Background. Small rivers are an important component of the natural environment. Water resources of small rivers are part of the shared water resources and are often the main and sometimes the only one source of local water. Small rivers are the regulators of the water regime of the landscapes, the factors for maintaining balance and redistribution of moisture. The aim is analysis of interaction between parameters of the quality of the water environment like conductivity and nitrates on the example of natural waters of small rivers. Objects are small rivers Bìst and Rosselle (Saardand lands, Germany) and Mertvovod (Mykolaiv region, Ukraine).
Methods. We used the method of correlative analysis which is effective and efficient for the determination of connections between the parameters of water quality that helps to identify sources of pollution, as well as interpret phenomena, forecast the situation related to the change in the quality of natural waters. The hydrochemical monitoring data were obtained from autonomous automated stations that are located on the rivers Bist, Rossel and Mertvovod. We investigated the following correlation dependencies between such combinations of natural waters quality parameters: nitrates and conductivity. Monitoring data are processed using software MS Excel; correlation dependence was defined using the CORREL.
Results. Correlation value is changed in the range from −1 to + 1 that demonstrates the indirect and direct dependence between the selected parameters. If the value is closer to +1, this means the presence of a strong connection, if closer to 0 – weak. The time periods for the calculation of the correlation between the parameters of natural waters quality is selected: 4, 8, 16 and 24 hours respectively. The following time periods allow the best to trace and predict changes in the natural aquatic environment. Correlation analysis of the concentration of nitrates and conductivity showed that for r. Bìst and r. Rosselle dominates is the positive value of the correlation between the study parameters, which proves their strong interaction. However, at certain concentrations of nitrate-ions observed custom phenomenon of sharp decrease in correlation to the «-1», which is explained by the Onsager equation, namely an excess concentration of nitrates is associated with erosion of different types of fertilizers from the fields as a result of rainfall.
Discussion. Trend analysis of the studied indicators of Mertvovod water quality was conducted on an average value of each indicator (pH, phosphates, nitrates, BOD, soluble oxygen). We used trend analysis for Mertvovod because we did not have enough data in time. Found a significant increase in phosphates with time. This can be explained by the arrival of various surface active substances and, to a lesser extent, the lack of quality sewage treatment facilities. Positive changes are founded in water object that is related to a decrease in the value of BOD.