Elementos potencialmente poluidores em solo construído de mineração de carvão sob o cultivo de gramíneas perenes aos 8,6 e 20 anos

Abstract

Coal mining causes significant environmental impacts, including soil degradation and contamination by potentially toxic elements (PTEs). This study investigated the dynamics of these elements in constructed soils from a mined area in Candiota, RS, cultivated with perennial grasses for 8.6 and 20 years. Soil samples were collected from the 0–0.10 m and 0.10–0.20 m layers, and PTEs were extracted using the Mehlich-1, DTPA, and USEPA 3050B methods. Additionally, PTE contents were analyzed in the tissues of the grasses Hemarthria altissima, Cynodon dactylon, and Urochloa brizantha. The results indicated that Cu, V, Ba, and Cr levels exceeded the reference values. For Mn, which lacks reference values, the Mehlich-1 and DTPA methods extracted higher amounts than USEPA 3050B, suggesting greater availability of this element to plants. The calculated contamination factor (CF) and pollutant load index (PLI) values indicated moderate pollution in the studied soils. Among the evaluated grasses, Urochloa brizantha exhibited the lowest PTE levels in the soil, highlighting its potential for reducing the mobility of these elements in mined areas. No Zn or V was detected in plant tissues, and except for Ba, no significant differences were observed in the absorbed PTE levels among species. These results demonstrate that both restoration age and plant species selection substantially impact PTE dynamics in constructed soils, contributing to the development of more effective and sustainable strategies for the environmental recovery of mined areas.