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Having in mind that there is a general lack of monitoring plans and precaution measures in the developing countries and that the Danube is the second longest river in Europe, the estimation of the relevant concentration levels of unregulated xenobiotics is a topic of interest both on local and international level. The selected pharmaceuticals, caffeine, and benzotriazole presented in the collected water samples from seven representative locations around the territory of Novi Sad, Serbia, during 1-year period, were analyzed with the use of solid-phase extraction followed by the liquid chromatography coupled with triple quad tandem mass spectrometry. The most frequently detected compounds were caffeine and carbamazepine in the concentrations up to 621 and 22.2 ng/L, respectively, while the maximum concentration of the analyzed pharmaceuticals was obtained for ibuprofen (60.1 ng/L). The presence of benzotriazole along the analyzed section of the river was confirmed in the concentration levels up to 26.7 ng/L. Although sulfamethoxazole and desmethyldiazepam were detected at trace levels (0.22 and 3.41 ng/L, respectively); the presence of these pharmaceuticals in complex mixtures should not be neglected. Due to the frequent detection caffeine, carbamazepine, ibuprofen, and benzotriazole could be proper candidate for hydrophilic anthropogenic markers for quantification of wastewater contamination in surface water in the analyzed Danube section. [ABSTRACT FROM AUTHOR]

The surface water samples (1 L) were collected in autumn (November 2012), winter (March 2013), spring (May 2013) and summer (September 2013), in amber glass bottles at eight representative locations (RI, GC, GC2, RP, RO, DM, DL, DR) along the Danube River of the Novi Sad municipality, Serbia and stored at 4 °C until the analysis were performed. Samples were collected on the same day in every season and the meteorological conditions were the same for all localities within a particular season. All 32 water samples were taken at a depth of 50 cm. The position of sampling points in relation to the flow of the river could be seen in Fig. S-1. The sampling sites were selected according to the recommendations of the ICPDR's experts (The International Commission for the Protection of the Danube-ICPDR, www.icpdr.org), in order to estimate the level of violation of the ecological status of the Danube by the municipality of Novi Sad. Location RI was chosen in order to determine the status of the Danube prior to any local urban and canal tributary impact. Sampling points GC, GC2, RO and RP were positioned 100 m downstream, i.e., transversely from the four sewage discharges of the city. The locations GC and GC2 were selected to determine the influence of two biggest untreated municipal wastewater discharges (with capacity of 400 L s-1 during the dry period). The location RO was chosen to determine the influence of untreated wastewater from the oil refinery and the rain and urban runoff water from the industrial (thermal-heating plant, oil refinery) and suburban underdeveloped area. Sampling point RP was selected in order to explore the impact of untreated municipal wastewater from numerous illegal settlements with waste disposal sites and unauthorized traffic, as well as the influence of wastewater coming from two clinical centers. The sampling locations DM (central part of the river) and DL and DR (along the bank) were chosen as control sites in order to estimate the possible existence and impact intensity of the municipality of Novi Sad on the river water quality after some period (estimation of the impact of dilution, sorption and sedimentation processes). [ABSTRACT FROM AUTHOR]