School of Water Conservancy and Civil Engineering, Northeast Agricultural University, Harbin 150030, China; Research Center for Ecological Agriculture and Soil-Water Environment Restoration, Northeast Agricultural University, Harbin, Heilongjiang 150030, China; Heilongjiang Academy of Environmental Sciences Postdoctoral Joint Scientific Research Station, Harbin 150030, China.
School of Water Conservancy and Civil Engineering, Northeast Agricultural University, Harbin 150030, China; Research Center for Ecological Agriculture and Soil-Water Environment Restoration, Northeast Agricultural University, Harbin, Heilongjiang 150030, China.
Sci Total Environ. 2024 Jan 15;908:168385. doi: 10.1016/j.scitotenv.2023.168385. Epub 2023 Nov 11.
Rice crab coculture is a new ecological agriculture model combining rice cultivation and crab farming. Current research related to rice crab coculture only focuses on production theory and technical system establishment, while ignoring the potential ecological risk of Polycyclic aromatic hydrocarbon(PAHs) in rice crab coculture sediment. In this study, rice straw was used to make rice straw biochar to explore the performance and mechanism of inhibiting release of phenanthrene(PHE) from rice-crab coculture sediments to overlying water with rice stalk biochar. The kinetic and isotherm adsorption data were best represented by the Langmuir model and pseudo-second-order model with a maximum adsorption capacity of 53.35 mg/g at 12 h contact time. The results showed that PHE was released from the rice-crab substrate to the overlying water in dissolved and particle forms as a result of bioturbation, and the PHE concentrations in dissolved and particle forms were 20.9 μg/L and 14.22 μg/L, respectively. This leads to secondary ecological risks in rice-crab co-culture systems. This is related to dissolved organic carbon(DOC) carrying the dissolved PHE and total suspended solids(TSS) carrying the particle PHE in the overlying water. Due to its large specific surface area, rice straw biochar is rich in functional groups, providing multiple hydrophobic adsorption sites. After adding rice straw biochar at 0.5 % w/w (dry weight) dose, the removal efficiency of dissolved and particulate PHE in the overlying water were 78.99 % and 42.11 %, respectively. Rice straw biochar is more competitively adsorbed PHE in the overlying water than TSS and DOC. The removal efficiency of PHE from the sediment was 52.75 %. This study confirmed that rice stalk biochar could effectively inhibit PHE migration and release in paddy sediment. It provides an environment- friendly in situ remediation method for the management of PAHs pollution from crab crops in rice fields.
稻蟹共养是一种将水稻种植与蟹类养殖相结合的新型生态农业模式。目前，与稻蟹共养相关的研究仅关注生产理论和技术体系的建立，而忽略了稻蟹共养沉积物中多环芳烃（PAHs）可能带来的生态风险。本研究采用水稻秸秆制备水稻秸秆生物炭，探索了利用水稻秸秆生物炭抑制稻蟹共养沉积物中菲向水体释放的性能和机制。动力学和等温吸附数据最符合 Langmuir 模型和准二级模型，在 12 小时接触时间下的最大吸附容量为 53.35mg/g。结果表明，由于生物扰动作用，菲从稻蟹基质中以溶解态和颗粒态的形式释放到上覆水中，溶解态和颗粒态的菲浓度分别为 20.9μg/L 和 14.22μg/L，这会导致稻蟹共养系统中的二次生态风险。这与上覆水中溶解态菲携带的溶解性有机碳（DOC）和颗粒态菲携带的总悬浮固体（TSS）有关。由于水稻秸秆生物炭具有较大的比表面积和丰富的功能基团，提供了多个疏水性吸附位点，因此能够有效地吸附水中的菲。当添加 0.5%w/w（干重）剂量的水稻秸秆生物炭时，上覆水中溶解态和颗粒态菲的去除效率分别为 78.99%和 42.11%。水稻秸秆生物炭对上覆水中的菲具有更强的竞争力吸附，而不是 TSS 和 DOC。沉积物中菲的去除效率为 52.75%。本研究证实，水稻秸秆生物炭可以有效地抑制稻蟹共养沉积物中菲的迁移和释放，为稻田蟹类作物中 PAHs 污染的管理提供了一种环境友好的原位修复方法。
