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排序方式: 共有62条查询结果,搜索用时 15 毫秒
21.
James C. Hower Jennifer M.K. O'Keefe Michael A. Watt Timothy J. Pratt Cortland F. Eble J.D. Stucker Allison R. Richardson Irena J. Kostova 《International Journal of Coal Geology》2009,80(2):135-143
Macrinite is a, generally, rare inertinite maceral, often incorporating remnants and fragments of other macerals, including vitrinite, liptinite, and other inertinite. The associated inertinites include multiple forms of funginite. Funginite is also commonly found in association with vitrinite of slightly elevated reflectance and with degraded varieties of vitrinite. Together with the highly degraded macrinite, the latter two associations are here inferred to be part of a continuum of fungal and microbial degradation of peat. In any case, the origin of some macrinite is potentially distinct from that of inertinite generated by fire. 相似文献
22.
A study of inorganic iodine speciation in the water column of a naturally eutrophicated anchialine pond (Rogoznica Lake, East Adriatic Coast) was conducted in a period between April and July 2004 to obtain information how close the inorganic iodine system is to that of inorganic nutrients during spring, when phytoplankton activity is at maximum, and how the system changes up to summer, when highly reducible redox-conditions prevail in deep water. 相似文献
23.
Irena Grgić Andreja Dovžan Gorazd Berčič Vida Hudnik 《Journal of Atmospheric Chemistry》1998,29(3):315-337
Laboratory experiments were conducted with real atmospheric aerosol particles as well as with synthetic solutions under dark conditions, to simulate some of the chemical features of aerosols. In solutions obtained by the leaching of aerosols (size range >D
ae: 0.4–1.6 m) that contained sufficient amounts of transition metal ions (e.g. Fe) and organic species (e.g. oxalate), S(IV) oxidation rates were significantly lower than those expected from the Fe-catalyzed S(IV) autoxidation in Milli-Q water. The results suggest that oxalate is responsible for much of the observed inhibition. Acetate and formate also inhibit the reaction, but to a much lesser extent. Oxalate has a strong inhibiting effect on the Fe-catalyzed S(IV) autoxidation at all investigated pH values (2.8, 3.7 and 4.5). It was established that Fe(III)-oxalato complexes affect the redox cycling of Fe(II)/Fe(III) and that the observed decrease of the reaction rate is caused by the reduced amount of catalytically active Fe(III) due to the complexation with oxalate. For the system Fe-S(IV)-O2-oxalate at initial pH 3.7 the reaction rate was calculated using exponential simplification to account for oxalate influence on the amount of free Fe(III) by the following equation:–rS(IV) = k · [S(IV)] · [Fe(III))] · e
-b·[Ox] 相似文献
24.
Bianca Mitrică Istvan Bogardi Eugen Mitrică Irena Mocanu Marin Minciună 《Norsk geografisk tidsskrift. Norwegian journal of geography》2017,71(1):12-29
The article examines the risk of water shortages due to the climate change on Leu-Rotunda Plain, which is part of Oltenia Plain in Romania. The region has been exposed to several extreme climatic phenomena, mostly droughts, which has created several problems related to water quality and quantity. The authors defined climate change scenarios using two regional climate models. Water resources under climate change were estimated by a regional numerical groundwater model covering a deep aquifer. The water demand components were estimated for households, industries, services, and livestock, based on specific socio-economic assumptions. A non-probabilistic risk assessment, using simplified fuzzy sets mathematics, was used to estimate water supply, water demand, and the consequences of water shortages. The results of the study revealed significant vulnerability in the water supply, a limited territorial expansion of sewerage networks, an expected increase in households’ demand, an expected increase in industrial and services water demand, a relatively stable demand for water for livestock farming, and an important water shortage in the study area. The authors conclude by highlighting a set of actions to mitigate the risk of the potential crisis. 相似文献
25.
26.
Shai Ezra Shimon Feinstein Ithamar Pelly Dan Bauman Irena Miloslavsky 《Organic Geochemistry》2000,31(12)
Residual fuel oil spilled into the sea from the Eshkol power station on 8 February, 1998 contaminated about 9 km of the foreshore north of the Ashdod harbour. A study of the aliphatic, polycyclic alkane and polyaromatic hydrocarbon (PAH) composition of the spilled oil shows rapid weathering in the early stages followed by gradual slowdown after about three months. Weathering of isoprenoids and PAH compounds and variation in Pr/Ph ratio appear to occur almost contemporaneously with that of n-alkanes, at a relatively moderate level of degradation, when much of the >C20 n-alkane envelope is still well preserved. Depletion of various compounds in accordance with molecular size rather than molecular structure appears to imply that physical weathering processes, i.e. evaporation and perhaps flushing due to wave energy, might have played an important role in the degradation of the spilled residual fuel oil in this study case. 相似文献
27.
28.
Schubert H Feuerpfeil P Marquardt R Telesh I Skarlato S 《Marine pollution bulletin》2011,62(9):1948-1956
Remane’s species-minimum concept, which states that the lowest number of taxa occurs at the horohalinicum (5-8 psu), was tested by investigating macroalgal diversity on hard substrates along the natural salinity gradient in the Baltic Sea. Field data on species occurrence and abundance were collected by SCUBA diving along 10 transects of the Finnish, Swedish and German coasts, covering a salinity range from 3.9 to 27 psu. Macroalgal species numbers declined steadily with salinity, decreasing until 7.2 psu was reached, but in the horohalinicum, a marked reduction of species number and a change in diversity were indicated by the Shannon index and evenness values. The non-linear decrease in macroalgal diversity at 5-8 psu and the lack of increase in species numbers at salinities below 5 psu imply a restricted applicability of Remane’s species-minimum concept to macroalgae. 相似文献
29.
Planktonic rotifers in mining lakes in the Silesian Upland: Relationship to environmental parameters 总被引:1,自引:0,他引:1
The effects of coal-mine waters on the structure and the density of planktonic rotifer communities were studied in lakes formed as a result of subsidence due to mining (collapse of underground tunnels). Water samples were collected according to the standard methods from four mining lakes in Tychy-Czu?ów (near Katowice, southern Poland), twice a month from June till October in 2004-2006. Two of the studied lakes were fed by mine waters but differed in flow rate, conductivity, water pH, and the amount of aquatic vegetation. The effects of those factors on the planktonic rotifer communities were analysed. In total, 83 species and forms of rotifers were recorded. The highest diversity of rotifers was found in the lakes with the largest patches of aquatic vegetation, while the highest density of rotifers was observed in the smallest and the most eutrophicated lake. High-water conductivity limited both species diversity and densities of rotifers. The rotifer communities of the studied lakes differed significantly in species diversity, although all the lakes were dominated by eurytopic species: Keratella cochlearis, Brachionus angularis, Brachionus calyciflorus, and Polyarthra sp. In the largest lake, characterized by the lowest conductivity and pH, the superdominant was Polyarthra luminosa, which in the other lakes was rare or absent. Higher conductivity was correlated with a lower density of P. luminosa, Brachionus diversicornis, K. cochlearis f. tecta, and a higher density of B. calyciflorus. In the lakes with the largest patches of aquatic vegetation, conductivity affected the number of dominant rotifer species. Apparently no other abiotic factors (pH, phosphates, and nitrates) affected the rotifer communities. 相似文献
30.