Provider: - Institution: - Data provided by Europeana Collections- Fizikalno-kemijska svojstva nanočestica (NČ), prvenstveno visoka reaktivnost, utječe na biodostupnost i sudbinu NČ u vodenom ...okolišu. Ovaj rad opisuje primjenu elektroanalitičkih metoda u određivanju i karakterizaciji NČ. Kronoamperometrijskim (CA) i voltametrijskim mjerenjima su detektirane NČ metalnih sulfida (MeS) i elementarnog sumpora (So) u modelnim sustavima. Na osnovu primijenjenog potencijala živine elektrode (Hg) određena je vrsta NČ MeS. Naboj detektiranih šiljastih signala u CA ovisi o dijametru NČ, dok frekvencija udara ovisi o udjelu NČ s dijametrom manjim od 200 nm. S CA je praćen proces aglomeriranja u ovisnosti o primijenjenim eksperimentalnim uvjetima. Kako bi se potvrdila elektroanalitička mjerenja na Hg elektrodi, provedena su mjerenja pri istim eksperimentalnim uvjetima metodama koje se standardno koriste u karakterizaciji NČ (DLS, NTA, AFM i EC-STM). Razvijena CA metoda je primijenjena za detekciju NČ u prirodnim euksiničnim vodenim sustavima.- Physico-chemical properties of nanoparticles (NPs), mainly high reactivity, affect their bioavailability and fate in aquatic environment. This work shows development of electroanalytical methods in detection and characterization of NPs. Chronoamperometry (CA) and voltammetry were used for detection of the metal sulphide (MeS) and sulphur (So) NPs in modal solutions. Based on the applied potential of the working mercury electrode (Hg) it is possible to differentiate between MeS NPs. The charge of recorded spike like signals is related to NPs size, while signal frequency depends on the presence of the NPs smaller than 200 nm. With use of CA agglomeration processes under different experimental conditions were monitored. In order to confirm electrochemical measurements in parallel intercomparison measurements with methods used in the characterization of NPs (STM, AFM, DLS, NTA) were done under same experimental conditions. CA was applied in detection of the NPs in natural aquatic euxinic systems.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: University of Zagreb. Faculty of Science. Department of Geology. Division of Geology and Paleontology. - Data provided by Europeana Collections- Na prostoru sjeverne ...Dalmacije pet je geoloških stupova ranopaleogenskih karbonatnih naslaga (Čikola I i II, Novigrad, Ostrovica i Grabova Glava) bilo predmetom detaljnih sedimentoloških i mikropaleontoloških istraživanja, te su biostratigrafskim pristupom u kombinaciji s mikrofacijesnom analizom rekonstruirani karbonatni taložni okoliši tijekom taloženja. Taloženje se odvijalo u okolišima unutarnjih, srednjih i vanjskih dijelova rampi, a organizmi koji su obilježili te okoliše bile su velike bentičke foraminifere. Tijekom paleogena kolizijski procesi između Jadranske mikroploče i Euroazijske kontinentalne ploče uzrokovali su formiranje predgorskog bazena ispred uzdižućeg dinaridskog orogena, te je ranopaleogenska transgresija započela u različitim bazenima, odnosno u različitim dijelovima Vanjskih Dinarida, u različito vrijeme taloženjem naslaga bočatih laguna, koje su u literaturi poznate pod imenom Kozinske naslage. Istraživane naslage nalaze su u dijelu bazena poznatom kao sjevernodalmatinski bazen. Tijekom postojanja sjevernodalmatinskog dijela predgorskog bazena optimalni uvjeti za taloženje karbonatnih naslaga postignuti su u dva navrata, u ranom eocenu, kada su taloženi Foraminiferski vapnenci na širokom području forebulge sustava, te u srednjem eocenu kada su na padinama wedge-top bazena taloženi Gornji Numulitni vapnenci. Tijekom različitih vremenskih intervala, od ipra do bartona, na prostorima predgorskog bazena, pružanja SZ–JI, u okolišima nastalim na rampama, uz kontrolu sinsedimentacijske tektonike, taložen je nekoliko stotina metara debeo slijed naslaga u okolišima koje opisujemo kao Dinaridski sustav karbonatnih rampa.- In the Northern Dalmatia area five outcrops of the lower Palaeogene carbonate deposits (Čikola I i II, Novigrad, Ostrovica i Grabova Glava) have been the subject of detailed sedimentological, micropaleontological and microfacies research. Furthermore, the biostratigraphic approach in combination with conventional facies analysis was used to reconstruct a range of carbonate depositional systems. Carbonate sedimentation took place in the inner, middle to outer ramp environments, where the dominant organisms were Large Benthic Foraminifera. The collision processes between the Adriatic continental microplate and Euroasia continental plate caused the formation of the Dinaridic foreland basin, developed during the Palaeogene in front of the uplifting mountain belt. Early Palaeogene transgression occurred in different times in different basins, as parts of the Outer Dinarides, firstly by the brackish lagoonal deposits known in literature as Kozina beds. Studied deposits are part of the Northern Dalmatian foreland basin and during its existence the conditions for the carbonate sedimentation were attained on two occasions. During the Early Eocene Foraminifera limestones were deposited on the vast forebulge area, and in the Middle Eocene Upper Nummulitic limestones deposited on the limbs of the wedge-top basins. During the different time intervals, spanning from the Ypresian to the Bartonian, in the NW–SE oriented foreland basin, carbonate ramps developed, controlled by synsedimentary tectonics, creating a couple hundreds of meters of deposits within environments described as Dinaridic Carbonate Ramps System.