PDF(Pubmed)
Abstract：
The increasing pressure on freshwater systems due to intensive anthropogenic use is a big challenge in central-northern Namibia and its catchment areas, the Kunene and the Kavango Rivers, and the Cuvelai-Etosha Basin, that provide water for more than 1 million people. So far, there is no comprehensive knowledge about the ecological status and only few knowledge about the water quality. Therefore, it is crucial to learn about the state of the ecosystem and the ecological effects of pollutants to ensure the safe use of these resources. The surface waters of the three systems were sampled, and three bioassays were applied on three trophic levels: algae, daphnia, and zebrafish embryos. Additionally, in vitro assays were performed to analyze mutagenicity (Ames fluctuation), dioxin-like potential (micro-EROD), and estrogenicity (YES) by mechanism-specific effects. The results show that acute toxicity to fish embryos and daphnia has mainly been detected at all sites in the three catchment areas. The systems differ significantly from each other, with the sites in the Iishana system showing the highest acute toxicity. At the cellular level, only weak effects were identified, although these were stronger in the Iishana system than in the two perennial systems. Algae growth was not inhibited, and no cytotoxic effects could be detected in any of the samples. Mutagenic effects and an estrogenic potential were detected at three sites in the Iishana system. These findings are critical in water resource management as the effects can adversely impact the health of aquatic ecosystems and the organisms within them.
摘要：
由于大量的人为使用，淡水系统面临的压力越来越大，这在纳米比亚中北部及其集水区是一个巨大的挑战，库内内河和卡万戈河,还有Cuvelai-Etosha盆地,为100多万人提供水。到目前为止,关于生态状况没有全面的知识，关于水质的知识很少。因此,了解生态系统的状况和污染物的生态影响对于确保这些资源的安全使用至关重要。对三个系统的地表水进行了采样,在三个营养水平上应用了三种生物测定：藻类，水蚤,和斑马鱼胚胎。此外,进行体外测定以分析诱变性(Ames波动)，二恶英样潜力（微EROD），和雌激素性(是)通过机制特异性效应。结果表明，对鱼类胚胎和水蚤的急性毒性主要在三个集水区的所有地点检测到。这些系统彼此明显不同，Iishana系统中的站点显示出最高的急性毒性。在细胞层面,只有微弱的影响被确定，尽管这些在Iishana系统中比在两个常年系统中更强。藻类生长没有受到抑制，并且在任何样品中都没有检测到细胞毒性作用。在Iishana系统的三个位置检测到诱变作用和雌激素潜力。这些发现对水资源管理至关重要，因为这种影响可能会对水生生态系统及其内部生物的健康产生不利影响。
