Environmental impact of potentially toxic elements on soils, sediments, waters, and air nearby an abandoned Hg-rich fahlore mine (Mt. Avanza, Carnic Alps, NE Italy)

Abstract

The decommissioned fahlore Cu-Sb(-Ag) mine at Mt. Avanza (Carnic Alps, Italy) is a rare example of exploited ore deposits, as the tetrahedrite (Cu6[Cu4(Fe,Zn)2]Sb4S13) is the main ore mineral found. This multi-compartmental geochemical characterisation approach provides one of the first case studies regarding the geochemical behaviour and fate of Hg, Sb, As, Cu, and other elements in solid and water matrices and of Hg in the atmosphere in an environment affected by the mining activity of a fahlore ore deposit. Elevated concentrations of the elements (Cu, Sb, As, Pb, Zn, Hg) associated with both (Zn-Hg)-tetrahedrite and to other minor ore minerals in mine wastes, soils, and stream sediments were observed. Concentrations in waters and stream sediments greatly decreased with increasing distance from the mining area and the Igeo index values testify the highest levels of sediment contamination inside the mine area. Thallium and Ge were associated with the “lithogenic component” and not to sulfosalt/sulphide minerals. Although mine drainage water often slightly exceeded the national regulatory limits for Sb and As, with Sb being more mobile than As, the relatively low dissolved concentrations indicate a moderate stability of the tetrahedrite. The fate of Hg at the investigated fahlore mining district appeared similar to cinnabar mining sites around the world. Weak solubility but the potential evasion of gaseous elemental mercury (GEM) into the atmosphere also appear to be characteristics of Hg in fahlore ores. Although GEM concentrations are such that they do not present a pressing concern, real-time field surveys allowed for the easy identification of Hg sources, proving to be an effective, suitable high-resolution indirect approach for optimising soil sampling surveys and detecting mine wastes and mine adits.

Bioaccumulation and Potential Risk Assessment of Heavy Metals in Tropical Bamboo Plantations of Dendrocalamus brandisii under Two Cultivation Patterns in Yunnan, China

“…Central Yunnan was renowned for its abundant gold deposits [45]. The long-term mining activities in the study area could lead to the enrichment of As in the soil [46,47]. In this study, soil Profile 2 and Profile 3 near an active gold mine exhibited significantly high As concentrations in all soil layers; even the As content of the surface soil in Profile 3 was 1.7 times higher than the permissible limit (Figure S3).…”

“…With the prosperity in industry and mining and the excessive use of dirty irrigation, the soils and crops of some farmlands and forestlands in the arid zone of China have accumulated a large number of HMs [48]. In this study, the investigated area was characterized by a developed mining industry and high background values of soil HMs, thus posing a potential threat to human health and the ecological environment [45,47]. Fortunately, our results indicated that the bamboo shoots of D. brandisii had a low health risk to adults based on the HM content in the study area (Figure 4a).…”