Papers by Elke S Reichwaldt
<p>Sites are clustered along the x-axis (Factor 1) in site 5 and all other sites and along ... more <p>Sites are clustered along the x-axis (Factor 1) in site 5 and all other sites and along the y-axis (Factor 2) in sites 6, 7 and 1–5. See text and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0066674#pone-0066674-t005" target="_blank">Table 5</a> for which parameters represent best each of the factors.</p
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Spatial and temporal variability in the relationship between cyanobacterial biomass and microcystins
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Water Research, 2021
Accurate estimations of gaseous emissions and carbon sequestration in wastewater processing are e... more Accurate estimations of gaseous emissions and carbon sequestration in wastewater processing are essential for the design, operation and planning of treatment infrastructure, particularly considering greenhouse gas reduction targets. In this study, we look at the interplay between biological productivity, hydrodynamics and evasion of carbon-based greenhouse gases (GHG) through diffusion and ebullition in order to provide direction for more accurate assessments of their emissions from waste stabilization ponds (WSPs). The ponds stratified in the day and mixed at night. Buoyancy flux contributed between 40 and 75% to turbulence in the water column during nocturnal cooling events, and the associated mixing lead to increasing carbon dioxide (CO2) and methane (CH4) concentrations by up to an order of magnitude in the surface. The onset of stratification and phytoplankton surface blooms, associated with high pH as well as low and variable CO2 partial pressure resulted in an overall reduction of CO2 efflux. Ebullition represented between 40 and 99% of the total CH4 efflux, and up to 95% of the integrated GHG release during wastewater treatment (in CO2 equivalents). Hydrodynamic conditions, diurnal variability and ebullition need to be accounted for reliable assessments of GHG emissions from WSPs. Our study is an important step towards gaining a deeper understanding in the functioning of these hot spots of carbon processing. The contribution of WSPs to atmospheric GHG budget is likely to increase with population growth unless their performance is improved in this regard.
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Journal of Environmental Management, 2019
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Water Research, 2017
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Water research, 2017
As the world's population continues to grow, water pollution is presenting one of the biggest... more As the world's population continues to grow, water pollution is presenting one of the biggest challenges worldwide. More wastewater is being generated and the demand for clean water is increasing. To ensure the safety and health of humans and the environment, highly efficient wastewater treatment systems, and a reliable assessment of water quality and pollutants are required. The advance of holistic approaches to water quality management and the increasing use of ecological water treatment technologies, such as constructed wetlands and waste stabilisation ponds (WSPs), challenge the appropriateness of commonly used water quality indicators. Instead, additional indicators, which are direct measures of the processes involved in the stabilisation of human waste, have to be established to provide an in-depth understanding of system performance. In this study we identified the sterol composition of wastewater treated in WSPs and assessed the suitability of human sterol levels as a bi...
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Water Research, 2017
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Environmental Science & Technology, 2016
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Toxins, Aug 31, 2016
Alert level frameworks advise agencies on a sequence of monitoring and management actions, and ar... more Alert level frameworks advise agencies on a sequence of monitoring and management actions, and are implemented so as to reduce the risk of the public coming into contact with hazardous substances. Their effectiveness relies on the detection of the hazard, but with many systems not receiving any regular monitoring, pollution events often go undetected. We developed toxicological risk assessment models for acute and chronic exposure to pollutants that incorporate the probabilities that the public will come into contact with undetected pollution events, to identify the level of risk a system poses in regards to the pollutant. As a proof of concept, we successfully demonstrated that the models could be applied to determine probabilities of acute and chronic illness types related to recreational activities in waterbodies containing cyanotoxins. Using the acute model, we identified lakes that present a 'high' risk to develop Day Away From Work illness, and lakes that present a ...
