长江中游湖泊柱状沉积物的垂直污染特征

发布时间：2018-03-20 23:02

  本文选题：湖泊沉积物　切入点：总有机碳　出处：《湘潭大学》2016年硕士论文　论文类型：学位论文

【摘要】：长江流域是我国淡水湖泊分布最密集地区,由于排放的重金属与营养盐等超过水体环境容量,各湖泊出现不同程度的水体污染和富营养化问题,而这些污染物质通过一系列的物理、化学和生物反应进入沉积物。本文通过对该流域典型湖泊沉积物的垂直研究,很好的了解长江地区古环境气候、污染来源、环境演变历程和规律,以期为长江流域环境保护和治理提供一定参考。根据这一角度,选取长江中游典型的湖泊,研究了武汉东湖、海口湖、钟祥南湖的柱状沉积物和梁子湖、洪湖的表层沉物,主要内容如下：(1)采集长江中游地区武汉东湖、海口湖、钟祥南湖3个不同类型湖泊的柱状沉积物,研究了总有机碳(TOC)、总氮(TN)的垂直分布特征,揭示各湖泊沉积物营养盐的变化规律和污染程度。结果表明：3个湖泊沉积物TOC、TN总体变化趋势是50～30 cm波动不大,30～10 cm增加,10 cm后减少,与各湖泊环境演变时间一致；其TOC含量最大的是海口湖,TN含量最大的是武汉东湖,且TOC和TN具有同源性。武汉东湖、海口湖有机指数和有机氮均为等级Ⅳ,属于严重污染范畴；钟祥南湖总体上处于等级Ⅲ,有机尚清洁。(2)武汉东湖、海口湖、钟祥南湖柱状沉积物中重金属(Zn、Cu、Ni、Cr、 Pb)的垂直分布特征表明：研究区Zn、Cu、Pb人为影响较大,Cr主要来自土壤环境,5种金属污染程度为武汉东湖海口湖钟祥南湖。主成分分析和相关性分析说明武汉东湖污染主要来自工业及生活废水,海口湖污染是人工种植,钟祥南湖是生活与农业废水,三个湖泊污染人为贡献率大于自然贡献率,营养盐和重金属Pb是共有的污染问题。地累积指数和内梅罗指数评价表明,研究区内三个湖泊Ni、Cr的潜在生态危害均较小,海口湖和武汉东湖Zn、Cu、Pb具有潜在污染风险,钟祥南湖沉积物中五种金属均无污染。(3)运用TOC、TN、C/N、δ13C和δ15N研究了梁子湖和洪湖的表层沉积物和有机质的贡献率,结果表明：梁子湖C/N变化范围为6.16～8.16,TN含量变化范围为0.19%～0.54%,δ15N值最高处为B点,最低处是C点,δ13C平均值是-27.19‰,最低处δ13C在B处-30.98‰,最高处于梁子岛附近F点为-23.09‰。δ13C来源于C3型植物水生藻类,δ15N显示梁子湖受到较大范围农业污染,其东北角有水土流失风险。洪湖表层沉积物C/N变化范围较大为13.71～65.9,有机质TN含量变化范围是0.03%～1.19%,属于高等类植物,陆源输入较明显；洪湖表层沉积物的δ13C平均值是-18.96‰,最低处δ13C在B处-28.02‰,最高处E为-8.31‰,显示洪湖表层沉积物主要来源属于C4型植物,除来源水生植物外,岸边点位陆源输入较明显,整个湖泊湿地水土流失有增加的风险。
[Abstract]:The Yangtze River Basin is the most densely distributed region of freshwater lakes in China. Due to the discharge of heavy metals and nutrients that exceed the environmental capacity of water bodies, various lakes have different degrees of water pollution and eutrophication problems. These pollutants enter the sediments through a series of physical, chemical and biological reactions. Through the vertical study of the sediments of typical lakes in this basin, we have a good understanding of the paleoenvironmental climate and the sources of pollution in the Yangtze River region. In order to provide some reference for the environmental protection and management of the Yangtze River basin, the typical lakes in the middle reaches of the Yangtze River are selected to study the columnar sediments and Liangzi Lake in East Lake, Haikou Lake, Zhongxiang South Lake in Wuhan. The surface sediments of Honghu Lake were collected from three different types of lakes, Donghu Lake, Haikou Lake and Zhongxiang South Lake in the middle reaches of the Yangtze River. The vertical distribution characteristics of total organic carbon (TOC) and total nitrogen (TNN) were studied. The results showed that the total variation trend of TOC TN in the sediments of three lakes was that 50 ~ 30 cm fluctuated slightly and then increased 30 ~ 10 cm and then decreased after increasing 10 cm, which was consistent with the evolution time of each lake environment. The largest content of TOC is the East Lake of Wuhan, and the content of TOC and TN is the same. The organic index and organic nitrogen of Donghu Lake and Haikou Lake in Wuhan are grade 鈪，

本文编号：1641174