Distribution and mobility of arsenic and antimony at mine sites in FYR Macedonia.

摘要

Soils, river sediments and waters from former As-Sb mining sites in FYR Macedonia have been chemically analysed to assess their impact on the local environment. Soils and river sediments contain very high concentrations of As and Sb (medians 117 and 37 mg kg-1), but values are heterogeneously distributed. These values are far in excess of various statutory thresholds and at the largest deposit, Lojane, the area is grossly contaminated. Sequential extraction has demonstrated that a large proportion of the As (50-90%) and Sb (20-60%) in these soils is in a weakly-bound form and is thus available for further mobilization. Surface and groundwaters are neutral to alkaline because of interaction with host lithologies (e.g. serpentinite, dolomite and limestone). Surface waters appear to have higher concentrations of As (55;33) and Sb (2.1;0.6) than the groundwaters (medians, υg/l). For all samples there is a close positive correlation between As and Sb, but As contents are generally much higher than those for Sb. Most of the waters have As concentrations which exceed the 10 υg l-1 value accepted for safe drinking water whereas most Sb concentrations are much lower and appear to be within the acceptable limits for this element. The alkaline waters have been able to mobilize the As and Sb directly from the primary ore minerals and the lack of pyrite in the ores has minimized the production of secondary Fe oxides which could adsorb and immobilize these elements. These sites are environmental ‘hotspots’ and need remediation. The reservoir of As and Sb which is able to be released over a long time period threatens a much larger area. Remediation strategies would have to take the mobility of these elements under alkaline conditions into account.