| 摘要: |
| 分析了闽江下游及河口区的表层水质、悬浮物和沉积物样品，探讨了沉积物总碳的地球化学特征和影响因素，及与其他河流的异同.结果表明，对于相同站位，夏季沉积物总碳占比平均为1.74%，略高于秋季的1.70%，两者差异不明显.研究区沉积物总碳占比为1.21%~4.84%，平均为1.82%，从水口水库至福州市区河段，其含量逐渐升高，在北港达到最高值，而后由河口向外海逐渐降低，呈现“低-高-低”的分布特征.秋季悬浮物含量和化学需氧量（COD）高值区范围大于夏季，且含量也更高.研究区悬浮物含量、COD、颗粒态总碳均呈现先升后降的分布特征，悬浮物中总碳的含量则呈现从库区经河口向外海减少的趋势.沉积物总碳与悬浮物总碳、悬浮物含量、COD总体显著相关，悬浮物的沉降-再悬浮-再沉降过程是影响沉积物总碳分布的重要因素；人类活动产生的污水、农田和畜禽水产养殖废物是有机物的主要来源.闽江口沉积物总碳含量低于黄河、长江，而与其他中小型河口相近，处于国内河口较低水平，这与流域内源岩特性、有机物输入量以及沉积物粒度等相关.北港段沉积物总碳含量显著高于其他河流，有机污染较为严重，将成为影响水体水质的潜在因素. |
| 关键词: 海洋化学 总碳 地球化学特征 影响因子 沉积物 闽江河口 |
| DOI：10.3969/J.ISSN.2095-4972.2018.03.003 |
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| 基金项目:国家自然科学基金资助项目（41376050） |
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| Geochemical characteristics of total carbon in sediments of the lower reaches of Minjiang and its estuary |
| ONG Song-bai,GAO Ai-guo,LIN Jian-jie,ZHU Xu-xu,HOU Yu-ting,ZHANG Yan-po |
| (College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China;Marine and Fisheries Technology Center of Fuzhou, Fuzhou 350026, China) |
| Abstract: |
| The surface water, suspended sediment (SS) and surface sediment samples collected in the lower reaches and estuary of Minjiang during 2014 were analyzed. Geochemical characteristics of total carbon (TC) in sediments, their influencing factors as well as the differences among rivers were discussed. The results showed that the average content of TC in the sediments in summer was higher (1.74%), than in autumn (1.70%) at the same stations but with no significant difference. The average content of TC in sediments was 1.82% (1.21%~4.84%) in the study area. The spatial distribution of TC showed a “low-high-low” feature, in other words, the content of TC in sediments increased gradually from Shuikou Reservoir to Fuzhou reach and it reached the highest in Beigang waterway, then decreased gradually towards the estuary and adjacent sea. The high value areas of SS and chemical oxygen demand (COD) were larger in autumn than in summer. The concentrations of SS, COD and particulate TC also showed the distribution that increased first and then decreased, while the content of TC in SS decreased from the reservoir to the estuary. There were significant correlations between TC in sediments and in SS, concentration of SS and COD. Distribution of TC in sediment was influenced by process of deposition-resuspension-redeposition of SS. The major sources of TC were from the inputs of domestic sewage of human activities, organism farming, poultries, animals and aquacultures. The content of TC in sediments of Minjiang Estuary was much lower than those of Yellow River and Yangtze River, while similar to other small and medium-sized estuaries. General speaking, it was at a low level compared with other estuaries, which showed the distribution of TC in sediments was controlled by source rocks, pollutant fluxes and grain size of sediments in different river basins. The content of TC in sediments in Beigang waterway was significantly higher than those in the other rivers, where it indicates that the organic contamination was serious, which will become a potential factor affecting the water quality. |
| Key words: marine chemistry total carbon geochemical characteristics influencing factors sediments Minjiang Estuary |
