Untreated wastewater impact and environmental risk assessment of artificial sweeteners in river water and sediments of the Danube River Basin in Serbia.

Artificial sweeteners are receiving increasing attention as newly recognized emerging contaminants that mainly reach the aquatic environment through the discharge of municipal wastewater containing large amount of these compounds. In this study, the impact of raw untreated wastewater discharges on the levels and the water/sediment distribution of artificial sweeteners in the Danube River and its largest tributaries in Serbia was evaluated, and a comprehensive assessment of environmental risks for freshwater and benthic organisms was performed. Acesulfame and sucralose were detected in all river water samples (100%), while saccharin (59%) and cyclamate (12%) were less frequently found, indicating long-term continuous sewage-derived pollution. Aspartame (100%) and neotame (60%) were the only artificial sweeteners recorded in the sediment samples due to their preference to sorb to particulate matter in the water/sediment system. In terms of ecotoxicological risk, a low risk for aquatic organisms was determined at the detected levels of saccharin in river water, while a high to medium risk was found for benthic biota at the concentrations of neotame and aspartame detected in sediments. The largest contribution to the pollution of the Danube River Basin with artificial sweeteners, and consequently the highest environmental risk, was determined in the two largest cities, the capital Belgrade and Novi Sad, which raises the issue of transboundary pollution.

The occurrence of selected xenobiotics in the Danube river via LC-MS/MS.

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.

Sterol ratios as a tool for sewage pollution assessment of river sediments in Serbia.

In this work, source pollution tracing of the sediments of the Danube River and its tributaries in Serbia was performed using sterol ratios. Improved liquid chromatography-tandem mass spectrometry method, which enabled complete chromatographic separation of four analytes with identical fragmentation reactions (epicoprostanol, coprostanol, epicholestanol and cholestanol), was applied for the determination of steroid compounds (hormones, human/animal and plant sterols). A widespread occurrence of sterols was identified in all analyzed samples, whereas the only detected hormones were mestranol and 17α-estradiol. A human-sourced sewage marker coprostanol was detected at the highest concentration (up to 1939 ng g(-1)). The ratios between the key sterol biomarkers, as well as the percentage of coprostanol relative to the total sterol amount, were applied with the aim of selecting the most reliable for distinction between human-sourced pollution and the sterols originated from the natural sources in river sediments. The coprostanol/(cholesterol + cholestanol) and coprostanol/epicoprostanol ratios do not distinguish between human and natural sources of sterols in the river sediments in Serbia. The most reliable sterol ratios for the sewage pollution assessment of river sediments in the studied area were found to be coprostanol/(coprostanol + cholestanol), coprostanol/cholesterol and epicoprostanol/coprostanol. For the majority of sediments, human-derived pollution was determined. Two sediment samples were identified as influenced by a combination of human and natural biogenic sources.

Genotoxicity assessment of the Danube River using tissues of freshwater bream (Abramis brama).

This study examines the use of freshwater bream (Abramis brama) as a sentinel organism for genotoxicity assessment of the Danube River using the comet assay. Sampling of bream was performed during February, April, August, and November in 2014 to assess seasonal variation of DNA damage level as a response to genotoxicity in annual cycle. Additionally, concentrations of fecal coliforms and enterococci were analyzed and they indicated a critical to strong level of fecal pollution on investigated locality during annual cycle. Comet assay was performed on blood, liver, and gill cells of bream. DNA damage level was expressed using tail intensity (TI %), Olive tail moment (OTM), and tail length (TL pix). According to TI and OTM, all three tissues had the highest level of DNA damage in August. The lowest level of DNA damage in liver was measured during February, in blood during November, and in gills during April. According to TL, gills had the highest level of DNA damage in February, and liver cells had the lowest level of damage during April. Multiple correspondence analysis (MCA) showed that DNA damage in blood cells is under the strong influence of variations in NO2, NO3-, NH4+ levels and also the variation in temperature and oxygen levels. DNA damage in liver cells is highly associated with the variations of Mn, Fe, Cu, Zn, and PO43- levels. DNA damage in gill cells is strongly affected by the variations of As, Cd, Pb, Cr, and COD (Mn) levels. Freshwater bream is shown to be a potentially good indicator organism in genotoxic potential field studies.

Common barbel (Barbus barbus) as a bioindicator of surface river sediment pollution with Cu and Zn in three rivers of the Danube River Basin in Serbia.

River sediments are a major source of metal contamination in aquatic food webs. Due to the ability of metals to move up the food chain, fishes, occupying higher trophic levels, are considered to be good environmental indicators of metal pollution. The aim of this study was to analyze the metal content in tissues of the common barbel (Barbus barbus), a rheophilous cyprinid fish widely distributed in the Danube Basin, in order to find out if it can be used as a bioindicator of the metal content in the river sediment. We analyzed bioavailable concentrations of 15 elements (Al, As, B, Ba, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, Se, Sr, and Zn) in sediments of the Danube (D), the Zapadna Morava (ZM), and the Juzna Morava (JM) using the inductively coupled plasma spectroscopy (ICP-OES). The barbel specimens were collected in the proximity of sediment sampling sites for the analysis of metals in four tissues, gills, muscle, intestine, and liver. The sediment analysis indicated that the ZM is the most polluted with Cu, Ni, and Zn compared to other two rivers. The JM had the lowest concentrations of almost all observed elements, while the Danube sediments were mainly characterized by higher concentrations of Pb. The fish from the ZM had the highest concentration of Cu and Ni in the liver and intestine, and of Zn in the muscle tissue, which was in accordance with the concentrations of these metals in the sediment. Scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM-EDS) was used for further analyses of metal interactions with fish tissues. The results suggest that the barbel can potentially be used as a bioindicator of sediment quality with respect to metal contamination.

Assessment of the genotoxic potential along the Danube River by application of the comet assay on haemocytes of freshwater mussels: The Joint Danube Survey 3.

In this study we assessed the level of genotoxic pollution along the Danube River by measuring the level of DNA damage in the haemocytes of freshwater mussels of Unio sp. (Unio pictorum/Unio tumidus) and Sinanodonta woodiana. The comet assay was used for the assessment of DNA damage. The research was performed on 34 out of 68 sites analysed within the Joint Danube Survey 3 - the world's biggest river research expedition of its kind in 2013. During research, 2285 river kilometres were covered with an average distance of 68 km between the sites. The complex data set on concentrations of various substances present in water, suspended particulate matter and sediment on investigated sites gave the opportunity to identify the groups of xenobiotics which mostly affect the studied biomarker - DNA damage. The highest levels of DNA damage were recorded in the section VI (Panonnian Plain), which is under the impact of untreated wastewater discharges. Both positive and negative influences of the large tributaries on the level of genotoxicity in the Danube River were evident. Significant correlation in response was detected between the studied species of freshwater mussels. The level of DNA damage in mussels correlated with concentrations of compounds from the group of hazardous priority substances (polycyclic aromatic hydrocarbons), persistent organic pollutants (dioxins) and emerging pollutants (Oxazepam, Chloridazon-desphenyl).