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- Nitrati predstavljaju jedno od glavnih onečišćivala podzemne vode u svijetu. U podzemnoj vodi zagrebačkoga vodonosnika ...okarakterizirani su kao jedna od pet glavnih grupa onečišćivala. Smanjenje koncentracije određenog onečišćivala najviše ovisi o definiranju njegovog podrijetla. Za potrebe određivanja podrijetla nitrata i povezanih geokemijskih procesa u podzemnoj vodi zagrebačkoga vodonosnika korištene su razne geokemijske i statističke metode. U okviru geokemijskih metoda određeni su stabilni izotopi kisika i vodika iz vode, te dušika i kisika iz nitrata. Također, napravljena je analiza molarnih omjera nitrata s kloridima, natrijem i kalijem. U okviru statističkih metoda korištene su korelacijske i multivarijatne statističke analize. Većina analiza napravljena je na dostupnim povijesnim kemijskim analizama podzemne vode, te na podacima izmjerenima u podzemnoj vodi i rijeci Savi uzorkovanoj za potrebe ovog rada. Stabilni izotopi vode pokazali su kako je podzemna voda izotopno najsličnija rijeci Savi i oborini iz Ljubljane. Interpretacijom rezultata stabilnih izotopa kisika i dušika iz nitrata utvrđeno je kako je podrijetlo nitrata za vrijeme uzorkovanja podzemne vode bilo organsko. Kao glavni izvori onečišćenja izdvojeni su otpadne vode i organsko gnojivo. Također, rezultati upućuju na to da denitrifikacija predstavlja zanemariv proces koji se odvijao u podzemnoj vodi zagrebačkoga aluvijalnog vodonosnika za vrijeme uzorkovanja. Korelacijske analize pokazale su kako kloridi i natrij predstavljaju vrlo bitne parametre u proučavanju podrijetla nitrata. Korištenje multivarijatnih statističkih analiza omogućilo je izdvajanje parametara koje su mogu koristiti kao pokazatelji antropogenog utjecaja. Također, korištenjem klaster analize određeni su piezometri na kojima glavni izvor onečišćenja predstavljaju otpadne vode, odnosno organsko gnojivo. Pritom se proučavanje molarnih omjera, prvenstveno nitrata i kalija, pokazalo kao ključno. Utvrđeno je kako se stabilni izotopi dušika i kisika iz nitrata, u kombinaciji s analizom molarnih omjera, mogu vrlo učinkovito koristiti u procjeni podrijetla nitrata na području zagrebačkoga vodonosnika. Osim toga, korelacijske i multivarijatne statističke analize pokazale su kako stabilnost i transformacija nitrata na promatranom području ovisi o koncentracijama otopljenoga kisika. Također, rezultati upućuju na to da se dušik u podzemnu vodu zagrebačkoga vodonosnika u velikim količinama unosi u obliku amonij iona nakon čega se nitrifikacijom pretvara u nitrate, što se slaže i sa izračunatim vrijednostima intervala karakterističnog za nitrifikaciju dušikovih spojeva. Trendovi su izračunati pomoću linearne regresije na četiri razine zajedno s njihovim intervalima pouzdanosti i predviđanja. Analiza
trendova nitrata utvrdila je postojanje statistički značajnih silaznih trendova koncentracija nitrata, osim u priljevnom području crpilišta Petruševec te Sašnjak i Žitnjak, na kojima su utvrđeni statistički značajni, uzlazni trendovi.- Nitrates present one of the major groundwater contaminants in the world. In the groundwater of Zagreb aquifer they are characterized as one of the five main groups of contaminants. The most important thing associated with decrease of contaminant concentration is the definition of its origin. Various geochemical and statistical methods have been used for the determination of nitrates origin and related geochemical processes in the Zagreb aquifer. Within geochemical methods, water stable isotopes and nitrate stable isotopes were calculated on sampled river and groundwater. Sava River and groundwater was sampled in the period from November 2015 to October 2016. Sampling was preliminarily performed on 56 observation wells, after which 30 observation wells were selected for monitoring of nitrate stable isotopes in time. Molar ratios of nitrate and chlorides, nitrate and sodium, and nitrate and potassium were calculated for both historical groundwater chemical analysis and for chemical analysis conducted on sampled river and groundwater. Correlation and multivariate statistical analysis have been used within statistical methods. All of the statistical analysis were done on historical groundwater quality data as well as on data measured on sampled river and groundwater. Historical data analysis of nitrate concentrations showed that there are two main areas of Zagreb aquifer where elevated nitrate concentrations have