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921.
922.
923.
Dissolved trace elements in river water: spatial distribution and the influencing factor, a study for the Pearl River Delta Economic Zone, China 总被引:1,自引:0,他引:1
T. P. Ouyang Z. Y. Zhu Y. Q. Kuang N. S. Huang J. J. Tan G. Z. Guo L. S. Gu B. Sun 《Environmental Geology》2006,49(5):733-742
Twenty-nine water samples were collected from different river channels of the Pearl River Delta Economic Zone, China. An inductively
coupled plasma-mass spectromonitor (ICP-MS) was used to measure concentrations of the trace elements in these samples. The
results suggest that the average concentrations of rare earth elements in river water show an increasing trend from the West
River, the North River, the rivers of the Pearl River Delta, and the Shenzhen River to the East River. Relatively high concentrations
of heavy metals appear in the East River, the rivers of the Pearl River Delta and the Shenzhen River, while the West River
and the North River have relatively low heavy metal concentrations. Trace element concentrations in samples collected near
urban or industrial areas are much higher than those of samples collected from distant areas, away from urban and industrial
areas. After natural conditions, human activities have significant influence on the trace element concentrations in river
water. This trace element concentration’s spatial distribution in the river water from the Pearl River Delta Economic Zone
is actually an integrated effect of natural conditions and human activity. 相似文献
924.
A. G. Rozanov I. I. Volkov N. M. Kokryatskaya M. V. Yudin 《Lithology and Mineral Resources》2006,41(5):483-501
Iron and manganese in bottom sediments studied along the sublatitudinal transect from Kandalaksha to Arkhangelsk are characterized by various contents and forms depending on sedimentation environments, grain size of sediments, and diagenetic processes. The latter include redistribution of reactive forms leading to enrichment in Fe and Mn of the surface sediments, formation of films, incrustations, and ferromanganese nodules. Variations in the total Fe content (2–8%) are accompanied by changes in the concentration of its reactive forms (acid extraction) and the concentration of dissolved Fe in the interstitial water (1–14 μM). Variations in the Mn content in sediments (0.03–3.7%) and the interstitial water (up to 500 μM) correspond to a high diagenetic mobility of this element. Changes in the valence of chemical elements results in the redox stratification of sediment strata with maximum concentrations of Fe, Mn, and sulfides. Organic matter of sediments with a considerable terrestrial constituent is oxidized by bottom water oxygen mainly at the sediment surface or in anaerobic conditions within the sediment strata. The role of inorganic components in organic matter oxidation changes from surface sediments, where manganese oxyhydroxide dominates among oxidants, to deeper layers, where sulfate of interstitial water serves as the main oxidant. Differences in river runoff and hydrodynamics are responsible for geochemical asymmetry of the transect. The deep Kandalaksha Bay serves as a sediment trap for manganese (Mn content in sediments varies within 0.5–0.7%), whereas the sedimentary environment in the Dvina Bay promotes its removal from sediments (Mn 0.05%). 相似文献
925.
Detailed data obtained on surface oil samples from the Bazhenovskaya Formation in the latitudinal segment of the Ob River
area indicate that the composition of the oil is largely controlled by the P-T conditions in the reservoir. It was determined that the generation of hydrocarbon fluids starts at higher temperatures (T
f > 100°C) if the fluid reflux is hindered and the formation pressures are anomalously high. In systems with the free reflux
of hydrocarbon fluids, the processes generating oil and gas are different. The composition of oil in the Bazhenovskaya Formation
with the free reflux of hydrocarbon fluids is largely controlled by migration processes, which determine, along with the P-T parameters, the physicochemical characteristics of the oils and their concentrations of hydrocarbon groups and individual
hydrocarbons.
Original Russian Text ? O.F. Stasova, A.I. Larichev, N.I. Larichkina, 2006, published in Geokhimiya, 2006, No. 9, pp. 996–1005. 相似文献
926.
I. N. Tomson O. P. Polyakova V. Yu. Alekseev V. A. Baskina 《Geology of Ore Deposits》2006,48(1):74-76
Two types of metalliferous carbonaceous rocks that differ in associated metals are considered. One of them is characterized by gold occurring in finely dispersed arsenopyrite and arsenic-bearing pyrite, and the other, by finely impregnated native metals in carbonaceous matter. Rocks of the first type also contain elements of the platinum group, while those of the second type bear rhenium, silver, iron, molybdenum, and other metals. Graphitic mineralization is usually localized in the shear zone associated with alkaline basalts. 相似文献
927.
L. N. Kogarko 《Geochemistry International》2006,44(1):3-10
Alkaline magmatism has occurred since 2.5–2.7 Ga and its abundance has continuously increased throughout the Earth’s history.
Alkaline rocks appeared on the Earth with changes in the geodynamic regime of our planet, i.e., when plume tectonics was supplemented
by plate tectonics. Global-scale development of plate tectonics at the Archean—Proterozoic boundary initiated subduction of
already significantly oxidized oceanic crust enriched in volatiles and large-scale mantle metasomatism caused the formation
of enriched reservoirs as sources of alkaline and carbonatite magmatism. Study of metasomatized mantle material showed the
occurrence of traces of primary carbonatite melts, which are strongly enriched in rare elements, according to ion-microprobe
analyses. The results obtained allowed us to propose a new two-stage genetic model for Ca-rich carbonatites including (1)
metasomatic wehrlitization and carbonatization of mantle material and (2) partial melting of wehrlitized mantle with formation
of carbonate-rich melts or three immiscible liquids (at high alkali contents), i.e., silicate, carbonatitic, and sulfide (at
high sulfur activity).
Original Russian Text L.N. Kogarko, 2006, published in Geokhimiya, 2006, No. 1, pp. 5–13. 相似文献
928.
Aierken Sidike X.-M. Wang Alifu Sawuti H.-J. Zhu I. Kusachi N. Yamashita 《Physics and Chemistry of Minerals》2006,33(8-9):559-566
Natural calcite from Kuerle, Xinjiang, China, shows orange-red fluorescence when exposed to short-wave ultraviolet (UV) light (Hg 253.7 nm). Photoluminescence (PL) emission and excitation spectra of the calcite are observed at room temperature in detail. The PL emission spectrum under 208 nm excitation consists of three bands: two UV bands at 325 and 355 nm and an orange-red band at 620 nm. The three bands are ascribed to Pb2+, Ce3+ and Mn2+, respectively, as activators. The Pb2+ excitation band is observed at 243 nm, and the Ce3+ excitation band at 295 nm. The Pb2+ excitation band is also observed by monitoring the Ce3+ fluorescence, and the Pb2+ and Ce3+ excitation bands, in addition to six Mn2+ excitation bands, are also observed by monitoring the Mn2+ fluorescence. These indicate that four types of the energy transfer can occur in calcite through the following processes: (1) Pb2+ → Ce3+, (2) Pb2+ → Mn2+, (3) Ce3+ → Mn2+ and (4) Pb2+ → Ce3+ → Mn2+. 相似文献
929.
930.