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[Effects of lower concentrations of Cd on micronutrients uptake and production of phytochelatins (PCs) in Ceratophyllum demersum].

A solution experiment with a range of lower cadmium concentrations (0.01-0.64 micromol/L) was conducted to study micronutrients uptake and production of phytochelatins (PCs) in a submerged aquatic plant Ceratophyllum demersum after exposure for 7 d, 14 d, 21 d. The results showed the uptake of Cu, Zn in Ceratophyllum demersum was promoted when exposed to lower concentrations of cadmium, whereas Mn uptake was inhibited. Unlike Cu, Zn and Mn, the content of Fe was unaffected by Cd uptake. Our data showed that Ceratophyllum demersum had stronger Cd tolerance and obvious absorption and cumulative effects to external lower concentrations of Cd exposure. The inhibition of growth was observed after 21 d in 0.08 micromol/L Cd. The production of PCs was significantly induced by 0.02-0.64 micromol/L Cd for 7 d (p < 0.05), while declined after exposure for 14 d, 21 d. The good dose-related response of PCs was observed in manner of linear for 7 d and parabola for 14 d and 21 d. Regressive analysis showed that there was a significantly positive correlation between PC contents and Cd toxicity in Ceratophyllum demersum. The results suggested that PCs could be a sensitive biomarker for estimating Cd phytotoxicity and subsequently a qualitative tool for studies on Cd contamination.