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161.
The concentrations of PCBs and DDT at the surface of sediments of rivers in the Canton of Geneva were examined. Concentration variations observed along the rivers are discussed. In the case of the Rhône River, recent pollution at the surface of sediments is compared with that of aged underlying layers. 相似文献
162.
Degradation and formation of refractory DOM by bacteria during simultaneous growth on labile substrates and persistent lake water constituents 总被引:3,自引:0,他引:3
Dr. Annette Geller 《Aquatic Sciences - Research Across Boundaries》1985,47(1):27-44
Changes in molecular size distribution associated with degradation of refractory DOM (macromolecules, apparent mol wt. ≥1500)
by 3 strains of bacteria were investigated by Sephadex G-15 gel permeation chromatography and DOC analysis of the eluates.
Macromolecules and bacteria were isolated from the same lake water sample, one taken in summer and one in winter. The decompositional
changes of the DOM fraction were compared with respect to substance- and bacterial species-specific differences, and with
respect to the action of photolysis and co-substrate supplementation. The metabolite patterns resulting from the simultaneous
growth of the bacteria on the persistent DOM fraction and the labile co-substrate, glutamic acid were analyzed. The macromolecules
differed in accessible components, and the bacteria degraded most effectively the DOM fraction of the parent lake water sample.
Photolysis was the prerequisite for the reduction of the inaccessible bulk of the macromolecules. Glutamic acid enhanced the
degradation of the macromolecules. The enhancement effect was impaired by the build up of waste products which balanced the
losses of the DOM fraction. Three formation modes of refractory metabolites could be distinguished: formation of intensely
UV absorbing small sized products which were poor in DOC during degredation of (1) the macromolecules of winter, and (2) of
glutamic acid, and formation of (3) apparent high molecular weight substances from glutamic acid in cultures containing the
macromolecules of summer which probably results from a stable linkage between the small sized metabolites of the amino acid
and the DOM fraction.
The research was supported by the Deutsche Forschungsgemeinschaft. 相似文献
163.
Ahmed Abdalla Ahmed Babikir Dr. 《GeoJournal》1985,11(2):165-172
Rainfall distribution over the Sultanate of Oman is analysed. Data from seven recently installed weather stations as well as supporting data from scattered sources were used. Distribution maps were drawn. NW and NE winter wind meet resulting in troughs and rainfall on the Mountains and Coastal Strips. Summer monsoon wind dominates the S. Central areas of overlap receive light showers from both summer monsoons and winter local troughs. Heavier amounts of rainfall are generally associated with high altitude. 相似文献
164.
Michael A. Collins Dr. 《GeoJournal》1985,11(3):215-228
The growing intensity of use of water in the urban environment of the United States is posing significant challenges for its supply, utilization, and protection. The development of traditional water sources is becoming more difficult, and water suppliers are turning to conservation and reuse as alternatives. Price disincentives and better water use management are being utilized to attempt to deal with limited capacity for distribution of water in periods of high demand. Urban runoff presents significant localized flooding problems. Management of floods and floodplains is given focus under the National Flood Insurance Act of 1968, which has as its goal the deterrence of development in flood-prone areas. Water quality goals, being developed and pursued under the Safe Drinking Water Act of 1974, are becoming more encompassing as the breadth of pollutants identified in the urban environment expands. Wastewater control strategies developed under the Federal Water Pollution Control Act of 1972 are expanding their emphasis upon nonpoint source pollution, as opposed to traditional emphasis upon point source pollution. Integrated management of the water resource will become increasingly necessary to adequately address water problems in the urban environment. State and local responsibilities for urban water management and control will likely increase. 相似文献
165.
R. O. Oyegun Dr. 《GeoJournal》1985,10(2):205-210
All over the world, cities that are crossed by large rivers, have the great advantage of being able to meet their water needs. In the humid tropics, such cities should normally not experience water scarcity.Ilorin, the city under study is crossed by two fairly large rivers. The town is just about 100 km2 in area with a population less than 500,000. 3km E of the city, is a dam with a storage capacity of 43 million m3. The daily water production to the city is 661/person. When it is realized that less than 25% of the houses in the city have modern sanitary conveniences, then 661/person per day borders on over supply. Yet there is the cry of inadequate water supply from sections of the city.The habits of the city dwellers make them waste water. For example, mouth brushing alone takes about 2.4 I/person when the tap runs continuously. Secondly a bath with a 221 bucket of water is adequate for an adult, but when a shower bath is taken, about 841 will be required for about 15 minutes.This paper has examined the use and waste of water among the physical strata in the city. These strata coincide with the socio-economic strata.For an affluent class, a threshold water requirement of 521 is manageable, whereas in the Government Reservation area, the average is 82 1 (often includes waste). For the indigenous area, about 351 per day for an individual is the need, though the demand might be much higher than this value. 相似文献
166.
