Screening of the microelements composition of drinking well water of Transcarpathian region, Ukraine

For Transcarpathian region, with a pronounced landscape diversity of territories and significant areas of nature reserves, well water is an important source of drinking water. Screening of the microelement composition of drinking well water in Transcarpathia has not been carried out before. The microelement composition of such well water can be considered as the natural (baseline) indicator of quality.We screened of the microelement (Cu, Zn, Fe, P, Ca, Mg, Mn, Mo, Co, As, Se, I, Br and F) composition of drinking well water in Transcarpathian region (for all 13 districts). Standard methods were used to determination the concentration of chemical elements in well water: electrothermal atomic absorption spectroscopy (Cu, Zn, Fe, Mn, Mo, Co), flame photometry (Ca, Mg), inverse voltammetry (total iodine), potentiometry (F, Br), fluorimetric (Se) and spectrophotometric methods (P, As).The content of chemical elements in well water varies over a wide range, in particular for Cu: 3.27–11.6 μg⋅L⁻¹, Zn: 8.16–38.2 μg⋅L⁻¹; Fe: 37.9–411 μg⋅L⁻¹; P: 51.4–193 μg⋅L⁻¹; Ca: 85–139 mg⋅L⁻¹, Mg: 10.2–18.9 mg⋅L⁻¹, Mn: 22.8–78.1 μg⋅L⁻¹; Mo: 2.33–8.96 μg⋅L⁻¹; Co: 1.72–3.38 μg⋅L⁻¹; As: 2.9–17.4 μg⋅L⁻¹; Se: 0.95–3.6 μg⋅L⁻¹; I: 0.94–4.4 μg⋅L⁻¹; Br: 712–3098 μg⋅L⁻¹; F: 71–149 μg⋅L⁻¹. The tendency that the content of microelements (Cu, Zn, Mn, Mo, Co, As, Se, I, Br, and F) in well waters of different landscape zones was evaluated through Spearman's coefficients. The content of trace elements in the waters of different landscape zones increases in the series: lowland landscape > foothill landscape > mountainous landscape (Spearman's coefficients: Cu – 0.62, Zn – 0.85, Mn – 0.69, Mo – 0.83, Co – 0.79, P – 0.74, As – 0.72, Se – 0.75, I – 0.80, Br – 0.91, F – 0.73).It is shown that the chemical composition of well water can be considered as the natural (baseline) indicator of quality of groundwater in Transcarpathia, taking into account topographic and geochemical features of the territories. Among the main problems of drinking well water in Transcarpathia are the relatively high content of Fe (typical for different landscape zones), as well as the low content of Se, I and F. The correlation of inter-elements content of chemical elements in drinking well waters of Transcarpathia has been revealed. The most pronounced correlations are observed for such pairs of microelements: Co–Mo (r > 0.95), I–Br (r > 0.92), Zn–Br (r > 0.89), Cu–Co (r > 0.84), Se–Co (r > 0.84), Mo–P (r > 0.84), Mo–I (r > 0.82) and Zn–Mo (r > 0.80).