【作者】 张文斌；

【导师】 陈雷；

【作者基本信息】 吉林建筑工程学院 ， 市政工程， 2010， 硕士

【摘要】 2008年6月采集了洪泽湖具有代表性的10个点位的沉积物,测定了沉积物中营养盐(氮、磷、有机质)和重金属(Cu、Zn、Pb、Cd、Fe、Al、Cr、Hg、Mn、As)含量,所有点位的表层沉积物还分析了氮、磷形态,分析了营养盐和重金属的空间分布情况,且进行了污染评价。选取了洪泽湖淮河入湖口附近、湖西和湖心3个柱状沉积物进行分析,分析了其垂直分布特征、来源和影响因素。研究表明:洪泽湖表层沉积物中营养盐和重金属的富集属典型的洪水冲刷型堆积模式(Turbidity Flood Model方式)。表层沉积物中的有机质和总氮有很好的相关性,且有机氮约占总氮的90%,说明碳、氮有同源性;沉积物中的无机磷约占总磷的70%,而其中钙-磷占无机磷的比重较大;表层沉积物有机质与总氮,有机氮,总磷的空间分布特性极为相似,通过C/N值得知沉积物中有机物主要来源为生物沉降。通过有机指数评价法和有机氮评价法对表层沉积物的评价表明:洪泽湖底质除局部区域如龙集乡北表现为一定程度的有机氮污染外,整体处于清洁至尚清洁范畴。表层沉积物重金属元素空间分布特性极为相似,空间差异较大。受河流冲刷等水动力学条件及湖盆地形的影响,重金属元素入湖口附近含量远低于出湖口;而在敞水区及水流滞留的湖湾区及汴河、安河入湖河口及其附近区域含量较高。重金属Cu、Zn、Pb、Cd、Fe、Al,Mn、As、Cr含量呈显著正相关,表明这些元素污染具有同源性。采用地积累指数和Hakanson潜在生态风险指数对沉积物重金属的污染现状和潜在生态风险程度的评价表明,重金属污染程度顺序依次为Cd>As>Cu>Cr>Zn>Hg>Pb;单个重金属潜在生态风险顺序为:Cd>As>Hg>Cu>Pb>Cr>Zn;Cd污染程度及生态风险程度均较重,其余重金属污染状况相对较轻;Cd单项潜在生态风险区域及全湖综合潜在生态风险区域完全一致。重金属污染可能存在的主要风险区域为:敞水区(S9)及出湖河口附近(S1,S8)风险区、北部湖湾(S6)风险区及西部湖湾(S5)风险区。对沉积柱各指标的来源及影响因素进行了讨论,从而揭示了营养盐和重金属的演化规律及污染历史。淮河口附近沉积环境受淮河流域影响较大,营养盐无变化趋势,Zn、Cd、Al、Fe和Mn受人类活动影响相对较小,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和入湖河流影响,TN、有机质(OM)和重金属元素从上世纪70年代末污染程度加剧,90年代以来污染情况有所改善,As和Cr受流域人类活动影响较大,其余重金属元素人为影响较小。湖心区污染来源主要为流域碎屑物质,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。沉积柱中营养盐相关性较好,有机物大部分来源于浮游动物和浮游植物,重金属的自然来源相对稳定,人类活动的干扰可能是造成重金属垂向分布波动的主要原因。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Turbidity Flood Model方式。洪泽湖作为典型的过水性湖泊,其“悬湖”这一显著特征表明对其沉积物研究的重要性。本研究全面地研究了其沉积物中营养盐及重金属的含量、沉积特征及空间分布,把握了洪泽湖沉积物的污染现状和可能存在的风险区域。本研究将为洪泽湖的水污染治理及其生态安全保障方案的制定提供有力的理论基础与支撑。本研究获得了环境保护部重点项目“全国重点湖库生态安全保障方案”(WFLY-2009-1-01,WFLY-2009-1-04)及国家“十一五”重大科技水专项(2008ZX07101-001)的资助。更多还原

