Long-term study of azoles in surface water and treated wastewater

Azole antifungals are commonly used as pharmaceuticals, cosmetics as well as agricultural fungicides. Such an extensive range of applications of azole compounds leads to their widespread occurrence in wastewater and surface waters. In this study, the quantitative determination of antifungal pharmaceuticals (fluconazole, climbazole, clotrimazole) and fungicides (tebuconazole, epoxiconazole, flutriafol, tiabendazole, and imazalil) was seasonally performed in surface water samples from rivers, lakes and field drainage ditches as well as wastewater treatment plants (WWTP) effluents in western Poland. Solid phase extraction (SPE) combined with high-performance liquid chromatography-tandem mass spectrometry was used to detect azole compounds in waters, obtaining recoveries up to 100.2% with relative standard deviations below 9%. Azole monitoring was conducted for 3 years in treated wastewater and surface water. Fluconazole was the compound determined at the highest concentrations in all analyzed WWTP effluents, reaching 739 ng L^-1. The concentration of 100 ng L^-1 was also exceeded by climbazole, clotrimazole, tiabendazole, and imazalil, which proves that these compounds are not completely removed by the degradation processes used in WWTPs and are released into the environment. In surface waters analysis, definitely the highest concentration was obtained for tebuconazole - 1383 ng L^-1 in Warta River and 1783 ng L^-1 in a field drainage ditch, which is caused by its extensive application as an agricultural fungicide. The majority of the analyzed azole antifungals are present in WWTP effluents and surface water, highlighting the need for future monitoring and investigation of their degradation methods. However, the present results show that determined concentrations are safe for aquatic organisms.