diplomsko delo
Anže Tesovnik (Avtor), Matej Dolenec (Mentor)

Povzetek

V sklopu diplomske naloge smo proučili sedimentno jedro VJ-43 iz Vranskega jezera na Hrvaškem. Izrisali smo sedimentološki profil vrtine, iz katerega ugotavljamo, da jedro predstavlja menjavanje tankih plasti in lamin sedimenta debeline od 1,0 cm do 10,5 cm. Sediment jedra prestavlja peščeni melj in melj, pri čemer prevladuje peščeni melj. V spodnjem delu vrtine so bile opažene štiri enote z ostanki polžev. Rezultati XRF so pokazali, da imajo deleži silicija, aluminija, železa in kalija pozitivne anomalije na intervalih globine 0,5-60 cm (A3), 100-150 cm (A2) in 185-225 cm (A1), za katere sklepamo, da so odraz večjega deleža terigene komponente. Deleži kalcija in magnezija kažejo negativno anomalijo A3 nižjih vrednosti na intervalu globine 0,5 cm do 60 cm. Sklepamo, da sta vezana na karbonate ter, da sta avtigenega izvora. Vrednosti cirkonija, rubidija, svinca, cinka, železa, titana, kalija in žvepla imajo pozitivne anomalije na intervalih globine 0,5-60 cm (A3), 100-150 cm (A2) in 185-225 cm (A1), katere pripisujemo večjemu doprinosu terigene komponente in antropogenemu vplivu. Vrednosti niklja in mangana kažejo trend padanja na globini od 0,5 cm do 16 cm. Povezuje ju prekrivanje nizkih vrednosti na podobnih globinah 16, 121 in 133 cm. Predpostavljamo, da sta verjetno vezana na organsko snov. Molibden kaže z visokimi vrednostmi na globinah 16, 121 in 133 cm na nasprotno korelacijo z nikljem in manganom, pri čemer predpostavljamo, da je verjetno njegovo variiranje povezano z organskimi kompleksi. Stroncij ima izraženo negativno anomalijo A3 na intervalu globine 0,5-60 cm in sklepamo, da je vezan na karbonate. Rezultati XRD so pokazali, da je sediment sestavljen iz mineralov kalcita, aragonita in kremena. Delež kalcita in kremena pada z globino do 80 cm, delež aragonita pa narašča. Na podlagi ujemanja kalcijeve negativne anomalije A3 s trendom variiranja deleža kalcita z globino, sklepamo, da je kalcit večinoma avtigenega izvora. Povečan delež aragonita v globini pripisujemo prisotnosti lupinic polžkov. Kremen je v vzorcih zastopan v manjših deležih in je verjetno terigenega izvora. S pomočjo Bayesovega starostnega modela smo ocenili starost sedimenta vrtine VJ-38 na globini 9 cm na 44,1 let in določili hitrost sedimentacije na 0,204 cm na leto. Glede na ocenjeno starost povezujemo anomalijo A3 na intervalu globine 0,5-60 cm z melioracijo in gradnjo kanala Prosika. Anomaliji A2 in A1 na intervalih globine 100-150 cm in 185-225 cm nismo uspeli povezati z znanimi dogodki.

Ključne besede

Vransko jezero;jezerski sediment;geokemija;rentgenska fluorescenčna spektroskopija XRF;rentgenska praškovna difrakcija XRD;

Podatki

Jezik: Slovenski jezik
Leto izida:
Tipologija: 2.11 - Diplomsko delo
Organizacija: UL NTF - Naravoslovnotehniška fakulteta
Založnik: [A. Tesovnik]
UDK: 55
COBISS: 83917315 Povezava se bo odprla v novem oknu
Št. ogledov: 251
Št. prenosov: 61
Ocena: 0 (0 glasov)
Metapodatki: JSON JSON-RDF JSON-LD TURTLE N-TRIPLES XML RDFA MICRODATA DC-XML DC-RDF RDF

Ostali podatki

Sekundarni jezik: Angleški jezik
Sekundarni naslov: variability of major and potential toxic elements from the Vrana Lake in Croatia
Sekundarni povzetek: In the extent of diploma thesis we analysed the sedimentary core VJ-43 from Lake Vrana in Croatia. Firstly, a sedimentological profile was plotted and the latter proved that the core consists of an alternation of thin layers and laminates of the sediment with thickness of 1.0 cm to 10.5 cm. The sediment consisted of sandy silt and silt, the first being the prevalent one when it came to proportion. Additionally, four units with snails were observed in the lower part of the core. XRF results proved that the elements silicon, aluminum, iron and potassium have significantly higher proportions (%) at depth intervals of 0.5-60 cm (A3), 100-150 cm (A2) and 185-225 cm (A1). We conclude that the positive anomalies A3, A2 and A1 are a reflection of a larger share of the terrigenous component. The proportions of calcium and magnesium show a trend of lower values or a negative anomaly A3 in the depth range of 0.5 cm to 60 cm. We conclude that they are bounded to the carbonate minerals and that they are of autigenic origin. The elements zirconium, rubidium, lead, zinc, iron, titanium, potassium and sulfur have significantly higher values (ppm) at depth intervals of 0.5-60 cm (A3), 100-150 cm (A2) and 185-225 cm (A1). Positive anomalies A3, A2 and A1 are attributed to the greater contribution of the terrigenous component (Zr, Rb, K) and the anthropogenic impact (Pb, Zn, Ti, S). The elements nickel and manganese show a declining trend at depths of 0.5 cm to 16 cm. They are connected by overlapping low values at similar depths of 16, 121 and 133 cm. We assume that they may be bounded to organic matter. Molybdenum shows inverse correlations with nickel and manganese with high values at depths of 16, 121 and 133 cm, and we assume that molybdenum may be bounded to organic complexes. Strontium has lower values or. negative anomaly A3 at a depth interval of 0.5–60 cm and we conclude that it is bounded to carbonates. The measurements of the XRD analysis have shown the sediment composition by the minerals, such as calcite, aragonite and quartz. The proportion of calcite and quartz decreased with depth by up to 80 cm whereas the proportion of aragonite increased. Based on the correspondence of the calcium negative anomaly A3 and the trend of varying the proportion of calcite by the depths, we conclude that calcite is mostly of autogenous origin. The increased proportion of aragonite in depth can be attributed to the presence of snail shells. Quartz was, in terms of samples, present only in small proportions and its origin is likely terrigenous. Using the Bayesian age model, we estimated the age of the sediment core VJ-38 at a depth of 9 cm to 44.1 years and the sedimentation rate at 0.204 cm per year. According to the estimated age, the A3 anomaly at the depth interval of 0.5-60 cm is associated with the melioration and construction of the Prosika canal. We were unable to associate the A2 and A3 anomalies at depth intervals of 100–150 cm and 185–255 cm with the aforementioned interventions in the natural surroundings.
Sekundarne ključne besede: Vrana lake;lake sediments;geochemistry;X-ray fluorescence (XRF);X-ray diffraction (XRD);
Vrsta dela (COBISS): Diplomsko delo/naloga
Študijski program: 0
Konec prepovedi (OpenAIRE): 1970-01-01
Komentar na gradivo: Univ. v Ljubljani, Naravoslovnotehniška fak., Oddelek za geologijo
Strani: XI, 51 f.
ID: 13595008