Wednesday November 15, 2023
Eos —
Rivers are awash with excess nutrients, chemicals, and other pollutants, including sewage. Globally, roughly 50% of wastewater is treated at facilities before being released into nearby bodies of water. But new research shows that even advanced treatment might not be enough to safeguard the health of freshwater ecosystems.
Researchers released dilute, treated wastewater into an unpolluted stream in northern Spain and made a before and after comparison of energy flows through the ecosystem.
“We found subtle yet fundamental shifts in ecosystem function after adding wastewater,” said Ioar de Guzman, a freshwater ecologist at the University of the Basque Country in Spain and lead author of the study. By manipulating a pristine ecosystem, she and her colleagues could isolate the effects of wastewater, which can be masked in streams that contain other types of water pollution.
Agricultural runoff, containing nitrogen-rich fertilizer, is a familiar blight, causing lurid green algal blooms that choke aquatic life.