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.
Predmet istraživanja ove doktorske disertacije je nesaturirana zona na području regionalnog
vodocrpilišta Kosnica. Ciljevi ovog doktorskog rada bili su: (i) identificirati dominantne
procese ...transporta u nesaturiranoj zoni; (ii) odrediti parametre toka vode i transporta
onečišćivala nesaturirane zone; (iii) odrediti geokemijsko ponašanje potencijalno toksičnih
elemenata u nesaturiranoj zoni; (iiii) izraditi prognozni model toka vode i transporta
potencijalno toksičnih elemenata (olovo, kadmij, cink) kroz nesaturiranu zonu. Temeljem
brojnih laboratorijskih analiza svojstava tla i eksperimenata definirani su parametri toka vode
(kapacitet tla za vodu, hidraulička vodljivost) i transporta onečišćivala (sorpcija, disperzija,
volumna gustoća, koncentracija potencijalno toksičnih elemenata). Brojnim kemijskim i
eksperimentalnim analizama uzoraka iz nesaturirane zone određeno je geokemijsko ponašanje
potencijalno toksičnih elemenata. Za primjenu numeričkih simulacija korišten je program
HYDRUS-1D. Kapacitet zadržavanja vode u tlu najveći je u A horizontu i iznosi ~45%. Na
temelju istraživanja hidrauličke vodljivosti utvrđene su najniže vrijednosti za A i IVGso/Gr
horizonte. Veće vrijednosti hidrauličke vodljivosti određene su u donjem dijelu profila u
kojima je zastupljena pjeskovito-šljunkovita i šljunkovita tekstura. U AC-IC horizontu je
određena manja vrijednost disperzivnosti koja iznosi 1 cm, dok je za horizont IIC/Gso
određena veća vrijednost i iznosi 1,7 cm. Utvrđene su male razlike u sorpciji između
pojedinih elemenata. Analizom otopina porušenih uzoraka dobivenih digestijom zlatotopkom
utvrđene su najveće koncentracije elemenata (Cd, Pb i Zn) u najplićem dijelu profila. Na
temelju dobivenih parametara toka vode i transporta potencijalno toksičnih elemenata kreiran
je prognozni model na istražnoj lokaciji. Ukoliko se usporede koncentracije potencijalno
toksičnih elemenata dobivene s prognoznim modelom transporta na dnu profila tla odnosno
na granici s otvorenim vodonosnikom s MDK granicama pravilnika za iste elemente onda se
može zaključiti da postoji velika opasnost od onečišćenja na istražnoj lokaciji. Mehanizmi
sorpcije imaju glavni utjecaj na transport elemenata u saturiranu zonu. Uslijed akcidentnih
situacija izlijevanja koncentracije potencijalno toksičnih elemenata od 1000 mg/l, rizik od
onečišćenja vodonosnika s time i regionalnoga vodocrpilišta Kosnica je visok. Ovim
istraživanjima nesaturirane zone na lokaciji Kosnica definirani su parametri toka i transporta
potencijalno toksičnih elemenata te je napravljen numerički model kao osnova za buduća
istraživanja akcidentnih situacija.
The subject of this thesis is the unsaturated zone in the area of the regional water well
Kosnica. The objectives of this thesis were: (i) to identify dominant processes in the
unsaturated zone; (ii) to determine water flow and solute transport parameters in the
unsaturated zone (iii) to determine geochemical behaviour of potentially toxic elements in the
unsaturated zone; (iiii) to build prognostic water flow and the transport model of potentially
toxic elements (lead, cadmium, zinc) through the unsaturated zone.
The research was conducted in the area of the Kosnica water well, dominated by Fluvisol soil
type. In order to better understand the water flow and the transport of the potentially toxic
elements through an unsaturated zone detail field, laboratory analyses and experiments were
made. For numerical simulation HYDRUS-1D program was used. The program models the
water flow using Richard's equation. The transport of potentially toxic elements is described
using the advection and dispersion equation.
Based on the laboratory analyses of soil properties, the parameters of water flow and solute
transport are defined. The bulk density rises with depth while the water holding capacity is the
largest in the A horizon due to particle size distribution. Minimum values of hydraulic
conductivity were determined in the A and IVGso/Gr horizons. The experimental results of
the sorption processes were used for the determination of correlation coefficients for
individual elements. The order of decreasing correlation coefficients was: Pb> Zn> Cd. Small
differences in sorption were found between the individual elements. The soil column
dispersivity was 1 cm for AC-IC horizon, and 1.7 cm for horizon IIC/Gso.
The higher cation exchange capacity, determined in the top of the profile, indicates the
possibility of more pronounced sorption of elements in shallow horizons. The highest element
concentrations, extracted by aqua regia, were found in the A and AC-IC horizons (for Zn 70
mg/kg and for Pb 51 mg/kg). The lead concentration obtained using sequential extraction
analysis is mostly bound to the organic fraction, while zinc is mostly bound to the residual
fraction. Illitic material is the most common mineral phase in the fraction <2 μm and
correlates with the sorption of lead in top horizons (A and AC-IC).
Measured values of water content in the soil using TDR probes for the period from September
1, 2011 to October 31, 2012 were used for the water flow model calibration. The comparison
of water simulations’ results and the measured data was performed using the HYDRUS 1D
software. The simulated water content was less variable than the measured values.
Low correlation (~ 0.40) was revealed between the measured and the simulated values of the
water content. Such a low correlation between the measured and the simulated water content
in the soil could be a consequence of the difference between the meteorological data obtained
from a weather station located 3.5 km from the investigated location. Based on the chloride
tracer experiments on soil columns in the laboratory, the calibration of the solute transport
model was made. The best correlation of the measured and the simulated values of tracer
concentration is 0.43 for AC-IC and 0.74 for IIC/Gso horizon.
Based on the parameters of the water flow and the transport of potentially toxic elements, the
prognostic model was created at the investigation site. If the concentrations of potentially
toxic elements, obtained by the transport prognostic model at the bottom of the soil profile are
compared with the MAC limits ordinance for the same elements, it can be concluded that
there is a high risk of contamination at the investigative site. Sorption mechanisms have a
major impact on the transport of potentially toxic elements in the saturated zone. In case of an
accidental spill of potentially toxic elements with concentrations of 1000 mg/l, the risk of
contamination of the aquifer is high. This research of unsaturated zone at the Kosnica location
defined the water flow and the transport of potentially toxic elements’ parameters and
designed a model for the future research and accident mitigation.
U članku su prikazani osnovni geološki, petrološki, geokemijski i rudnoležišni podaci za pet glavnih magmatsko-metalogenetskih formacija sjeverozapadnih i središnjih Dinarida: (1) permo-trijaske ...andezit-sko-diuritske riftne formacije; (2) jursko-donjokredne akrecione (ofiolitske) formacije; (3) gornjokredno-paleogene subdukcijske bazalt-riolitne formacije; (4) paleogene kolizijske granitne formacije, i (5) oligocensko-neogene postsubdukcijske andezitske formacije.
Sve te magmatsko-metalogene formacije stvarane su u različitim geotektonskim ambijentima za vrijeme alpinotipne evolucije dinarskih dijelova Tetisa i postorogene evolucije Paratetisa, odnosno bazena Panona.
