engleski

SELENIUM AND TRACE METAL LEVELS IN VEGETABLES GROWN ON LAND CONTAMINATED WITH SUPERHIGH- ORGANIC-SULFUR RAŠA COAL AND ASH

Mining, processing and combustion of coal are potential sources of selenium and many trace metals which are being emitted into the surficial environment. There is an increasing concern about their effects on humans and animals consuming vegetables grown on land contaminated with coal and ash. One such locality is a Mediterranean Labin city area (east coast of the Istrian Peninsula, North Adriatic, Croatia). It has been a major source of the electricity production in Croatia since the early 20th century. Local Raša coal seams had been mined at six localities around Labin from the 17th century till late 1990s, while significant quantities of that coal were used in a local coal-fired power plant during the period 1970-2000. Raša coal is a one-of-a-kind coal, belonging to a class of superhigh- organic-sulfur coal (SHOS), as it contains exceptionally high levels of sulfur (up to 11- 14%) ; it is present in organic form, while it usually exists in inorganic mineral form in coal. Also, it is characterised by increased levels of selenium, up to 150 mg/kg, while its ash was found to have up to 70 mg/kg Se. This element is of a great concern as it is characterized by a narrow range between dietary essentiality and toxicity for life forms. Herewith, the Labin city area is a significant hotspot in terms of possible threat to local animal and people’s communities. Therefore, the aim of this study was to determine the concentrations of Se and potentially toxic trace metals in following vegetables: kale, lettuce, beet, zucchini, potato and a fruit Japanese apple (Diospyros kaki Linn.). Samples were collected within a vicinity of industrial areas of an old coal-mining Krapan town, and a former coal separation Štalije unit. Prior to acid digestion, edible parts were washed with tap and distilled water, and rinsed with deionized water. Element analysis was carried out by inductively coupled plasma instrument with mass detector Agilent ICP-MS system Model 7900, and data were expressed on fresh weight (µg/kg f.w.). The average values of analysed elements (Cr, Mn, Fe, Cu, Zn, As, Se, Mo, Cd, Pb) in the vegetable and fruit samples were as follows: 1420.3, 8499.5, 142865.7, 1985.0, 4367.2, 79.2, 214.6, 292.1, 28.9, and 272.7 µg/kg f.w., respectively. Average values of Cr, Fe, and Pb in analysed items were found to be elevated compared to the Croatian legislatively prescribed values. Although Se values were increased compared to the World relevant published levels, calculated Se levels were below the allowed daily intake doses in terms of food consumption. Herewith, the results of this study call for further research.

Raša coal ; selenium ; trace metals ; contamination ; vegetables ; fruit

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