Spolic Technosols pollution assessment based on the cumulative maximum concentration index: a case study for the north-east of the Eastern Carpathians (Romania)

This study reports on the potential of a newly introduced indicator, the maximum cumulative concentration index (MCCI), for ranking spolic Technosols. For the pairs of Technosols–reference soils, trace elements (TE) (Sr, Pb, As, Se, Cr, Mo, Mn, Co, Ni, Cu, and Zn) were analysed using the ICP-MS technology. The concentration factor (FC) reveals a high degree of Sr contamination of the site located near the dolomite quarry (P6). The maximum concentration index (MCI) was calculated for the TE concentration in the parent material, for the threshold-lower guideline value (R1) and threshold-higher guideline value (R2). The results show that selenium (Se) ranges in (R2) due to the elevated Se concentration specific to the rocks pertaining to the Tulghes Group. However, the data do not support the hypothesis of Sr contamination. The MCCI is a ranking tool that uses a set of common elements to assess soil quality. The Ni and Se cluster dendrogram shows that all profiles rank above the (R1) range, with the exception of the reference soil evolved on limestone (P6). These results reveal a higher degree of contamination in soils which formed on Mn carbonate (P7) and shale schists (P9). Result validation was performed for three elements (As, Cu, Mn) at P1, P7, and two profiles with similar geochemical characteristics reported in the literature. The cluster dendrogram places the four profiles within the R1–R2 interval, thus indicating ecological risk. MCCI is relevant for prioritising informed decision-making regarding the rehabilitation of mining dump sites and land use management.