Showing papers by "Anas Ghadouani published in 2016"
TL;DR: In this paper, the authors evaluated whether halogen radicals (i.e., reactive halogen species (RHS)) could significantly contribute to microcystin photodegradation during transport within estuaries.
Abstract: The transport of microcystin, a hepatotoxin produced by cyanobacteria (e.g., Microcystis aeruginosa), to estuaries can adversely affect estuarine and coastal ecosystems. We evaluated whether halogen radicals (i.e., reactive halogen species (RHS)) could significantly contribute to microcystin photodegradation during transport within estuaries. Experiments in synthetic and natural water samples demonstrated that the presence of seawater halides increased quantum yields for microcystin indirect photodegradation by factors of 3–6. Additional experiments indicated that photoproduced RHS were responsible for this effect. Despite the fact that dissolved organic matter (DOM) concentrations decreased in more saline waters, the calculated photochemical half-life of microcystin decreased 6-fold with increasing salinity along a freshwater-estuarine transect due to the halide-associated increase in quantum yield. Modeling of microcystin photodegradation along this transect indicated that the time scale for RHS-mediate...
48 citations
TL;DR: Emissions from WSPs were of the same order of magnitude as those reported in hydroelectric reservoirs and constructed wetlands in tropical climates, whereas CH4 fluxes were considerably higher compared to other aquatic ecosystems and N2O fluxe were in the same range of values reported for WSPS in subtropical climate.
37 citations
TL;DR: 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 are developed, to identify the level of risk a system poses in regards to the pollutant.
Abstract: 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 ‘low’ or ‘medium’ risk to develop First Aid Cases when used for swimming. The developed risk models succeeded in categorising lakes according to their risk level to the public in an objective way. Modelling by how much the probability of public exposure has to decrease to lower the risks to acceptable levels will enable authorities to identify suitable control measures and monitoring strategies. We suggest broadening the application of these models to other contaminants.
11 citations
TL;DR: In this article, the suitability of nitrogen stable isotopes as measured in mussels (Mytilus edulis), as an indicator able to resolve spatial and temporal variability of nitrogen pollution in an urban, tidally influenced estuary (Swan River estuary in Western Australia).
Abstract: . Urbanization 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 (δ15N), which can then be detected in higher trophic levels such as mussels. The main aim of this study was to assess the suitability of nitrogen stable isotopes as measured in mussels (Mytilus edulis), as an indicator able to resolve spatial and temporal variability of nitrogen pollution in an urban, tidally influenced estuary (Swan River estuary in Western Australia). Nitrogen concentrations were generally low and nitrogen stable isotope values of nitrate throughout the estuary were well within natural values of uncontaminated groundwater, organic nitrate from soils, or marine-derived sources, indicating groundwater inflow rather than pollution by human activity was responsible for differences between sites. The δ15N signature in mussels was very stable over time within each site which indicated that mussels can be used as time-integrated sentinel organisms in urban systems. In addition, our study shows that the nature of the relationship between δ15N in the mussels and the nitrate in the water can provide insights into site-specific biogeochemical transformation of nutrients. We suggest that mussels and other sentinel organisms can become a robust tool for the detection and characterization of the dynamics of a number of emerging anthropogenic pollutants of concern in urban water systems.
9 citations