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11.
Determination of the apparent copper complexing capacity of seawater by anodic stripping voltammetry
A new experimental technique using differential pulse anodic stripping voltammetry with a thin-film mercury electrode and efficient mixing of the electrolyte for the apparent copper complexing capacity of seawater is proposed. The effects of some factors such as type of electrode and cell, pH of the solution, potential of deposition, time of equilibration, and influence of a non-ionic surface active agent on the measurements are examined. Experimental results for the apparent copper complexing capacity of seawater are calculated presuming 1:1 inert complex formation. By using EDTA as a model ligand, it is shown that the proposed procedure with efficient mixing of the solution excludes any appreciable kinetic influence upon the electroanalytical results. 相似文献
12.
Damir Šegon Željko Andreić Peter S. Gural Korado Korlević Denis Vida Filip Novoselnik Ivica Skokić 《Earth, Moon, and Planets》2014,112(1-4):33-44
The predicted Draconid meteor shower outburst during October 2011 had been observed by a portion of the Croatian Meteor Network whose stations encountered clear weather. A total of 95 Draconid orbits have been calculated from 18 contributing stations, and in this paper we present results for 63 orbits obtained from the fully automatic observation and processing pipeline. Two methods of trajectory estimation were applied, showing better fit results using a linearly changing velocity model versus a constant velocity model. The estimated mean radiant position has been found to be at RA = 262.6°, Dec = +55.7°, with estimated geocentric velocity Vg = 20.7 km/s. 相似文献
13.
Rais Latypov Tony Morse Brian Robins Richard Wilson Grant Cawthorn Christian Tegner Marian Holness Charles Lesher Steve Barnes Brian O’Driscoll Ilya Veksler Michael Higgins Allan Wilson Olivier Namur Sofya Chistyakova Richard Naslund Peter Thy 《Contributions to Mineralogy and Petrology》2015,169(2):1-10
14.
Damir Magaš 《GeoJournal》1999,48(2):123-131
Zadar, the ex capital of Dalmatia (South Croatia), within the borders of Austro-Hungarian Monarchy, reached the 20th century as a well developed administrative and governing centre. It is a city situated on the eastern (Croatian) Adriatic coast, with an almost 3000 years old tradition and rich cultural and art heritage. After the disintegration of Austria-Hungary, the Kingdom of Slovenes, Croats and Serbs was proclaimed (later: the Kingdom of Yugoslavia). Zadar, as a separate enclave (in Italian named Zara), was annexed to the Kingdom of Italy. It was the result of the Treaty of Rapallo, by which Zadar was separated from its region. This alienated enclave covered 57 km2 and there were about 20,000 inhabitants. In this way, the normal regional function of Zadar was interrupted which lasted untill the end of WW II. It was a period of isolation, economic stagnation, smuggling, political marginality and military-strategical importance. Zadar became not only one of the symbols of the failure of Croats to create their independent state after Austro-Hungarian disintegration but also a symbol of the realisation of nationalistic aspirations of the Kingdoms of Italy and Serbia. In the first place Zadar lost its function as a leading governmental and strong economical centre of South Croatia (Dalmatia). The great majority of Croatian inhabitants had to leave the city. Thousands of Italians immigrated, which led to a complete change in the ethnic structure. The most disastrous consequence was the air-raid destruction of Zadar during WW II., in which about 5000 people died. After the destroyed town had been returned to the motherland Republic of Croatia, the restoration took a long time. The borders of Zadar district were often changed, its territory reduced or increased. Since Croatia gained independence, the role of this geographic area has become politically extremely important. Today, Zadar numbers 80,000 inhabitants. The recent NATO intention of installing a logistic basis near it (1998) also proves that strategic and geopolitical interests, regarding this city and its region, continue. 相似文献
15.
Rais Latypov Brian O’Driscoll Andrey Lavrenchuk 《Contributions to Mineralogy and Petrology》2013,166(1):309-327
The current debate on the origin of platinum-group element (PGE) reefs in layered intrusions centres mostly on gravity settling of sulphide liquid from overlying magma versus its introduction with interstitial melt/fluids migrating upward from the underlying cumulate pile. Here, we show that PGE-rich chromitite seams of the Rum Eastern Layered Intrusion provide evidence for an alternative origin of such deposits in layered intrusions. These laterally extensive 2-mm-thick chromitite seams occur at the bases of several cyclic mafic–ultramafic units and show lithological and textural relationships suggesting in situ growth directly at a crystal–liquid interface. This follows from chromitite development along the edges of steeply inclined culminations and depressions at unit boundaries, even where these are vertically oriented or overhanging. High concentrations of PGE (up to 2–3 ppm Pd + Pt) are controlled by fine-grained base-metal sulphides, which are closely associated with chromitite seams. The following sequence of events explains the origin of the PGE-rich chromitite seams: (a) emplacement of picritic magma that caused thermal and mechanical erosion of underlying cumulate, followed by in situ growth of chromite against the base, (b) precipitation of sulphide droplets on chromite grains acting as favourable substrate or catalyst for sulphide nucleation, (c) the scavenging of PGE by sulphide droplets from fresh magma continuously brought towards the base by convection. Since the rate of magma convection is 105–107 times higher than that of the solidification (km/year to km/day versus 0.5–1.0 cm/year), the in situ formed sulphide droplets can equilibrate with picritic magma of thousands to million times their own volume. As a result, the sulphide-bearing rocks are able to reach economic concentrations of PGE (several ppm). We tentatively suggest that the basic principles of our model may be used to explain the origin of PGE-rich chromitites and classical PGE reefs in other layered mafic–ultramafic intrusions. 相似文献
16.
