Water touches virtually every aspect of human society, and all life on earth demands it. Yet clean, fresh water is becoming increasingly scarce – one in eight people on the planet does not have access to safe drinking water. Freshwater saline pollution factors such as de-icers on roads and parking lots, water softeners and sewage, and industrial discharges further threaten the health of the freshwater ecosystem and the safety of the environment. human water.
“Saline pollution of inland freshwater is increasing nationally and globally, and we investigated the potential conflict between managing saline freshwater pollution and the sustainable practice of increasing water supply through ‘adding highly treated wastewater to surface water and groundwater,’ said Stanley Grant, professor of civil and environmental engineering at Virginia Tech College of Engineering. “If we don’t figure out how to reverse this trend of salt pollution soon, it could become one of our country’s biggest environmental challenges.”
Grant and colleagues recently published their findings in the journal Sustainability of nature.
In a recent modeling study, it was predicted that saline pollution will increase by more than 50 percent in more than half of US rivers by 2100. Freshwater saline pollution is associated with the decline of biodiversity, critical freshwater habitat and lack of potable water.
“We have found that there are many opportunities to reduce the contribution of saline pollution in the highly treated wastewater discharged into the Occoquan reservoir and freshwater pollution more generally,” said Peter Vikesland, professor in the Department. of Civil and Environmental Engineering and Affiliate Faculty Member. in the Global Change Center, housed within the Fralin Life Sciences Institute at Virginia Tech. “These efforts will require deliberative engagement with a diverse community of watershed stakeholders and careful consideration of the local political, social and environmental context.”
Using time series data collected over 25 years, researchers quantified the contributions of three sources of salinity – highly treated wastewater and runoff from two rapidly urbanizing watersheds in northern Virginia – to increasing sodium concentration. , a major ion associated with freshwater pollution. .
The Occoquan Reservoir, a regionally significant drinking water reservoir in the mid-Atlantic United States, is located approximately 19 miles southwest of Washington, DC, in northern Virginia, and is one of the two primary sources of water supply for nearly 2 million people in Fairfax County, Virginia and surrounding communities. On an annual basis, approximately 95% of the water that flows into the reservoir comes from its tributaries of the Occoquan River and Bull Run.
“This study illustrates the power of combining historical data and new calculation tools; it underscores the incredible value of long-term monitoring, ”said Grant, co-director of the Occoquan Watershed Monitoring Laboratory and an affiliate faculty member of the Center for Coastal Studies at Virginia Tech. “This is a testament to the vision of Virginia Tech and the Occoquan Watershed Monitoring Laboratory and their collaboration with watershed stakeholders, including Fairfax Water and the Upper Occoquan Service Authority, over the past two decades. .
The researchers found that the increase in salt pollution in the reservoir came mainly from runoff from watersheds in wet weather and highly treated wastewater in dry weather.
On all the time scales evaluated, the sodium concentration in the treated wastewater is higher than in the outflow from the two watersheds. Sodium in treated wastewater comes from chemicals added during wastewater treatment, industrial and commercial discharges, human excretion, and downstream disposal of sodium-rich drinking water and household products.
“Our study is unique because it brings together engineers, environmentalists, hydrologists and social scientists to investigate and tackle one of the biggest threats to water quality in the world,” said Sujay Kaushal , co-author of the article, professor of geology at the University of Maryland and an international expert in freshwater salinization.
Researchers are considering at least four ways to reduce salt pollution: limiting sources of sodium from watersheds that enter the water supply (such as through the use of de-icers), applying more stringent pre-treatment requirements to industrial discharges, and commercial, switch to and encourage households to switch to low sodium products.
Drinking water supply and wastewater collection systems contribute salt for the former, ultimately also contribute salt for the latter.
“Citizens can start today or tomorrow by thinking more critically about what they put in the sewers and how it harms the environment, and in turn, their own drinking water supply.” , said Vikesland.
This research aligns with the One Water vision used nationally and globally by several water resource sectors, and it catalyzes strong, stakeholder-driven decision-making against seemingly conflicting goals.
This research was part of a partnership between Virginia Tech, the University of Maryland, Vanderbilt University and North Carolina State University. It was funded by a recent multi-million dollar grant Grant and coworkers received from the National Science Foundation aimed at tackling saline pollution in freshwater and is part of the Growing Convergence Research (GCR) program of the National Science Foundation, which aims to catalyze solutions to the great challenges by fusing ideas, approaches and technologies from a wide variety of fields of knowledge to stimulate innovation and discovery. The experience gained and lessons learned from this research will be used nationally and globally in partnership with the Water Research Foundation.
“The collaborative effort of this highly interdisciplinary team exemplifies the type of paradigm-shifting science we seek to catalyze and promote,” said William Hopkins, professor at the College of Natural Resources and Environment, director of the Global Change Center and associate executive director. from the Fralin Life Sciences Institute. “Salt pollution of freshwater has become a major focus for various researchers at Virginia Tech because the problem is so widespread, worsening, and affecting both the environment and society. the team are advancing our understanding of important sources of salt pollution. Principle-based interventions can be identified and implemented. The study has far-reaching implications globally as we attempt to resolve this complex environmental problem.
This study reflects the exciting convergent approach taken by the NSF-funded project.
“While biophysical findings are at the forefront here, they recognize the complex socio-political contexts in which this information will be applied and foreshadow the collaborative and multi-stakeholder approaches to tackle the problem of saline pollution in freshwater that we are currently conducting,” said Todd Schenk, assistant professor in the School of Public and International Affairs at the College of Architecture and Urban Studies and an affiliate faculty member of the Global Change Center and the Center for Coastal Studies.