Lead and zinc determinations in Festuca arundinacea and Cynodon dactylon collected from contaminated soils in Tandil (Buenos Aires Province, Argentina)

摘要

Heavy metal soil contamination is one of the most serious environmental problems, considering both their persistence and progressive accumulation which makes possible the transference to other systems, and could potentially affect human health and ecosystems functioning. The total concentration of lead (Pb) and zinc (Zn) in soil and plant samples from Festuca arundinacea and Cynodon dactylon naturally developed (in situ) and within experimentally contaminated soils (ex situ) was measured. Pb and Zn obtained results showed that the average values in industrial soils were significantly higher (p < 0.0001) than those corresponding to controls values (472 % more for Pb and 288 % more for Zn). There was a positive significant correlation between Pb levels in soil and roots (r = 0.99) and leaves (r = 0.98) of C. dactylon, and between Zn levels in soil and roots (r = 0.94) and leaves (r = 0.91) of C. dactylon. Festuca arundinacea plants were experimentally exposed to Pb-contaminated soil during different times (0, 5 and 10 days). Two indicators were calculated: the bioaccumulation factor (BCF) and translocation factor (TF). Five day BCF was 0.25, while for 10 days one was 0.72. This showed that the value of BCF varied according to the exposure time, and F. arundinacea showed to be highly tolerant to Pb species. TF was low (T-1: 0.18 and T-2: 0.09) because the higher accumulation occurred in roots. Considering that roots of F. arundinacea and C. dactylon were their largest metals reservoir, they could be used as indicators of metal contamination within soils.