太湖沉积物理化性质及营养盐的时空变化

Temporal and spatial distribution of physicochemical characteristics and nutrients in sediments of Lake Taihu

在不同季节,采集太湖梅梁湾和贡湖湾沉积物柱状样,研究沉积物Eh、pH、总氮、总磷以及有机质四季垂向部面分布变化特征.研究结果表明,在表层下(0-3cm).Eh随沉积物深度的增加迅速下降,很快进入还原状态.沉积物剖面上pH变化幅度不大,在6.4-7.8之间,冬季沉积物pH均有所降低.太湖沉积物中含有丰富的营养盐,总氮和总磷最高浓度分别为2.68和0.864 mg/g,其剖面分布特征表明,沉积物表层总氮和总磷含量远高于底层,其含量随深度增加而降低,但四季变化趋势不明显.沉积物中有机质含量在10 cm以上变化幅度较大,随着沉积物深度的增加,有机质含量明显减少,季节变化幅度不大.比较不同采样点发现,位于梅梁湾生态系统试验区内的S1位点沉积物氮磷内源负荷最大.

Three sites were selected for samples in Lake Taihu to observe temporal and spatial distribution of redox potential （Eh）, pH, total nitrogen （TN）, total phosphorus （TP） and organic matter （OM） in sediments. Below the surface of sediments Eh declined rapidly with the increase of sediment depth and it was under anaerobic condi- tion except the top layer of sediment, pH value changed silightly in the profile of sediments, which ranged from 6.4 to 7.8. With a comparison between four seasons, pH value was the lowest in winter. TN and TP concentrations in sediments of Lake Taihu were higher, and the maximum concentrations reached 2.68 mg/g and 0. 864 rag/g, respectively, Their vertical profiles showed that TN and TP concentrations in surface sediments were much higher than in deeper layers and decreased steeply with the increase of the depth on the top 15 cm of sediment layers. OM concentrations declined rapidly at the top 15 cm of sediment layers, but there was little change in four seasons. The sediment loads of TN and TP were much higher at S1 than that at other sites.