# A Snapshot on the Occurrence and Risk Assessment of Organic Pollutants in an Urban River
###### Abstract  
A snapshot screening was carried out in an urban river at the end of a dry period in the water and sediments to assess the presence and environmental risk for the following CECs: paracetamol, ibuprofen, diclofenac, clofibric acid, carbamazepine, ofloxacin, caffeine, tonalide, galaxolide, and bisphenol-A. Concomitantly, the occurrence and environmental risk of sixteen PAHs congeners, six indicator PCBs, and twelve dioxin-like PCBs were evaluated in sediments. The most abundant and ubiquitous CECs were bisphenol A (BPA) and caffeine, and the total contents in the surface water varied between 90.95-212.18 and 3.17-167.38 ng.L\({}^{-1}\), respectively. The concentrations found in lixiviates ranged from 134.94-772.85 (BPA) and 14.43-92.60 ng.L\({}^{-1}\) (caffeine). Other CECs were detected in lower concentrations, and their presence varied between sampled sites. Values of total PAHs congeners in sediment varied between 10.39-52.91 ng.g\({}^{-1}\) dw. The majority of the detected PAHs seem to have a pyrolitic origin with a small petrogenic contribution. Total PCBs' concentrations ranged from 5.06 to 6.13 ng.g\({}^{-1}\) dw. Despite the relatively low concentration of most of the detected compounds, the overall environmental risk, considering the screened compounds altogether, cannot be considered negligible. The obtained results are discussed in terms of other data available (though highly dispersed) in the literature. A four-color alert system is included to inform about the level of risk associated with the amount of each CEC, PAH, and PCB. urban river; water and surface sediments; CECs; PAHs; PCBs; risk evaluation +
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transformation into other compounds that may cause undesired effects on ecosystems and health and, therefore, become hazardous, persistent, or semi-persistent and ubiquitous contaminants [7; 8; 9; 10; 11; 12; 13; 14; 15; 16]. PAHs are generally persistent, semi-volatile, and hydrophobic, with low water solubility and, despite being widely distributed in the environment, their concentrations are usually very low in water, with a clear tendency to be adsorbed onto sediments [17]. Most PAHs are generated by pyrolysis or an incomplete combustion of organic material [18; 19], being toxic, mutagenic, carcinogenic, teratogenic, and very bioaccumulative compounds [19; 20; 21; 22; 23; 24]. PCBs are a group of chlorinated persistent organic pollutants. Like PAHs, PCBs are hydrophobic with low water solubility, persistent, ubiquitous, and bioaccumulative [25]. PCBs were widely spread during the last century through many industrial processes, as undesired reaction products. Due to their persistent nature and harmful impacts on organisms and environment, PCBs have been banned in different countries since the 1970s. Because of their long half-life, they can still be detected long after the ban [18; 26; 27; 28; 29; 30; 31; 32]. More than 700 substances included in 20 classes have been identified in European aquatic ecosystems (NORMAN network, 2016, [33]). Despite this vast number, the legal control over their discharge and environmental levels has not been set up yet from many of them. Indeed, only 33 substances or compound classes are considered priority substances by WFD and EC Directive, 2013/39/EU. The management of these substances in freshwater aquatic environments faces two challenges: the consequences of chronic exposure to these mixtures are mostly unknown [34], and there is a serious lack of information concerning most aquatic ecosystems' chemical and ecological status [2; 35]. Despite the many references that focus on monitoring the occurrence of CECs in surface water in European freshwater ecosystems, monitorization of these compounds in surface waters is still not routinely carried out in (Table S1) and PAHs' and PCBs' monitoring in European riverine sediments is even scarcer (Table S2).