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| In situ remediation of heavy metals in aquaculture pond sediment by wheat straw biochar addition |
| Received:April 20, 2022 |
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| KeyWord:wheat straw biochar;aquaculture sediment;heavy metal;in situ remediation |
| Author Name | Affiliation | E-mail | | DU Shengnan | College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China | | | ZHANG Hanlin | College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China | | | ZHAO Hanyin | College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China | | | CHEN Yiqin | College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China | | | LI Juanying | College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China | jyli@shou.edu.cn |
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| Abstract: |
| The pollution of farming substrates, as the carrier of the pond environment, directly affects the quality of aquatic products. Thus, the development of approaches to ensure the quality and safety of aquatic products and human health is of great importance. In this study, wheat straw biochar was applied as a remediation agent to heavy metal-contaminated farming substrates in situ. Samples were then collected using a thin-film gradient diffusion device over various periods of aquaculture after biochar addition, and changes in the accumulated heavy-metal concentration, risk factor, bioavailability, and diffusion flux at the sediment-water interface were evaluated. The addition of wheat straw biochar decreased the accumulation of the heavy metals Cr, Cu, Pb, and Cd in aquatic products by 15%-55%, and the overall decrease in the accumulated concentration of these metals showed the order of Cd>Pb>Cr>Cu. The decrease rates of these metals in benthic organisms were higher than those in fishes. The maximum decrease rates of Pb and Cd reached 39% in the seedling stage, whereas the maximum decrease rates of Cu（40%）and Cr（24%）occurred in the growth stage. The decrease rates of the target hazard factors of the heavy metals also ranged from 15% to 55%, similar to the decrease rates of their accumulated concentration. During in situ wheat straw biochar remediation, the concentrations of the four heavy metals in the pore water decreased most rapidly during the seedling stage. After complete remediation, the concentrations of Cu, Pb, Cd, and Cr decreased by 21%, 48%, 71%, and 19%, respectively. Calculations of the apparent diffusion flux of each heavy metal at the sediment-water interface during the restoration period showed that the addition of biochar to the substrate not only enhanced the function of the substrate as a sink and promoted the deposition of heavy metals from the water column into the aquaculture sediment, but also reduced the heavy-metal content of aquatic organisms. |
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