Nickel hyperaccumulation by natural plants in Turkish serpentine soils

Natural plants in Turkish serpentine soils were surveyed to determine their Ni accumulation capability. Geographic distribution and diethylene triamine pentaacetic acid (DTPA)-extractable nickel contents of the western Anatolian serpentine soils and their vegetative contents were studied to find the possible relationships between the phytoavailable Ni amount in the soil and the Ni content of potential accumulator plants. Over half of the surface area of Turkey was targeted in the study. Aboveground parts of 413 herbaceous plants and the surface soil (0-15 cm) of 192 serpentine samples were collected. A digital elevation model and ANUSPLIN and ArcGIS 8.1 software packages were employed for generation of climatic surfaces and analysis in preparation of comparative maps. Scientifically approved Ni hyperaccumulator plant taxa as well as readily emerging species were tested under greenhouse and climate chamber conditions. The varying magnitude of nickel determined in the aboveground parts of the test plants indicated that the resistance or vulnerability and Ni requirements of a plant species were species-specific and were more effective than the Ni amount in the soil on the uptake of the element. Significant differences were found between the amount of DTPA-extractable Ni in the soil and the Ni content of hyperaccumulator Brassicaceae plants grown in the same soil bodies. Isatis pinnatiloba, which is endemic to Turkey, was introduced as a nickel hyperaccumulator species. Bottlenecks and drawbacks of phytoremediation techniques for commercial use were discussed.