【作者】 唐璐璐；

【导师】 韩宗珠； 陈志华；

【作者基本信息】 中国海洋大学 ， 海洋地质， 2008， 硕士

【摘要】 近年来,沿海地区的开发,特别是滩涂资源的开发、滨海旅游业的兴起等人类活动已使广西海岛、海岸带发生了很大变化,本文通过对广西典型离岸海岛——涠洲岛、典型滨岸海岛——龙门岛和西村岛潮间带表层沉积物重金属分析、粒度分析、有机碳与碳酸钙的分析,得到以下主要结论和认识:涠洲岛潮间带表层沉积物中7种重金属的含量水平相对较低,均在海洋沉积物质量一级标准以内,Cu、Pb、Cd、Cr略高于广西近岸海域平均含量;龙门、西村潮滩沉积物中Hg、Cu、Pb、Zn、Cr、As的含量明显高于涠洲岛潮间带,但除Cu已高出海洋沉积物质量一级标准以外,其它元素均没有超标。涠洲岛潮间带各重金属元素在垂岸方向上的分布规律不明显,沿岸方向上在人为活动相对频繁的W05、XKZ两断面附近相对富集;龙门、西村段低滩重金属含量略高于中滩和高滩,区域分布上受不同岸段水动力条件差异及钦州湾泥沙运移机制的影响,西村高于龙门。涠洲岛潮间带表层沉积物中Pb、Zn、Cr显著正相关,Hg、Cd、As正相关,两组元素分别具有相似的物源或迁移累积特征,但受缺失63μm以下细颗粒组分的影响,它们与粒度、有机碳均不存在相关性。龙门、西村段除LM-02外,Hg、Pb、Zn、Cr、As之间及其与粒度、有机碳之间均显著正相关,这5种元素以自然沉积为主;LM-02站Cu、Pb、Zn的异常则说明重金属的人为来源占很大比重;研究区内Cu与其它元素均无相关关系,具有独特的物源或沉积特征。当重金属以自然来源为主时,沉积动力环境的差异造成沉积物粒度特征、有机碳及碳酸钙含量的不同,进而影响重金属的分布;当人为来源的重金属占很大比例时,物源差异成为影响重金属分布的主导因素。利用地质累积指数法与潜在生态风险指数法对海岛潮间带沉积物质量进行评价,发现涠洲岛潮间带沉积物质量较好,仅Cu在个别站位出现轻度污染,潜在生态风险性极低。西村岛潮间带普遍出现Pb与Cu的轻度至偏中度污染,风险性程度明显高于涠洲岛。龙门岛潮间带主要污染元素为Cu,为轻度至偏重度污染;此外,LM-02站出现Pb与Zn的偏中度污染,潜在生态风险性较高。更多还原

【Abstract】 In recent years, as the development of coastland, the island tidal zone of Guangxi has greatly changed because of human activities such as mariculture, coastal tourism and etc. The thesis particularly chooses the representative islands as study area, such as Weizhou Island which is near by the mainland, Longmen Island and Xicun Island which are far off the mainland. According to the analysis of heavy metals, grain size, TOC and CaCO3 in the tidal surface sediment, the following results are showed.The content level of heavy metals in Weizhou tidal zone is lower. All 7 elements are less than State StandardⅠ. Content of Cu, Pb, Cd and Cr is slightly higher than it in Grangxi offing sediments. The content level of Longmen and Xicun is observably higher than Weizhou, but only Cu’s content runs over the State StandardⅠ.Heavy metals’distribution of Weizhou is erratic in the direction which is perpendicular to the coastline. But in the landscape orientation, Section W05 and XKZ have more enrichment level. In Longmen and Xicun zone, heavy metals’contents are slightly higher in low tidal zone than in middle and high tidal zone. For regional distribution, Xicun is higher than Longmen because of difference of water motivity and bedload removal of Qinzhouwan.The correlation of Pb, Zn, Cr is positive in Weizhou tidal zone, the same as Hg, Cd, As. They have similar source or transfer mode. But they have no correlation with grain size and TOC, because the sediments of this area have no granule component below 63μm. In Longmen and Xicun tidal zone except for LM-02, the correlation of Hg, Pb, Zn, Cr, As, grain size and TOC is observably positive, and it is showed that the 5 elements mainly comes from nature. There are a great deal of Cu, Pb and Zn which come from human activities in LM-02. Cu has no correlation with other elements and its source or transfer mode is particular. While heavy metals mainly come from nature, sediment environment will effect the grain size, TOC and CaCO3 and finally effect the content of heavy metals. But when human activity is the main source, it will effect the distribution of heavy metals directly.According to the results of Index of Geoaccumulation and Potential Ecological Risk Indices, the tidal environment is well in Weizhou Island. Only Cu is slightly polluted in some area and the Potential Ecological Risk Indices are extremely low. In Xicun tidal zone, Pb and Cu are polluted and Xicun’s RI is higher than Weizhou’s. Cu is polluted in Longmen tidal zone. Furthermore, Pb and Zn are polluted in LM-02. The RI of Longmen Island is equivalent with Xicun besides LM-02 has a high ecological risk.更多还原