Occurrence and seasonality of pharmaceutical compounds in urban wastewaters in two Portuguese regions
Catarina Silva, Cristina Almeida, João A. Rodrigues, Sofia Silva, Maria do Rosário Coelho, António Martins, Rita Lourinho, Eugénia Cardoso, Vítor Vale Cardoso, Maria João Benoliel, Maria João Rosa
Abstract
The occurrence of a representative range of pharmaceutical compounds (PhCs) in urban wastewaters was studied in two Portuguese water-scarce regions (Lisbon great area, and Faro – Algarve), involving 55 sampling campaigns during 2.5 years. The results show 16 PhCs (out of the 24 analysed) were quantified in all samples, with similar concentrations in both wastewaters. To understand to what extent seasonality affects PhC occurrence, a statistical analysis was conducted, and daily maximum air temperature was identified as a key factor, with a turning point of 20°C in Lisbon and 22°C in Faro. Some PhCs showed lower concentrations in colder (wet) months due to rainwater dilution (combined sewer systems), whereas others showed higher concentrations, reflecting an increased seasonal consumption and/or slower transformation under lower temperatures and/or shorter hydraulic retention times. Seasonal studies should therefore focus on temperature rather than on calendar seasons, increasingly uncertain due to climate change.