Wondrous Wetlands

By Tarlie Townsend

What’s your favorite ecosystem? Rainforest? Tundra?

Scenic wetlandsAfter talking with EPA postdoctoral researcher Amanda Nahlik, I’d answer “wetlands”— those water-saturated areas like swamps, bogs, and marshes. They’re so much more than the dreary, monster-infested settings of the movies. In fact, they do great things for us!

Here are just three examples of benefits (“ecosystem services”) we all get from wetlands:

  • Wetland as barrier (storm protection): They reduce the size and speed of waves hitting the shore, helping protect coastal communities during storms.
  • Wetland as sponge (flood amelioration): Amanda recounted one firsthand example: it was springtime in Ohio, the snow had just melted, and heavy rains were imminent. Scientists at The Ohio State University (OSU) Olentangy River Wetland Research Park (where Amanda worked), were concerned that their downstream campus might flood. The solution: manage the nearby experimental wetlands by installing weirs so the wetlands could hold and absorb the floodwater. It worked! The wetland functioned like a sponge, and OSU went flood-free. After the storm, the scientists removed the weirs and slowly released the water back into the river.
  • Wetland as kidney (water purification): Wetlands even clean our water! Myriad wetland organisms absorb contaminants and excessive nutrients (primarily nitrogen and phosphrous) cleaning the water flowing through them.

Here’s where Amanda’s current research comes in. One substance “cleaned” by wetlands is excess nitrogen (primarily from fertilizer runoff). How much nitrogen is absorbed, and how that correlates with other wetland conditions, isn’t well understood. But it matters, because wetlands across the world—under stress from physical destruction, climate change, pollution, and more—are changing, compromising their ability to provide ecosystem services in the form of nitrogen removal.

Existing methods of measuring nitrogen removal are both expensive and time-intensive. And because the amount of denitrification varies, numerous rounds of testing are necessary.

Amanda and colleague J. Renée Brooks may have a solution: comparing the ratio of different nitrogen isotopes (Nitrogen-15 and Nitrogen-14) to measure how much denitrification occurs in a given wetland over time. If more nitrogen-15 is found in the soil, they reason, the wetland is reducing nitrogen pollution and its harmful effects—a good way to help assess the condition of the wetland, and the “ecosystem services” it provides.

Amanda is in the preliminary phase of testing soil isotope measurements in order to develop an indicator of denitrification. So far, the results look good, and could lead to a quick, easy, and inexpensive way to measure how much nitrogen is being removed. Learning about the research also gave me better appreciation for the value of wetlands—my new favorite ecosystem!

About the Author: Tarlie Townsend recently completed an internship in EPA’s Office of Research and Development.