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Hydrology and Earth System Sciences Discussions, 2016
Urbanisation strongly impacts aquatic ecosystems by decreasing water quality and altering water c... more Urbanisation strongly impacts aquatic ecosystems by decreasing water quality and altering water cycles. Today, much effort is put towards the restoration and conservation of urban waterbodies to enhance ecosystem service provision leading to liveable and sustainable cities. To enable a sustainable management of waterbodies, the quantification of the temporal and spatial variability of pollution levels and biogeochemical processes is essential. Stable isotopes have widely been used to identify sources of pollution in ecosystems. For example, increased nitrogen levels in waterbodies are often accompanied with a higher nitrogen stable isotope signature…
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Water Research, 2016
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Climate Change and Marine and Freshwater Toxins, 2015
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Environmental Monitoring and Assessment, 2015
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Hydrology and Earth System Sciences Discussions, 2014
Toxic cyanobacterial blooms in urban lakes present serious health hazards to humans and animals a... more Toxic cyanobacterial blooms in urban lakes present serious health hazards to humans and animals and require effective management strategies. In the management of toxic cyanobacteria blooms, understanding the roles of environmental factors is crucial. To date, a range of environmental factors have been proposed as potential triggers for the spatiotemporal variability of cyanobacterial biomass and microcystins in freshwater systems. However, the environmental triggers of cyanobacteria and microcystin variability remain a subject of debate due to contrasting findings. This issue has raised the question if the environmental triggers are site-specific and unique between water bodies. In this study, we investigated the site-specificity of environmental triggers for cyanobacterial bloom and cyanotoxins dynamics. Our study suggests that cyanobacterial dominance and cyanobacterial microcystin content variability were significantly correlated to phosphorus and iron concentrations. However, th...
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Toxins, 2015
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European Geosciences Union Conference; Vienna (2014) Wastewater stabilisation ponds (WSPs) are hi... more European Geosciences Union Conference; Vienna (2014) Wastewater stabilisation ponds (WSPs) are highly productive systems designed to treat wastewater using only natural biological and chemical processes, but they are known to operate at different levels of efficiency. Phytoplankton, microbial communities and hydraulics play important roles for ecosystem functionality of these pond systems. Although WSPs have been used for many decades, they are still considered as ‘black box’ systems as very little is known about the fundamental ecological processes which occur within them. However, a better understanding of how these highly productive ecosystems function is important, as treated wastewater is commonly discharged into streams, rivers, and oceans, and subject to strict water quality guidelines.
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Water Research, 2012
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Toxicon, 2014
Microcystins are produced by several species of cyanobacteria and can harm aquatic organisms and ... more Microcystins are produced by several species of cyanobacteria and can harm aquatic organisms and human beings. Sediments have the potential to contribute to the removal of dissolved microcystins from the water body through either adsorption to sediment particles or biodegradation by the sediment&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s bacterial community. However, the relative contribution of these two removal processes remains unclear and little is known about the significance of sediment&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s overall contribution. To study this, changes in the concentration of microcystin-LR (MCLR) in the presence of sediment, sediment with microbial inhibitor, and non-sterile lake water were quantified in a laboratory experiment. Our results show that, in the presence of sediment, MCLR concentration decreased significantly in an exponential way without a lag phase, with an average degradation rate of 9 μg d(-1) in the first 24 h. This indicates that sediment can contribute to the removal of MCLR from the water immediately and effectively. Whilst both, the biodegradation and adsorption ability of the sediment contributed significantly to the removal of MCLR from the water body, biodegradation was shown to be the dominant removal process. Also, the sediment&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s ability to degrade MCLR from the water was shown to be faster than the biodegradation through the bacterial community in the water. The present study emphasizes the importance of sediments for the removal of microcystins from a water body. This will be especially relevant in shallow systems where the interaction between the water and the sediment is naturally high. Our results are also useful for the application of sediments to remove microcystins at water treatment facilities.
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PLoS ONE, 2013
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Oikos, 2012
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Papers by Elke S Reichwaldt
Toxic cyanobacterial blooms threaten the safety of many water resources around the world and their occurrence is thought to increase even further in the future as a consequence of climate change. Up to date we still have an insufficient understanding of the variability of blooms and of the environmental triggers that control this variability. It has been suggested that an increase in the variability of ecosystems precede ecological regime shifts. Thus, it is urgent to advance our understanding of the mechanisms that control bloom and toxin dynamics. The objectives of this study were to establish the spatial and temporal variability of cyanobacterial blooms and their toxins in water bodies in Western Australia and to identify key drivers of this variability. The temporal variability is analysed on a seasonal and an inter-annual level. Early data suggest that there are gradients of biomass, toxicity and variability that seem to be controlled by total phosphorous, however iron is believed to play a role as well. Our results emphasize the fact that toxin production is a complex process that might be highly site-specific.
