Nitrogen and Phosphorus are the major end products of fish feed loading and affect the water environment as a whole. A magnetic stirrer was used to simulate the intensity of water flow by using different stirring strengths (0, 600, 1,200 rpm), and kinetic experiments on nutrients release from different fish feed (0.2500 and 0.5000 g) were performed. Results have shown that total phosphorus (TP) increase rapidly and become stable in about 96 hr, while orthophosphate ( ), total nitrogen (TN) and ammonia nitrogen ( ) increase relatively slowly and gradually reach stable from 200, 300 and 300 hr respectively. Both released contents of unit weight fish feed (i.e. released nutrients contents) and released nutrients concentrations in the condition of stirring were higher than those in the static condition. All of the pseudo‐first‐order, pseudo‐second‐order and Elovich kinetic models can be used to describe variations of released TP, , TN and contents with time, while the pseudo‐first‐order kinetic and Elovich kinetic models give better results with R² = .66–.99 and R² = .57–.99 respectively. Variance analysis showed that both stirring strength and fish feed type have significant effects on released TP, TN and contents (p < .05), while fish feed dosage has no significant effects (p > .05). In addition, only the fish feed type does have significant effects on contents (p < .05). In sum, the release kinetics and the factors related to the release of nutrients from fish feed are essential in planning strategies of nutrient management and pollution control.

中文翻译：

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鱼饲料中氮磷的释放动力学研究

氮和磷是鱼饲料装载量的主要最终产物，并影响整个水环境。使用磁力搅拌器通过使用不同的搅拌强度（0、600、1,200 rpm）来模拟水流的强度，并进行了从不同鱼饲料（0.2500和0.5000 g）释放养分的动力学实验。结果表明，总磷（TP）迅速增加并在约96小时内变得稳定，而正磷酸盐（），总氮（TN）和氨氮（TP））相对缓慢地增加，并分别在200、300和300小时逐渐达到稳定。单位重量鱼饲料中释放的养分含量（即释放的养分含量）和搅拌条件下释放的养分含量均高于静态。所有伪一阶，伪二阶和Elovich动力学模型都可用于描述释放的TP ，TN和含量随时间的变化，而伪一阶动力学和Elovich动力学模型可提供更好的结果。其中R ²  = .66–.99和R ²  = .57–.99。方差分析表明，搅拌强度和鱼饲料类型均对释放的TP，TN和含量（p  <.05），而鱼饲料的添加量则无明显影响（p  > .05）。此外，只有鱼饲料类型对含量有显着影响（p  <.05）。总之，释放动力学和与鱼饲料中养分释放有关的因素对于养分管理和污染控制的规划策略至关重要。