The Role of Confluence in Shaping Water Quality Parameters on Example of the Flow-Through Lake Bikcze (Eastern Poland)

Abstract

Abstract:The role of confluence (flowability) in shaping the concentration of dissolved oxygen (DO), chlorophyll-a (chl-a) and pH was determined using a model approach. The calculations considered both horizontal and vertical variability of parameters. There was a general tendency for the pH and oxygen to increase along the transect connecting the place of surface water inlet, deepest point of the lake basin and the place of water outlet, and the reverse tendency for chlorophyll. The average gradient for particulate radius was calculated as arithmetic mean value of six partial gradients (corresponding to individual depths, every 0.5 m). Values of average gradients indicated high dynamics of DO and pH concentration changes as well as low chlorophyll-a variability. A slight inclination of the final resultant vector gradients of DO and pH from the surface water inlet, deepest point of the lake basin and the place of water outlet transect indicated the dominant role of confluence in these parameters variability (values amounted to 6.08 mg·km −1 and 3.34 pH units·km −1 , respectively). The value of the chlorophyll-a gradient vector (1.86 µg·km −1 ) indicated a slight differentiation of the parameter in the basin, independent of the hydrological conditions. The concentration of chl-a in the polymictic Lake Bikcze resulted from the effect of the limnic conditions; the flowability of the lake was just one of many factors affecting the variability of the parameter.

Assessment of Spatial and Vertical Variability of Water Quality: Case Study of a Polymictic Polish Lake

“…Higher temperature accelerates reproduction of phytoplankton, therefore, homogenization of chlorophyll a was also favored during sampling [39]. However, the studied parameters showed both vertical and horizontal variation, despite the fact that Lake Bikcze is a polymictic reservoir, flow-through, and is susceptible to wind influence [40].…”

“…The highest variability of chlorophyll a suggested that processes shaping its concentration in the lake waters are complex and multidirectional [47]. Chl-a in Lake Bikcze is determined by in-lake processes rather than hydrological ones [40]. In the southern part of the lake basin, positive values of Chl-a differences indicated a higher concentration of the parameter in the upper layers of the water column.…”