Toxicity and removal of heavy metals (cadmium, copper, and zinc) by Lemna gibba |
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Authors: | Smain Megateli Saida Semsari Michel Couderchet |
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Institution: | 1. Laboratoire d’amélioration des plantes, département des Sciences Agronomiques, Université Saad Dahlab, BP 270, route de Soumaa, Blida 09000, Algérie;2. Laboratoire de génie chimique, département de génie des procédés, Université Saad Dahlab, BP 270, route de Soumaa, Blida 09000, Algérie;3. Laboratoire des plantes, pesticides et développement durable, URVVC-SE. Université de Reims Champagne-Ardenne, BP 1039, 51687 Reims cedex 02, France |
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Abstract: | Effects of cadmium, copper, and zinc on the aquatic plant Lemna gibba were determined under controlled conditions; in parallel their removal from the growth medium was followed. The results showed that the three heavy metals affected growth, a physiological stress index defined as the ratio of Chlorophyll to phaeophytin (D665/D665a), and the contents of proline. After 4 days, 10−3–10−1 mg/L Cd inhibited growth by 25–100%, reduced D665/D665a by 35–89%, and increased proline content by 44–567%. Under the same conditions, 10−4–10−1 μg/L Cu inhibited growth by 36–75%, reduced D665/D665a by 19–81%, and increased proline content by 67–288%. Comparable concentrations of Zn had little effect. However, higher concentrations (4, 30, and 50 mg/L) inhibited growth by 50–79%. Also, 0.1 and 30 mg/L induced a small reduction of D665/D665a (−3.8% and −22%) and an increase in proline contents (+144% and +177%). When it was observed, proline accumulation was always transient and the maximum was reached after 4 days. Monitoring metal concentration in the medium showed that L. gibba was able to remove metals from the medium. Zn and Cu removal was biphasic, it was rapid during the first 2 days (> 60% reduction) and slow (10–20%) during the following 8 days. For Cd, removal was linear and depended on the initial concentration. It reached approximately 90% after 6 or 8 days for initial concentrations of 10−1 and 10−3 mg/L, respectively. |
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Keywords: | Heavy metals Toxicity Lemna gibba Phytoremediation |
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