Paul Johan Oberholster

Paul Johan Oberholster
University of the Free State | ufs · Center for Environmental Management

pHD

About

120
Publications
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Publications

Publications (120)
Chapter
The search for effective and sustainable techniques for the decontamination of polluted water bodies has led to significant progress over the last two decades with the emergence of the concept of bioremediation, i.e., the use of naturebased solutions (NBSs) to eliminate pollution. The sustainability of these processes is based on the availability o...
Article
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The Grootspruit valley bottom wetland in South Africa, due to the impact of acid mine drainage (AMD) from an abandoned coal mine, was severely degraded before ecologically engineered interventions, as a passive treatment process, in 2014. The surface water flow of the wetland was redirected using concrete structures to enlarge the surface area of t...
Article
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Toxic phytoplankton in the aquatic ecosystems are dynamic, affecting water quality. It remains unclear as to how possible toxic phytoplankton assemblages vary vertically and temporally in Swakoppoort and Von Bach dams, located in a dry subtropical desert region in central Namibia. The following variables were analyzed: pH, Secchi depths, turbidity,...
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Rapid commercialisation of nano-enabled products (NEPs) elevates the potential environmental release of engineered nanomaterials (ENMs) along the product life cycle. The current review examined the state of the art literature on aquatic environment exposure and ecotoxicity of product released (PR) engineered nanomaterials (PR–ENMs). Additionally, t...
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The reuse of wastewater has been observed as a viable option to cope with increasing water stress in Africa. The present case studies evaluated the optimization of the process of phycoremediation as an alternative low-cost green treatment technology in two municipality wastewater treatment pond systems that make up the largest number of domestic se...
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Globally, increased stress on water resources and associated ecosystems is reported. Reducing overdependence on a single water resource grows, with growing global interest on hydrological cycle interactions, impacts of land uses and impacts of these interactions on dependant ecosystems. Through a case study, groundwater exchanges between wetlands a...
Article
The Olifants River catchment has been adversely affected by anthropogenic land-use activities over the last decade. This study aims to determine the variation in surface and groundwater concerning heavy metal pollution. The collection of surface and groundwater was performed at three different land-use locations; namely, wastewater treatment works...
Article
Ecological restorations of reservoirs are implemented worldwide; however, minimal successes are reported and understood for warmer African lakes like Swakoppoort Dam, Namibia. The objectives of the study were (a) to establish the effectiveness of the two control measures in reducing cyanobacteria growths in comparison with untreated control areas a...
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The iron and steel industry is a major global industry that consumes vast quantities of energy and causes environmental degradation through greenhouse gas emissions and industrial waste generation, treatment, and disposal. There is a need to manage complex iron and steel industrial waste in Africa, which requires a system engineering approach to ze...
Article
The study aimed to investigate the waste characteristics and management activities in the iron and steel industry in Southern Africa based on a case study in South Africa. A four-phased decision-support framework (DSF) has been suggested to approach industrial waste management in Southern Africa’s iron and steel industry, consisting of a desktop-ba...
Article
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 w...
Article
With the potentially fatal effect of COVID-19 and its devastating impact on economies worldwide, some environmental scientist has suggested the use of waste from household sewage to trace the movement of SARS-CoV-2, within a given country. However, this approach is not without challenges where developing countries lack proper and adequate hygiene a...
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The Value Stream Mapping (VSM) method was applied to a case study in the iron and steel industry in Southern Africa as a supporting management tool to identify, demonstrate, and evaluate industrial waste and comprised of three steps. The first step included collecting and verifying waste generation and flow data as the VSM data input step. The seco...
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The Olifants River in South Africa, is well known to be one of the most polluted rivers in Southern Africa. Water quality issues in the River Catchment are known catchment are known to be primary related to salinity, eutrophication and acid mine drainage. This study aimed to assess the efficiency removal of metal ions in effluent wastewater from a...
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Metal(loid) pollution in aquatic ecosystems has become a cause for concern, particularly in areas where communities depend on services from these systems for their livelihood. This dataset presents the metal(loi) concentrations recorded in the water column, bottom sediment, and tissues of Oreochromis mossambicus and Labeo rosae from Flag Boshielo D...
Article
International scientific partnerships are key to the success of strategic investments in plant science research and the farm-level adoption of new varieties and technologies, as well as the coherence of agricultural policies across borders to address global challenges. Such partnerships result not only in a greater impact of published research enha...
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Wastewater stabilization ponds (WSP) are a common method to treat wastewater before release. The purpose of the current study was to find the most inexpensive coagulation and flocculation reagents to use during harvesting of WSP algae from effluent so that water without algae can be generated for irrigation purposes. In the study, the toxicity of e...
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Effluent from abattoir industries containing metals ions is known to adversely affect the quality fresh water. Water pollution is a global concern and its effects are difficult to reverse. This study evaluates the efficiency of the use of the shrimp chitosan cross-linked with glutaraldehyde as an adsorbent for the removal of cations in poultry and...