been identified. One area is located on the left bank of the Sava River, in the dominantly urban area, while other is located on the right bank, in the dominantly rural area, where agricultural activity is also present. Water stable isotopes showed that groundwater is isotopically most similar to Sava River and precipitation from Ljubljana, and least to the precipitation that falls in the area of Zagreb aquifer. Interpretation of nitrates stable isotopes showed that nitrate origin within the sampling period was organic. Wastewater and manure have been recognized as main sources of nitrate contamination. Comparison of δ15N-NO3- with nitrate concentrations, as well the values of calculated enrichment factors, suggest that denitrification is a negligible process that takes place in alluvial part of Zagreb aquifer. Results also suggest that nitrogen in Zagreb aquifer is in large extent introduced in the form of ammonium ions, after which is transformed to nitrates by nitrification. This assumption is supported by the calculated interval of δ18O-NO3- characteristic for nitrification of organic nitrogen compounds. Correlation analysis showed that chloride and sodium concentrations present very important parameters in study of nitrate origin. Factor and cluster analysis conducted on chemical analysis data showed that chlorides, sulphates, sodium and potassium present variables that can be used as main indicators of anthropogenic influence on groundwater
quality in the Zagreb aquifer. The use of cluster analysis allowed the definition of observation wells where nitrates concentrations were mostly related to wastewater or manure. Four clusters of observation wells were defined based on nitrate, chlorides, sulphates, sodium and potassium concentrations, values of stable nitrate isotopes and molar ratios of nitrates to all other used ions. For observation wells in three clusters wastewater was defined as main source of contamination. In that sense the study of the molar ratios, especially nitrate and potassium, was found to be crucial. Groundwater from observation wells were manure was identified as main source of contamination had the highest molar ratios and lowest δ15N-NO3- values. It has been concluded that investigation of molar ratios, in combination with nitrate stable isotopes, can be very effectively used in estimation of nitrate origin in groundwater of Zagreb aquifer. In addition, correlation and multivariate statistical analysis have shown that nitrates present parameter whose stability and transformation in the groundwater of Zagreb aquifer is basically dependent on the dissolved oxygen concentrations. The nitrate trend analysis established the existence of statistically significant decreasing trends of nitrate concentrations, except in Petruševec and Sašnjak and Žitnjak well field influence area. It has been shown that evaluation of nitrate trends in different levels, in combination with confidence and prediction intervals, can provide more realistic insight in areas where nitrates contamination occurs. Also, it has been concluded that linear regression presents appropriate method for estimation of nitrate trends.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- Tijekom srednjega trijasa na području Vanjskih Dinarida tektonika povezana s
otvaranjem Tetiskog oceana dovela je do značajne ...diferencijacije taložnih okoliša. Istovremeno
su egzistirala izdignuta područja sa značajkama subaerske vulkanske aktivnosti i trošenja
starijih stijena te njihova pretaloživanja, kao i plitkomorski prostori obilježeni karbonatnom
sedimentacijom te dublja, pelagička morska korita u kojima su taloženi različiti sedimenti
uključujući i vulkanoklastične i vulkanske stijene. Cilj provedenog istraživanja je bio definirati
i opisati srednjetrijaske vulkanoklastične naslage, odrediti njihov stratigrafski položaj u
Vanjskim Dinaridima, definirati taložne okoliše u kojima su nastale, geokemijskim podacima
povezati ih s geotektonskim okolišem u kojem je nastala magma koja je producirala
vulkanoklastične naslage te usporediti razvoj prostora Vanjskih Dinarida s okolnim prostorima
zapadnog Tetisa. Analizirane su petrološko-sedimentološke, mineraloške i geokemijske
karakteristike vulkanoklastičnih naslaga s pet lokaliteta u Vanjskim Dinaridima (Donje
Pazarište i Jovanović Draga u okolici Gospića, Bosansko Grahovo u Bosni i Hercegovini,
Zelovo u blizini Sinja, i Plavno u blizini Knina). Mikropetrografskim metodama određeni su
facijesi istraživanih stijena i mehanizmi njihova postanka čime je omogućena rekonstrukcija
taložnih okoliša. Analizama konodontnog materijala biostratigrafski je određena starost te je
postavljen vremenski okvir taloženja vulkanoklastita srednjega trijasa. Geokemijskim
analizama dobiveni su podaci koji su korišteni za klasifikaciju istraživanih stijena, odredbu
geotektonskog okvira i porijekla magme iz koje su nastale vulkanoklastične naslage, te je
omogućena rekonstrukcija petrogenetskog modela u srednjem trijasu Vanjskih Dinarida.
