Darko Tibljaš

The effect of mineral carrier composition on phosphate-accumulating bacteria immobilization.

The goal of this study was to determine the dynamics and yield of immobilization of the phosphate-accumulating bacterium Acinetobacter junii on mineral carriers. As mineral carriers natural clinoptilolite tuff from Turkey (T) and Serbia (S) and natural bentonite (TER), in original and magnesium (Mg)-exchanged form were used. The key feature which determined the extent of immobilization of A. junii was the type of carrier; the immobilization yield decreased in order T>TER>S. The number of immobilized cells was significantly higher for the Mg-exchanged carriers when compared to their original counterparts (95 and 75 x 10(8)CFU g(-1) for T, 74 and 58 x 10(8)CFU g(-1) for TER, 19 and 6 x 10(8)CFU g(-1) for S). The Mg-exchanged T and S displayed a prolonged biofilm growth up to 24h, while the original counterparts reached the mature biofilm after 12h of incubation. Both forms of TER reached the mature biofilm after 24h of incubation, due to swelling property of the material. The number of immobilized cells correlated significantly negatively with particle size of the carrier, indicating that particle size is another important feature which determined the extent of immobilization. The Mg-exchange of original carriers resulted in significant increase of the zeta potential. When all of the materials were compared, the increase of the zeta potential of carriers correlated negatively with the number of immobilized cells, suggesting that the zeta potential of material is not a crucial factor which determined the immobilization of cells.

Geochemical and Petrographic Evidence of Meteoric Diagenesis in Tufa Deposits in Northern Dalmatia (Zrmanja and Krupa Rivers, Croatia)

SummaryHolocene tufa deposits in the Northern Dalmatia region of Croatia occur along the banks and at present sites of waterfalls of the Zrmanja river and its tributary the Krupa river. Petrographic, geochemical and statistical analyses have been used to relate textural features and trace element composition to the degree of meteoric diagenesis. Trace metal concentrations associated with carbonate phase were determined by sequential extraction procedure. The insoluble residue (I.R.) is predominantly of primary origin and its amount ranges from 3% to 29%, averaging 13.75%, thus permitting variable water/rock ratios of the stabilazing meteoric system. All the evidence points to a scarcity of post-depositional recrystallization and cementation, but where present these features are accompanied by I.R., Mg, Sr and Zn depletion and Fe enrichment.

Jabuka Shoal, a New Location with Igneous Rocks in the Adriatic Sea

Petrographic and XRF analyses of the magmatic rock from Jabuka Shoal, 2300 m west of Jabuka Islet (central Adriatic Sea) revealed that the rock is gabbro. This new location of magmatic rocks in the Adriatic confirms their linear arrangement, and indicates the presence of an important fault line which predisposed the occurrences of magmatic rocks.

Selective immobilization of Acinetobacter junii on the natural zeolitized tuff in municipal wastewater

The immobilization of desired bacteria onto material was usually performed in synthetic media. The aim of this study was to test the immobilization of phosphate (P)-accumulating bacteria Acinetobacter junii onto natural zeolitized tuff (NZ) in the raw or sterilized municipal wastewater containing the common bacteria Escherichia coli and Enterococcus faecalis and the performance of immobilized A. junii in the same type of wastewater. In the sterilized wastewater which contained the mixture of A. junii, E. coli and E. faecalis, the A. junii was selectively immobilized onto NZ in significantly higher numbers than E. coli and E. faecalis. The A. junii added in the form of bioparticles to the wastewater containing E. coli and E. faecalis, multiplied and removed P from wastewater. The P removal from wastewater was a function of biomass of P-accumulating bacteria and not the amount of NZ or bioparticles used. The performance of A. junii was significantly better in membrane filtered than in autoclaved wastewater. The experiments that were performed in raw non sterilized wastewater showed that A. junii can be successfully immobilized onto NZ in competition with natively present heterotrophic bacteria, retain its metabolic activity and successfully remove P from such water, which makes this technology feasible from biotechnological aspect.

Discovery of Blueschists in the Medvednica Mountain (Northern Croatia) and Their Significance for the Interpretation of the Geotectonic Evolution of the Area

Blueschists were discovered in the metamorphic rocks of the Medvednica mountain. Two varieties of blueschists are recognised, one with garnets and another with omphacite. Determined mineral associations are composed of sodic amphibole (glaucophane and crossite), garnet, omphacite and white mica. These mineral associations indicate metamorphic conditions which are transitional between blueschist and eclogite facies, i.e. high pressures at relatively moderate temperatures (LG, HP/LT). Such conditions are often characteristic of subduction zones. The occurrence of high-pressure metamorphic rocks in the Medvednica mountain, together with local outcrops of ultramafic rocks (serpentinised harzburgite, dunite and serpentinite) indicate subduction related rocks of the Dinaric part of the Tethyan oceanic crust. In the northern part of the Dinarides, ultramafic rocks and glaucophane schists have also been found in the Motajica and Fruska gora mountains. The Medvednica-Motajica-Fruska gora zone probably represents a relict subduction zone in the Dinaridic part of Tethys, along which regional high-pressure metamorphism took place.

