Hidrogeohemija elemenata retkih zemalja u podzemnim vodama Srbije

Abstract

Osnovni ciljevi doktorske disertacije bili su definisanje prirodnih koncentracija (engl. background values) elemenata retkih zemalja (REE) u podzemnim vodama, kao i sticanje saznanja o njihovoj migraciji i sudbini u vodi, kako bi se na regionalnom nivou sagledala hidrogeohemija REE. Primenom odgovarajućih statističkih metoda (neparametarske metode zasnovane na analizi preživljavanja). na uzorku od 190 pojava podzemnih voda, definisane su osnovne koncentracije REE, za individualne elemente La-Lu i Y, kao i za sumarne koncentracije LREE, MREE, HREE i REE. Suština primene REE u hidrogeološkim istraživanjima nalazi se u izučavanju porekla podzemnih voda, a pretpostavka je da podzemne vode koje poseduju slične REE potpise imaju slične uslove formiranja hemijskog sastava. Jedinstven REE potpis svakog uzorka dobijen je analizom frakcionacije kroz postupak normalizacije - istovremenom analizom svih REE u odnosu na isti referentni standardni materijal, što je omogućilo poređenje podzemnih voda iz različitih hidrogoloških sistema. Važan cilj istraživanja predstavljao je definisanje dominantnih faktora i mehanizama koji doprinose formiranju sastava podzemnih voda i izdvajanju regionalnih hidrogeoloških sistema. Kroz primenu multivarijantnog statističkog pristupa (two-way HCA) izdvojeno je osam grupa podzemnih voda sa karakterističnim REE potpisima. Izvršeno grupisanje pojava doprinelo je daljoj karakterizaciji hidrogeoloških uslova i razlikovanju hidrogeoloških sistema formiranih u basenima, u magmatskim i metamorfnim stenama, ali i karbonatnim sredinama. Ovom doktorskom disertacijom istaknut je značajni naučni potencijal upotrebe REE u spoznaji porekla hemijskog sastava podzemnih voda, kao i pri karakterizaciji i funkcionisanju hidrogeoloških sistema u regionalnom smislu.

The primary objectives of this Ph.D. thesis were to determine background concentrations of rare earth elements (REE) in the groundwater, as well as gaining knowledge about their migration and fate in the water, to perceive the hydrogeochemistry of REE at the regional level. By applying appropriate statistical methods (non-parametric methods based on survival analysis) on a sample of 190 occurrences of groundwaters, background REE concentrations were defined, for individual elements from La to Lu and Y, as well as for summary concentrations LREE, MREE, HREE, and REE. Considering the primary application of REE in hydrogeological research as tracers of groundwater flow, it was assumed that groundwater with similar REE signatures shares similar conditions in chemical composition formation. A unique REE signature of each sample was obtained by fractionation analysis through the normalization process, which allowed a comparison of groundwater from different hydrological systems. An important goal of the research was to define the dominant factors and mechanisms that contribute to the formation of the groundwater composition and the separation of regional hydrogeological systems. Through the application of the multivariate statistical approach, eight groups of groundwater with characteristic REE signatures were isolated. The obtained results contributed to further characterization of hydrogeological conditions and differentiation of hydrogeological systems formed in basins, igneous and metamorphic rocks, and carbonate environments. This doctoral dissertation highlights the significant scientific potential of the use of REE in understanding the origin of the chemical composition of groundwater, and characterization and the functioning of hydrogeological systems on the regional scale.