【Abstract】 Sediment samples of Hongze Lake at 10 representative sampling sites were collected In June, 2008. Sediment nutrients (nitrogen, phosphorus, organic matter) and heavy metals (Cu, Zn, Pb, Cd, Fe, Al,Cr, Hg, Mn, As) content were measured, the patterns of nitrogen and phosphorus in the surface sediments from all sampling sites were also determined. The spatial distribution of heavy metals and nutrients were analyzed and their pollution assessment were carried out. Three core sediment samles (one was near the Huaihe River inlet of Hongze Lake, one was western and the other came from the lake center) were selected and their contaminant vertical distribution characteristics, resources and influencing factors were analyzed. The result showed that:The accumulation of nutrients and heavy metals in the surface sediments of Hongze Lake belonged to a typical flood washed type stacking mode (Turbidity Flood Model).Organic matter and total nitrogen in surface sediments had a very good correlation, and the organic nitrogen accounts 90% of total nitrogen, indicating that the carbon and nitrogen are homology; the inorganic phosphorus in sediment accounted about 70% of total phosphorus, in which calcium - phosphorus accounted a larger proportion of inorganic phosphorus; the spatial distribution of organic matter in surface sediment was very similar to total nitrogen, organic nitrogen, and total phosphorus, the C/N rate showed that the main source of organic matter in sediments should be biological settlement. Aaccording to organic matter index evaluation standards and organic nitrogen evaluation standards, the pollution levels of sediment at each sampling sites in the lake were classified as clean category, except that at north part of Longji, which was polluted by organic nitrogen.Influenced by the hydodynamical and topographical condition, the contents of heavy metals in the inflow river mouth areas were significantly lower than that of open water area in the eastern part of the lake, and that of bays and outflow river mouth areas. These heavy metals were highly positively related with each other, indicating that they were from the same pollution source. The geo-accumulation index (Igeo) and the Hakanson potential ecological risk index were applied for assessing the status of sediment heavy metal enrichment and the extent of potential ecological risk. The pollution extent of heavy metals followed the order: Cd>As>Cu>Cr>Zn>Hg>Pb, while the single potential ecological risk of heavy metals followed the order: Cd>As>Hg>Cu>Pb>Cr>Zn. The pollution extent and potential ecological risk of Cd were most serious than those of other heavy metals. The distribution pattern of Cd individual potential ecological risk indices was exactly the same as that of general potential ecological risk indices for all heavy metals, indicating the important contribution of Cd in the general indices. The analyse results showed that heavy metal pollution and the potential ecological risk existed in three risk regions: the central open water area and outflow river mouth region (S9, S1 and S8), the northern bay region (S6) and the western bay region (S5).The sources and factors of core sediment samples indexs were discussed, which revealed the nutrients and nutrient evolution rule and pollution history. Huaihe River estuary sediment environment influenced more by the Huaihe River Basin, and nutrients had no change potential, Zn, Cd, Al, Fe and Mn affected less than the rest heavy metals by human activities,.Western Lake sediment environment was affected by the Huaihe River, the inlet river and the cities surrounding western lake. The pollution degree of TN, OM and heavy metal elements was exacerbated since the late 1970s, but the contamination situation was improved since the 1990s. As and Cr were influenced by human activities greater than rest heavy metals. Main pollution source of the lake center were clastic material. The correlation of nutrients and heavy metals was obvious, and their vertical distribution was similar with the content raised from the bottom to the surface.Different nutrients of the core sediment samples had good correlation. The majority of organic matters came from zooplankton and phytoplankton. The natural sources of heavy metals were relatively stable, and the disturbance of human activity may be the main reason for fluctuations in vertical distribution of heavy metals. Nutrients and heavy metals pollution had the consistent characteristics with close relationship with the river basin development stage.The sediment environment in Hongze Lake was fitted in Turbidity Flood Model. This project was supported by the key research programme of Ministry of Environemntal Protection, guaranteeing scheme for ecological safty of the important lakes and reservoirs in China(WFLY-2009-1-01,WFLY-2009-1-04).更多还原