Summary The crystal structure of hendricksite, a trioctahedral mica of biotite type, characterized by high Zn2+ and Mn2+ contents has been refined by least square methods. The structural formula is: (K0.89Na0.10Ba0.04)(Mg1.57Zn0.54Mn
0.40
2+
Fe
0.25
2+
Al0.07Ti0.07Cr0.01)(Si2.92Al1.08)O10 (OH)2. The space group isC2/m and the cell parameters are:a=5.340(2) Å,b=9.524(2) Å,c=10.235(3) Å, =100.07(2)o, the cell volume isV=497.98 Å3. The final unweightedR=0.072. Average cation-anion distances in polyhedra are: T–O=1.659 Å, M(1)–O=2.093 Å, M(2)–O=2.088 Å, A–Olong=3.316 Å and A–Oshort=3.004 Å; A is the alkaline cation. The rotation angle of tetrahedra is =6.7°. The analysis of electron densities, of the dimensions and distorsions of polyhedra shows that Zn2+ is exclusively in octahedral sites; there is no order between six-fold coordinated cations. A comparison between the structural features of hendricksite and those of the two main end-members of biotites, phlogopite and annite, is presented.The effect of the strong covalence of Zn–O bonds is particularly visible on the dimensions and orientations of the thermal ellipsoids of octahedral sites M(1) and M(2) which contain zinc. In all the published structures of trioctahedral micas, the ellipsoids of cationic sites are uniaxial positive, elongated parallel toc
*. In hendricksite, this is observed only for the two zinc-free sites (T and A; in the octahedra M(1) and M(2), which contain zinc, the ellipsoids are approximately uniaxial negative, flattened parallel toa, which is a unique situation.Zinc which habitually favours the tetrahedral coordinations with oxygen, enters the octahedra only, i.e. the chemically anisotropic sites, in hendricksite. The strong polarizability of Zn2+ is proposed to explain this behaviour.An examination of the behaviour of Zn2+ in other compounds shows that this situation is general, zinc favours chemically anisotropic sites and specially those adjacent to OH or H2O.
Affinement de la structure cristalline de la hendricksite, mica trioctaédrique potassique riche en Zn et Mn; une contribution à la connaissance cristallochimique des minéraux zincifères
Résumé On a affiné par moindres carrés la structure de la hendricksite, mica trioctaédrique de type biotite, caractérisé par une teneur élevée en Zn2+ et Mn2+. La formule structurale de ce mica est: (K0m89Na0,10Ba0,04)(Mg1,57Zn0,54Mn 0,40 2+ Fe 0,25 2+ Al0,07Ti0,07Cr0,01)(Si2,92Al1,08)O10(OH)2. Le groupe spatial estC2/m et les paramètres de la maille:a=5,340(2) Å,b=9,254(2) Å,c=10,235(3) Å, =100,07(2)°; le volume de la maille estV=497,98 Å3. Le résidu final non-pondéré estR=0,072. Les distances cation-anion moyennes dans les polyèdres sont les suivantes: T–O=1,659 Å, M(1)–O=2,093 Å, M(2)–O=2,088 Å, A–Olong=3,316 Å et A–Ocourt=3,004 Å où A désigne le cation alcalin. L'angle de rotation tétraédrique, =6,7°, est très semblable à celui de la phlogopite. L'analyse des densités électroniques, des dimensions et distorsions des polyèdres montre que Zn2+ est exclusivement en coordinance octaédrique et qu'il n'y a pas d'ordre entre les cations hexacoordonnés. On présente une comparaison des caractères structuraux de la hendricksite avec ceux des deux principaux pôles des biotites, la phlogopite et l'annite.L'effet de la forte covalence de la liaison Zn–O est particulièrement visible sur les dimensions et orientations des ellipsoides d'agitation thermique des deux sites octaédriques, sites zincifères. Dans toutes les structures de micas trioctaédriques publiées, les ellipsoides des sites cationiques sont uniaxes positifs, allongés parallèlement àc *, ce qui s' observe effectivement dans les deux sites non-zincifères (T et A) de la hendricksite, par contre, dans les octaèdres M(1) et M(2), qui contiennent le zinc, les ellipsoides sont approximativement uniaxes négatifs, applatis parallèlement àa, ce qui est une situation unique.Le zinc, qui se fixe généralement en sites tétraédriques dans les structures de type oxyde, occupe les sites octaédriques, c'est-à-dire les sites chimiquement anisotropes dans la hendricksite. La forte polarisabilité de Zn2+ est proposée pour expliquer ce comportement.Un examen du comportement de Zn2+ dans d'autres phases montre que cette situation est tout à fait générale, le zinc privilégiant les sites chimiquement anisotropes et en particulier ceux adjacents à OH où H2O.相似文献
167.
