Multiple stressors on water quality and availability

Ann Louise Heathwaite ( Heathwaite 2010) of Lancaster University looked at the multiple stressors that impact fresh water availability such as changing climate, land use, demands on water resources and nutrient cycles because it is important to sustain the long-term quality, not just quantity, of water from rivers and groundwater. The paper focuses on diffuse pollutants which are characterized by sources that are generally widespread and hard to detect and by highly variable fluxes. She found that elevated levels of nitrogen and phosphorous compromise the ecosystem services that we depend on through the degradation of soil and freshwater resources. — Winnie Wong
Heathwaite, A. L., 2010. Multiple stressors on water availability at global to catchment scales: human impact on nutrient cycles to protect water quality and water availability in the long term. Freshwater Biology 55, 241—257.

 Predicting ecosystem response to diffuse pollutants is challenging due to the multiple factors that regulate biogeochemical transformations in freshwater systems. There is a lack of understanding of internal in-stream processes that may transform, immobilize, or eliminate diffuse pollutants. These relationships deserve further research because riverbeds are transitional environments between groundwater and surface water that serve as a sink for sediment and pollutants. The focus of restoration measures on the riparian zones may not deliver sustainable solutions for freshwater ecology. We need to understand the spatial controls on the delivery of diffuse pollutants to better understand how restoration measures would give the best return. This requires advances in sensor technologies and the development of cyber infrastructure to make simultaneous observations at appropriate ranges of time and space scales.
Environmental systems are undergoing a period of unprecedented change due to climate change and associated human-induced changes. The importation of nitrogen and phosphorous from land to water has been of considerable concern because the human-induced changes in nutrient cycles are becoming evident at the ecosystem level. Prior research confirms that we can no longer assume a hydroclimatic stationarity basis for models of water resource availability and management. Unforeseen consequences for land and freshwater systems could result in assumptions being built into predictions of climate change impacts that are misleading. 

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