98 research outputs found
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Influences of cadmium and zinc interaction and humic acid on metal accumulation in Ceratophyllum demersum
Interactions between Zn and Cd on the accumulation of these metals in coontail, Ceratophyllum demersum were studied at different metal concentrations. Plants were grown in nutrient solution containing Cd (0.05–0.25 mg l−1) and Zn (0.5–5 mgl−1). High concentrations of Zn caused a significant decrease in Cd accumulation. In general, adding Cd solution decreased Zn accumulation in C. demersum except at the lowest concentration of Zn in which the Zn accumulation was similar to that without Cd. C. demersum could accumulate high concentrations of both Cd and Zn. The influence of humic acid (HA) on Cd and Zn accumulation was also studied. HA had a significant effect on Zn accumulation in plants. 2 mg l−1 of HA reduced Zn accumulation at 1 mg l−1 level (from 2,167 to 803 mg kg−1). Cd uptake by plant tissue, toxicity symptoms and accumulation at 0.25 and 0.5 mg l−1, were reduced (from 515 to 154 mg kg−1 and from 816 to 305 mg kg−1, respectively) by addition of 2 mg l−1 of HA. Cd uptake reached a maximum on day 9 of treatment, while that of Zn was observed on day 15. Long-term accumulation study revealed that HA reduced toxicity and accumulation of heavy metals
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Batch and continuous packed column studies of cadmium biosorption by Hydrilla verticillata Biomass
The removal of heavy metal ions by the nonliving biomass of aquatic macrophytes was studied. We investigated Cd biosorption by dry Hydrilla verticillata biomass. Data obtained in batch experiments indicate that H. verticillata is an excellent biosorbent for Cd. Cd was rapidly adsorbed and such adsorption reached equilibrium within 20 min. The initial pH of the solution affected Cd sorption efficiency. Results obtained from the other batch experiments conformed well to those obtained using the Langmuir model. The maximum adsorption capacity qmax for H. verticillata was 15.0 mg/g for Cd. The breakthrough curve from the continuous flow studies shows that H. verticillata in the fixed-bed column is capable of decreasing Cd concentration from 10 to a value below the detection limit of 0.02 mg/l. The presence of Zn ions affected Cd biosorption. It can be concluded that H. verticillata is a good biosorbent for treating wastewater with a low concentration of Cd contaminants
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Plant screening and comparison of Ceratophyllum demersum and Hydrilla verticillata for cadmium accumulation
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