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A. Świeca

CONCLUSIONS AND DISCUSSION

1.    In the years 1989-1992 about 6.5 million m³ of wastewater was discharged annually into surface waters of the Łabuńka river catchment up-stream of the gauging station at Krzak; this constituted 18% of the mean annual river outflow. Waters of the upper Łabuńka river and its left tributary

—    the Topornica were not polluted with wastewater; a smali amount of wastewater (0.2% of the mean annual volume) was received by the Czarny Potok river waters; as much as 99.8% of wastewater was discharged into the Łabuńka river. It is polluted with wastewater coming largely from Zamość (as much as 98.4% of the mean annual volume of wastewater is delivered by the Company for Water Supply and Treatment in Zamość).

2.    On the basis of the author’s measurements and the data from the Provincial Inspectorate of Environment Protection in Zamość for the years 1989-1992 it has been found that the Łabuńka river waters at Krzak are most polluted largely with municipal-industrial wastewater from Zamość. They are characterized by the highest concentration of solutes (473 mg dm^-3); increased amounts of ions: Cl^- — 37 mg dm^-3, SO ^2- — 34, Na⁺ + K⁺ — 34, and biogenic components: N-NH£ — 6.3 and PO^3- — 3.11 mg dm"³; bad oxygen conditions (2.7 mg dm^-3) and considerable pollution with organie compounds (BOD₅ — 20.3 mg 0₂ dm^-3).

3.    In the Łabuńka river catchment the chemism of waters unpolluted with wastewater shows a differentiation controlled by lithology of the bedrock. Higher solute concentration indices (419-443 mg dm^-3) were found in waters drained off from bogs; they are distinguished by the highest content of Ca²⁺ ions (126-136 mg dm^-3) and a relatively high concentration of SO ²' ions (22-34 mg dm^-3). Waters with lower solute concentration (322-333 mg dm^-3) were found in partial catchments with loess cover; they contain fewer Ca²⁺ ions (95-102 mg dm^-3) and fewest Cl^- ions (14-16 mg dm^-3).

4.    The results of studies of the upper Łabuńka river and its tributaries

—    the Topornica and the Czarny Potok, allowed the author to determine indices characteristic for the present hydrochemical background of the river water in the Łabuńka river catchment. This background is characterized by: a solute concentration of 364 mg dm^-3, concentration of ions: Ca²⁺ — 110 mg dm^-3, Mg²⁺ — 9, Na⁺ + K⁺ — 11, SO ^2- — 28 and CI^- — 17 mg dm^-3, good oxygen conditions (about 9 mg dm^-3) and a Iow content of organie compounds (BOD₅ — about 2.9 mg 0₂ dm^-3) and biogenic ones (PO T — 0.20 mg dm^-3 and N-NH⁺ — 0.94 mg dm^-3).

5.    In the years 1989—1992 the Łabuńka river waters at Krzak sh)wed solute concentrations higher by about 30% in relation to the hydrochemical background. They were characterized by a considerably higher concentration of all macrocomponents (in the case of Cl^- ions about two times higher. and Na⁺ + K⁺ about three times higher); 3 times lower oxygen concentratim, 7 times greater concentrations of organie compounds and ammonium nitiogen and 12 times greater concentration of phosphates.