Institut Pasteur d'Abidjan, Abidjan, Côte d'Ivoire.
Université Jean Lorougnon Guédé, Daloa, Côte d'Ivoire.
PLoS One. 2021 May 6;16(5):e0251065. doi: 10.1371/journal.pone.0251065. eCollection 2021.
The supply of drinking water is a vital challenge for the people who live on the African continent, as this continent is experiencing strong demographic growth and therefore increasing water demands. To meet these needs, surface water resources are becoming increasingly mobilized because underground resources are not always available or have already been overexploited. This situation is the case in the region of Abidjan in the Ivory Coast, where the drinking water deficit is a growing problem and it is therefore necessary to mobilize new water resources to ensure the supply of drinking water. Among the potential resources, local managers have identified a freshwater lagoon, Lagoon Aghien, That is in close proximity to the city of Abidjan. With the aim of enhancing knowledge on the ecological functioning of the lagoon and contributing to the assessment of its ability to provide drinking water, several physical and chemical parameters of the water and the phytoplankton community of the lagoon were monitored for 17 months (December 2016-April 2018) at six sampling stations. Our findings show that the lagoon is eutrophic, as evidenced by the high concentrations of total phosphorus (>140 μg L-1), nitrogen (1.36 mg L-1) and average chlorophyll-a (26 to 167 μg L-1) concentrations. The phytoplankton community in the lagoon is dominated by genera typical of eutrophic environments including mixotrophic genera such as Peridinium and by cyanobacteria such as Cylindrospermopsis/Raphidiopsis, Microcystis and Dolichospermum that can potentially produce cyanotoxins. The two rainfall peaks that occur in June and October appeared to be major events in terms of nutrient flows entering the lagoon, and the dynamics of these flows are complex. Significant differences were also found in the nutrient concentrations and to a lesser extent in the phytoplankton communities among the different stations, especially during the rainfall peaks. Overall, these results reveal that the quality of the lagoon's water is already severely degraded, and this degradation could increase in future years due to increasing urbanization in the watershed. These results therefore raise questions about the potential use of the lagoon as a source of drinking water if measures are not taken very quickly to protect this lagoon from increasing eutrophication and other pollution sources.
饮用水供应是非洲大陆居民面临的一项重要挑战，因为非洲大陆正经历着强劲的人口增长，因此对水资源的需求也在不断增加。为了满足这些需求，地表水的开发利用变得越来越重要，因为地下水资源并非总是可用或已经过度开采。科特迪瓦阿比让地区就是这种情况，那里的饮用水短缺是一个日益严重的问题，因此有必要调动新的水资源来确保饮用水的供应。在潜在的水资源中，当地管理者已经确定了一个淡水泻湖，即阿希恩泻湖，该泻湖紧邻阿比让市。为了增强对泻湖生态功能的了解，并为评估其提供饮用水的能力做出贡献，在 17 个月的时间里（2016 年 12 月至 2018 年 4 月），在六个采样站监测了水的几个物理和化学参数以及泻湖的浮游植物群落。我们的研究结果表明，泻湖富营养化，这表现在总磷（>140μg/L）、氮（1.36mg/L）和平均叶绿素-a（26 至 167μg/L）浓度高。泻湖中浮游植物群落主要由富营养化环境中典型的属组成，包括混合营养型属，如双鞭甲藻属和蓝藻属，如柱孢藻属/束丝藻属、微囊藻属和鱼腥藻属，这些藻类可能会产生蓝藻毒素。6 月和 10 月出现的两次降雨高峰似乎是营养物质流入泻湖的重要事件，这些物质的流动非常复杂。在不同的站点之间，营养物浓度也存在显著差异，在浮游植物群落中差异较小，特别是在降雨高峰期间。总的来说，这些结果表明，泻湖的水质已经严重恶化，如果不迅速采取措施保护泻湖免受富营养化和其他污染源的影响，未来几年水质可能会进一步恶化。因此，如果不采取措施保护泻湖免受富营养化和其他污染源的影响，这些结果引发了关于该泻湖是否可用作饮用水源的问题。
