长江口潮滩表层沉积物对NH4+-N的吸附特征
The characteristics of NH4+-N adsorption on intertidal sediments of the Changjiang Estuary in China
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摘要: 沉积物对NH4+-N的吸附是氮素生物地球化学循环的关键过程之一,它在河口潮滩生态系统内氮素循环过程中起着非常重要的作用.以长江口滨岸潮滩为研究区域,运用实验模拟的方法,研究了沉积物对NH4+-N的吸附特征,结果表明,在长江口潮滩上覆水和孔隙水中NH4+-N含量的变化范围内,沉积物对NH4+-N的吸附呈线性变化;研究区域内沉积物对NH4+-N的吸附系数为3.81~9.00,且与沉积物中有机碳(TOC)含量有良好的相关关系,它揭示了有机质控制着长江口潮滩沉积物中NH4+-N的吸附行为.实验模拟与实测结果对比发现,在潮滩自然环境条件下,研究区域内沉积物对NH4+-N的吸附处在非热力学平衡状态过程中.盐度是影响NH4+-N吸附过程的重要环境因子,且导数方程关系式在低盐度范围内,盐度的微小变化对NH4+-N的吸附有显著的影响.Abstract: Adsorption of sediments on NH4+-N is one of the key biogeochemical processes,which plays an important role in the cycle of nitrogen in an estuary and tidalflats.NH4+-N adsorbed by intertidal surface sediments was studied with simulation experiment from the Changjiang Estuary.It is indicated that the adsorption of sediments on NH4+-N shows linear Changes in the possible range of NH4+-N in overlying waters and porewaters from the intertidal flat of the Changjiang Estuary.The adsorption coefficients of NH4+-N vary from 3.81 to 9.00,and are closely related to sedimentary organic carbon,showing that or ganic matter may control NH4+-N adsorption behavior.Compared with the in situ measured data,it is concluded that NH4+-N adsorption is under the non-thermodynamic balance status under natural conditions in the Changjiang Estuary.In addition,it is also showed that salinity has an important effect on NH4+-N adsorption,and that the little change of salinity has a pronounced influence on NH4+-N adsorption in sediments within the range of lower salinity.
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Key words:
- ammonium /
- adsorption /
- sediments /
- intertidal flat /
- Changjiang Estuary
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