洪泽湖沉积物中营养盐和重金属的垂向分布特征研究

为了揭示洪泽湖沉积物中营养盐和重金属的垂向分布特征,2008年6月采集了洪泽湖淮河入湖口附近、湖西和湖心3个柱状沉积物样品.通过测定分析其总氮、总磷、有机质和重金属Cu、Zn、Pb、Cd、Fe、Al、Cr、Hg、Mn、As的垂向分布特征,揭示了营养盐演化规律及重金属污染历史.结果表明,淮河口附近沉积环境受淮河流域影响较大,营养盐中TN、TP、OM的含量分别为390.8～643.7、428.6～538.6、5 194.3～9 164.9 mg.kg-1,Zn、Cd、Al、Fe和Mn受人为影响较小,其余重金属人为影响较大.湖西区沉积环境受淮河及湖西周边城市影响,TN、TP、OM的含量为633.4～2 677.3、480.0～1 115.9、7 140.8～47 849.7 mg.kg-1,TN、OM和重金属污染程度从20世纪70年代末加剧,90年代以来有所改善,As和Cr受流域人类活动影响较大,其余重金属受人为影响较小.湖心来源主要为流域碎屑物质,TN、TP、OM的含量为904.7～1 585.4、526.3～750.1、10 635.6～19 020.6 mg.kg-1,营养盐和重金属相关性显著,垂向分布均相似,含量从底层至表层呈上升趋势.沉积柱中营养盐、重金属元素具有比较一致的污染特征,与洪泽湖流域发展阶段相吻合,洪泽湖沉积环境属于洪水冲刷型堆积模式(Turbidity Flood Model方式).

Vertical Distribution Characteristics of Nutrients and Heavy Metals in Sediments of Lake Hongze

In order to understand the vertical distribution characteristics of nutrients and heavy metals in sediments of Lake Hongze, three core sediment samples at 3 sites (one near the Huaihe River inlet of Lake Hongze, one at the western part of the lake and one at the lake center) were collected in June of 2008. By measurement of total nitrogen (TN), total phosphorus (TP) and heavy metals (Cu, Zn, Pb, Cd, Fe, Al, Cr, Hg, Mn, As) and by analyzing of their vertical characteristics, investigation revealed the nutrient evolution processes and pollution history. Sediment near Huaihe river mouth was more polluted by the Huaihe River watershed. The nutrients TN, TP and organic matter (OM) concentrations in this core sample were 390.8-643.7,428.6-538.6,5194.3-9164.9 mg·kg^-1 respectively. Zn, Cd, Al, Fe and Mn in the sediment in this area were affected by human activities less than other heavy metals. Western Lake sediment was affected by the Huaihe River, inlet river and human activities in cities along western lake shoreline. TN, TP and OM concentrations in this core sample were 633.4-2677.3, 480.0-1115.9, 7140.8-47849.7 mg·kg^-1 respectively. The pollution extents of TN, OM and heavy metals in sediment were exacerbated since the late of 1970s, but the situation was improved since the 1990s. As and Cr in the sediments were influenced by human activities more than other heavy metals. Main pollution source in sediment at the lake center were detritus from the lake watershed. TN, TP and OM concentrations in this core sample were 904.7-1585.4, 526.3-750.1, 10635.6-19020.6 mg·kg^-1 respectively. The correlations among nutrients and heavy metals in sediment are significant, and their vertical distribution patterns were similar. The concentrations of nutrients and heavy metals increased from bottom to surface. Nutrients and heavy metal pollution in sediment had the same vertical distribution characteristics which coincided with the lake watershed economic development stage. The sediment in Lake Hongze can be described by the Turbidity Flood Model.