The content of heavy metals in crops grew in metallically polluted region of Slovakia | Obsah ťažkých kovov v poľnohospodárskej produkcii dopestovanej v metalicky zaťaženom regióne Slovenska

The quality of the environment of surveyed locality is the subject of interest of many authors, whose effort is the finding of suitable solving quality agricultural production available for human nutrition. Target of this investigation was to evaluate the level of heavy metal contamination of monitored area of Štiavnica region (central Slovakia), where the source of contamination is long-lasting mining industry in close Štiavnica hills. Innundant area of Štiavnica stream which is a vector of soil profile area contamination was exposed to negative effects. In soil samples from 0.0–0.2 m horizons the physical-chemical characteristics (active soil reaction (pH/H2O), exchangeable soil reaction (pH/KCl), C organic (Corg.), humus, sand, silt, clay) were determined. The total content of heavy metals by aqua regia extract (HNO3 + HCl 1 : 3) and mobile forms in extract NH4NO3 c = 1 mol per cubic dm (MP SR 2004) using atomic absorption spectrometry method (AAS) by instrument VARIAN AA 240 FS were determined. The sample of plants maize (Zea mays L.) and oat (Avena sativa L.) grains to the same place were collected the soil sample after their dryining, regulation and decomposition by HNO3 on the microwave digestion instrument MARRS X-PRESS. The solutions were analyzed by graphite furnance GFAAS VARIAN AA 240 Z. The obtained results were evaluated by mathematical-statistical methods – multiple range analysis by program STATISTICA 6.0. Achieved data were compared to allowed limit values. Total content of heavy metals in soil fluctuated highly above allowable concentration, Cd: 7.12–15.04 mg per kg (limit exceeded to 2,148 percent); Pb: 612–1,526 mg per kg (limit exceeded to 2,180 percent); Zn: 822–2,084 mg per kg (limit exceeded to 1,389 percent) and Cu: 65.0–121.6 mg per kg (limit exceeded to 210 percent). Selected land was monitored in years 2006–2008 and extreme high contents of mobile fraction of analyzed soil contaminants affected also growth production of maize (Zea mays L.) and oat (Avena sativa L.) grains. According to results obtained in this study these grains are not allowed for food industry.