# A Snapshot on the Occurrence and Risk Assessment of Organic Pollutants in an Urban River
## 3 Results and Discussion
### CECs Monitoring in Water  
All the targeted CECs were found in the Fervenca river, and the results are summarized in Table 2 and Figure 2. A four-color alert system is included to inform about the level of risk associated with the amount of each CEC. Paracetamol and clorofibric acid concentrations found in the present study were near or below the LOQ. As expected, the highest diversity and compound abundance was detected in F3 (the sampling site downstream Braganca city and its WWTP). The most abundant compounds were diclofenac (398.35 ng\(\cdot\)L\({}^{-1}\)), ofloxacin (376.16 ng\(\cdot\)L\({}^{-1}\)), tonalide (231.43 ng\(\cdot\)L\({}^{-1}\)), galaxolide (224.36 ng\(\cdot\)L\({}^{-1}\)), BPA (212.18 ng\(\cdot\)L\({}^{-1}\)), Caffeine (167.38 ng\(\cdot\)L\({}^{-1}\)), carbamazepine (52.10 ng\(\cdot\)L\({}^{-1}\)), and ibuprofen (21.81 ng\(\cdot\)L\({}^{-1}\)). The assumption that WWTP effluents are the main sources of superficial water contamination has been proven in several studies: [39; 40] observed that the diclofenac and ibuprofen concentrations ranged between 79-380 and 370-3600 ng\(\cdot\)L\({}^{-1}\), respectively, in Braganca WWTP effluent samples obtained in summer and autumn; Ref. [74] analyzed several Portuguese WWTP effluents and despite the effluent concentrations of carbamazepine, clorofibric acid, diclofenac, ibuprofen, caffeine, HHCB, and AHTN were generally much lower than the influent concentrations (clorofibric acid and diclofenac demonstrated a high level of adsorption to the sludge), none of these compounds were totally removed in the WW treatment process. Other international approaches [13; 15; 75; 76; 77] also demonstrate that the conventional WWTPs are neither specifically designed nor operated to remove residual concentrations of organic pollutants, causing the potential accumulation of such pollutants in the receiving water bodies. Nevertheless, in the sampling points located upstream the WWTP, ibuprofen ranged between 7.65 (F1) and 6.94 ng\(\cdot\)L\({}^{-1}\) (F2), and caffeine ranged between 3.17-10.23 ng\(\cdot\)L\({}^{-1}\) in F1 and F2, respectively. AHTN in F2 showed a similar concentration to F3 (207.92 ng\(\cdot\)L\({}^{-1}\)). The highest BPA concentration observed in the Fervenca river was achieved in F1 (642.69 ng\(\cdot\)L\({}^{-1}\)). The concentrations achieved in F1 and F2 indicate the occurrence of non-point pollution sources [78].  
\begin{table}
\begin{tabular}{c c c c} \hline
**Parameters** & **F1** & **F2** & **F3** \\ \hline  & 41.79454 N & 41.7985 N & 41.7716 N \\ Location and height over sea level & \(-\)6.8008 W & \(-\)6.7645 W & \(-\)6.7136 W \\  & 692.9 m & 668.7 m & 497.8 m \\ Temperature (\({}^{\circ}\)C) & 7.04 & 6.54 & 6.68 \\ Dissolved oxygen (mg\(\cdot\)L\({}^{-1}\)) & 9.8 (8) \({}^{\circ}\) & 10.3 (85) \({}^{\circ}\) & 9.0 (74) \({}^{\circ}\) 1 \\ Conductivity (uS\(\cdot\)cm\({}^{-1}\)) & 149 & 209 & 290 \\ Total dissolved solids (mg\(\cdot\)L\({}^{-1}\)) & 75 & 105 & 145 \\ pH & 7.0 & 6.5 & 7.2 \\ PO\({}_{4}\)\({}^{3-}\)(mg\(\cdot\)L\({}^{-1}\)) & 0.03 & 0.04 & 0.42 \\ Total phosphorus (mg\(\cdot\)L\({}^{-1}\)) & 0.08 & 0.23 & 1.10 \\ Riparian Quality & Some disturbance & Some disturbance & Disturbance \\  & Good quality & Good quality & Fair quality \\ \hline \end{tabular} \({}^{\star}\) (DO\(\%\)); \({}^{1}\) in summer months, dissolved oxygen can reach 2.3 mg\(\cdot\)L\({}^{-1}\)[73].  
\end{table}
Table 1: Location, channel and riparian indexes, macroinvertebrate community structure and some water parameters (mean values) in F1, F2, and F3 at the time of the present study.