image: Austin Gray.
Credit: Photo by Spencer Coppage for Virginia Tech.
The Earth is on its way to being covered with microscopic particles, which can take anywhere from 20 to 500 years to degrade.
However, scientists still don’t fully understand how microplastics will impact the environment or living organisms over the next half a century.
What we do know, said biologist Austin Gray, is that plastics are pervasive. They’ve been found in sea birds, in the exhaled breath of bottlenose dolphins, and in human blood and breast milk.
Microplastics also have brought about massive changes for tiny organisms like bacteria, viruses, and fungi. Plastics are composed of carbon. Microbes metabolize carbon, including novel carbon in the form of plastics or microplastics. Not only are plastics increasingly serving as a habitat for microbes, but microbes can prefer the surfaces of plastics.
“Microbes are showing selection for plastic surfaces versus rock and stone and wood,” Gray said.
Because microbes also govern certain biogeochemical processes, plastic-pollution can impact carbon cycling and nitrogen cycling with ramifications for the global biosphere.
“It’s a new world for microbes, and we don’t know what that means for aquatic environments and various processes that take place in them,” Gray said.
But Gray is going to try to figure it out.
With support from a $1.3 million National Science Foundation Faculty Early Career Development Program (CAREER) award, he will be leading an investigation into the influence common plastic items have on microbial community structure in ponds — the Virginia Tech Duck Pond, to be specific.
The Duck Pond is a microcosm of the water-plastic interaction. Fed by two small inlets, water moves slowly through the pond to a single outlet. Prolonged storage of plastic debris in the slow-moving water gives plastic litter enough time to break down into smaller particles.
The questions Gray and team will be asking include:
- What microbes colonize different types of plastic polymers? Does that change over time?
- How do microbes metabolize other types of carbon after metabolizing plastic-derived dissolved organic carbon? Do plastic additives leaching from degrading plastic inhibit or stimulate microbial activity?
- Can we use mass-balance approaches to understand effectiveness of ponds in mitigating plastic and microplastic pollution to downstream waterways?
Gray plans to use what’s known as a mass-balance approach to understand if ponds can efficiently capture and remove microplastics from the environment. This technique involves closely monitoring what’s coming in and going out of the pond over the course of a year.
Students in Gray’s special topics course will take point on sample collection and processing. The Gray Lab has also partnered with the Peddrew Yates Institute for the past three years, drawing in high school students as an integral part of Gray’s research project and outreach.
“They get to collect samples from boats and at the inlet stream sites and see exactly what it means to be an environmental scientist in the field,” said Gray. “Through this work, I hope to foster a belief and understanding that there's a space for them as well in STEM disciplines.”
The high school students will be mentored by the undergraduates, who in turn will be mentored by Gray’s graduate students and postdoctoral associates.
Gray’s goal is to create a mentoring cycle through ecological research to build leadership skills and expand STEM while answering urgent questions about our changing world.