Vulkanoklastične naslage srednjega trijasa nastajale su u kopnenim i marinskim okolišima.
Većina istraživanih lokaliteta ima obilježja dubljevodne pelagičke sedimentacije. Taloženje
ovih naslaga u Vanjskim Dinaridima vezano je za prijelazni interval iz anizika u ladinik, kao i
u većini okolnih prostora zapadnog dijela nekadašnjeg Tetiskog oceana. Geokemijska obilježja
vulkanoklastičnih i vulkanskih stijena ukazuje na kalcijsko-alkalijsku magmu kontaminiranu
krustalnim materijalom nastalu u složenom geotektonskom sustavu. Sedimentološka obilježja
istraživanih vulkanoklastita i s njima udruženih sedimentnih stijena dokazuju postojanje
nepotpuno razvijenih malih riftnih sustava.- In the Middle Triassic times, the External Dinarides were a part of the Western Tethyan
domain (Haas et al., 1995; Stampfli & Borel, 2002; 2003; Scotese et al., 2004). A deposition of
the Early Triassic low energy carbonate-siliciclastic sediments of the epeiric ramp (Aljinović
et al., 2014) was interrupted in the Middle Triassic by vigorous and extensive tectonic activity
related to the opening of the Tethyan Ocean. Tectonic activity was accompanied by volcanism
and formation of volcanic and volcaniclastic rocks. These tectonic movements caused the
differentiation of the relief, thus forming different rift related tectonic structures. Some tectonic
blocks were uplifted and prone to subaerial erosion while others were subsided and developed
different deep marine, pelagic facies. All depositional environments were under the influence
of volcanic activity. However, some areas experienced long lasting shallow marine, mostly
carbonate sedimentation. The Middle Triassic volcanic and volcaniclastic rocks were
investigated by various authors (e.g. Poljak & Tajder, 1948; Lugović & Majer, 1983; Pamić,
1984; Marci et al., 1991; Trubelja et al., 2004; Garašić et al., 2006; Preglej, 2006; Hrvatović et
al., 2011; Aljinović et al., 2011). Some of them pronounced the controversial relation between
the geochemical data of volcanic rocks and geotectonic setting in the Middle Triassic (Lugović
& Majer, 1983; Pamić, 1984; Trubelja et al., 2004; Garašić et al., 2006). That resulted in the
unambiguous interpretation of the magma origin. Geochemical data all indicate calc-alkaline
magma composition, which is more common in the subduction areas than in rift zones. The
typical Middle Triassic rift related magmatic rocks (ophiolites) are still not found in the External
Dinarides.
The aim of this dissertation is to present the petrological, sedimentological,
stratigraphical and geochemical data of the investigated volcaniclastic rocks and to unravel its
genesis and origin. Therefore, volcaniclastic rocks at five localities in the External Dinarides
were investigated. The field methods included recording the sedimentary sections in which
different volcaniclastic rocks crop out. Petrographical methods were used to analyse
micropetrographic composition (in thinsections) and differentiate sedimentary facies based on
the lithology and depositional processes. The differentiation of the facies allowed
reconstruction of the depositional mechanisms and prediction of the sedimentary model for
each of the investigated localities. Carbonate sedimentary rocks associated with the
volcaniclastics served for conodont analysis that enabled the biostratigraphic constrains of the
volcanic activity. The high-resolution conodont biostratigraphy also enabled the correlation of
the investigated sequences. Geochemical analysis aimed to determine the magma composition
and according to that interpret geotectonic position of the investigated area.
In Lika, part of the Velebit Mts., the five small localities were investigated adjacent to
the village Donje Pazarište. In all five localities, the different volcaniclastic deposits were
recorded in different sedimentary sequences. The three sedimentary sequences, called Donje
Pazarište 1, Donje Pazarište 2 and Donje Pazarište 3 form almost continuous 97 m thick
succession with six different facies: Flysch facies (FF), Carbonate shale facies (KS),
Syneruptive resedimented pyroclastic facies (FSP), Platy limestone and pyroclastic facies
(FPV), Limestone breccia facies (VB) and Slumped limestone, chert and pyroclastic facies
(FSV). Near the investigated sections (Donje Pazarište 1, 2, 3) the Pyroclastic flow facies (FPT)
was determined (similarly as investigated by Preglej, 2006). The whole sequence has the
characteristics of deposition in the open marine, pelagic environment. The beginning of the
sequence was influenced by Flysch facies (FF) deposited by turbidity currents. Flysch facies
was conformably overlain by Carbonate shale facies (KS) slightly influenced by deposition of
pyroclastic material. Syneruptive resedimented pyroclastics (FSP) were redeposited from
relatively shallow parts of the depositional area to the deep pelagic areas via pyroclastic
turbidity currents. Deposition of the Platy limestone and pyroclastic facies (FPV), indicates
shallowing of the environment envisaged by prevalence of limestones. Limestone breccia facies
(VB) occassionaly occurres in the sequence and imply periods of intense tectonic activity.
