Abstract In aquaculture, dissolved oxygen (DO) is vital to crab growth. Different from DO in flowing water area, the dynamics of DO in a crab pond is deeply affected by complex interactions between organism communities and meteorological factors. Significant fluctuations of DO content occurs within 24 h. It is thus important to explore DO dynamics related to various environmental factors for real time DO content prediction, water quality analysis, and artificial aeration control. In this work, a dynamic model based on the diffusion theory was developed to reflect daily variations of DO content at different depths in a crab pond. The model focuses on evaluating the effects of macrophyte and aerator on the production of DO, and the effects of extinction coefficient and diffusion coefficient on the vertical distribution of DO. Photosynthesis and respiration of aquatic macrophyte, mechanical aeration, mineralization, and meteorological conditions were considered. The model can fit experiment data with mean absolute percentage error about 6%. Simulation results show that the main process that produces DO in the pond is photosynthesis of macrophyte, which accounts for 88.2% of the DO source. Mechanical aeration adds 9.2% of DO while reaeration adds 2.6% of DO. The main process that consumes DO is mineralization which accounts for 86.9% DO sink, followed by respiration of macrophyte which utilizes 13.1% DO, the effect of crabs on DO content is small. DO at different depths was also simulated, and it can be found that hypoxia is more likely to occur in the bottom water where diffusion coefficient decreases. The established DO model serves as a launching point for further research on artificial aeration control to improving aquaculture water environment.

中文翻译：

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模拟蟹塘中的溶解氧

摘要 在水产养殖中，溶解氧（DO）对螃蟹的生长至关重要。与流域溶解氧不同，蟹塘溶解氧动态受生物群落和气象因素复杂相互作用的影响较大。DO 含量在 24 小时内发生显着波动。因此，探索与各种环境因素相关的 DO 动态对于实时 DO 含量预测、水质分析和人工曝气控制非常重要。在这项工作中，建立了基于扩散理论的动态模型，以反映蟹塘中不同深度溶解氧含量的每日变化。该模型重点评价大型植物和曝气器对溶解氧产生的影响，以及消光系数和扩散系数对溶解氧垂直分布的影响。考虑了水生大型植物的光合作用和呼吸作用、机械曝气、矿化和气象条件。该模型可以拟合实验数据，平均绝对百分比误差约为 6%。模拟结果表明，池塘中产生DO的主要过程是大型植物的光合作用，占DO来源的88.2%。机械曝气会增加 9.2% 的 DO，而再曝气会增加 2.6% 的 DO。消耗DO的主要过程是矿化，占DO汇的86.9%，其次是利用13.1% DO的大型植物呼吸作用，螃蟹对DO含量的影响较小。还模拟了不同深度的溶解氧，可以发现扩散系数降低的底水中更容易发生缺氧。