Chapter
The response of biological indicators with ecosystem food web and agricultural relevance were examined in biologically treated cyanobacteria culture water. To assess bioindicator responses to variations in the toxicity measurements, a case study on the filtrate of treated cyanobacteria was conducted. Cyanobacterial cultures of dominant Oscillatoria...
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In the meat production industry, large volumes of wastewater are generated containing great quantities of organic matter that requires y safe disposal or utilization. As a result, management of poultry wastewater is of great concern worldwide. However, problems associated with wastewater disposal are a well-known phenomenon. Nevertheless finding so...
Article
The Loskop Dam in South Africa is the most contaminated waterbody in the Olifants River which is a transboundary river that flows into Mozambique. The present study measured selected metal concentrations in the muscle of Labeo rosae and Oreochromis mossambicus from Loskop Dam, and assessed the human health risks associated with consumption of these...
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The presence of heavy metals such as chromium within water sources are considered as one of the most vital problem to the environment. Accumulating of chromium within the human body, can cause various diseases and disorders. Chitosan cross-linked glutaraldehyde adsorbent (formed from the acetyl group of chitin from alkaline solution) is widely a we...
Article
The success and long term effectiveness of extensive and expensive engineering solutions to restore streams impacted by Acid Mine Drainage (AMD) is rarely tested. Concentrations of pollutants were measured in water along a longitudinal gradient from a stretch of the Tweelopie stream, South Africa, that receives pH-treated acid mine drainage (AMD) f...
Article
Biological control of cyanobacteria is a viable means of controlling nuisance bloom occurrences; however the majority of studies done are against Microcystis sp., with a commonly lytic effect caused. Filamentous cyanobacteria such as Oscillatoria are not as extensively studied in this area of biological control and are often part of Microcystis dom...
Article
The eutrophication of waterways has become an endemic global problem. Nutrient enrichment from agriculture activities and waste water treatment plants are major drivers, but it remains unclear how lowland sandy rivers respond to eutrophication. The objective of this study was the development and verification of eutrophication index for sandy rivers...
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Employing specific algae treatment to treat municipal domestic wastewater effluent presents an alternative practice to improving water quality effluent of existing rural pond systems in Southern Africa. In the present study, domestic wastewater was treated by using existing infrastructure and inoculated specific selected algae strains in a pond sys...
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Freshwater resources in semi-arid countries are under constant threat from pollution. One of the major pollutants is acid mine drainage (AMD), which not only lowers the pH of the water, but contains high sulphuric acid and high metal concentrations. Bacteria and algae are the first organisms to respond to stressors such as reduced pH and high metal...
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Biological control of cyanobacteria is a well-researched area with a central focus on laboratory-scale studies. Numerous reports have been made on algicidal isolates, with bacteria as a major component of the antagonists. The research in this review draws a brief summary of what is currently known in the area of freshwater cyanobacteria being inhib...
Chapter
Coal mining has the potential to affect and disturb water ecosystems throughout the life cycle of a mining operation, by point and nonpoint source pollution. Impacts of direct water pollution can result from any activities that involve direct discharges into waterbodies e.g., riverine tailings or tailing impoundment releases or acid mine drainage (...
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The regulation of anthropogenic pollution inputs into large rivers is an important aspect of ecological resilience of aquatic systems and river pollution management. The current study examined the relationship between contamination loads, hydrological and morphological patterns and the distribution of macroinvertebrates and epipelic diatoms in the...
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The presence of harmful algal blooms (HABs) and cyanotoxins in drinking water sources poses a great threat to human health. The current study employed molecular techniques to determine the occurrence of non-toxic and toxic cyanobacteria species in the Limpopo River basin based on the phylogenetic analysis of the 16S rRNA gene. Bottom sediment sampl...
Article
Globally, the dependence of river systems to delayed discharge of subsurface water to augment flows during dry seasons is well documented. Discharge of fresh subsurface water can dilute concentrated river flow quality during reduced flow. Observed and reported results on the Berg River’s declining water quantity and quality are a concern to the reg...
Preprint
Full-text available
The presence of harmful algal blooms (HABs) and cyanotoxins in drinking water sources poses a great threat to human health. The current study employed molecular techniques to determine the occurrence of non-toxic and toxic cyanobacteria species in the Limpopo River basin based on the phylogenetic analyses of 16S rRNA gene. The bottom sediments samp...
Article
Full-text available
The assessment of ecological integrity of river systems is multidisciplinary and necessary for effective river management. The objectives of this study were (i) to characterize the spatial and temporal distribution of macroinvertebrate and algae community assemblages; (ii) to determine the environmental variables that affect assemblage distribution...
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Filamentous algae biomass is very limited in aerobic constructed wetlands and totally absent in anaerobic constructed wetlands. Its contribution to the removal of sulphur from acid mine drainage will therefore rarely reach a significant level if not used in association with secondary algae treatment ponds as part of a biological hybrid treatment sy...
Article