Slumped limestone, chert and pyroclastic facies (FSV) was deposited in pelagic environment
influenced by the deposition of pyroclastic material primary sedimented through water settled
fall out on slopes. The sequence was strongly influenced by tectonic activity and tectonic block
movements. The Pyroclastic flow facies (FPT), located in vicinity of the youngest strata of the
Donje Pazarište section, has the characteristics of subaerial emplaced ignimbrite flow, as does
the same facies in the vicinity of the village Brušane, in the foothill of Vinac. Lithological
similarities of these rocks allow the interpretation that they possibly represent a unique
pyroclastic flow generated by pyroclastic column collapse and subaerial of shallow marine
emplacement. The time constraint of this facies is unfortunately missing due to lack of conodont
species in the associated shallow water limestones.
In the same area, the recorded profile Jovanović Draga consists completely of
volcaniclastic deposits (81 m thick) that are associated with the olivine basalt of Coherent facies
(KF). Among volcaniclastics, the Hyaloclastic facies (HF) was differentiated. It was formed by
autoclastic processes and limited pyroclastic activity. Fragments formed by autoclastic
processes were mixed with fragments of carbonate rocks probably formed by fragmentation of
the lithified carbonates during magma ascent. Explosive eruption was restricted due to water
depth that limited the spread of pyroclastic material (dominantly volcanic glass shards).
The recorded profile near the village Bosansko Grahovo (Bosnia and Herzegovina),
consists of 79 m thick dominantly autoclastic deposits. Four different volcaniclastic facies were
determined. The base of the profile is represented by the significant Limestone peperite facies
(FVP). It consists of bioclastic peckstones-weckstones with thin-shelled bivalves and
radiolarians indicating emplacement of hot lava in the pelagic environment. The Limestone
peperite facies is conformably overlain with the Pyroclastic flow facies (FPT), followed by a
Hyaloclastic facies (FH) divided into three lithotypes: resedimented basalt-andesite
hyaloclastite (Pba), in situ basalt hyaloclastite (ISb) and resedimented basalt hyaloclastite (Pb).
The top of the sequence is characterized by the occurrence of the Breccia-conglomerate peperite
(FBP). The facies distribution possibly represents both, the lateral and the vertical exchange of
recorded facies. According to the fossil content in the limestone parts of the peperite, the
sedimentary environment is determined as pelagic. Pyroclastic flow facies in this profile is
represented by a small volume ignimbrite formed in the low fountaining volcanic vent and was
constantly in contact with warm ascending magma throughout the emplacement time.
Hyaloclastic facies (FH) was formed by quenching fragmentation of the coherent facies. The
accurence of in situ basalt hyaloclasti
U radu se analizira znanstvena produkcija o Jadranu, sa naglaskom na jadransku oceanografiju i meteorologiju. Znanstvena produktivnost mjerena je analizom objavljenih publikacija i njihovih citata u ...bazi publikacija Thomson Reuters Web of Science u razdoblju 1994–2008. Najproduktivnija zemlja je Italija, no najbolju citiranost su postigle publikacije iz Njemačke (sve jadranske publikacije) i Španjolske (publikacije iz jadranske oceanografije i meteorologije). Druga zemlja po znanstvenoj produkciji, Hrvatska, ima najslabije citirane publikacije. Suradnja jadranskih istraživanja u smislu zajedničkih publikacija nije posljedica geografskog položaja pojedinih zemalja (npr. Italija i Hrvatska), već je prvenstveno posljedica uloženih investicija u istraživanje Jadrana (npr. Italija i SAD, Hrvatska i SAD). Zajedničke publikacije su značajno poboljšale vidljivost (citiranost) provedenih istraživanja, naročito publikacija tranzicijskih zemalja kao što je Hrvatska.
This paper aims to quantify the productivity of research concerning the Adriatic Sea, with a focus on oceanography and meteorology. Productivity and impact were measured by analysing articles and ...citations from the Thomson Reuters Web of Science database, spanning the period 1994–2008. The most productive country was Italy but the highest number of citations was achieved by articles from Germany (all Adriatic publications) and Spain ("Oceanography" and "Meteorology and atmospheric sciences", only). By contrast, the second-most productive country, Croatia, had the lowest citation rate. Collaborations between Adriatic researchers were driven not only by the geographical position of a country (e.g., Italy vs. Croatia), but also by investment rates in Adriatic research (e.g., Italy vs. USA and Croatia vs. USA). Such collaborations substantially improved the impact of the research, especially from transitional countries such as Croatia.
