太湖大浦口河口区沉积物中铁、磷的地球化学特征

Geochemical Characteristics of Iron and Phosphorus in the Sediment from the Dapu Estuary of Taihu Lake

对太湖西部大浦口河口区沉积物中的w（Fe2＋）,w（TP）和w（Fe-P）及间隙水中ρ（Fe2＋）和ρ（PO43-）的空间及垂向分布特征进行了测定分析.结果表明,上覆水中,河道的各项指标均大于湖区及河口,而在河道与河口沉积物中w（TP）基本相似,均小于湖区.在河口沉积物垂向剖面上,存在约5,9及11 cm的3个明显变化阶段.w（Fe-P）占w（TP）的16.7%-47.8%,与ρ（TP）的相关性较好（R=0.526）,但与其他指标的相关性并不明显.Fe-P是重要的磷形态,厌氧状态下有向间隙水解析扩散的潜力,并形成Fe3＋与Fe2＋间的转换.间隙水中ρ（PO43-）与w（Fe-P）/w（TP）和ρ（Fe2＋）存在非对应性,但与ρ（Fe）呈显著相关（R=0.853）.河口区PO43-的迁移转化受多种因素的作用,复杂的水动力活动和地球化学作用是主要控制因素.

The spatial and vertical distributions of p（Fe^2＋ ） and ρ（PO4^3- ） in interstitial water, and w（Fe^2＋）, w（TP） and w（Fe-P） in sediments from Dapu estuary of Taihu Lake were determined, and the correlations were subsequently studied. The results showed that in the overlying water, each index in the river was greater than that in the estuary and lake, but the concentrations of phosphorus in the river and estuary were less than that in the lake. At the vertical section of sediments of the estuary, three relatively distinct stages （ ca. 5, 9 and 11 cm） were illustrated, w （Fe-F） accounted for 16.7% -47.8 % of w （TP）, which was posltively correlated with ρ （TP） （ R = 0. 526）, but had no distinct correlations with other parameters. Fe-P was an important phosphorous fraction. It has the potential to desorb and diffuse to interstitial water in anaerobic conditions, promoting the conversion of Fe^3＋ to Fe^2＋ . ρ （PO43- ） in interstitial water was not significantly correlated with w（Fe-P）/w （TP） or p（Fe^2＋ ）, but was correlated with ρ（Fe） （R = 0.853）. Heterogeneous geochemical activities and complicated hydrodynamic activities were important factors that controlled the conversion of phosphorus in the estuary.