Seasonal evolution and depth variability of heavy metal concentrations in the water of Firiza-StrÎmtori lake, nw of Romania

Abstract

The paper follows the spatial variability and seasonal evolution of the heavy metal content of the Firiza-Strîmtori Reservoir that is the main source of drinking water for Baia Mare city located in the northwestern part of Romania. Water samples were collected from 10 sampling points located along the median line of the lake at different depths (at surface, at 5 m, 10 m, 15 m and 20 m). The experiments were carried out in the winter, spring, summer and autumn of 2015. We determined the concentration – depth profiles, both for the heavy metals iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), cadmium (Cd), lead (Pb) and also for sodium (Na), potassium (K), calcium (Ca) and magnesium (Mg). We determined the concentrations of heavy metals by atomic absorption spectrometry. We found that concentrations of heavy metals increase with depth. Generally, the concentrations of heavy metals are within the legal limits for the water used as drinking water sources. Mathematical models with high correlation coefficients were obtained in the case of heavy metal concentrations depending on depth and also for the seasonality of heavy metals upload.