Eoalpine (Cretaceous) very low- to low-grade metamorphism recorded on the illite-muscovite-rich fraction of metasediments from South Tisia (eastern Mt Papuk, Croatia)

Eoalpine (Cretaceous) very low- to low-grade metamorphism recorded on the illite-muscovite-rich fraction of metasediments from South Tisia (eastern Mt Papuk, Croatia) Eoalpine very low- to low-grade metamorphism related to Cretaceous orogenesis has been investigated in the Slavonian Mts, Croatia. Samples belonging to the Psunj metamorphic complex (PMC), the Radlovac metamorphic complex (RMC) and Permian-Triassic and Triassic sedimentary sequences (PTSS) were studied. The Kübler and Árkai indices of all the analysed samples indicate high-anchizonal to epizonal metamorphism. The degree of Eoalpine metamorphism tends to be constant in all samples implying that the different complexes passed through and recorded the same event. Measurements of illite-white K-mica b0-parameter of the RMC samples imply transitional low- to medium-pressure character of the metamorphism. These data together with K-Ar ages (~100-80 Ma) measured on illite-white K-mica rich < 2 μm grain-size fractions point to Late Cretaceous very low- to low-grade regional metamorphism presumably related to the main nappe-forming compressional events in the Pannonian Basin and the Carpathians. The P-T-t (pressure-temperature-time) evolution of the studied area is in good agreement with similar scenarios in the surrounding areas of Tisia, but also in Eastern Alps, Carpathians and Pannonian Basin (ALCAPA).

Early Miocene European loess: A new record of aridity in southern Europe

The intercalation of silty units and coarse-grained units represented by conglomerates and breccia characterizes a Lower Miocene terrestrial sedimentary sequence in the North Croatian Basin, a part of the southwestern Pannonian Basin system. These sediments were previously interpreted as alluvial sediments, where the silty units would reflect deposition on a floodplain. However, in this study, we show new results that support a different interpretation of the genesis of the silty units. The units, which vary in thickness between 6 and 180 cm, are mostly composed of structureless loose silt. They are brownish yellow to yellowish brown in color and do not contain fossils. Scanning electron microscopy indicated that quartz grains show fracture faces, conchoidal fractures, V-shaped percussion marks, linear steps, and conchoidal crushing features. Such microtextures together with the macroscopic characteristics of the silt units indicate that they were deposited by wind. Therefore, this study reports the first occurrence of Miocene loess outside of China. Silt-sized particles were probably produced by salt-weathering processes on salina-type lake flats during long arid periods. Alluvial deposition was controlled by a more humid climate, so the intercalation of eolian silty units with alluvial conglomerates and breccias reflects alternation of arid and more humid periods in the early Miocene. This agrees with regional paleoclimate studies that show cyclicity in the climate, with a dry cycle and orbital-scale climate variability controlling paleoenvironmental and sedimentary changes in the area during the early Miocene.

Impressions of the Biota Associated With Waterfalls and Cascades from a Holocene Tufa in the Zrmanja River Canyon, Croatia

The following types of calcified deposits characterize Holocene waterfall tufas in the Zrmanja river: mossy deposits, algally laminated crusts and algally coated grains. Petrological examination revealed, that abundant organic remains belonging to mosses and algae provide supporting material, over which tufa accretion takes place, leaving well-defined impressions of the biota. Postgenetic features like meniscus, isopachous and drusy mosaic calcite spar cementation, as well as aggradational neomorphism are only rarely present.

Preliminary results on degree of thermal alteration recorded in the eastern part of Mt. Papuk, Slavonia, Croatia

In order to improve present knowledge of metamorphic conditions to which rocks of the Mt. Papuk have been subjected, selected samples belonging to the Radlovac metamorphic complex as well as overlying sedimentary rocks and parts of Psunj metamorphic complex beneath it were studied. Rocks from Mt. Papuk were investigated, in order to determine thermal conditions, by Kubler index (illite “crystallinity”) and Arkai index (chlorite “crystallinity”) while b0-parameter of K-white mica was used for pressure conditions estimation. Treatment with dimethyl-sulfoxide (DMSO) was used in order to extend application of chlorite “crystallinity” measurements to kaolinite containing samples. Obtained results are: T=250-300°C and P=2-3 kb. Similar T data recorded on various lithologies imply the existence of unknown post lower Triassic thermal event (Alpine very low to low grade metamorphism) affecting different complexes on Mt. Papuk. New data presented and discussed in this paper will set fundament for further research and interpretation of tectono-metamorphic history of the studied area and its correlation with other similar European metamorphic complexes.

Diagenesis of Miocene pelitic sedimentary rocks in the Sava Depression (Croatia)

Abstract Miocene pelitic sedimentary rocks from six wells in the Sava Depression (sub-basin in the south-western part of the Pannonian Basin System) were investigated in order to determine the degrees of diagenetic alteration. Qualitative and semiquantitative mineral compositions of samples and the content of smectite in illite-smectite (I-S) were determined by X-ray powder diffraction (XRD). Vitrinite reflectance and thermal alteration index (TAI) were measured in order to estimate the palaeotemperatures. Carbonate minerals, clay minerals and quartz are the main constituents of the pelitic sediments. Feldspars (albite), pyrite, opal-CT and hematite are present as minor constituents in some rocks. The mineral composition of the rocks, apart from previously known differences caused by various depositional environments and clastic material provenance, is dependent on the degree of diagenetic processes. At elevated temperatures and large burial depths the minerals formed by alteration processes or precipitated at the surface; smectite, kaolinite and calcite were gradually replaced by minerals formed by diagenetic processes, i.e. by illite-smectite, illite, chlorite, Ca-excess dolomite/ankerite and albite. Based on XRD data for smectite, I-S and illite, three stages of diagenetic development have been established. The early stage was characteristic of samples at depths <1.8 km containing smectite, I-S of the random R0 type and detrital illite. The middle stage begins with the appearance of the ordered R1 type of I-S at the depths >1.8 km and temperature above 80℃. At depths >4.6 km with corresponding temperatures >190℃, the late stage began, characterized by the presence of R>1 I-S with <10% smectite.