Microplastics in Marine Mud


Ocean plastics present serious problems. Plastics choke and starve wildlife, pollute the water and degrade living conditions in coastal and island communities, introduce toxins into the marine food web that extend up to us in our seafood, damage fish stocks, and decrease overall ocean health.

The “Great Pacific garbage patch” formed by the North Pacific Gyre got a lot of attention after Oprah Winfrey proclaimed it was twice the size of Texas. Skeptics challenged that if it was so big, why could you not see a floating mass of plastic covering the water? While it may be easier to think of plastic pollution in terms of plastic bottles and bags, the truth is much more insidious. Most of the plastics we throw in our oceans are not easily seen – they break down into small, microscopic pieces – these are micro-plastics. 

Scientists have studied micro-plastics for decades. A few of them have looked for micro-plastics in remote places like the Arctic. This usually involves towing a net behind a boat, pulling in what you collect, and counting the tiny plastic pieces under a microscope. This kind of sampling gives us a glimpse of what is in one part of the ocean, from which we can extrapolate how much is in the rest of the ocean. But people have not yet looked for micro-plastics in the ocean sediment. We’ve skimmed the surface, but not searched the bottom. 

The mud at our seafloor holds clues to the history of our planet. Anything that sinks will eventually end up on the seafloor, unless it dissolves on the way down. By looking at what’s sunk in the mud, we can mark the Industrial Revolution and when DDT was introduced. Plastics did not exist naturally before we created them and do not easily, if at all, degrade. If there are plastics in the ocean, their presence will be marked in the mud. The questions are where and when. 

Erin Guillory and Miguel Goñi are looking for plastics using sediment cores here perhaps for the first time. At worst (or best) they won’t find any in this remote place, and their data will be a baseline for future studies of plastics in the Arctic; unfortunately there will almost inevitably be plastics here in the future. The average American throws away about 185 pounds of plastic per year, and most of it ends up in the ocean.

Erin Guillory joined the Goni lab after spending five days at sea on Oregon State University’s research vessel, the R/V Oceanus, as part of an introductory oceanography class. She may have spent half of that time seasick, but she was still hooked. She loved watching special oceanographic instruments like the CTD, gravity cores, and bongo nets in use. She was close to switching her major to geology, but then was made certain of her choice to take the oceanography path after seeing it in practice. For the past year, she’s worked in the Goñi lab, processing samples and going on cruises on the Oregon coast and now to the Arctic. 

Guillory and Goni received the Undergraduate Research, Innovation, Scholarship & Creativity (URISC) Award from OSU, which provided the funding to undergo their novel project of looking for micro-plastics in marine mud. Guillory will use some of the samples collected from the multi-core on this cruise to analyze for micro-plastics back in the lab in Corvallis. There, she will use a new method for measuring plastics, using a series of processes that include density fractionation, flash pyrolysis, and gas chromatograph-mass spectrometry. Density fractionation isolates the plastics by “floating” them to the surface of a very dense solution that has a special material called sodium polytungstate. Flash pyrolysis then degrades the plastics into a form that can be measured by the mass spectrometer. 

Their hypothesis is that higher inputs of terrestrial materials from enhanced erosion and human activities along the Arctic margin will result in higher amounts of plastic-derived materials in the top layers of ocean mud compared to those found deeper in the mud when there was less human activity.  

Guillory is entering the final year of her undergraduate degree in oceanography at OSU. She hopes to attend graduate school in oceanography and continue in a career as an oceanographer. 

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Erin Guillory and Miguel Goñi in front of the multi-core

 

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Part of the Goñi lab team on a research cruise on the Oregon coast. Miguel Goñi, Kylie Welch, Emmanuel Alegria, and Erin Guillory
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Emmanuel Alegria and Issie Corvi at the Goñi lab station on the Sikuliaq
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A filtration cabinet – Part of the Goñi lab station on the Sikuliaq
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Kylie Welch and Erin Guillory
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Erin Guillory
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Miguel Goñi, Bern McKiernan, and Deb Greene deploy the multi-core

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Miguel Goñi helps to retrieve the multi-core after it has collected tubes of sediment from the ocean floor

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The aft deck with the multi-core
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Laurie Juranek and Issie Corvi get ready to cut a multi-core
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The cores will be cut into 1cm segments and put into individual bags. The bags are frozen and taken back for analysis at the OSU lab.

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Issie Corvi holds a brittle star found in one of the sediment cores

 

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