Assessment of water quality using chemometric methods : a case study of Rusałka Lake, NW-Poland

Chemometric methods, such as cluster analysis, factor analysis and discriminant analysis were applied to identify and assess the quality of lake water. Samples were collected from the Rusałka Lake, located in Szczecin City from September 2012 to September 2015 with frequency once a month. 25 water quality indices were evaluated in particular: Chl a, Eh, temperature, pH, COD-Mn, COD-Cr, BOD₅, DO, NO₃^-, NO₂^-, NH₄⁺, TN, SRP, TP, Ca²⁺, Mg²⁺, Cl^-, SO₄^2- ,HCO₃^-, Fe_tot, Mn_tot, Pb, Zn, Cd, Cu. Cluster analysis was performed to determine the similarity in terms of variation of the examined water quality indices and to determine seasonal variation between inflow and outflow areas of the lake. Factor analysis revealed that water quality is shaped by high anthropogenic activities. Discriminant analysis was used for the final assessment of which of the studied variables discriminate between the inflow and outflow zones and seasons. The chemometric approach and results provided useful information on the type of parameters affecting the quality of water in the analyzed lake. The data and information obtained can lead to better understanding of changes which are present in small flow lakes under high anthropopressure.