U radu se analizira znanstvena produkcija o Jadranu, sa naglaskom na jadransku oceanografiju i meteorologiju. Znanstvena produktivnost mjerena je analizom objavljenih publikacija i njihovih citata u bazi publikacija Thomson Reuters Web of Science u razdoblju 1994–2008. Najproduktivnija zemlja je Italija, no najbolju citiranost su postigle publikacije iz Njemačke (sve jadranske publikacije) i Španjolske (publikacije iz jadranske oceanografije i meteorologije). Druga zemlja po znanstvenoj produkciji, Hrvatska, ima najslabije citirane publikacije. Suradnja jadranskih istraživanja u smislu zajedničkih publikacija nije posljedica geografskog položaja pojedinih zemalja (npr. Italija i Hrvatska), već je prvenstveno posljedica uloženih investicija u istraživanje Jadrana (npr. Italija i SAD, Hrvatska i SAD). Zajedničke publikacije su značajno poboljšale vidljivost (citiranost) provedenih istraživanja, naročito publikacija tranzicijskih zemalja kao što je Hrvatska.
Provider: - Institution: - Data provided by Europeana Collections- Dva tipa implementacije 14C metode za mjerenje asimilacije ugljika pri fotosintezi se
razlikuju s obzirom na svjetlosne uvjete pri ...kojima se vrše eksperimenti: in vitro i in
situ. In vitro inkubacije se vrše u laboratoriju pod kontroliranim svjetlosnim uvjetima,
dok se in situ inkubacije vrše u moru pod prirodnim svjetlosnim uvjetima. Ovisnost
primarne proizvodnje o svjetlosti se matematički opisuje funkcijama svjetlosnog zasićenja
čiji parametri određuju brzinu asimilacije ugljika pri fotosintezi. Vrijednosti fotosintetskih
parametara se odreduju na temelju rezultata in vitro mjerenja i poslije se koriste u modelima
primarne proizvodnje. U ovom radu je razvijen inverzni model koji koristi in situ
mjerenja za procjenu vrijednosti fotosintetskih parametara. Pritom upotrebljava optimizacijski
algoritam koji tretira fotosintetske parametre modela proizvodnje kao varijable
optimizacije i nalazi optimalne vrijednosti parametara za koje model najmanje odstupa od
in situ mjerenja. Inverzni model koristi model primarne proizvodnje formuliran pomoću
dva različita formalizma, od prije poznatog analitičkog formalizma i ovdje razvijenog matričnog formalizma.
Korištenjem analitičkog formalizma, uz pretpostavku idealiziranih
svjetlosnih uvjeta, nađeno je analitičko rješenje za profil proizvodnje i analitičko rješenje
za proizvodnju vodenog stupca s biomasom ovisnom o dubini. Inverzni model je testiran
na 194 in situ prola primarne proizvodnje s Hawaii Ocean Time-series i procijenjene su
vrijednosti parametara za različite funkcije svjetlosnog zasićenja. Korištenjem optimalnih
vrijednosti parametara modeli su opisali preko 95% varijabilnosti izmjerene proizvodnje
po dubini i preko 95% varijabilnosti izmjerene proizvodnje vodenog stupca. Kao rezultat
ovog rada, inverzni model je postao novi alat za procjenu vrijednosti fotosintetskih
parametara iz in situ prola primarne proizvodnje.- Two types of implementation of the 14C method for measuring carbon assimilation in
photosynthesis are differentiated with respect to light conditions under which the experiments
are performed: in vitro and in situ. In vitro incubations are performed in the
laboratory under controlled light conditions, whereas in situ incubations are performed
at sea under natural light conditions. The dependence of primary production on light
is mathematically described with light saturation functions, whose parameters determine
the rate of carbon assimilation in photosynthesis. The values of photosynthesis parameters
are determined based on the results of in vitro measurements and are afterwards used
in models of primary production. In this work an inverse model is developed which uses
in situ measurements to estimate the values of the photosynthesis parameters. It employs
an optimization algorithm which treats the photosynthesis parameters of the production
model as optimization variables and estimates optimal parameter values for which the
model deviates the least from the in situ measurements. The inverse model uses the primary
production model formulated with two different formalisms, an already established
analytical formalism and here developed matrix formalism. Using the analytical formalism,
under the assumption of idealized light conditions, an analytical solution for the
production prole and the analytical solution for water column production with depth
dependent biomass were derived. The inverse model was tested on 194 in situ primary
production proles from the Hawaii Ocean Time-series and the parameters of dierent
light saturation functions were estimated. When using optimal parameter values the models
explained over 95% of variability in measured production at depth and over 95% of
variability in the measured water column production. As a result of this work, the inverse
model became a new tool for estimating the values of the photosynthesis parameters from
