Herbicide micropollutants in surface, ground and drinking waters within and near the area of Zagreb, Croatia.

The frequency and mass concentrations of 13 herbicide micropollutants (triazines, phenylureas, chloroacetanilides and trifluralin) were investigated during 2014 in surface, ground and drinking waters in the area of the city of Zagreb and its suburbs. Herbicide compounds were accumulated from water by solid-phase extraction using either octadecylsilica or styrene-divinylbenzene sorbent cartridges and analysed either by high-performance liquid chromatography with UV-diode array detector or gas chromatography with mass spectrometric detection. Atrazine was the most frequently detected herbicide in drinking (84 % of samples) and ground (61 % of samples) waters in mass concentrations of 5 to 68 ng L-1. It was followed by metolachlor and terbuthylazine, the former being detected in 54 % of drinking (up to 15 ng L-1) and 23 % of ground (up to 100 ng L-1) waters, and the latter in 45 % of drinking (up to 20 ng L-1) and 26 % of ground (up to 25 ng L-1) water samples. Acetochlor was the fourth most abundant herbicide in drinking waters, detected in 32 % of samples. Its mass concentrations of 107 to 117 ng L-1 in three tap water samples were the highest of all herbicides measured in the drinking waters. The most frequently (62 % of samples) and highly (up to 887 ng L-1) detected herbicide in surface waters was metolachlor, followed by terbuthylazine detected in 49 % of samples in mass concentrations of up to 690 ng L-1, and atrazine detected in 30 % of samples in mass concentrations of up to 18 ng L-1. The seasonal variations in herbicide concentrations in surface waters were observed for terbuthylazine, metolachlor, acetochlor, chlortoluron and isoproturon with the highest concentrations measured from April to August.