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1.
There is determined the LC50 for 24 … 96 h of phenol, 2,4-dinitrophenol and pentachlorophenol as sodium salt by static assay at water temperatures of 16, 23 and 36°C. In addition, the combinations of the three substances were tested in the same way. With decreasing temperature, the toxicity of the individual substances decreased by 6.5 … 22%, that of the mixtures by 10 … 87%; with rising temperature, the toxicity increased by 38 … 747% and 75 … 744%, respectively. The safety limits at 23°C lie between 0.3 μg/l for a synergistically acting mixture and 0.9 mg/l for an antagonistically acting one; for the individual substances this range is 3.5 μg/l to 0.5 mg/l.  相似文献   

2.
Eggs of Coregonus albula were incubated at temperatures of 1.1, 2.0, 4.9, 6.6, 8.4 and 9.9 °C. The successful hatching is optimum with 61 % at 4.9 °C; incubation time and period of hatching decrease significantly with rising temperature. The length of eleutheroembryos decreases with rising temperature, the yolk sac volume increases. Between the incubation time till hatching and the body length a significantly positive regression exists in the range of 4.9… 8.4 °C, for the yolk sac volume the regression is negative, it is significant in the range of 2.9… 6.6 °C; at the same time a negative regression exists between the yolk sac volume and the body length. Thus, low temperatures cause a delay of hatching, higher temperatures accelerate hatching and at the same time result in a reduced utilization of the yolk reserves. Besides these influences of temperature on the rate of ontogenetic processes, some autoecological consequences of the influence of temperature result, which have to be taken into account in further investigations.  相似文献   

3.
This paper reports the variations of strength, resistivity and thermal parameters of clay after high-temperature heating. Experiments were carried out to test the physical properties of clay heated at temperatures ranging from room temperature to 800°C in a furnace. The experiment results show that below 400°C the uniaxial compressive strength and resistivity change very little. However, above 400°C, both increase rapidly. At a temperature under 400°C, the thermal conductivity and specific heat capacity decrease significantly. The thermogravimetric analysis (TG) and differential scanning calorimeter (DSC) test indicate that a series of changes occur in kaolinite at temperatures from 400 to 600°C, which is considered the primary cause of the variation of physical and mechanical properties of clay under high temperatures.  相似文献   

4.
The ability of adsorbed water to react with feldspar-rich lunar soils, create fine pores, and expand the specific surface area is reduced about five-fold if the fines are heated at 700°C rather than 300°C. The loss of reactivity is attributed to the annealing of radiation damage tracks which reduces their etchability by water. Although the pore volume which can be induced decreases drastically, the distribution of pore sizes is not altered significantly. Most of the induced pores have a width of about 45Åwith a smaller population concentrated at about 120Å. For fines without water treatment, loss of specific surface area by sintering does not occur at temperatures below 700°C.  相似文献   

5.
The need for most efficient use of energy is abruptly in conflict with the need to maintain environmental quality in terms of heated effluents released from power plants. This study synthesizes biological results found from four effluent canals from power plants releasing heat on shallow estuaries: tropics, edge of tropics and subtropics. The dominant near-shore community in the Gulf of Mexico and Caribbean is that of Thalassia, rich in animal and plant abundance and biomass. Summer mean temperatures in all three estuaries ranged around 30°C. Results show sustained temperatures of +5°C in summer denude the area of the Thalassia community. Temperatures +1 and +1.5°C were minimally damaging to the studied areas and can be considered rational release temperatures. Insufficient data was available at +2°C to make a statement; +4°C areas showed intense damage to the biological communities at all locations; +3°C effect varied from severe damage in the subtropics to 40% damage in the tropics. Recommended summer heated effluent release for power plants eliminating heat onto Thalassia beds would certainly nerver be greater than +3°C. A trade-off decision must be made by decision-makers as to +3 or +2°C as the upper permissable limit. Winter release of effluent temperature in areas where winter temperatures fall below 25°C could be above +3°C apparently without damage. Tropical and subtropical ecosystems are on the brink of disaster and small increments of change by man's activities can push them beyond tolerance limits. Evidently the marine tropics differ from marine temperate zones in their capacity to assimilate man's activities.  相似文献   

6.
High pressure experiments have been made on the stability of richterite50-tremolite50 solid solution by the piston-cylinder type high pressure apparatus in the pressure range from 15 to 40 kb, at temperatures from 700 to 1150°C. This amphibole is stable up to 40 kb at 700°C, and the breakdown pressure gradually decreases with increasing temperatures. It is suggested that this amphibole, on the basis of high pressure experiments, may occur in the upper mantle.  相似文献   