Toxic cyanobacterial blooms have major consequences for freshwater food web structures. However, little is known about how the patchy occurrence of blooms within systems affects the spatial distribution of zooplankton communities. We analysed spatial zooplankton community structures in comparison with the spatially distinct distribution of a toxic cyanobacterial bloom in a shallow, eutrophic lake. While cyanobacterial biomass was present at all sites, there were large spatial differences in the level of cyanobacterial biomass and in the zooplankton communities; sites with persistently low cyanobacterial biomass displayed a higher biomass of adult Daphnia and higher zooplankton diversity than sites with persistently high cyanobacterial biomass. Wind was the most likely reason for the spatially distinct occurrence of the bloom; however, our study suggests that it was the differences in cyanobacterial biomass that caused spatial differences in the zooplankton community structures. Overall, our study suggests that even in small systems with extensive blooms ‘refuge sites’ exist that allow large grazers to persist. This might be an important mechanism for a successful re-establishment of the biodiversity of an ecosystem after periods of cyanobacterial blooms.
Stable isotopes have widely been used to identify sources of human impact in ecosystems. Increased nitrogen concentrations in waterbodies are often associated with higher nitrogen δ15N values, which can then be detected in the organisms, and mussels have been identified as long-term bioindicators of such nutrient pollution.
The purpose of this study was to identify the spatial variability of nitrogen concentration in an urban, microtidal estuary (Swan River Estuary), Perth, Western Australia; Fig. 1), and to test if δ15N of the blue mussel (Mytilus edulis) can be used as a bioindicator of nitrogen variability in this system.
Toxic cyanobacterial blooms represent a serious hazard to environmental and human health, and the management and restoration of affected waterbodies can be challenging. While cyanobacterial blooms are already a frequent occurrence, in the future their incidence and severity are predicted to increase due to climate change. Climate change is predicted to lead to increased temperature and changes in rainfall patterns, which will both have a significant impact on inland water resources. While many studies indicate that a higher temperature will favour cyanobacterial bloom occurrences, the impact of changed rainfall patterns is widely under-researched and therefore less understood. To be able to assess and mediate the significant threat cyanobacterial blooms pose to our water resources, more effort is needed to understand the relationship between rainfall patterns and cyanobacterial bloom dynamics, and in particular toxin production.
In this presentation, we synthesize the predicted changes in rainfall patterns and their potential impact on inland waterbodies, and identify mechanisms that influence the occurrence and severity of toxic cyanobacterial blooms. We investigate the correlations between the intensity of rainfall events or the length of the dry period on waterbody conditions that could lead to cyanobacterial blooms. We will also present a framework that explores the future trend of the toxicity of blooms. We will conclude this presentation with the identification of knowledge gaps that need further investigation to enable a better understanding of the impact of changed rainfall patterns on cyanobacterial biomass and toxicity.
Waste stabilization ponds (WSPs) are designed to treat wastewater using only biological and natural chemical processes, and phytoplankton and microbial communities play important roles in their functionality. As WSPs are known to operate at different levels of efficiency, it is important to gain a better understanding of the microbial communities and their metabolite composition, and the respective links with pond performance. Therefore, the purpose of this study is to investigate the biochemistry of WSPs to identify biochemical factors that are influencing their efficiency and functional stability. A special focus is on WSPs that develop toxic cyanobacterial blooms, as these are often associated with low performance.
We use a novel approach by combining flow cytometry and metabolomics to investigate the biochemical characteristics of WSPs, including the microbial community and the metabolite composition. While flow cytometry can give a detailed description of the microbial community, metabolomics is used to analyse the metabolite composition, which is linked to the biological community and physiological processes in a system.
Flow cytometry gave us a detailed picture about the composition, diversity, structure and activity of the microbial community. Non-targeted metabolomics, which analyses the sum of all metabolites, enabled us to identified patterns that correlate with efficiency and cyanobacterial occurrence, and delivered “fingerprints” that were characteristic for ponds. Targeted metabolomics, which analyses the amount of specific metabolites (e.g., coprostanol), allowed us to identify treatment stages. In addition, the combined use of these two methods allowed us to identify correlations between the microbial community and metabolite patterns, which explained performance levels of WSPs.
In summary, our results indicate the high potential of the combined use of flow cytometry and metabolomics to understand the performance level of WSPs. The identification of biomarker patterns that correlated with the performance level can ultimately help to improve WSP efficiency and reliability.
Wastewater stabilisation ponds (WSPs) are highly productive systems designed to treat wastewater using only natural biological and chemical processes, but they are known to operate at different levels of efficiency. Phytoplankton, microbial communities and hydraulics play important roles for ecosystem functionality of these pond systems. Although WSPs have been used for many decades, they are still considered as ‘black box’ systems as very little is known about the fundamental ecological processes which occur within them. However, a better understanding of how these highly productive ecosystems function is important, as treated wastewater is commonly discharged into streams, rivers, and oceans, and subject to strict water quality guidelines.