The impact of the environment on the surface tension of natural waters

V diplomskem delu sem raziskoval, če okolje in človeška dejavnost kakorkoli vplivata na površinsko napetost naravnih vodotokov. Kot primer, na katerem sem skušal to tematiko preučiti, sem izbral potok Želimeljščico. Vzdolž tega vodotoka sem izbral štiri vzorčevalna mesta, na katerih sem vzorčil vodo iz tega vodotoka ter tem vzorcem določil vrednost površinske napetosti. Za merjenje površinske napetosti sem uporabil tenziometrično metodo z uporabo Wilhelmyjeve ploščice. Dodatno sem izmeril še električno prevodnost teh vzorcev, da bi ugotovil, če v tem primeru obstaja kakšna povezava med obema izmerjenima lastnostima vzorcev. Rezultati na primeru vodotoka Želimeljščica so pokazali, da okolje in človeška dejavnost vplivata na vrednost površinske napetosti naravnih voda. Površinska napetost vode omenjenega vodotoka je bila najvišja pri izviru (73,7 mN/m), hkrati pa je bila tam najvišja tudi specifična prevodnost vode (627 μS/cm). Za opazovani vodotok so meritve pokazale, da površinska napetost pada od izvira proti izlivu, nisem pa uspel nedvoumno odkriti vzroka za ta pojav.In my thesis, I studied whether the environment and human activity have any effect on the surface tension of natural watercourses. As an example, on which I tried to examine this topic, I chose the Želimeljščica stream. Along this watercourse, I selected four sampling points where I sampled water from this watercourse and determined the surface tension value for these samples. I used a tensiometric method using the Wilhelmy plate to measure surface tension. I also measured the electrical conductivity of these samples to see if there was any correlation between the two measured properties. The results of the case of the watercourse Želimeljščica showed that the environment and human activity influence the value of the surface tension of natural waters. The surface tension of the said watercourse was the highest at its source (73,7 mN/m) and this was valid also for the specific conductivity of the water (627 μS/cm). For the observed watercourse, measurements showed that the surface tension was falling from the spring, but I was unable to unequivocally identify the cause of this phenomenon