7.
40Ar/39Ar age spectrum analyses of samples from Broken Hill, New South Wales, indicate that the region has experienced a complex thermal history following high-grade metamorphism, 1660 Ma ago. The terrain cooled slowly (～3°C Ma?1) until about 1570 Ma ago, when the temperature fell below about 500°C. Following granitoid emplacement ～1500 Ma ago, the region remained relatively cold until affected by a thermal pulse 520±40Ma ago, causing temperatures to rise to～350°C in some places. During this event, accumulated40Ar was released from minerals causing a significant Ar partial pressure to develop. Laboratory Ar solubility data combined with the40Ar/39Ar age spectra gives a local estimate of this partial pressure of ～10?4atm. The region finally cooled below 100°C about 280 Ma ago.40Ar/39Ar age spectrum analyses of hornblende, plagioclase and clinopyroxene containing excess40Ar are characterized by saddle-shaped age spectra. Detailed analysis of plagioclase samples reveals a complex diffusion behaviour, which is controlled by exsolution structures. This effect, in conjunction with the presumed different lattice occupancy of excess40Ar with respect to radiogenic40Ar, appears to be responsible for the saddle-shaped age spectra.  相似文献   

8.
The lake without any outlet (11 ha, 55000 m3, zmax 2,25 m) has a weak thermal stratification with maximum surface temperatures of 32.5 °C. The annual variation of temperature and depth of visibility is unimodal, with the maxima or minima in August. Phytoplankton consists mainly of Cyanophyceae. The primary production determined by the light-dark bottle technique (oxygen method) varies in the annual variation between 0.3… 0.5 g m?2 d?1 C (winter) and 3.4… 4.6 g m?2 d?1 C (summer); as the annual means of 1975 and 1976 there were found 1.9 and 2.4 g m?2 d?1 C, resp., gross production at a utilization of 0.42… 2.85% of the radiation energy. The chemism is a well-buffered hydrogen-carbonate water (pH 8.1… 9.0) with 74… 90 mg/1 Na and 20.5… 31.5 mg/1 K and with a good nutrient supply (20… 40 μg/1 PO4—P and 100… 240 μg/1 NO3—N) at the same time.  相似文献   

9.
SEM, optical and chemical observations have been performed on 12 H3-6 chondrites, 9 of them being also studied by other groups. Morphological features of chondrules and crystals (growth steps) are shown; the significance of the finely crystallised troilite in Menow and Ambapur Nagla is discussed in the light of the discovery that the NiFe blebs associated with it are Ni-rich (50–60% Ni). Sulphur should have been mobilized without shock evidence possibly as a result of solar heating. Pre-chondritic relict material is recognized by anomalous or variable mineral compositions, and in some cases, by the presence of overgrowths on relict cores. After short notes on individual chondrites, a tentative history of H chondrites is proposed. The chondrule-forming episode is considered as a remelting of pre-existing material. The accretion would immediately follow this event for type 6 (around 1000°C), and would occur at progressively lower temperature for types 5 and 4. Type 3 would represent material coming from an extended source region, an hypothesis consistent with the broader range composition of the particles and with their cooling before accretion to much lower temperatures (below 350°C).  相似文献   

10.
The Shizishan copper-gold deposit at Tongling, Anhui Province consists of two magmato-hydrothermal mineralization types: the crypto-explosive breccia type and the skarn type. At least four episodes of boiling occurred to the ore-forming fluids in this deposit. The first episode took place in accompany with the formation of the crypto-explosive breccias. The melt-fluid inclusions giving temperatures above 600℃ and salinities higher than 42% NaCl equiv represent a residual magma related to this episode. The second episode occurred during skarnization, giving fluid temperatures of 422℃-472℃, averaging 458℃, and salinities of 10.2%-45.1% NaCl equiv. The third episode corresponds to the main mineralization stage, i.e., the quartz-sulphide stage. Fluid temperatures of this episode vary in a range of 337℃-439℃ with an average of 390℃, and salinities in a range of 3%-30% NaCl equiv. The forth episode happened at the waning stage of mineralization, giving fluid temperatures below 350℃ with an average of 265℃ and salinities of 2.1%-40.4% NaCl equiv.  相似文献   

11.
The hydrogen isotope fractionation factors between epidote and aqueous 1 M and 4 M NaCl, 1 M CaCl2 solutions, and between epidote and seawater, have been measured over the temperature range 250–550°C over which the degree of dissociation of dissolved species varies significantly. Measured fractionations at 350°C are decreased by up to 12‰, 9‰ and 7‰ relative to pure water in seawater, 1 M CaCl2 and 1 M NaCl respectively, while above 500°C fractionations are not measurably dependent on fluid composition. Water—solution fractionation factors are derived which are generally applicable to the correction of mineral—water hydrogen isotope fractionations for the composition of the fluid phase.The hydrogen isotope compositions of natural epidotes are interpreted in the light of experimental fractionation data for situations where temperature, δD (fluid), and, in some cases, fluid chemistry, are independently known. Epidotes from active geothermal systems have hydrogen isotope quench temperatures consistent with or close to measured well temperatures unless the measured temperature has declined substantially since epidote formation or there is uncertainty in the D/H ratio of the water associated with the epidote because of isotopic heterogeneity in the well waters. Hydrothermal and metamorphic epidotes show closure temperatures of 175–225°C and 200–250°C. There is no evidence that retrograde metamorphic fluids, if present, are isotopically different from prograde fluids.The water-solution fractionations indicate strong solute-solvent interactions between 250 and 450°C and imply that both dissociated and associated species contribute to the fractionation effects through modification of the orientations and structure of the water molecules. Solute-solvent interactions become negligible at temperatures around 550°C.  相似文献   

