| 坦噶尼喀湖东北部入湖河流沉积物重金属分布特征与生态风险评价 |
| 摘要点击 2107 全文点击 888 投稿时间：2015-07-20 修订日期：2015-09-10 |
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| 中文关键词 坦噶尼喀湖 入湖河流 表层沉积物 重金属 潜在生态风险 土地利用 |
| 英文关键词 Lake Tanganyika inflow river surface sediments heavy metals potential ecological risk land use |
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| 中文摘要 |
| 坦噶尼喀湖是非洲第二深的湖泊,拥有独特的生态系统,为沿湖居民提供丰富的鱼类蛋白,随着沿湖社会经济的发展和人口的快速增长,坦噶尼喀湖面临着环境污染威胁. 为了揭示坦噶尼喀湖的重金属外源输入,本研究采集了湖泊东北部入湖河流的表层沉积物(16个样点),对沉积物重金属含量进行分析,并应用潜在风险指数法对沉积物重金属的生态风险进行了评价,同时分析了重金属分布与土地利用的关系. 结果表明Cu、 Zn、 Cd、 Pb和Hg的平均含量分别为18.4、 21.2、 0.05、 6.6mg ·kg-1以及8.4ng ·g-1; Zn、 Pb、 Cd的含量最高值均位于布琼布拉城市入湖河流. 潜在生态风险指数(RI)表明,各重金属在各点位的生态风险系数均较低,其中Cd > Hg > Cu > Pb > Zn,Cd 是最主要的生态风险贡献因子,所有点位均属于低潜在生态风险区. 重金属含量与土地利用的关系表明,城镇附近采样点重金属含量最高,其次是河口湿地,远离城镇的林草地重金属含量最低,表明人类活动会增加河流表层沉积物重金属含量. 在以后的研究中,对城镇附近及河口湿地应给予重点关注. |
| 英文摘要 |
| As the second deepest lake in Africa, Lake Tanganyika plays an important role in supplying fish protein for citizens in the catchment. However, the lake is increasingly threatened by environmental pollution with the development of social economy and expanding of population. In order to reveal the external source of heavy metals in Lake Tanganyika, 16 surface sediment samples from the rivers which flow into the northeast of the lake were collected and analyzed. Besides the contents, the potential ecological risk indices (RI) of each heavy metal were also analyzed. Furthermore, the relationship between land use and the spatial distribution of heavy metals was also discussed. The average contents of Cu, Zn, Cd, Pb and Hg were 18.4, 21.2, 0.05, 6.6mg·kg-1and 8.4ng ·g-1, respectively, with the maximum values of Zn, Pb and Cd located in Bujumbura urban rivers. The data indicated that all the inflow rivers were at low potential ecological risk. RI of heavy metals ranked as the following order: Cd > Hg > Cu > Pb > Zn, as Cd being the key element contributing to the risk. The relationship between land use and heavy metals showed that the contents of heavy metals were highest in urban areas, followed by estuarine wetlands, and woodlands were least polluted by heavy metals. This distribution type implied that human activities could cause the heavy metal accumulation in the surface sediments of nearby rivers. The urban areas and estuarine wetlands need to be concerned in the further study. |
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