Analyses of the ground waters in respect of presence of residues of plant protection products, i.e. active substances as well as environmental metabolites thereof are performed in the Institute of Plant Protection since the end of 80ties of the past Century. Based on the results obtained in 1993–1994 for 40 wells located in administrative territories of former Poznań, Toruń and Bydgoszcz voivodeships, in the vicinity of intensive agricultural production areas (orchards, farms), wells where significant amounts of residues of triazines group and dealkylated metabolites thereof had been found previously were qualified to further studies. There were 6 wells in which triazine residues were determined most often. Additionally, based on hydrogeological maps, directions of underflows in the areas of well’s locations were determined as well. The aim of the above was to find the additional places for sampling waters distant from pollution sources and estimation of the level of residues of target compounds depending on distance from the basic wells. Seven triazine compounds including basic active substances (atrazine, simazine) and their metabolites [desethyl atrazine, desisopropyl atrazine, desethyldesisopropyl atrazine, hydroxyatrazine and hydroxysimazine] were selected for the presented studies. Residues were analyzed using methodologies designed in the Institute, i.e. solid-phase extraction (SPE) followed by determination by chromatographic techniques HPLC-PDA, GC-NPD and GC-MS. Generally, during 11 years of investigations (1993–2003) samplings were performed 52 times and 323 samples of groundwater including that from additional wells were analyzed. Most often residues of atrazine and deethylatrazine in wells located in environs of Poznań were detected.

In the period of 1993-1998 six wells known as being contaminated were monitored 3-6 times per year (a total of 143 samples) for the presence of atrazine, simazine and respective chloro-dealkyl metabolites. Samples were prepared for analysis by solid phase extraction (SPE) and determination was by HPLC/UV or GC/NPD techniques, GC/MSD and HPLC/DAD were employed as secondary (confirmatory) techniques. Residues of analysed compounds were present in more than 90% of samples with exception for DeDiA that was found in 81.6% of samples. The highest concentrations of atrazine, simazine, DeA, DiA, and DeDiA were 16.80; 18.60; 7.49; 2.98 and 3.43 μgil respectively. New inputs of atrazine and simazine were observed in ground water of three wells occasionally, probably resulting from fresh herbicide treatments. In the other wells contamination was rather stagnant at lower levels (0.X mg/I).