# Antibiotics in Groundwater and River Water of Bialka--A Pristine Mountain River
## 1 Introduction  
Nowadays, it is impossible to imagine the functioning of humans in the modern world without chemicals, including antibiotic agents, which in the 20 th century were considered a miracle discovery of medicine. However, they are excessively used in various branches of human activity; they are widely prescribed to treat bacterial infections, for prophylactic purposes in both human and veterinary medicine as well as growth-promoting agents in farm animals [1]. The main sources of antibiotics in the environment include: domestic misuse, agriculture and aquaculture, clinical waste and, recently, unjustified self-medication during the COVID-19 pandemic [2]. Because of their wide application for a number of purposes, antibiotics are continuously released into the environment. The metabolism rate of antibiotics in human and animal organisms is very low; therefore, about 25-75% of antibiotics enter the environment in the form of a parent compound [3]. Their persistence and mobility in the environment are high enough to allow them to penetrate from wastewater treatment plants, household and agricultural waste or manure used as natural fertilizers into surface water and groundwater. The use of antibiotics in farmingand ineffective elimination of these compounds by wastewater treatment plants are the main reasons for antibiotics' presence in the aquatic environment [4]. Antibiotics have been considered as emerging pollutants of greatest concern because of their potential detrimental effect on the environment, including their impact on accelerating the bacterial resistance to these compounds and the resulting implications on human health [5]. The concentrations of antibiotics in the aquatic environment are not high enough to directly threaten human health, but they exert selective pressure on the microbial community, affecting the occurrence of genetic mutations and promoting the antibiotic resistance transfer rate through vectors [3]. The fact that antibiotic-resistant bacteria from anthropogenic sources can mix with naturally occurring environmental strains in the aquatic environment provides a risk of the occurrence of new resistant strains [6]. Moreover, the detrimental effect of antibiotics on microbial communities includes the disappearance or inhibition of some microbial groups involved in key ecosystem functions. In such ways, they reduce microbial diversity, which is crucial in the maintenance of biological processes in various environments, including water [7]. The monitoring of antibiotics' presence and concentrations in the aquatic environment is of fundamental importance to the environmental management of water resources and their quality. There is a large gap in the data on the presence and concentration of antibiotics in the aquatic environment in Poland. In 2014, [PERSON] et al. [8] examined the occurrence of veterinary antibiotics in fresh water, sediment and fish of rivers and lakes by using liquid chromatography-tandem mass spectrometry. However, they did not detect any of the examined 45 antimicrobial agents above the limit of quantification. The second study on the detection of antimicrobial agents in water [9] was conducted on six sites along the sewage-impacted Vistula river and aimed to determine the presence of 32 antimicrobial agents. Similarly, as in the study by [PERSON] et al. [8], many substances were below the method detection limits or quantification limits. However, azithromycin, clarithomycin, funconazole and sulfamethoxazole were detected in the concentrations exceeding 10 ng/L. Apart from these two studies, a paper by [PERSON] et al. [10] presents the initial results of the antibiotic detection in three sites along the Bialka river and their effect on the microbial community in water. A further study [11] focused on the effect of the COVID-19 pandemic's lockdown on a number of water-quality parameters, including antibiotic content. However, the examinations of antibiotic presence and content started in [10] and [11] go much further and deeper.