海岸带表层沉积物中磷的地球化学特征

通过连续提取法对莱州湾主要入海河流及近岸海域表层沉积物中5种形态磷进行了定量分析.结果表明,近海沉积物自生钙结合磷含量(45.6%)高于河流(37.3%),而铁结合磷(Fe-P)含量(18.2%)却低于河流(31.3%).在近海,可交换或弱结合磷含量和粉砂比例呈正相关,表明该形态磷主要吸附于细粒粉砂．河流沉积物Fe-P与Fe浓度呈显著正相关(P<0.01),表明河流沉积物Fe-P分布受沉积物活性铁含量的控制．河口处Fe-P普遍低于相应河流,这可能与海相泥沙输入及河口厌氧区硫酸盐还原或硫化物累积有关.近海沉积物总可提取态磷平均浓度总体呈现出由海洋向河口方向递减的趋势.

Gochemistry characteristic of phosphorus in costal surface sediments

Five fractions of phosphorus in marine and fluvial surface sediments of Laizhou Bay wereinvestigated by a sequential extraction method. The results indicated that the authigenic calcium-bound phosphorus (ACa-P) in marine sediments (average 45.6%) was higher than that (average 37.3%) in fluvial sediments, but iron-bound phosphorus (Fe-P) in marine sediments (average 18.2%) was lower than that in fluvial sediments (average 31.3%). In coastal zone, a positive correlation was found between exchangeable and loosely sorbed phosphorus (E&L-P) and silt (grain size), indicating that E&L-P was mainly sorbed onto fine particles. A significant correlation (P<0.01) was observed between Fe-P and Fe concentrations in fluvial sediments, which indicates the distribution of Fe-P in fluvial sediments was determined by Fe concentration. The Fe-P concentration in estuary sediments was lower than that in corresponding river sediments. This may be attributed to the input of marine sediments and the reduction of sulfate or the accumulation of sulfide under anaerobic section (Fe fixed by sulfide). The mean values of total extracted phosphorus in sediments presents a decrease trend from offshore to estuaries.