Mineralogical and geochemical study of Lake Dojran sediments (Republic of Macedonia)

• The XRD results revealed close association with the Lake Dojran geology background.
• CIA values of 67% suggest a moderate degree of weathering in the lake catchment area.
• Sediments are minorly/moderately enriched with Cr, Zn, Pb, Cu, Co, Ni, Au, and Sb.
• Elemental enrichment originates from various geogenic and anthropogenic sources.
• Use of Lake Dojran sediments for balneotherapeutic treatments cannot be recommended.

In this study the mineralogical and geochemical characteristics of Lake Dojran surficial (0–5, 5–10, 10–15 cm) sediments were studied in order to determine their suitability for use as potential raw material in balneotherapeutic treatments. X-ray powder diffraction (XRD) and inductively coupled plasma mass spectrometry (ICP-MS) analyses were performed, and thereupon chemical index of alteration (CIA) and enrichment factor (EF) values were calculated.The XRD results revealed close association of sediment mineralogy with the prevailing metamorphic, volcanic and igneous rocks of the region surrounding Lake Dojran. CIA values of around 67% suggest a moderate degree of weathering in the lake catchment area.According to the EF value results, surficial Lake Dojran sediments are little enriched with Co, Cr, Cu, Pb, and Zn, moderately enriched with Au, Ni and Sb, moderately severely enriched with Au, severely enriched with Sb and very severely enriched with As. This elemental enrichment likely originates from various different geogenic (geological background and polymetallic mineralization) and anthropogenic (tourism, traffic, coatings, untreated wastewater discharge and agrochemicals) sources. The abundances of the major elements, trace elements and rare earth elements (REEs) were almost constant, changing very little throughout the surficial (0–5, 5–10, 10–15 cm) sediments. Comparison of sediment trace element concentrations with consensus-based threshold effect concentration (TEC) and probable effect concentration (PEC) values showed that lake biota may be under threat of contamination with As, Cu and Ni.Given the present results, we cannot recommend/confirm the application of Lake Dojran dark mud sediment in balneotherapeutic treatments.