a) Location map where grow at the same site species of the genus Viola : b) V. allcharensis G. Beck, c) V. arsenica G. Beck, and d) V . macedonica Boiss. & Heldr (color figure available online). 

Contexts in source publication

Context 1

... regions of the Balkans, and belongs in to the Balkan endemic species group (Micevski 1995). From six sampling points (Fig. 2, 1–6), plant and soil samples were collected in the summer of 2011 (Table 1), at the Majdan locality around the abandoned mine described above (Fig. 2a). Soil samples were chosen based on the presence of the three Viola species. At each study site, soil samples (5–10 replicates) were taken from the rhizosphere of plant specimens. The eventually present organic horizon was excluded. The soil samples were air-dried indoors, after which they were cleaned of extraneous material and sifted through a plastic sieve with a 2 mm mesh. For chemical analysis, this fraction was ground in an agate mill to below 0.125 mm. Plant species were sampled according to their abundance and biomass: 10–20 replicates in the case of V. arsenica, V. macedonica, and V. allcharensis. It must be mentioned that in the period when these plants samples were collected, only the samples 1, 4, and 5 had seeds. The whole plant samples were washed carefully with bidistilled water to remove soil particles, and then separated into roots, stems, leaves, flowers and seeds. The plant material was dried and homogenised to a constant weight at room temperature for 5–10 days. Plant samples (0.5000 g) were placed in a Teflon digestion vessels, 5 ml HNO 3 (69%, m/V ) and 2 ml H 2 O 2 (30%, m/V ) were added, and the vessels were capped closed, tightened and placed in the rotor of the Mars microwave digestion (CEM, USA). Plant samples were digested at 180 ◦ C. After cooling, the digested samples were quantitatively transferred into 25 ml calibrated flasks. For total digestion, soil samples (0.2500 g) were placed in a Teflon digestion vessel and were digested on a hot plate. In the first step, HNO 3 was added to remove all organic matter, then a mixture of HF and HClO 4 was added, followed by a third step where HCl and water were added to dissolve the residue. The solution was transferred quantitatively to the 25 ml volumetric flask. Three methods were applied for the study of the plant-availability of the elements: extraction in 0.1 M HCl for 1 h and filtered with an acid-resistant filter; extraction with H 2 O and extraction of the soluble species of trace elements in a mixed buffered solution (pH = 7.3) of triethanolamine (0.1 mol l − 1 TEA) with CaCl 2 (0.01 mol l − 1 ) and diethylen- etriaminepentaacetic acid (DTPA, 0.005 mol l − 1 ) according to the ISO 14870 method. The extracts were filtered through filter paper, diluted with bidistilled water into 25 ml calibrated flasks and then analysed for element ...

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... The Allchar deposit is classed as large in terms of Tl reserves (over 500 t) (Volkov et al. 2006). Three species of the genus Viola grow at the same site, around the abandoned As- Sb-Tl-Au mine of Allchar: Viola arsenica G. Beck, Viola allcharensis G. Beck, and Viola macedonica Boiss. & Heldr. (Fig. 2). All species belong to the section Melanium Ging. of the family Violaceae . According to Erben (1985), in the Southeast Europe there are 50 species of Scect. Melanium , 28 of which are known to be located within the Republic of Macedonia. The investigated species are autochthonous plants, endemic to the Balkan Peninsula. V. arsenica and V. allcharensis grow only in the locality of Allchar, and are considered to be local endemic species, while V. macedonica is widespread in central ...