Integrated approach to assess the environmental impact of mining activities: estimation of the spatial distribution of soil contamination (Panasqueira mining area, Central Portugal)

摘要: Through the years, mining and beneficiation processes in Panasqueira Sn-W mine (Central Portugal) produced large amounts of As-rich wastes laid up huge tailings open-air impoundments (Barroca Grande Rio tailings) that are main source pollution surrounding area once they exposed to weathering conditions leading formation acid drainage (AMD) consequently contamination environments, particularly soils. The active started exploration during nineteenth century. This study aims look at extension soil due activities tailing erosion by combining data on degree allows a better understanding dynamics inherent leaching, transport, accumulation some potential toxic elements their environmental relevance. Soil samples were collected soils mine, digested aqua regia, analyzed for 36 inductively coupled plasma mass spectrometry (ICP-MS). Selected results (a) an association like Ag, As, Bi, Cd, Cu, W, Zn strongly correlated controlled local sulfide mineralization geochemical signature was revealed; (b) global discloses significant concentrations W linked exchangeable acid-soluble bearing phases; (c) wind promotes mechanical dispersion rejected materials, from milled waste rocks mineral processing plant, with subsequent deposition waters. Arsenic- sulfide-related heavy metals (such as Cu Cd) associated fine materials transported suspension surface waters or acidic waters, draining these sites contaminating Part this fraction, especially is temporally retained solid phases precipitation soluble secondary minerals (through hydrated metal sulfates) warm, dry periods, but such easily dissolved rainy periods. Climate important instability factor, hot summers cold, rainy, windy winters region physical phenomena enhance good receptivity retain present primary also mineralogy. Considering obtained both sequential chemical extraction risk assessment according code, classified very high while As medium risk.