Copper (Cu) and Cobalt (Co) are among the most toxic heavy metals from mining and other industrial activities. Both are known to pose serious environmental concerns, particularly to water resources, if not properly treated. In recent years several filamentous fungal strains have been isolated, identified and assessed for their heavy metal biosorption capacity for potential application in bioremediation of Cu and Co wastes. Despite the growing interest in heavy metal removal by filamentous fungi, their exploitation faces numerous challenges such as finding suitable candidates for biosorption. Based on current findings, various strains of filamentous fungi have high metal uptake capacity, particularly for Cu and Co. Several works indicate that Trichoderma, Penicillium, and Aspergillus species have higher Cu and Co biosorption capacity compared to other fungal species such as Geotrichum, Monilia, and Fusarium. It is believed that far more fungal species with even higher biosorption capability are yet to be isolated. Furthermore, the application of filamentous fungi for bioremediation is considered environmentally friendly, highly effective, reliable, and affordable, due to their low technology pre-requisites. In this review, we highlight the capacity of various identified filamentous fungal isolates for biosorption of copper and cobalt from various environments, as well as their future prospects.

A Water Quality Index (WQI) is a tool that describes the overall water quality by combining complex and technical water quality information into a single meaningful unitless numerical value. WQIs predict water quality since they reflect the impact of multiple Water Quality Parameters (WQPs) and allow for spatial-temporal comparison of water quality status. Most African countries employ adapted WQIs by modifying the original index (or indices) and propose their concepts for evaluating the quality of surface and groundwater, which is normally accompanied by irregularities. The current review examined the process(es) involved in WQI modifications for monitoring water quality in Africa, explored associated limitations, and suggested areas for improvement. A review of 42 research articles from five databases in the last ten years (2012–2022) was conducted. The findings indicated Weighted Arithmetic (WAWQI) and the Canadian Council of Ministers of Environment (CCMEWQI) as the most adapted WQIs. However, several limitations were encountered in WQI developmental steps, mainly in parameter selection and classification schemes used for the final index value. Incorporation of biological parameters, use of less subjective statistical methods in parameter selection, and logical linguistic descriptions in classification schemes were some recommendations for remedying the limitations to register the full potential of adapted WQIs for water quality monitoring in Africa.

Africa accounts for nearly 30% of the discovered world’s mineral reserves, with half of the world’s platinum group metals deposits, 36% of gold, and 20% of cobalt being in Southern Africa (SA). The intensification of heavy-metal production in the SA region has exacerbated negative human and environmental health impacts. In recent years, mining waste generated from industrial and artisanal mining has significantly affected the ecological integrity of SA aquatic ecosystems due to the accelerated introduction and deposition of heavy metals. However, the extent to which heavy-metal pollution associated with mining has impacted the aquatic ecosystems has not been adequately documented, particularly during bioassessments. This review explores the current aquatic ecological impacts on the heavily mined river basins of SA. It also discusses the approaches to assessing the ecological risks, inherent challenges, and potential for developing an integrated ecological risk assessment protocol for aquatic systems in the region. Progress has been made in developing rapid bioassessment schemes (RBS) for SA aquatic ecosystems. Nevertheless, method integration, which also involves heavy-metal pollution monitoring and molecular technology, is necessary to overcome the current challenges of the standardisation of RBS protocols. Citizenry science will also encourage community and stakeholder involvement in sustainable environmental management in SA.

