Scientists Fear Rise of Waterborne Pathogens
Climate change is not only making our world warmer, but also affecting the sun’s ability to disinfect the world’s water, particularly lakes and rivers.
In a study conducted by researchers from all discipline, climate change has reduced the penetration of pathogen-killing ultraviolet (UV) sunlight in inland lakes, rivers, and coastal waters. This key finding worries researchers, pointing to potential increase in waterborne pathogens, thus endangering humankind.
The study was a collaboration among multiple scientists from different disciplines who serve on the United Nations Environment Programme Environmental Effects Assessment Panel (UNEP EEAP).
Climate Change Increases ‘Browning’ of World’s Waters
Scientists have blamed climate change as the culprit for “browning”of the world’s waters, a phenomenon caused by more organic matter washing in from the surrounding land. Aside from that, dissolved organic matter became a hindrance for UV radiation from the sun to kill pathogens in the water.
Kevin Rose, the Frederic R. Kolleck ’52 Career Development Chair in Freshwater Ecology at Rensselaer, said “Water clarity is dropping in many regions due to factors such as browning, and this research demonstrates that this change is likely decreasing natural disinfection of potentially harmful pathogens.”
The Study and Key Results
To quantify the impact of dissolved organic matter on the potential for UV radiation from the sun to kill pathogens in the water, the researchers led by Miami University in Ohio used samples of water from lakes around the world,specifically from Pennsylvania and Wisconsin, to Chile and New Zealand. Tests determined the amount of dissolved organic matter contained in each sample, and the wavelengths of light – including ultraviolet wavelengths – absorbed by that organic matter.
The team also used the Tropospheric Ultraviolet-Visible model – which simulates how UV light is scattered and absorbed as it passes through Earth’s atmosphere. The innovative model also calculates the expected disinfecting power of UV light in a particular body of water based on its dissolved organic matter and other characteristics, a measurement known as “solar inactivation potential (SIP).”
The researchers found that an increase in dissolved organic matter make it more difficult for sunlight to disinfect bodies of water. And worse thing also, it also makes it more difficult for water treatment plants to work effectively, said lead author Craig Williamson, a Miami University ecologist.
To cite an example, the researchers found that SIP of California’s Lake Tahoe can be as much as 10 times greater than at Tahoe Meeks Bay, an area at lake’s edge that is more populated and has a higher level of dissolved organic matter.
The scientists also showed how SIP can dramatically decrease after a heavy rainfall event using water samples collected from the region where the Manitowoc River flows into Lake Michigan, which supplies drinking water to more than 10 million people.