Trend of the occurrence of bentazone and the concentration of selected azoles in the Czech part of the River Elbe in the years 2009–2022

The presence of selected substances in water in the Czech Republic is monitored by river basin enterprises, in this case by the River Elbe Basin Enterprise. The results of the monitoring are stored and processed in the National Water Quality Information System operated by the Czech Hydrometeorological Institute. The occurrence of selected pesticides (bentazone, flusilazole, propiconazole, tebuconazole and epoxiconazole) was monitored by the River Elbe Board at 24 sampling points of the River Elbe during the years 2009–2022. The highest concentration found was for tebuconazole (0.81 µg/l in Lysá nad Labem in 2020). The most prevalent substance detected was bentazone with a maximum concentration of 0.28 µg/l at Loubí in 2015. The trend for bentazone content in certain localities exhibited a downward trajectory, with a substantial decline observed in the last three years compared to 2013 and 2014, when its concentrations reached their peak. Monitored azoles were not detected in water samples from the River Elbe at the localities of Jiřice, Střekov, Štětí, Verdek and Opatovice.