## 3 Results and Discussion
### Occurrence of PhACs in the Five WWTPs and Surface Waters
Regarding the overall upstream and downstream results obtained for all the surface waters surrounding the WWTPs of interest (Table 4), 14 out of 26 monitored PhACs were detected with a wide range of median concentrations. DCF can be considered the most prevalent PhAC, due to having the highest median concentrations for the upstream and downstream samples, 0.85 and 1.6 \(\upmu\)g/L, respectively. CAF behavior was similar for both types of samples, with an occurrence percentage of 100%. Frequencies ranged from 2.74 to 3.4 and median concentrations fluctuated from 0.15 \(\upmu\)g/L in upstream samples and 0.10 \(\upmu\)g/L for downstream samples. NPX showed occurrence percentages of around 70%, with median concentrations ranging from 0.07 to 0.11 \(\upmu\)g/L for upstream and downstream samples, respectively. CBZ was only detected in 45% of upstream samples; however, it had a median concentration of 0.22 \(\upmu\)g/L. Conversely, in downstream samples, the median concentration was similar, 0.29 \(\upmu\)g/L; however, this corresponds to a 94% detection rate and a frequency of 3.2. The remaining detected PhACs had occurrence percentages varying between 9% and 36% and median concentration in upstream samples ranging from 0.07 to 0.15 \(\upmu\)g/L (SMX and ATN, respectively). While in downstream samples, the detection percentage ranged from 6% to 71%, with median concentrations ranging from 0.054 to 0.13 \(\upmu\)g/L (PPNL and ATN, respectively). As expected, the PhACs that were never detected in wastewater samples, namely CFA, GTD, E1, E3, E2, EE2, and DES were also not detected in any surface water samples. Furthermore, PhACs that are completely removed during the treatment stages, such as CTS and TTE, were also not detected. Moreover, most PhACs mean concentrations increased in the samples collected downstream from the WWTP as opposed to the upstream samples that were collected. Not many studies regarding the quantification of PhACs in surface waters that have direct influence from WWTPs were found in the Evora region. Only one study was found that included the Xarrama River as one of the sampling points, with samplings in 2014 and 2015 [37]. However, no similarities were found between our two studies, considering that most of the PhACs that were monitored were either not detected or only detected in considerably lower concentrations compared to the current study. The occurrence profile of influent and effluent of each WWTP is represented in Figure 2 and detailed in Tables S2-S6 of Supplementary Material. The individual influent profile was similar in all target WWTPs. However, for the most representative compounds, acetaminophen and caffeine, the median concentrations were different. The median concentration of CAF ranged between 26.3 (Portel WWTP) and 46.3 \(\upmu\)g/L (Evora WWTP). The median concentration of APAP can be grouped in three ranges: the lowest around 70 \(\upmu\)g/L (Portel and Evora WWTPs), the median range around 100 \(\upmu\)g/L (Reguengos de Monsaraz and Redondo WWTP), and the highest was Borba WWTP with 225 \(\upmu\)g/L. NSAIDs, IBUP, and NPX showed significant differences between influents of WWTPs, with median concentrations ranging between 5.2 (Portel WWTP) and 21.6 \(\upmu\)g/L (Reguengos de Monsaraz WWTP), and between 6.2 (Evora WWTP) and 13.4 \(\upmu\)g/L (Borba WWTP), respectively. Apart from diclofenac, with a median concentration between 1.35 (Portel WWTP) and 2.52 ug/L (Borba WWTP), the remaining PhACs (>MQL) showed concentrations lower than 1.5 ug/L in all WWTPs. Portal WWTP presented the lowest values of PhACs in influuents due to having the lowest population equivalent. Regarding effluents, the difference between WWTPs was more significant, especially due to the values of certain target PhACs. Borba WWTP showed higher median concentrations of diclofenac (3.29 ug/L), acetaminophen (4.26 ug/L), and caffeine (4.78 ug/L). Redondo WWTP showed the highest concentration of acetaminophen (7.79 ug/L). Regueros de Monsaraz WWTP showed the highest median concentration of atenol (0.11 ug/L).