Journal of Ecology and Rural Environment ›› 2018, Vol. 34 ›› Issue (2): 161-168.doi: 10.11934/j.issn.1673-4831.2018.02.009

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Impacts of Biochar Derived From Activated Sludge on Ecotoxicity of Cd in Sediment

TIAN Bin1, WANG Meng2, CHEN Huan-yu1, LIANG Cui1, GONG Shuang-jiao1, MA Tao-wu1   

  1. 1. College of Biology and Environmental Sciences, Jishou University, Jishou 416000, China;
    2. College of Environmental Science and Engineering, Tongji University, Shanghai 200092, China
  • Received:2017-08-09 Online:2018-02-25 Published:2018-02-09


Biochar has emerged as an important green environmental sorbent of great potential in in-situ remedying contaminated soils and water. However, little is known regarding how biochar mitigates potential ecotoxicity risks of the pollutants in the environment through interaction with the pollutants. To evaluate the effects of biochar on ecological toxicity of cadmium (Cd), a heavy metal element, in sediments, Cd bioaccumulation, DNA damage, superoxide dismutase (SOD) activities and malondialdehyde (MDA) levels in the hepatopancreas of benthic macroinvertebrate Bellamya aeruginosa following 14-day exposure to sediments spiked with Cd and/or activated-sludge-derived biochar were investigated. Results show that activated-sludge-derived biochar significantly reduced Cd content in porewater. In the treatments relatively low in Cd concentration (10 μg·g-1), the addition of biochar did not significantly reduce Cd bioaccumulation, while in the treatments relatively high in Cd concentration (50 μg·g-1), the addition of only 5% of biochar was enough to significantly reduce Cd accumulation. The applied activated-sludge-derived biochar was not toxic to B. aeruginosa. In the treatments spiked with 10 μg·g-1, no effect of biochar affecting DNA damage index, SOD activities, and MDA contents in the hepatopancreas was observed, indicating the addition of biochar in sediments low in Cd content did not mitigate Cd toxicity. In the treatments spiked with 50 μg·g-1, the addition of 1% biochar did not show any effect on Cd toxicity, either, however, the addition of 5% biochar significantly alleviated DNA damage, increased SOD activity, lowered MDA levels, and estimatedly reduced Cd toxicity by about 60%. It could, therefore, be concluded that reduced bioavailability of Cd in sediments does not invariably lead to decreased bioaccumulation in B. aeruginosa. The application of biochar at a high rate in sediments may reduce Cd bioaccumulation and hence Cd toxicity to some extent through inhibiting Cd adsorption. The effects of biochar alleviating ecotoxicity of pollutants in sediments may possibly be related to type and concentration of the pollutant and amendment rate of biochar.

Key words: activated sludge, biochar, sediment, Cd, Bellamya aeruginosa, ecotoxicity

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