12.
The rate of oxidation of different organic matters varied greatly at combustion temperatures lower than 800 °C. While some materials were oxidized rapidly, others produced peaks with extremely long tails which were difficult to integrate accurately. At 550 °C, where calcium carbonate still remained intact, the determination of carbon consumed much more time and yielded a poorer accuracy when compared with combustion at 950°C. Above 550 °C calcium carbonate decomposes and produces peaks which overlap with those of organic carbon. An accurate correction for carbonate in the results of organic carbon analysis cannot thus be established, in practice, and separate determinations of total and inorganic carbon should be carried out, organic carbon being obtained by subtraction. To achieve the most accurate results the use of 950… 1000°C is recommended for the determination of both total, and carbonate, carbon.  相似文献   

13.
Biotite granite from the Sierra Nevada batholith was reacted, with known water contents in sealed platinum capsules, in a piston-cylinder apparatus between 10 and 35 kb. With the liquid just over-saturated with respect to water, temperatures for solidus and liquidus (quartz/coesite-out curve), respectively, are: 2 kb, 680°C, 715°C; 10 kb, 620°C, 725°C; 25 kb, 655°C, 800°C; 35 kb, 700°C, 850°C. The temperature interval is 35°C at 2 kb, 105°C at 10 kb, and 150°C at 35 kb, indicating that granite departs from a eutectic composition at depths greater than about 40–50 km. We conclude that crystal-liquid equilibria are not likely to yield primary rhyolite or granite magmas by partial fusion of oceanic crust in subduction zones. The solubility of water in granite liquids, in wt%, is 22.5 ± 2.5 at 25 kb and 810°C and 27 ± 2.5 at 35 kb and 850°C. These results indicate that a miscibility gap persists between water-saturated silicate magmas and aqueous vapor phase at least to pressures corresponding to 100 km depth in the mantle. The formation of kyanite near the liquidus of water over-saturated granite indicates that the aqueous vapor phase is enriched in alkalis and possibly silica, relative to the condensed phases.  相似文献   

14.
The method is based on the determination of the number of the nonmotile sperms and/or the lethally damaged sperms with the aid of the fluorescent dye primuline. Incubation takes place at a suspension density of 10.000/mm3… 38.000/mm3, at 40°C or 46 °C for 15… 60 min. During the test with sublimate the loss of motility amounts to 55% at 4 mg/l Hg2+, the LC50 is 7.3 mg/l Hg2+. Phenyl-mercuric acetate causes the total loss of motility with 20 mg/l, the LC50 is above 168 mg/l (equivalent to 100 mg/l Hg2+). The LC50 of sodiumpentadecylmonosulphonate and dodecylpyridinchloride are 11.6 and 15.8 mg/l, resp. Filtrates of blooming of cyanophyceae on Baltic, having been digested by repeated freezing and thawing, with 1.5… 6.4 g/l dry matter showed motility losses of 30… 100 % for Nodularia spumigena, whereas no significant effect was produced by a filtrate of Microcystis aeruginosa with 28.2 g/l dry matter as well as water-blooming of Nodularia spumigena from the Small Jasmund Bodden.  相似文献   

15.
To prevent infection with Dracunculus medinensis, a carrier host, the copepod Cyclops, has to be controlled. After preceding laboratory investigations a field trial with well water and different additions of chlorine and sodium permanganate is carried out. The exposure is performed at an ambient temperature of 25… 40 °C and in bright and dark samples (5… 11 h of sunshine/d) as well as in the well. The residual concentrations of the two chemicals are an exponential function of the time of exposure with half-times between 6 and 23 h for chlorine and 11… 30 h for sodium permanganate. The depletion of the two oxidizing agents under light is faster than in darkness. Dosage should be done in such a way that the LC90,24h after 24 h of exposure will not be fallen below; in a specific case, this guarantees at the same time that the permissible concentrations for drinking water will not be reached 96 h after addition. For this, initial concentrations of 30 mg 1 Cl2 or 50 mg/l KMnOr are necessary. Under these conditions, the Cyclops population had died on the seventh day after the application of chemicals, but after seven weeks it reached the original density again. With one application of chloride or sodium permanganate a week Dracunculiasis can be completely controlled.  相似文献   

