河口潮滩沉积物对氨氮的等温吸附特性

AMMONIA NITROGEN ADSORPTION ISOTHERM OF TIDAL FLAT SURFACE SEDIMENTS FROM THE YANGTZE ESTUARY

以长江河口滨岸潮滩为研究对象 ,运用模拟实验的方法 ,研究了潮滩沉积物对氨氮的等温吸附特征 .结果表明 ,在模拟实验上覆水中氨氮的浓度 ( <1 40 μg·ml- 1 )范围内 ,沉积物对氨氮的吸附呈线性特征 .长江河口潮滩沉积物对氨氮的吸附系数在 3 81— 9 0 0之间 ,且与沉积物中有机碳 (TOC)的含量有良好的相关关系 (相关系数r =0 779,α =0 0 5 /) ,揭示了有机质控制着长江河口潮滩沉积物中氨氮的吸附行为 .模拟实验结果还发现 ,在淡水控制区域内 ,潮滩沉积物中固定态氨氮的含量处在 1 6 68— 33 73μg·g- 1 (dw)之间 ,而在海水所控制的潮滩沉积物中固定态氨氮的含量在 0 5 7— 6 36μg·g- 1 (dw)之间 。

Ammonia nitrogen adsorption on sediments plays an important role in the cycle of nitrogen in the estuarine tidal flat ecosystem.Ammonia nitrogen adsorption isotherm on tidal flat sediments from the Yangtze estuary was studied with simulation experiment.The results indicated that the adsorption by the tidal flat sediments for the lower ammonia nitrogen concentration in the overlying waters was linear.The adsorption coefficient ranged from 3 81-9 00,and had a positive correlation with organic carbon( r =0 779, α =0 05),showing organic matter controlled ammonia nitrogen adsorption behavior.The fixed ammonia in the sediments from the study area controlled by the freshwater ranged from 16 68-33 73μg·g -1 (dw),whereas it was from 0 57-6 36μg·g -1 (dw) in the sediments from the seawater areas,indicating the salinity had an important influence on fixed ammonia nitrogen.