Travertine increases the concentration of trace elements in groundwater in Chahar Takab, Fariman county, northeast Iran

Abstract Groundwater has emerged as a crucial water source, supplying half of the world’s domestic water needs, particularly in rural areas without supply systems. This study assesses the impact of travertine formations, on water quality in Chahar Takab village, Iran, focusing on suitability for human consumption and ecosystem sustainability where groundwater is the primary source. Thirty-four samples from various sources, including travertine springs, surface water, and groundwater, underwent ICP-OES analysis. Travertine springs exhibited higher electrical conductivity (EC), lower pH, and elevated concentrations of major cations (Na, Ca, Mg) and anions (Cl, HCO 3 ). In them, all samples exceeded European Union limits for Cl and Na in drinking water. Hydrochemical facies were influenced by water-rock interactions, leading to Ca-HCO 3 dominance in surface and groundwater samples and Ca-Mg-Cl dominance in travertine springs. Heavy metal analysis revealed high concentrations of As, B, Fe, Mn, and Pb in travertine spring and surface water samples, with As exceeding World Health Organization limits by up to 28.5 times. Additionally, the Metal Index indicated values exceeding drinking water guidelines set by the World Health Organization in 58% of the samples. Travertine springs had the highest toxicity risks, especially for As, Cd, and Pb. Results suggest a tectonic origin for heavy metal contamination (As-containing travertine springs), emphasizing the need for mitigation measures and regular monitoring. Action is necessary to address water quality issues in the region.