16.
Petrography, mineral and host-rock chemistry of the mantle-derived spinel lherzolite xenoliths in the nephelinites of Kutch, a late variant of the Deccan Traps province, India, are reported. The xenoliths register equilibration temperatures between 920° ± 70°C and 1060° ± 50°C and an ascent time between 19 and 168 days. Representing a palaeogeotherm of minimum heat flow between 60 and 70 mW/m2, the xenoliths possibly came from the oceanic lithosphere under the Deccan field, following the Cretaceous-Eocene fragmentation of Gondwanaland.  相似文献   

17.
Thermal loading of rocks at high temperatures induces changes in their mechanical properties. In this study, a hard gabbro was tested in the laboratory. Specimens were slowly heated to a maximum temperature of 1,000°C. Subsequent to the thermal loading, specimens were subjected to uniaxial compression. A drastic decrease of both unconfined compressive strength and elastic moduli was observed. The thermal damage of the rock was also highlighted by measuring elastic wave velocities and by monitoring acoustic emissions during testing. The micromechanisms of rock degradation were investigated by analysis of thin sections after each stage of thermal loading. It was found that there is a critical temperature above which drastic changes in mechanical properties occur. Indeed, below a temperature of 600°C, microcracks start developing due to a difference in the thermal expansion coefficients of the crystals. At higher temperatures (above 600°C), oxidation of Fe2+ and Mg2+, as well as bursting of fluid inclusions, are the principal causes of damage. Such mechanical degradation may have dramatic consequences for many geoengineering structures.  相似文献   

18.
Basaltic lavas from the southern Alborz, an area about 40 km northeast of Tehran, Iran, have been paleomagnetically investigated. The lavas are of Late Devonian-Early Carboniferous age, and belong to the basal member of the Geirud Formation. At 11 sites a total of 80 cores was drilled.Detailed analyses by means of progressive demagnetization of the natural remanent magnetization (NRM) were made both by the application of alternating magnetic fields and by heating. Also, on a number of specimens a study was done both with thin sections and with polished sections. There proved to be general agreement between the properties of the characteristic NRM and the kind of Fe-Ti oxides in the lavas. In the case of specimens containing magnetite only the characteristic NRM was entirely removed at temperatures just below 600°C, or in alternating fields up to 1500/2000 Oe peak value; on the other hand, in specimens containing both magnetite and a substantial part of hematite (martite) the final part of the characteristic remanence was removed at temperatures above 600°C, and this remanence resisted alternating fields above 2000 Oe peak value. From the characteristic site-mean directions of 5 sites an average paleomagnetic direction is computed withD = 210.8°,I = 66.9°, and α95 = 3.9°.This result might be taken as an indication that at the Devono-Carboniferous transition the southern part of the Alborz was located in the present Indian Ocean off the Arabian coast.  相似文献   

19.
In batch experiments with 0.5 nM benzo(a)pyrene in artificial sea water there are investigated the distribution and degradation of benzopyrene in the presence of various plants: Cladophora glomerata, Enteromorpha intestinalis, Fucus vesiculosus and Chara aspera (in each case 10 … 20 g/l dry weight). The conversion of benzopyrene in the presence of the plants is considerably promoted compared with the pure autoxidation, except in the presence of Fucus. Obviously, there prevails initially the accumulation of benzopyrene in the biomass. Whereas for Fucus even after 10 d still 89% of benzopyrene can be detected in the biomass, in the other species a degradation of benzopyrene in the biomass takes place, the respective oxidation products as diols, quinones and phenols being detected in the biomass in proportionately higher concentrations. With the exception of Fucus, the degradation of benzopyrene comes up to 40 … 60% within a period of 5 … 6d with the other species tested.  相似文献   

20.
Prerequisite to the nitrogen leaching from agricultural soils in spring is the ecologically optimum control of the first nitrogen fertilizer application. On the basis of investigations having been carried out for some years, a method for determining the optimum time of fertilization with the aid of phenological data is presented. The blossoming data of Anemone nemorosa proved to be a suitable sensitive indicator, their onset of blossoming is the optimum time for the first nitrogen application. In dependence on the height and variation of weather, in the subdued mountains this time is 90 … 116 d after the beginning of the year and corresponds to a temperaturetotal ≥ 5°C of 80 … 120°C or > 0°C: 160 … 230°C. Possibly, the leaf development of Alchemilla vulgaris or the first development of Poa pratensis are suitable as other bioindicators. The boundary conditions and disturbance variables of the bioindication are discussed. By the phenological date-determination of the beginning of fertilization the nitrogen losses can be reduced by 10 … 20% and the nitrate leaching can be considerably reduced especially in drinking-water protection areas.  相似文献   

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