Physico-chemical and biological characteristics of the Vranča stream and draw-well water from the surrounding households

U ovom radu opisano je istraživanje provedeno tijekom osam tjedana u rujnu i listopadu 2019. godine. Područje istraživanja obuhvatilo je pet postaja na potoku Vranča te tri bunara okolnih kućanstava u selu Gornji Fodrovec (Koprivničko-križevačka županija), smještenih na udaljenosti od ca. 50 – 170 m od potoka Vranča. Kroz deset terenskih izlazaka provedena su mjerenja fizikalnokemijskih parametara za vodu na svih osam postaja, a dva puta mjesečno uzeti su uzorci makrozoobentosa s početne (referentne) i krajnje postaje na potoku za biološku analizu. Naknadno su uzeti i uzorci bunarske vode za mikrobiološku analizu. Rezultati mjerenja potvrdili su dobru kakvoću vode na referentnoj postaji te zagađenje, odnosno visoko opterećenje vode potoka organskim tvarima nizvodno od referentne postaje, odnosno u području utjecaja naselja i poljoprivrednih djelatnosti. Bunarska voda prema rezultatima također pokazuje opterećenje nutrijentima, na što ukazuju povišene koncentracije nitrata i ortofosfata. Zastupljenost pojedinih taksonomskih skupina makrozoobentosa na potoku ukazuje na dobru kakvoću vode na referentnoj postaji (npr. prisutnost vrste roda Gammarus sp. i predstavnika Plecoptera, koji se smatraju indikatorima čistih tekućica), dok dominacija jedinki Oligochaeta i Chironomidae (indikatora za vode opterećene organskim tvarima), potvrđuju zagađenost potoka nizvodno u području naseljenog poljoprivrednog mjesta. Dodatnom mikrobiološkom analizom bunarske vode utvrđena je prisutnost koliformnih bakterija kao glavnih indikatora bakterijskog zagađenja vode. Utvrđena je i prisutnost ukupnih koliforma, enterokoka te bakterija vrste Escherichia coli i roda Pseudomonas. Bunarska voda prema rezultatima mikrobiološke analize nije za piće.The research described in this thesis was carried out over eight weeks during September and October 2019. The research area included five sampling sites along Vranča stream and the three surrounding households' draw-wells in Gornji Fodrovec village (belonging to Koprivnica-Križevci county), positioned at the distance of approximately 50-170 m from the Vranča stream. During the ten field occasions, water physico-chemical parameters at the eight sampling sites were measured, whereas the macrozoobenthos samples were taken at the first sampling site (a reference point) and at the last sampling site at the beginning and at the end of each month for the biological analysis. Additionally, the draw-well water samples were taken for microbiological analysis. The results showed good water quality at the reference site, but a considerably high load of organic matter at the downstream sites, which were influenced by the human settlement and the agricultural activities. According to the results, a high nutrient levels were present in the draw-well water samples, as shown by the elevated concentrations of nitrates and orthophosphates. The presence of specific stream macroinvertebrate taxa indicated a good water quality at the reference site (e.g., the presence of Gammarus sp. and the representatives of Plecoptera, considered as the indicators of a high stream water quality), while the dominance of Oligochaeta and Chironomidae specimens (i.e., indicators of high load organic matter in streams) confirmed the water pollution at the downstream sites, within the inhabited agricultural areas. The additional microbiological analysis of the draw-well water confirmed the presence of the coliform bacteria, being the main indicators of bacterial water contamination. The results confirmed the presence of the total coliforms, enterococci, Escherichia coli and Pseudomonas specimens. According to the results, the draw-well water was not proved suitable for drinking