Freshwater, alternative water sources

Contaminants polluting our water may be chemical or microbiological. Chemical hazards are caused by the chemical compounds which may be inorganic or organic. They may be present in the water due to the natural source, such as arsenic, which is a natural component of some soils and may be dissolved in groundwater. Alternatively, the contaminant may have been introduced into the ecosystem or the water source by human activity, such as pesticides, that trickle down sediment layers and streams and find their way into our freshwater. Some contaminants are by-products of chemicals used during the disinfection processes applied. 

For example, assume that a pond is contaminated with metals. One goal of the ecological risk assessment is to identify if a known sensitive aquatic species (e.g., freshwater shrimp) is impacted by the concentrations of metals in the pond. This shrimp is a source of food for predatory fish in the pond, and therefore its abundance is linked to the health of the community. Literature values could be used to identify safe concentrations of metals for various species, but not for the specific one of interest at our site. These could be used and extrapolated to the target species, which introduces uncertainty into the results. Alternatively, water and/or sediment from the site could be brought into the laboratory and the species of interest could be directly tested for toxicity. These studies are known as bioassays. Results of bioassays are used to develop a protective concentration relevant to the species and site of interest. 

Planning for the future in Mediterranean climates requires serious investments in water conservation and consideration of alternative freshwater sources. Alternative... 

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