This study intends to assess the extent of the occurrence of CECs in different water types based on the literature data reported for the countries from a lower part of the Middle Danube Basin, including those belonging to the Western Balkan (WB) region and two upstream neighboring EU Member States, Croatia and Slovenia. These countries share main freshwater courses important for drinking water supply, agriculture, industry, navigation, tourism, etc, but in some of them there are low rate of wastewater treatment, impacting the chemical status of water resources in the region and probably beyond, if downstream countries are considered. The literature survey revealed 38 investigative studies reporting data on CECs in water matrices sampled in the region in the period 2008-2022. Surface water was the most frequently studied water type in WB countries, while wastewater was the dominant water type studied in Slovenia and Croatia. The most often analyzed compounds in the studies dealing with surface water and wastewater were the anti-epileptic drug carbamazepine, some non-steroidal anti-inflammatory drugs, and antibiotics; pharmaceutically active compounds were also the most analyzed CECs in groundwater and drinking water. Additionally, similarities/dissimilarities among the experimental approaches in these studies were discussed in relation to the state-of-the-art research directions for the CECs surveillance in the European Union, resulting in summarized strengths and gaps in capacities for the wide-range surveillance of CECs in the lower part of the Middle Danube Basin. This is the first integral overview of the studies on CECs in waters from the countries belonging to this part of the Danube Basin, representing a valuable baseline for further enhancement of the relevant monitoring efforts and chemical status of the regional water resources, especially in countries with poor wastewater management.

The occurrence and temporal variation of selected priority substances and contaminants of emerging concerns, i.e., eleven perfluorinated compounds (PFCs, belonging to perfluorosulphonates, perfluorocarboxylic acids, and perfluorinated sulphonamides) have been investigated in composite surface water samples of the Danube River at the upstream and downstream locations from the discharge point of wastewater. Among the analyzed compounds, six PFCs (PFOA, PFOS, PFHxA, PFNA, PFDA and PFUnA) were quantified. Overall, the detection frequency for most quantified compounds was very high (>90 %), only PFDA and PFUnA were quantified with less frequency, 33 and 67 %, respectively. The highest quantified concentrations of PFOA and PFOS were 14.9 ng/L (average 12.1 ng/L) and 14.2 ng/L (average 6.11 ng/L), respectively. These ones together with PFHxA (average 10.0 ng/L) were quantified at the highest concentrations in comparison to the other investigated compounds. However, the determined levels of PFOS during investigated sampling period, for all samples analyzed, were always lower than the maximum allowable concentration set for inland river waters but always higher than the environmental quality standard threshold value-AA-EQS of 0.65 ng/L sets by the Directive of European Parliament. Moreover, the levels of PFOA were always several times lower than the set AA-EQS value.

Wastewater treatment plants (WWTPs) have been identified as the major sources of contaminants of emerging concern (CECs) in water bodies, as they are not designed to remove organic micropollutants efficiently. Consequently, many technologies have been explored for WWTP upgrading, including activated carbon adsorption. However, the high production cost and environmental challenges associated with activated carbon production limit its application in industrial settings. Therefore, a wide range of alternative materials has been investigated as potential replacements. In this study, biochar produced from waste raspberry biomass was evaluated as an adsorbent for the removal of pharmaceuticals and pesticides quantified in the secondary effluent of municipal WWTP. The results showed that the biochar efficiently removed almost all detected compounds, except for three compounds (clarithromycin, propranolol, and linuron). The wastewater pH (6–8) did not significantly affect removal efficiency significantly, and kinetic tests demonstrated rapid adsorption. The potential for biochar reuse was confirmed through three consecutive batch adsorption cycles. A comparative study between biochar and powdered activated carbon (PAC) revealed some differences in efficiency, primarily attributed to the larger surface area of PAC. π-π interactions, hydrogen bonding, and pore-filling were proposed as possible adsorption mechanisms based on the adsorption efficiency and biochar characterization.

Occurrence of five heavy elements (HEs) was analyzed in indoor dust (n = 45) in households from four settlements in Vojvodina Province, Serbia. Overall medians (mg/kg) of Pb (5.6), Ni (5.2), Cu (27), and Cr (6.8) were below soil background values, while median for Cd (1.1) exceeded it. Pollution load index showed that the households’ microenvironment in examined region might be regarded as unpolluted. Integrated pollution index revealed low contamination by Pb, Ni, and Cr, but high with Cu and Cd. Source apportionment by principal component analysis and positive matrix factorization suggested two possible sources: outdoor pollution and household materials. Hazard index was below safe limit (<1), indicating no adverse non-carcinogenic health effects. Estimated total carcinogenic risk for children and adult population was not negligible. Results indicated that attention should be paid to the presence of HE in indoors to conduct effective control measures and to ensure the health of the population.

This study presents the first comprehensive assessment of per- and polyfluoroalkyl substances (PFAS) in surface waters of northern Serbia (Middle Danube region), combining targeted analysis of 25 PFAS with high-resolution mass spectrometry suspect screening (SSA) at 12 settlement-adjacent sites on major rivers and part of the Danube–Tisa–Danube (DTD) canal network. The sum of 10 quantified PFAS showed pronounced spatial variability: the Great Bačka Canal (GBC) exhibited the highest mean and maximum values (18.4 ng/L and 52.6 ng/L, respectively); the Danube averaged 9.05 ng/L (2.92–22.2 ng/L); the Tisa averaged 10.5 ng/L (4.53–16.5 ng/L); and the Sava and Tamiš exhibited the lowest means (~5.4 ng/L each). In total, 19 of 24 sites exceeded the proposed EU group Environmental Quality Standard (EQS) of 4.4 ng/L, expressed as PFOA-equivalents, with exceedances of 5.4–20.2 ng/L; PFOS exceeded the 0.65 ng/L inland surface water annual average (AA) EQS in 17 samples. SSA expanded coverage beyond targets, revealing ultra-/short-chain PFAS and replacements, with TFA as the most abundant (337–1165 ng/L; mean 513 ng/L) and notable maxima for PFPrA (51.3 ng/L), ADONA (24.9 ng/L), and TFMS (11.2 ng/L). Compared with European freshwaters, the maximum obtained here lies in the lower-mid part of the reported range, consistent with short-chain perfluoroalkyl carboxylic acids (PFCA) dominance and diffuse-source influences.