Environmental geochemistry of water, sediments and slimes of Semnan Spas

In order to study the environmental characteristics of Semnan spas, water, sediment, and slime samples were collected. The concentration of Ag, As, Cd, Pb and Zn (0.7, 33, 0.4, 128.5, and 297 mg/kg, respectively) in the sediment samples are much higher than their respective values in mean crust and mean sediment compositions. The sediments are not enriched in Mo, Ni, Th, Co, Cr, Mn, Fe and U, while moderately enriched in Sb and Cu, significantly enriched in Cd, As, Zn and Pb, and highly enriched in Ag. The Bioconcentration Factor (BCF) values of As, Mn, Cu, Ni, Pb and Zn in slime samples are very high (1286, 2863, 2340, 1053, 1236, and 976, respectively). The water samples are classified as neutral-high-metal, and the concentrations of B, Li, Ba, Zn, Pb, Se, Cu, As, Ni and Mn in all samples are higher than their mean concentrations in unpolluted natural waters. The values of Contamination Degree (Cd) and Heavy Metal Pollution Index (HPI) in all samples are higher than 3 and 75, respectively, confirming the high level of pollution in the samples. The Water Hazard Index (WHI) values of the studied samples are lower than 5, indicating the non-toxicity of the target elements. The high concentration of potentially toxic elements in water, sediments and slime samples of Semnan Spa should be taken into account by people who use the Semnan spas for therapeutic purposes.