【作者】 李桂海；

【导师】 曹志敏；

【作者基本信息】 中国海洋大学 ， 海洋地质， 2007， 博士

【摘要】 河口和海湾地区,由于海陆相互作用活跃,对自然过程和人类活动的响应敏感,因而,该区域的环境演化直接关系到人类的生存空间、生存质量和社会的可持续发展。在这些海域的沉积物中,重金属元素的分布特征及地球化学行为与区域内的沉积环境密切相关。本文以具有复杂水动力条件及复杂地形特征的厦门海域4个海区为研究对象,通过表层和柱状沉积物的粒度分析、沉积物中重金属元素的横向和垂向分布变化及其赋存形态分析、沉积物中有机碳和硫化物含量分析、沉积物中重金属元素的环境质量评价等,对厦门海域不同海区的沉积环境及现代沉积环境变化、重金属元素的环境地球化学特征、重金属元素在厦门海域的污染状况进行了较深入的研究。本文研究得到以下几方面成果:详细分析了厦门海域不同海区间、同一海区不同站位间的沉积环境特征,同时以各海区典型柱状沉积物的粒度特征为依据,分别探讨了4个海区的现代沉积环境变化。在重金属元素Cu、Zn、Pb、Cd、Cr、Hg和As含量及分布特征的基础上,根据不同站位间沉积物组成的较大差异,采用多种分析方法,获得了不同元素在厦门海域表层沉积物中相应的富集组分。研究发现,Zn、Cu、Pb、As、Cr在细砾和粗砂中的含量可以反映它们在该地区背景值的大小。这为分析和判别沉积物中这些元素的人为污染程度提供了更便捷的途径。对不同海区、不同站位表层沉积物中Cu、Zn、Pb、Cd、Cr和As元素的各形态含量及分布特征进行了详细分析。发现尽管各元素物理性质不同,各形态在各站位分布情况各异,但形态分析中各元素的“非稳态”含量可以反映各海区间、同一海区不同站位间人为因素的影响。通过对厦门西港重金属元素累计特征及剖面沉积物的粒度分析,对该海区沉积环境变化、人为活动的影响及重金属元素的污染历史进行了较为客观的反演。研究发现:20世纪30年代以来,厦门西港沉积环境和水动力有较大变化,尤其自高集海堤建成(1956年)后,海域内沉积环境明显不同。海堤建成后沉积物粒度组成相对稳定,水动力变弱,沉积物来源相对集中。总体来看,重金属在1947~1990年间污染最严重,从20世纪90年代初期以来,污染程度呈减轻趋势。沉积物来源越稳定,沉积物粒径越小,分选性越好,则重金属含量越高。同时,绝大部分重金属元素与有机碳和硫化物呈显著正相关关系,个别元素因受污染源的影响,与有机碳或硫化物间的相关关系不明显。采用目前国内外主要的评价方法,全面、客观评价了厦门海域各海区、各站位表层沉积物中重金属元素的污染程度。综合各种评价方法,我们认为,Cu在厦门西港,尤其是在16和21号站位的高含量,应引起足够重视。同时发现,Cd元素不适合采用次生相与原生相分布比值法进行污染评价,该结论有待进一步研究探讨。更多还原

【Abstract】 Estuarine and coastal areas, which interact actively for ocean and land, respond sensitively for natural processes and human activities. There are good connections within living space, survival quality of human and social continuable development and environment evolvement of these areas. In sediments of these areas, the distribution and geochemistry characteristic of heavy metals are influenced directly by depositional environment.In this paper, 4 sea areas of Xiamen seas, which have complex hydrodynamic feature and landform were investigated. Basing on the data of grain size analysis of surficial sediment and core sediment, the spatial distribution and morphological analysis of heavy metals in the sediments, concentrations of TOC and AVS, environmental quality valuation et al., we analyzed the depositional environment of different sea areas. The variety of depositional environment was reappeared by analysis of the sediment cores. The environmental Geochemistry characteristic of heavy metals was discussed. The pollution level of the main heavy metal elements was impersonality appraised. The results of this investigation were just as follows: The depositional environment in different sea area, different station in the same sea area of Xiamen seas was analyzed in full. On the base of granularity of the typical core sediment, the variation of modern depositional environment of the four sea areas in Xiamen seas were discussed.According as content and distribution characteristics of Cu, Zn, Pb, Cd, Cr, Hg and Arsenic, and a rather large difference of sediment composition in different station, the enrichment components of each element in surface sediment were acquired by multi-analytical method.It is found that the content of Zn, Cu, Pb, Arsenic and Cr in fine gravel and in coarse sand could reflect their background value. Which offer a more handy means for analyzing and judging the man-made pollution of these elements. The speciation analysis of the elements Cu, Zn, Pb, Cd, Cr and Arsenic was carried out among the surface sediment in different sea areas, different stations. The content of heavy metals unsteady states reflected different influence of anthropogenic factors among different sea areas, different stations of the same sea area.The variation of depositional environment, influence of anthropogenic factors and pollution history of heavy metals in Xiamen seas were reviewed objectively, according to the vertical distribution of heavy metals and grain size analysis of the sediment cores. It is found that since 1930s, a rather large variation of hydrodynamic feature and depositional environment in the Xiamen West Harbour was found. The depositional environment was different distinctly, grain size composition of the sediment was stable relatively, hydrodynamic became weak, sediment source was concentrated relatively, especially after the Gaoji sea wall was built (1956a). On the whole, the highest polluted period was 1947~1990. Since 1990s, the pollution levels appeared lighten trend. For the sediment, the more stable of the source, smaller of the grain size, better of the separation, then the content of heavy metals in sediment was higher. There was markedly positive correlation between the concentrations of the most heavy metals and the concentration of organic carbon and sulfide. For the influence of point source pollution, there was not evidence correlativity among one or two element of heavy metal, organic carbon and sulfide.The pollution degree of heavy metals in surface sediment was appraised fully and impersonality. As a synthesis point of appraising views, there was different pollution degree of Cu, Zn, Pb and Arsenic in different sea areas, different station of the Xiamen seas. The element of Cu has elevated concentrations in Xiamen West Harbour, and should be paid more attention. At the same time, it was found that for the element Cd, it did not fit to appraise by the ratio of secondary phase and primary phase. As a result of that, need more investigation.更多还原