The potential toxic element contents of Berriasian–Aptian carbonate rocks: distribution of elements in dolomite and limestone and possible sources (Gümüşhane/NE Türkiye)

The aim of this study is to determine the potential toxic element (PTE) content linked to the geochemical features of Berriasian–Aptian carbonate rocks commonly outcropping in Gümüşhane, along with the degree of pollution and possible sources of these toxic elements, and to compare dolomite with limestone in terms of toxic metal abundance. In the field, dolomite and limestone samples were collected by measuring stratigraphic sections around Yuvacık, Ünlüpınar, Çukutbaşı, Bağlarbaşı, Mescitli and Gülaçar (Gümüşhane). The samples were analyzed using inductively coupled plasma mass spectroscopy (ICP-MS). The mean values for Mo, Cu, Pb, Zn, Ni, As, and Co were 3.1, 23.8, 7.1, 14.5, 13.5, 30.9, and 8 mg/kg in Yuvacık; 6, 2.3, 1.1, 3.5, 8.1, 12.3 and 2.5 mg/kg in Ünlüpınar; 17.9, 1.8, 1.5, 8.6, 7.9, 13.9 and 1.7 mg/kg in Çukutbaşı; 3.7, 6.5, 31.7, 82.7, 9.5, 32.0 and 1.9 mg/kg in Bağlarbaşı; 0.7, 0.7, 7.1, 21.3, 2.6, 11.8 and 0.7 mg/kg in Mescitli; and 1.2, 1.1, 2.4, 5.2, 1.3, 4.0 and 0.2 mg/kg in Gülaçar, respectively. According to geochemical pollution parameters [geo-accumulation (Igeo), pollution index (Pi), and pollution load index (P_ln)], the rocks were generally significantly polluted by Mo and As, without notable pollution by the other elements. Limestone samples from the Yuvacık, Ünlüpınar, and Çukutbaşı areas were more polluted in terms of Mo and As compared to dolomites. This pollution in Yuvacık and Ünlüpınar was identified to have geogenic sources (Pb–Zn–Cu mineralization) and in Çukutbaşı was identified to have lithogenic sources. Dolomites from the Bağlarbaşı area were more polluted in terms of As and less polluted in terms of Mo compared to limestones. In the Mescitli location, both dolomites and limestones were occasionally polluted in terms of As, while limestones were polluted in terms of Mo. In these two areas, the sources of As and Mo are geogenic (Pb–Zn mineralization), In Gülaçar, dolomites were more polluted in terms of Mo and less polluted in terms of As compared to limestones. In this locality, As and Mo are thought to have a geogenic source (Pb–Zn–Cu mineralization).