Currently water resources in nature conservation areas are under severe pressure due to external drivers of anthropogenic pollution. There is a lack of monitoring tools to determine water quality status of dams situated in nature reserves receiving a mixture of pollutants over space and time. The present study was conducted over a 12-month period with the aim of applying a modified pollution index (PILD) to determine the water quality and phytoplankton status of the Loskop Dam situated in the Loskop nature reserve, South Africa. From the data generated in the current study, it was evident that the PILD effectively determined nutrient enrichment and heavy metal pollution in the dam. Furthermore, the study showed that the most pollution tolerant phytoplankton species was the diatom Melosira varians followed by the dinoflagellate Ceratuim hirundinella and the cyanobacteria Microcystis aeruginosa. Chemical variables during the sampling period that exceeded the limits of the South African, Canadian, Australia and New Zealand guideline levels were Zn, TP, Cl, Fe, Mn and NH₄. The occurrence of concentrations of Cl above the target water quality range for aquatic ecosystems (5 µgl⁻¹) over the entire sampling period, may have been related to point source sewage pollution in the upper catchment. The PILD showed poor water quality conditions during the months of September and October during the dam’s destratification (lake overturn). By modifying an existing index to incorporate physico-chemical variables that are strongly related to a mixture of pollutants, it should have application on global scale applied to different waterbodies with differ phytoplankton indicator species across different geographical regions. Furthermore, it could also in the future serve as a decision support tool for conservation managers to determine the pollution status of a dam situated in nature conservation areas receiving a mixture of pollutants.

Graphic abstract

中文翻译：

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使用修改后的污染指数评估AMD和污水混合排放对自然保护区中亚热带水坝的不利影响

当前，由于人为污染的外部驱动因素，自然保护区的水资源承受着巨大的压力。缺乏监测工具来确定位于自然保护区内的大坝的水质状况，这些大坝在空间和时间上会混合污染物。本研究为期12个月，目的是应用修正的污染指数（PILD）来确定位于南非洛斯科普自然保护区的洛斯科普水坝的水质和浮游植物状况。从当前研究得出的数据来看，很明显PILD有效地确定了大坝中的养分富集和重金属污染。此外，研究表明，最耐污染的浮游植物是硅藻Melosira varians其次是鞭毛藻Ceratuim hirundinella和蓝细菌微囊藻铜绿藻。在抽样期间，超出南非，加拿大，澳大利亚和新西兰准则水平限制的化学变量为Zn，TP，Cl，Fe，Mn和NH ₄。在整个采样期内，Cl的浓度超过水生生态系统目标水质范围（5 µgl ^-1）的发生，可能与上游流域的点源污水污染有关。该PILD在9月和10月的大坝脱层（湖面倾覆）期间，水质状况不佳。通过修改现有指标以纳入与污染物混合物密切相关的物理化学变量，它应在全球范围内应用于不同地理区域具有不同浮游植物指示物种类的不同水体。此外，它将来还可以用作保护管理者的决策支持工具，以确定位于自然保护区内的大坝的污染状况，该大坝接受污染物的混合。

图形摘要