THE USE OF A GEOCHEMICAL METHOD IN THE DETECTION OF GROUNDWATER DISCHARGE TO FLOODPLAIN LAKES

Water quality parameters of floodplain lakes may be indicative of the intensity of groundwater recharge. The main assumption made in the study is that the direct influence of groundwater re-charge is reflected in the vertical gradient of temperature and aeration along the whole water col-umn. Considering this, we seasonally monitored physical and chemical properties of 22 oxbow lakes in postglacial river valleys (the Słupia, Drwęca and Łyna rivers) in temperate climate zone in the southern watershed of the Baltic Sea (N Poland). The results were compared with groundwater samples from transects of piezometers located near the floodplain lakes. The floodplain water bod-ies showed variability (both in vertical and spatial dimensions) in temperature, aeration and elec-trolytic conductivity, affected mainly by different sources of water supply. The temperatures and dissolved oxygen contents declined not only with the increasing depth of water and a distance from the river channel, but also a significant drop in the parameters ’ values have been associate