Damir Krznarić 《Marine Chemistry》1984,15(2):117-132
Model systems consisting of a heavy metal ion (Cu2+ or Cd2+), complexing ligand (EDTA or NTA), a surfactant (9,12-octadecadienoic acid, C18H32O2, i.e., linoleic acid), and a surfactant which is at the same time a complexing ligand (tert-octylphenol etoxylate, C8H17(C6H4)(OC2H4)9–10OH, i.e., Triton-X-100) in seawater and NaCl solution were used in order to investigate the influence of the surfactant adsorption (on the electrode surface) on the heavy metal speciation measurements. The samples were titrated with either the metal, complexing ligand or surfactant and were measured by differential pulse anodic stripping voltammetry. It was shown that the surfactant adsorption exerts a strong influence upon the overall metal redox process and, thus, changes considerably both the apparent complexing capacity and the conditional stability constant of the system. Considering the presence of high concentrations of surfactants in polluted seawaters, the danger of measuring the apparent complexing capacity with the anodic stripping voltammetry method, without a detailed knowledge of surfactant properties and influence upon the system, is discussed. 相似文献
17.
Damir Viličić Tarzan Legović Vera Žutić 《Aquatic Sciences - Research Across Boundaries》1989,51(1):31-46
We present a fine vertical distribution of physico-chemical parameters and phytoplankton density around the halocline (freshwater/seawater interface) in the Krka estuary on the East coast of the Adriatic Sea. Suspended matter, surfactant activity, surface active aggregates, particulate organic carbon and phaeophytin all show largest concentrations in the 20–50 cm thick interface layer. The highest concentration of chlorophyll-a is found on the upper boundary of the interface and it is a consequence of majority of viable freshwater phytoplankton cells that accumulate there. The phytoplankton accumulates selectively in the interface: larger size fractions accumulate faster than smaller ones. In particular, nanoplanakton accumulates the least. The visible interface is also populated by dead phytoplankton cells. Most of the freshwater phytoplankton dies and decomposes in the interface, as revealed by a small chlorophyll-a/phaeophytin ratio, and it represents the main source of surface active dissolved and particulate organic matter. Marine flagellates migrate and divide in the interface, while some species likeProrocentrum micans andSyracosphera sp. are also found in the upper freshwater layer. 相似文献
18.
Summary The 100 m thick and 700 m long Nadezhda body in the Lukkulaisvaara layered intrusion exhibits concentric zonation with an
inward progression from a 0.5 to 1.0 m thick marginal layer of medium- to coarse-grained norites and gabbronorites that abruptly
give way to fine-grained oikocrystic gabbronorites composing the rest of the body. The concentric zonation is additionally
emphasized by well-developed alignment of plagioclase laths and orthopyroxene oikocrysts parallel to the outer contacts of
the body, pegmatitic gabbronorite segregations in the centre of the body and slight inward decrease in whole-rock Mg# and
Cr and increase in incompatible elements. The body has distinctly higher whole-rock Mg# and lower concentrations of all incompatible
components than its host rocks. It is enveloped by highly altered marginal anorthosites belonging to host norites and gabbronorites.
We interpret the Nadezhda body as a portion of high Mg# (∼75%) and incompatible element-poor (∼20 ppm, Zr; ∼10 ppm, total
REE; ∼0.20 wt%, TiO2) magma that replenished the evolving chamber and became trapped within the cumulate pile. Recrystallization of adjacent rocks
by volatiles exsolved from the magma upon emplacement resulted in formation of marginal anorthosites. Upon cooling the magma
started to crystallize medium- to coarse-grained norites along its margins, but subsequent decompression and loss of volatiles
led to rapid crystallization of magma into fine-grained oikocrystic gabbronorites. Solidification of the remaining residual
liquid gave rise to pegmatitic gabbronorite segregations.
Supplementary material to this paper is available in electronic form at
Tables 3–6 available as electronic supplementary material
Authors’ addresses: R. M. Latypov, S. Yu. Chistyakova, Kola Science Centre, Geological Institute, Fersman Str. 16, 184200 Apatity, Russia; Present address: Department of Geosciences,
University of Oulu, P.O. Box 3000, Oulu, FIN-90014, Finland; T. T. Alapieti, Department of Geosciences, University of Oulu, P.O. Box 3000, Oulu, FIN-90014, Finland 相似文献
19.
A. A. Kovalev A. G. Kolesnik S. A. Kolesnik A. A. Kolmakov R. R. Latypov 《Geomagnetism and Aeronomy》2009,49(4):476-482
The influence of solar eclipses on the ionospheric plasma is considered based of the data of midlatitude vertical sounding stations during the entire period from the beginning of ionospheric studies in Russia. Changes in the electron density in the F and E regions during solar eclipses have been quantitatively estimated. 相似文献
20.
The spectral method is based on the assumption of exponential forms of autocorrelation functions of the input and output time series. The results of practical applications of the spectral method on several karst springs in Croatia show that this assumption cannot always be reliably applied to the time series of rainfall and spring discharge, especially if short time periods are analysed. For this reason, the method is modified. The scale factor between the transfer function of total rainfall and the transfer function of groundwater recharge is considered as an additional model parameter which is determined in the optimization procedure. In addition to the theoretical background, this paper also presents the results of application of the modified spectral method on the springs Jadro and ?rnovnica located in the Dinaric karst area in Croatia. The parameters of groundwater recharge model are determined separately for both the springs and the obtained values are discussed and compared with the results of previous investigations. The values of the scale factors determined in the optimization procedure are compared to the values calculated using the theoretical equation. The comparison shows that the theoretical equation underestimates the optimal values of the scale factor. The underestimations are especially evident for periods of one year. Finally, the characteristics of rainfall–runoff relations of two springs are compared using the identified transfer functions and the results of simulations of the periodogram of observed discharge by the parametric periodogram. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献