Restoration of contaminated sediment using crop plants

This case study is focused to evaluate the feasibility of phytoextraction strategy to reduce boron level in sediments from the Cecina basin (Tuscany, Italy) and to limit its diffusion through the environment. The greatest part of Cecina basin is located in the geothermal zone of Larderello, where for about a hundred years mine activities were practiced and the geothermoelectric industry spilled in the Possera and Pavone creeks (tributaries of Cecina River) until the 70'es. Recent studies indicates that contamination is still present in certain area of the basin. The study was performed analyzing total and availahle B fraction in sediment samples. The sediment was investigated on the genotoxicity effect on plants by micronuclei assay on Vicia faba. Phytoextraction tests was performed to assess boron-tolerant plant species able to reduce the content of this metal in the sediments. Three high biomass crops (B. juncea, Z. mays and H. annuus) grew in the most contaminated sample in two consecutive grown. In minonuclei test the cytological analysis on primary root tips (3th day) showed no effect on mitotic activity of meristematic centers but a big presence of micronuclei was found (a frequency of 5% of micronuclei in contaminated soils compared to 1% in control). Moreover mitotic anomalies, as chromosome bridges, chromosome lagging and C-metaphases, were found. Phytoextraction tests showed that B. juncea were able to remove about 45% of the initial available B fraction in only two growing cycles.