Before the introduction of reclamation legislation in South Africa, final cut lakes in mining areas were left without any restoration while the final excavation was not back filled. Characteristics of these lacustrine water bodies vary considerably, but they are often linear in shape, large (1-30 ha), deep (2-30 m) and have poorly developed littora...
Article
Rising environmental pressures on water resources and resource quality associated with urbanisation, industrialisation, mining and agriculture are a global concern. In the current study the upper Olifants River catchment as case study was used, to show that acid mine drainage (AMD) and acid precipitation were the two most important drivers of possi...
Article
Acid mine drainage (AMD) from coal mining in the Mpumalanga Highveld region of South Africa has caused severe chemical and biological degradation of aquatic habitats, specifically depressional wetlands, as mines use these wetlands for storage of AMD. Diatom-based multimetric indices (MMIs) to assess wetland condition have mostly been developed to a...
Article
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Information on the response of temporary depressional wetland diatoms to human-induced disturbances is a limited and important component for the development of temporary wetland biological assessments in human-modified landscapes. Establishing a reference condition of variation due to natural disturbances in depressional wetlands using diatoms is n...
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Thyroid function and nutritional indicators were measured in obese, steatitis-affected Mozambique tilapia Oreochromis mossambicus from Loskop Reservoir (LR), South Africa. Plasma thyroid hormones (especially T3) and thyroid follicle histomorphology revealed high levels of activity in every aspect of the thyroid cascade measured in fish from LR comp...
Article
Functional-based assessments to identify the effects of human-induced disturbances on diatom communities are increasingly used. However, information on the response of functional groups to natural disturbances in temporary depressional wetlands is limited although important for the development of temporary wetland biological assessments. We assesse...
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The alien invasive silver carp Hypophthalmichthys molitrix established a self-sustaining feral population in an oligotrophic impoundment, Flag Boshielo Dam, in South Africa. The ability of this population to persist in a dam with low algal biomass (median annual suspended chlorophyll a = 0.08 µg l⁻¹), and limited access to rivers considered large e...
Article
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Interdisciplinary research in the fields of ecohydrology and ecogeomorphology is becoming increasingly important as a way to understand how biological and physical processes interact with each other in river systems. The objectives of the current study were 1) to determine changes in invertebrate community due to hydrological stages, 2) to link loc...
Article
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Over the past decade, several clustered, multispecies, wildlife mortality events occurred in the vicinity of two man-made earthen dams in the southern and south central regions of the Kruger National Park, South Africa. On field investigation, heavy cyanobacterial blooms were visible in these impoundments and analysis of water samples showed the do...
Article
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Knowledge regarding the potential impacts of crude oil on endocrine signalling in freshwater aquatic vertebrates is limited. In this study, the expression of selected genes as biomarkers for altered endocrine signalling were studied in African clawed frog, Xenopus laevis tadpoles, and juvenile Mozambique tilapia, Oreochromis mossambicus exposed to...
Article
Water treatment is an important ecosystem service in natural systems and wetlands are well-known to have increased functionality in this regard. The rehabilitation of productive wetlands plays an important role in improving this functionality in degraded wetlands, but it is not well-known to what extent these activities improve acid mine drainage i...
Article
The regulation of nutrient inputs into rivers dominated by agriculture land use activities is an important aspect of ecological resilience of aquatic systems and the management of river eutrophication. The overabundance of benthic filamentous algae mats in river systems due to nutrient enrichment can modify the habitats of macroinvertebrate and fis...
Article
Full-text available
This paper presents estimates of the monetary value of the impact of eutrophication (algae) on commercial agriculture in two different catchments in South Africa. A production function approach is applied to estimate the monetary value of the impact of filamentous green algae on commercial agriculture in the Dwars River, Western Cape and the Loskop...
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Since the industrial revolution, the impact of effluents produced by human activities on ecosystems has been a major international environmental concern. This study was aimed at observing the changes in water and sediment qualities at a watershed level of two different river systems facing the same land use practices, but impacted to different degr...
Technical Report
Full-text available
BACKGROUND By virtue of their positions in the landscape and relationship to drainage networks, wetlands are frequently impacted by coal mining activities, especially opencast methods. These impacts will be ongoing, since coal is a strategic resource and will continue to be mined extensively to support the country’s development. At the same time,...
Technical Report
Full-text available
Wetlands ecosystems are vital ecological infrastructure that provide valuable services to people and are important biodiversity assets. Wetlands help to buffer flood waters, soak up water to release more gradually over time, filter sediments, purify water, and provide forage for livestock and refuge for numerous species. While remarkably resilient...
Technical Report
Full-text available
By virtue of their positions in the landscape and relationship to drainage networks, wetlands are frequently impacted by coal mining activities, especially through opencast mining methods. These impacts will be ongoing, since coal is a strategic resource and will continue to be mined extensively to support the country's development. At the same tim...
Article
Full-text available
Endocrine-disrupting contaminant (EDC) loads in rivers, and the associated risk to wildlife, may be linked to different anthropogenic stressors occupying river catchments. The aims of this study were to evaluate seasonal and spatial variation in steroid estrogen loads, and (anti)estrogenic and (anti)androgenic activity in a river catchment (upper O...