in situ primary production profiles.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- Rekristalizacija uzoraka allanita različitog stupnja metamiktnosti je inducirana žarenjem uzoraka na zraku, te u uvjetima inertne i ...reduktivne atmosfere na odabranim temperaturama. Do 800C metamiktni uzorci allanita djelomično rekristaliziraju u kristalnu strukturu allanita, no kod jače metamiktnih uzoraka već na ovoj temperaturi dolazi do pojavljivanja novih faza, cerijanita i hematita. Zbog oksidacije Fe2+ i Ce3+, te posljedično otpuštanja OHaniona, u danim uvjetima, nemoguće je ostvariti potpunu rekristalizaciju, a na višim temperaturama (> 900C) kristalna struktura allanita se u potpunosti raspada na jednostavnije okside (cerijanit, hematit), fosfate (britholit) i silikate (anortit). Iz tog razloga su odabrani uzorci hidrotermalno tretirani na nižim (150 -250C), te višim (400-800C) temperaturama na kojima dolazi do potpune rekristalizacije metamiknih uzoraka allanita, neovisno o stupnju metamiktnosti, bez pojave dodatnih faza. Jedan uzorak allanita je podvrgnut bombardiranju neutronima radi rušenja kristalne strukture, što je djelomično uspješno izvršeno. Svi procesi su praćeni difrakcijom rentgenskih zraka na prahu, visokorazlučujućom transimisijskom elektronskom mikroskopijom, te elektronskom difrakcijom, IR, Raman i Mössbauer spektroskopijom te termičkim metodama.- Recrystallization of allanite with different degrees of metamictization is induced by annealing of samples in air, inert and reductive atmosphere at chosen temperatures. Up to 800C metamict samples of allanite partially recrystallize to allanite crystal structure, but with heavily metamictized samples, already at these temperatures, new phases such as cerianite and hematite, occur. It is impossible to accomplish complete recrystallization in these conditions due to oxidation of Fe2+ and Ce3+, and escape of OHanion from the structure, and at higher temperatures (> 900C), allanite crystal structure breaks down to a mixture of simple oxides (cerianite an hematite), phosphate (britholite) and silicate (anorthite). Thus, chosen samples were hydrothermally treated at lower (150 -250C), and higher (400-800C) temperatures when complete recrystallization, without additional phases and regardless of the degree of metamictization, occurs. One allanite sample was bombarded with neutron flux, in order to destroy its crystal structure, what was partially accomplished. All processes were monitored by X-ray powder diffraction, high-resolution transmission electron microscopy coupled with electron diffraction, IR, Raman and Mössbauer spectroscopy, and thermal methods.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- After the general introduction presented in Chapter 1, Chapter 2 tackles the problem of disjointed and conflicting data, and ...explores to what extent do loggerhead turtle populations and life stages differ in morphology. In order to take into account the possible geographic and life stage variability, I study two neighboring populations and all postembryonic life stages by comparing the ratio of carapace length, width and height of sea turtles. I conduct a detailed analysis of empirical models (growth curves, conversion formulae). One of the aims is to answer a somewhat technical question whether or not can the growth of loggerhead turtles be considered isomorphic. Considerable deviations from isomorphy would require additional steps when defining through out the life the acquisition (or use) of energy in relation to the surface area-volume ratio. The focus of Chapter 3 is on developing a full life cycle model of loggerhead turtles. Due to substantial variability present in data related to loggerhead turtles living in different sea basins, I decided to focus on a geographically defined population rather than the whole species. In this chapter the North Atlantic population of loggerhead turtles is analyzed as it has one of the largest nesting aggregations of loggerhead turtles. After estimating the parameter values using the covariation method 126 of the package DEBtool implemented in Matlab, I compare model predictions to observations, and discuss the implications of the results. In Chapter 4 another population of loggerhead turtles, the Mediterranean population, is the main focus, together with the comparison between individuals belonging to the Mediterranean, and individuals belonging to the North Atlantic population. Individuals belonging to the two populations are first compared based solely on their morphology (length, weight, and the ratio of the two) at two life events: hatching and nesting. The average egg size reported for each population is taken into account, as it has been generally reported to account for most of the variation in hatchling sizes. As the next step, I develop a DEB model for the individuals of the Mediterranean population, analyze the model predictions, and discuss the implications of the results. Then I compare the model parameters between the populations, and suggest a physiological (maturity based) explanation for the adults having such markedly different sizes at nesting. In