿带,北带与中带为重晶石矿带。成矿条件与成矿类型各不相同。在秦巴山区寻找大型、超大型钡矿前景乐观。 相似文献
20.
Meagan Eagle Gonneea Paul J. Morris Henrieta Dulaiova Matthew A. Charette 《Marine Chemistry》2008,109(3-4):250
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. 相似文献