Mercury (Hg) pollution remains an environmental global concern due to its non-degradable and toxic nature. Natural and anthropogenic sources of Hg adversely affect the functioning of aquatic ecosystems and biological processes. In sub-Saharan Africa (SSA), unregulated artisanal and small-scale gold mining (ASGM) contributes up to 20% of global gold production and uses 205–496 tonnes/yr of Hg. Despite being a vital economic driver for 20–30 million people, ASGM threatens the health of aquatic systems from Hg pollution, presenting a complex challenge that demands urgent interventions. This review seeks to (1) establish the current status of aquatic Hg pollution, (2) explore the environmental impacts of aquatic Hg, and (3) highlight the proposed interventions for aquatic Hg pollution in SSA. We examined publications and institutional reports between 2000 and 2023 addressing aquatic Hg pollution, impacts, and interventions in the ASGM of SSA. Results indicate a rise in aquatic Hg pollution due to the expansion and intensification of ASGM. West Africa remained the highest contributor (50.2%), followed by Central Africa (39.6%), Southern Africa (9.6%), and Eastern Africa (<1%). Contamination of freshwater ecosystems, toxicity to aquatic biota, and environmental health risks to humans were evident. Alternative Hg-free ASGM technologies, including physical, metallurgical, and pyrometallurgical, were investigated from case studies and recommended for adoption.

This review elucidated the recent advances in integrating microalgal communities in monitoring metal pollution in aquatic ecosystems of sub-Saharan Africa (SSA). It also highlighted the potential of incorporating microalgae as bioindicators in emerging technologies, identified research gaps, and suggested directions for further research in biomonitoring of metal pollution. Reputable online scholarly databases were used to identify research articles published between January 2000 and June 2023 for synthesis. Results indicated that microalgae were integrated either individually or combined with other bioindicators, mainly macroinvertebrates, macrophytes, and fish, alongside physicochemical monitoring. There was a significantly low level of integration (< 1%) of microalgae for biomonitoring aquatic metal pollution in SSA compared to other geographical regions. Microalgal communities were employed to assess compliance (76%), in diagnosis (38%), and as early-warning systems (38%) of aquatic ecological health status. About 14% of biomonitoring studies integrated microalgal eDNA, while other technologies, such as remote sensing, artificial intelligence, and biosensors, are yet to be significantly incorporated. Nevertheless, there is potential for the aforementioned emerging technologies for monitoring aquatic metal pollution in SSA. Future monitoring in the region should also consider the standardisation and synchronisation of integrative biomonitoring and embrace the “Citizen Science” concept at national and regional scales. Graphical abstract

Anthropogenically accelerated metal pollution of lotic systems draining mining landscapes remains a global concern due to its non‐degradability and ecotoxic nature. Nevertheless, the efficacy of macrophytes as indicators and remediators of metal(loid) pollutants in aquatic ecosystems in mining regions is recognised globally. However, in the mineral‐rich Central African Copperbelt (CACB), there is limited research on the effectiveness of macrophytes for mining pollution management. Therefore, this study investigated the phytopotential of Typha domingensis Pers. (Typhaceae), as a nature‐based approach for managing aquatic metal(loid) pollution on the CACB. A total of 252 samples each for sediment and T. domingensis were collected monthly between May 2022 and April 2023 from seven streams in the Kansanshi sub‐catchment of the CACB and analysed to evaluate the spatiotemporal variability of the phytoindication and phytoremediation potential of T. domingensis for As, Cu, Pb and Zn in stream sediments. Metal(loid)s in T. domingensis at 71% of the streams were predominantly accumulated in the below‐ground biomass with mean concentrations of 3–6 mg/kg As, 9–259 mg/kg Cu, 25–36 mg/kg Pb and 38–69 mg/kg Zn. The BAF was above 1 for As (0.8–2.6), Pb (10.7–24.3) and Zn (1.4–4.3), indicating T. domingensis as an accumulator of these elements but an excluder for Cu (BAF < 1). Additionally, TF was above 1 for As (1.5–2.0), Pb (1.4–1.5) and Zn (1.0–2.0), indicating the macrophyte's extraction efficacy. For Cu (TF < 1), the limited translocation characterised T. domingensis as a potential metal phytostabiliser. Similar seasonal trends for BAF and TF for As, Cu, Pb and Zn were also observed. Therefore, the spatiotemporal response of T. domingensis as a phytoindicator and phytoremediator of metal contaminants in sediments should be considered in the nature‐based management of CACB's aquatic ecosystems.