EN
The concentrations of dissolved organic compounds (DOC) in the waters of small and large agricultural drainage basins were analyzed. It was found that the average DOC concentrations in surface water of the large agricultural drainage basin was 15.6 mg/1. Much higher DOC concentrations were noted in ground and surface waters of the small agricultural drainage basin. Groundwater under a cultivated field contained on average 22.4 mg/1 DOC, while the water of a small mid-Held pond contained 47.6 mg/1 of DOC. Dissolved humic substances (HS) constitute a prevailing fraction of DOC and amount to 86.2% of DOC in the groundwater, and 71.4% of DOC in the water of a small mid-field pond. Moreover, concentrations of Cd, Cu and Pb in the ionic form and in the bound form with HS were studied in the waters. It was observed that HS isolated from the groundwater has 4 times more complexing properties in relation to Pb and 2.5 times Cd than HS obtained from surface water.