Variability Of The Cadmium Content In HypericumSpecies Collected In Eastern Austria

In Hypericumspecies some specimens have been found to display higher levels of the toxic heavy metal Cd than the proposed guide value of 0.5mgkg. Plant and soil samples from various regions in Eastern Austria were collected to study the variability in the Cd content of the herbs and relate it to selected soil properties and soil micronutrient contents. The soils contained between 0.01 and 0.44mgkg−1Cd in the dry soil. Altogether about 7% of the collected plant samples exceeded 0.5mgkg−1Cd of dry shoots, the proposed guide value for the drug Herba Hyperici. Plants low in Cd were found on sites in the Alpenvorland, the Hainburger Berge, the Eastern Viennese Basin and the Northern Limestone Alps where the levels did not exceed 0.3mgkg−1Cd of dry shoots. Higher Cd levels in the plants were present in material from the Waldviertel, the Southern Wienerwald and the Semmering region where often bioaccumulation factors for Cd above 1 could be calculated. In these regions the soil pH and carbonate content was somewhat lower than in other regions whereas the soil organic carbon varied greatly. In the Waldviertel some plants from a field were somewhat higher in Cd than nearby plants from the natural vegetation. In a regression analysis, the soil pH, soil organic carbon and soil Cd content were the main factors influencing Cd accumulation in the plant shoots.