UMCES-led research team quantifies nutrient pollution reductions from urban stream restoration

New technology could help coastal restoration efforts

Researchers have been able to quantify the amount of nitrogen reduced through environmental restoration efforts in Minebank Run in Baltimore County, Md. Click here for more information.

A team of researchers led by University of Maryland Center for Environmental Science researcher Dr. Sujay Kaushal has been among the first able to quantify the amount of excess nitrogen removed from an urban stream during environmental restoration projects. This breakthrough will allow environmental managers to accurately assess the pollution reducing benefits of stormwater management and urban stream restoration, and could lead to new nitrogen reduction opportunities as public works managers make repairs to our nation’s aging urban infrastructure.

“The key to expanding urban stream restoration efforts nationwide is being able to quantify the environmental benefits gained from those efforts,” said UMCES Chesapeake Biological Laboratory researcher Dr. Sujay Kaushal. “This research is opening the door to a new technology that has the potential to help improve water quality in our urban environment.”

Using state-of-the-art techniques in a long-term study, Kaushal’s team injected stable isotope tracers into restored and unrestored sections of an urban stream, and measured how microbes in the streambanks naturally absorb nitrate and convert it into inert nitrogen gas. By analyzing those samples, the team was able to determine in-the-field nitrogen reductions by stream microbes through a process known as denitrification.

The research showed that stream restoration techniques that “reconnected” the banks to the stream doubled nitrogen removal rates by microbes, and reduced nitrogen levels in ground water by 40%, contributing to significantly lower nitrogen levels in the stream compared to unrestored conditions. Getting water out of the stream channel into denitrification “hot spots” in floodplain wetlands helped improve water quality.