Working with a team headed by Arthur Gold, URI professor of natural resources science, Grande’s research was designed to better understand the capacity of wetlands to remove nitrate from groundwater. Nitrate is a soluble form of nitrogen that originates from fertilizers, septic systems, exhausts, manure and other pollutants that leach into the groundwater.
“The project is all about groundwater denitrification, or how wetlands remove the nitrogen before the polluted groundwater reaches a lake or coastal pond,” explained Grande, 22. “We’re looking at the characteristics of the land that are best at getting the nitrates out and turning it into nitrogen gas.”
According to Grande, when it rains, a wide variety of pollutants seep into the ground. If those pollutants make their way into local estuaries, it increases the growth of algae, which can choke out native plants like eelgrass. When the algae die and decay, it can also use up the available oxygen and suffocate all the other creatures in the estuary.
On a typical day, Grande and his research team visited one of five wetlands in southern Rhode Island and pumped a small quantity of nitrate into a tube in the wetland. Several hours later, they pump it back out again.
“The sample that we pump out tells us how much denitrification has taken place,” Grande said. “Microbes in the soil use the nitrate for respiration. They metabolize it and then ‘breathe’ out nitrous oxide or nitrogen gas, which don’t harm wildlife.”
Grande also conducted soil tests, measured the water table, checked the groundwater monitoring wells, and assessed the direction in which the groundwater flows.
Although the project isn’t yet complete, Grande said that it’s clear that wetlands, with their deposits of oxygen poor, organic soils are especially good at removing nitrates. In contrast, uplands with a high groundwater oxygen level do not remove nitrate because the microbes prefer to use oxygen for respiration and they leave the nitrate alone. These conclusions can play a significant role in the debate over land protection.
“Next time someone wants to develop a wetland, this information can help show how valuable wetlands are,” said Grande. “Ultimately, we really need to protect them.”
Funding for Grande’s research was provided by the Rhode Island Agricultural Experiment Station through the URI Coastal Fellows Program, a unique program designed to involve undergraduate students in addressing current environmental problems. Now in its sixth year, the Coastal Fellows Program teams students with faculty, research staff and graduate students to help them gain skills that will ensure their future success.
“What I took out of this project the most was an understanding of the scientific process, what goes into the process of scientific discovery and getting a lab team together,” he said. “That was a big part of it for me, taking some things that I did in class and using them out in the field.”
Following graduation next May, Grande is considering working on a similar research project in Baltimore. “It might just be a summer project, it might turn into a full time job, and it might lead to graduate school. I’ll just have to wait and see.”
NOTE TO EDITORS: Digital photos of Drew Grande conducting his research are available by calling Todd McLeish in the URI News Bureau at 401-874-7892.