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Research on the Toxicity of Heavy Metals on Chlorella sp. and the Adsorption of Hg2+ by Chlorella sp.

Author: ShiLei
Tutor: JiangBinHui；ShiJian
School: Northeastern University
Course: Environmental Engineering
Keywords: heavy metal chlorella sp. toxicity absorption desorption
CLC: X173
Type: Master's thesis
Year: 2009
Downloads: 185
Quote: 0
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Abstract


With the increasing movement of the humanity and natural migration of the material, heavy-metal contamination appeared in a variety of environments, which caused a serious threat to human health and ecological balance. The algae are the primary producers in aquatic ecosystems, and they play a very important role in the food chain. With the further understanding of heavy metal pollution, the researches on toxicity effect as well as its mechanism of heavy metals on algae are increasing. The research will be theoretically and practically valuable on toxicity effect and its mechanism of heavy metals on algae, for that could reveal heavy metals to the toxicity of algae, assess the ecological risk of heavy metals, and reduce its toxic effects.In this paper, we selected heavy metals contamination on the strong role of direction for the study of chlorella sp. the best conditions were determined for 4 kinds of heavy metal ions (Ni2+, Cd2+, Pb2+, Hg2+) on the growth of chlorella sp., and discussed the Hg2+ absorption factor of chlorella sp. in the impact and absorption in the best conditions, a preliminary study of Hg2+ desorption role.The results showed that the best develop conditions of chlorella sp. are pH for 8, 3660 Lux light intensity, and uninterrupted aeration for 84h.The toxicity of 4 kinds of heavy metals to chlorella sp. was very strong, Ni2+, Cd2+, Pb2+, Hg2+of the 84hECso were 0.457ug/mL、0.083 ug/mL、0.162 ug/mL、0.041 ug/mL,and toxic order was Hg2+> Cd2+> Pb2+>> Ni2+.All the 4 kinds of heavy metal ions could restrain chlorella sp. the growth of chlorella sp.. This impact was obvious even at just a small concentration of heavy metal ions. With the increasing concentration of heavy metals, the chlorophyll content reduced, the color faded, chlorella sp. cells became flat and smaller slightly and chlorella sp. cells form of significant change.Chlorella sp. cells can absorb heavy metals and the environment is conducive to the removal of heavy metals.The results of a series experiments was that the absorption rate of Hg2+ remained in 80% or more in the best absorption conditions. The adsorption process can be described by more Langmuir models than Freundlich models. Which showed chlorella sp. has a good adsorption performance to Hg2+, and also proved that chlorella sp. has a certain value of practical application as a good absorbent to Hg2+.Chlorella sp. to Hg2+desorption conditions test show:When ultrasonic was 5 min and pH was 7,the desorption rate was 30.5 percent.

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CLC: > Environmental science, safety science > The basic theory for the Environment and Science > Environmental Biology > Environmental botany
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