Paleolimnological assessment of human impacts on an urban South African lake
Paleolimnological assessment of human impacts on an urban South African lake
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DOI：
10.1007/s10933-006-9076-8
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发表时间：
2007-01
影响因子：
2.1
通讯作者：
F. García-Rodríguez;C. Anderson;J. B. Adams
中科院分区：
文献类型：
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作者：
F. García-Rodríguez;C. Anderson;J. B. Adams
北端湖（North End Lake）是位于南非伊丽莎白港的一个受污染且富营养化的淡水系统。由于该湖预计到2010年将用于娱乐/旅游目的，因此必须设计一个修复方案。出于这个原因，我们从湖的中心区域取回了一个沉积物芯，以破译历史上人类对水体的影响。前干扰古湖泊学推断表明，湖泊可能是中营养。1831年后，当绵羊养殖活动进行的集水区，增加营养状态和沉积物成分的变化进行了观察。1937年后，记录到微量金属水平、有机物、球状碳质颗粒（SCP）的增加和沉积物成分的变化。该系统成为富营养化所示的优势，放线菌normanii，一个世界性的物种，经常观察到的系统，水质已显着下降。1986年后，由于建造了一个雨水保留系统，故意将雨水径流引入湖中，情况进一步恶化。因此，在水柱中测得极高的粪大肠菌群值（即每100毫升2 × 106）。古湖沼信息确定了有机物含量急剧增加的核心的最高部分，这可能与雨水滞留系统的操作。因此，作为一项直接的管理措施，我们建议，雨水保留系统应不再使用，或雨水径流处理前处置到湖泊。此外，还必须建立有效的污水处理系统。
North End Lake is a polluted and eutrophic freshwater system located in Port Elizabeth, South Africa. Since the lake is expected to be used for recreational/tourist purposes by 2010, a rehabilitation program will have to be designed. For this reason, we retrieved a sediment core from the central region of the lake to decipher the effect of historical human impacts on the water body. Pre-disturbance paleolimnological inferences indicate that the lake was likely mesotrophic. After ∼1831, when sheep farming activities were undertaken in the catchment, increases in trophic state and changes in sediment composition were observed. After ∼1937, increases in trace metal levels, organic matter, spheroidal carbonaceous particles (SCP) and changes in sediment composition were recorded. The system became eutrophic as indicated by the dominance of the diatomActinocyclus normanii, a cosmopolitan species often observed in systems where water quality has been dramatically degraded. The conditions worsened after 1986 because of the construction of a storm-water retention system, which intentionally channeled storm-water runoff into the lake. Because of this, extremely high values of fecal coliforms (i.e. 2 × 106every 100 ml) have been measured in the water column. The paleolimnological information identified the sharp increase in organic content in the uppermost section of the core, and this could be correlated to the operation of the storm-water retention system. Therefore, as an immediate management measure, we suggest that the storm-water retention system should either no longer be utilized, or the storm-water runoff should be treated before disposal into the lake. In addition, an effective sewage system has to be constructed.