Sule R. A. Olu Dr. 《GeoJournal》1985,10(4):401-407
Conclusion Generally, the arguments in favour of medium-size cities in Nigeria are rationalize on the environmental circumstances examined in this paper. They are not however tenable in countries of advanced technology. For example, the argument that there is direct relationship between urbanization and problems, the magnitute of which varies with the size of the community is quite logical and apt for situation in a non-western country like Nigeria than for developed nations. 相似文献
168.
Yung C. Shang Dr. 《GeoJournal》1985,10(3):299-305
The economics of aquaculture is reviewed on two levels: micro and macro. Micro-economics in aquaculture deals mainly with the management measures and elements affecting the efficiency of operation at the farm level, while macro-economics addresses the assessment of social benefits and costs of an aquaculture project. If aquaculture is socially beneficial but unattractive to private investors, public support on credit, marketing, extension, training, and research may be appropriate, especially during the early stages of development.The importance of economic analysis is emphasized since it provides a basis not only in the decision making of the individual farmer, but also in the formulation of aquaculture policies. Thus, greater attention should be focused on the improvement of economic data for analysis. 相似文献
169.
Dr. J. P. Lorand 《Mineralogy and Petrology》1985,34(3-4):183-209
Summary A volumetrically minor Cu–Fe–Ni–S component derived from the uppermost mantle is found within the Beni Bousera (northern Morocco) and Ronda (southern Spain) Alpine-type peridotites; it occurs today as inclusions within primary silicates or as assemblages disseminated in the intergranular sites of the host rocks. Detailed microtextural and microprobe data indicate that inclusions and intergranular assemblages behaved as two contrasting systems during the low temperature, incipient serpentinization of the host rocks. The former were equilibrated in closed systems whereas the latter behaved as open systems with respect to hydrothermal fluids; as a result, intergranular assemblages were controlled by redox conditions generated by serpentinization. An early stage of alteration is characterized by a slight decrease of the sulfur content and would be due to the first influx of water inside peridotites; a further transformation was produced by anomalous highly reducing conditions responsible for the crystallization of native iron-bearing alloy assemblages as well as for a preferential partioning of Fe from silicate into pentlandite. The production of anomalous, reducing conditions during incipient serpentinization is ascribed to a low permeability of the host rocks with respect to the diffusion of hydrogen out of the sites of serpentinization. Because of its low temperature behaviour, the intergranular sulfide component would not be of use reconstructing the initial composition of the upper mantle sulfide component; thus, it is concluded that only the sulfide inclusions would provide such informations.
With 9 Figures 相似文献
Le comportement du composant sulfuré du manteau supérieur pendant les premiers stades de serpentinisation des péridotites de type alpin; une discussion a partir de l'exemple des massifs ultramafiques de Beni Bousera (Maroc) et de Ronda (Espagne)
Résumé Des traces d'un composant sulfuré du système Cu–Fe–Ni–S d'origine mantellique sont présentes dans les péridotites alpines de Beni Bousera (Maroc) et Ronda (Espagne); il forme actuellement des inclusions dans les silicates primaires ou des plages intergranulaires disséminées dans les interstices des roches. Une analyse minéralogique et chimique détaillée démontre qu'inclusions et plages intergranulaires sulfurées ont eu un comportement opposé dès les premiers stades de serpentinisation des roches encaissantes. Les premières ont été reéquilibrées en système chimique ouvert vis-à-vis des fluides de serpentinisation; en conséquence les paragenèses intergranulaires résultent d'une suite de transformations du composant sulfuré mantellique, controlée par le degré d'oxydo réduction du fluide de serpentinisation. Dans un premier stade, l'entrée de l'eau dans les péridotites a provoqué une légère baisse de la fugacité du soufre et la cristallisation d'assemblages sulfurés riches en mackinawite. L'augmentation du degré de serpentinisation a ensuite engendré des conditions inhabituellement réductrices responsables d'un important fractionnement du fer libéré par la serpentinisation de l'olivine dans la pentlandite ainsi que de la cristallisation d'une paragenèse complexe de phases métalliques incluant localement le fer natif; ces conditions anormalement reductrices sont imputées à une faible perméabilité des roches encaissantes vi-à-vis de la diffusion de l'hydrogène en dehors dessites de serpentinisation. En raison de leur comportement à basse température, les plages sulfurées intergranulaires sont inutilisables pour reconstituer le composant sulfuré du manteau supérieur; sur ce plan, on conclut que seules les inclusions blindées dans les silicates peuvent apporter des informations.
With 9 Figures 相似文献
170.