In order to better track the effect of marine culture in floating cage on water quality, the sediments of three representative sites in the aquaculture area of Daya Bay were sampled in October 2011. The water percentage, porosity percentage and density of sediments, and the vertical distributions of nitrogen and phosphorus in the interstitial water were measured in laboratory experiments. The release rate and yearly release quantity of nutrients at the sediment-water interface were calculated by means of Fick’s Law. Based on the theory of environmental hydraulics, a two-dimensional numerical model was applied to calculate diffusion regularities of the nutrients. The results show that, the yearly release contents of ammonia across the interface of sediment-water at Aotou, Shenshuigang and Hutoumen were 13.5, 5.2, 0.56 t·a-1, and that of dissolved reactive phosphorus were 0.34, 0.03, 0.02 t·a-1, respectively. The release fluxes were high enough to make the sediments close to the aquaculture area become a potential pollution source. The released nutrients from the sediment-water interface were affected by tidal flow, wind, and depth, and the diffusion region in seawater had a strip shape. The pollution belt was about 1 km in length and 50 m in width at each sampled site of the aquaculture area, which made eutrophication a potential risk to the water body.%为了更好地跟踪水产养殖活动对海湾水环境的影响,于2011年10月采集了3个具有代表性的大亚湾海域水产养殖区的水样和底泥样品,研究了底泥含水率、孔隙率、密度以及孔隙水中的氨氮和可溶活性磷酸盐的垂直分布。采用经典的Fick定律,计算了氮和磷在沉积物-水界面的释放速率和年释放量。基于环境水力学理论,应用水平二维数学模型,计算了氮和磷在沉积物-水界面释放之后在海水中的扩散迁移时空分布。结果表明,澳头、深水港、虎头门采样点沉积物-水界面的氨氮年释放量分别为13.5、5.2、0.56t·a-1,可溶活性磷酸盐的释放量分别为0.34、0.03、0.02t·a-1,使水产养殖区域沉积物成为极具潜力的污染内源。释放到海水中的氮和磷受潮流、风、水深的影响,其扩散迁移范围呈长条形带状分布。每个养殖区域的污染带长度约为1km,横向宽度约为50m。该区域的海水极易呈富营养化状态。
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