Bioavailability of tungsten and associated metals in calcareous soils in the vicinity of an ancient metalliferous mine in the Corbières area, southwestern France.

The mobility and bioavailability of tungsten and associated metals are examined in calcareous soils and subsequent bioaccumulation by four species of plants is determined. Apparent bioavailability of metalliferous cations indicated by accepted monitoring methods and actual bioaccumulation is compared using regression analysis. Two soil extraction procedures were used without significant correlation between the methods at all stages, with the exception of copper and arsenic. More importantly, perhaps, the bioaccumulation by various tissues of Buxus sempervirens did not significantly correlate for the majority of target metals for each extraction procedure. Possible accumulation of toxic cations by a dying tree species was also examined. The availability of tungsten and associated metals in calcareous soils was compared with previous investigations on acidic soils, resulting in confirmation that tungsten in particular, in naturally occurring ores, is more readily mobilized under alkaline conditions.

An evaluation of the bioavailability and bioaccumulation of selected metals occurring in a wetland area on the volcanic island of Guam, Western Pacific Ocean.

This initial research examined the presence, distribution and bioavailability of Cu, Cr, Ni, Mn and Fe in a wetland area of southern Guam. The research sites are within an area covered with saporite, a soil type derived from volcanic deposits on the island. Leaf tissue of Pandanus tectorius was extracted and analysed to determine the bioaccumulation of the target metals. Metal accumulation at sites considered aerobic and anaerobic was investigated together with an attempt to correlate actual accumulation of the target metals in the plant tissue with a recognised bioavailability indicator, in this case, three step sequential extraction scheme. Manganese was found to be accumulated in relatively high concentrations and to a lesser extent Cu was also accumulated. Chromium, Ni and Fe however exhibited very low accumulation factors. Accumulation of Mn in particular was significantly affected by aerobic conditions whereas the converse effect was experienced by Cu. Significant correlation between various steps of a Sequential Extraction Scheme and actual accumulation was not achieved although the degree of aerobic conditions at each site and soil pH did affect concentrations of metals extracted by differing steps of SES. Results obtained suggest that further research in the area should be undertaken using different plant species and tissues.

Bio-availability of tungsten in the vicinity of an abandoned mine in the English Lake District and some potential health implications.

This research addresses the occurrence, detection and possible fate of tungsten in the vicinity of an abandoned mine in the English Lake District. Aqua regia extraction and subsequent analysis of spoil and vegetation confirmed the presence of tungsten and other heavy metals. Spoil samples examined were last worked almost 100 years ago and the concentrations of copper, zinc, tungsten and arsenic detected demonstrate the environmental persistence of these metals in an area of relatively high rainfall. The bioaccumulation of tungsten by two species of plants is indicated and partitioning within different tissues of Calluna vulgaris is demonstrated. Mechanisms relating to mobility and speciation of the metals present were explored using sequential and single stage extraction systems. Tungsten appears to be relatively immobile when subjected to sequential extraction but increased bioavailability is indicated when single stage extraction using EDTA is employed.

The dispersion of heavy metals in the vicinity of Britannia Mine, British Columbia, Canada.

Britannia Mine in British Columbia, Canada, is a major source of copper and other heavy metal pollutants, which enter the sea at Howe Sound. This investigation aims to determine whether there is sufficient Cd, Cu, Pb, and Zn, in the terrestrial environment surrounding the mine to suggest that dispersion and subsequent bioaccumulation has occurred in the past and continues. Samples of spoil, vegetation, and water were collected in January 2003 from areas at sea level and up to an altitude of 790 m. The samples of soil and vegetation were digested with aqua regia. The subsequent extracts and water samples were analyzed using flame atomic absorption spectrophotometry. The target metal concentrations were found to be much higher on the hillside spoil tips than on the seashore where the ore concentrators had formerly been located. The dispersion of heavy metals into the surrounding biosphere is discussed and further investigations into dispersion and partitioning within organisms including humans are suggested.