addition, posthatchling growth is analyzed in more detail, expanding the results of the previous chapter which suggested faster growth of posthatchlings than predicted by the model. Lastly, I reproduce a pattern of biphasic growth by modifying the food availability during the first part of the life cycle. Chapter 5 showcases the applications of the DEB model to study the effects of temperature and food availability, and the effects of plastic ingestion on the energy budget and life cycle of the loggerhead turtle. I simulate a realistic range of temperatures and food densities to explore their effect on the energy budget, i.e. observable quantities such as size and reproduction output. I present a mechanism for the effects of plastic ingestion on 6 General introduction the energy budget, applicable to any species for which the DEB parameters are known. I simulate a range of observed amounts of ingested debris, and study their effects on the processes of growth, maturation, and reproduction while assuming the plastic has (a) the same, and (b) several times longer gut residence time compared to that of food. Finally, in Chapter 6 I discuss my results in a broader context, and present an outlook on future studies, applications, and possible expansions of the developed model.- Glavate želve (Caretta caretta, Linnaeus 1758) prisutne su u umjerenoj klimatskoj zoni svih svjetskih oceana, evoluirajući u nekoliko populacija i lokalnih subpopulacija. Žive duže od 65 godina, a njihov spol određen je temperaturom inkubacije tijekom zadnje trećine embrionalnog razvoja (koji traje oko dva mjeseca). Tijekom svog života, mogu narasti do veličine čak 25 puta veće od one pri izlijeganju: u prosjeku 4 cm dugačka i 20 g “teška” kornjačica koja izađe iz gnijezda, može postati odrasla jedinka teška preko 100 kg s oklopom dugačkim 100 do 130 cm. Ženke dolaze položiti jaja na istu plažu na kojoj su se izlegle, zbog čega ponekad preplivaju stotine kilometara. Životni ciklus morskih kornjača je dugo vremena bio u grubo podijeljen u tri životna stadija: embrio, seksualno nezrele (juvenilne) jedinke, i odrasle (adultne) jedinke. Iako je provedeno mnogo studija i objavljeno mnogo literature na tematici glavatih želvi i morskih kornjača općenito, fokus određene studije je najčešće bila određena karakteristika ili određen životni stadij. Odabrala sam teoriju dinamičckog energijskog proračuna (eng. Dynamic Energy Budget, DEB) kao stazu koja će me dovesti do mog “Svetog Grala”: DEB modela glavate želve. Pristup ove teorije je sveobuhvatan: praćenje zakona termodinamike, nekoliko tipova homeostaze (ravnoteže) koju svaki sustav (od stanice preko jedinke do ekosustava) pokušava postići i održati, utjecaj hrane i temperature na energijski proračun, međuovisnost energijskog proračuna i procesa kao što su rast, održavanje, sazrijevanje,i reprodukcija. Dodatno, DEB teorija bila je i ostala jedna od najbolje razrađenih i dosljednih dostupnih teorija.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- Kisela DNaza je lizosomalni enzim koji ima važnu ulogu u metabolizmu deoksiribonukleinskih kiselina. Aktivnost kisele DNaze utvrđena ...je u probavnoj žlijezdi i škrgama dagnje Mytilus galloprovincialis. Kao dominantna DNaza, identificirana je i karakterizirana DNaza II koja je lokalizirana u lizosomu. Utvrđene promjene aktivnosti kisele DNaze u probavnoj žlijezdi povezane su s dostupnosti hrane u okolišu i ciklusom razmnožavanja, dok je aktivnost kisele DNaze u škrgama povezana sa sezonskim promjenama temperature i saliniteta. Aktivnost kisele DNaze u oba organa u dagnjama na onečišćenoj postaji razlikuje se od aktivnosti u dagnjama s referentne postaje. Integracija aktivnosti kisele DNaze u probavnoj žlijezdi s histokemijski detektiranim lizosomalnim promjenama doprinijela je boljem razdvajanju odgovora obzirom na onečišćenje. Podatci koji se odnose na aktivnost kisele DNaze u probavnoj žlijezdi predstavljaju dobru osnovu za buduća istraživanja koja uključuju integrirani odgovor lizosoma prilikom procjene stanja okoliša.- Acid DNase is lysosomal enzyme that plays an important role in the deoxyribonucleic acid metabolism. DNase II was identified and characterized in digestive gland and gills lysosomes of mussel Mytilus galloprovincialis as the dominant and representative acid DNase. Acid DNase activity in the digestive gland was associated with food availability and reproduction cycle, while the acid DNase activity in the gills was associated with seasonal changes in seawater temperature and salinity. Acid DNase activity in both investigated organs differs between mussels from contaminated and reference sampling site. Integration of digestive gland acid DNase activity and histochemical perturbation of lysosomes enabled better differentiation of sampling station due to contamination. Observed acid DNase activity in the digestive gland represents a good basis for future environmental monitoring studies that would include integrated lysosomal response.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
