Tracing Stenungsund's plastics industry in Hakefjorden
Factories have been producing plastics in Stenungsund since the 1960s. But how has plastic production affected the marine environment in the area? An interdisciplinary research team from the University of Gothenburg is investigating this on board the R/V Skagerak - one sediment core at a time.
"Today we are taking sediment cores from the bottom of the sea to trace back history of pollution by plastic pellets from plastic factories in Stenungsund on the Swedish West Coast", says Irina Polovodova Asteman, marine geologist and micropalaeontologist at the University of Gothenburg.
She is one of the researchers in the interdisciplinary team on board the R/V Skagerak with the mission to investigate microplastics in the fjord system in the Stenungsund area.
Stenungsund is home to Sweden's largest manufacturer of plastic pellets. There are two industries, one that produces pellets of so-called polyethylene (PE), and one that produces polyvinyl chloride (PVC) pellets since 1963. Production amounts to around 0.75 million tonnes of PE pellets, which is five percent of the European market. And some of the plastic ends up in the marine environment off Stenungsund.
"These pellets sometimes disappear during transport, and now we can find them in the bottom sediments. Last year we did a pilot study here with a group of students, and we could clearly see an accumulation over time of pellets in the sediment. This is something that hopefully mimics the industrial development in this region," says Irina Polovodova Asteman.
New rules may have affected the marine environment
Martin Hassellöv is a professor of analytical environmental chemistry. He is also on board the R/V Skagerak to seek answers to how plastic pellets released into the marine environment eventually break down into microplastic particles that often sink to the seabed - where they can now be found in layers of bottom sediment.
As there have been some changes in environmental regulations regarding how much plastic pellets can be discharged, the researchers are interested in studying the environmental effects of these changes in the area.
"The aim is both to increase focus on how this is handled today and to look back in time at what developments have looked like. It is also an interesting case study to understand more about how plastic spreads in the marine environment," says Martin Hassellöv.
During the expedition, the scientists and crew of the R/V Skagerak will collect sediment samples at seven different locations in the Hakefjord, at varying distances from the plastics industry. On this day, they are using a twin corer, which takes two sediment cores simultaneously, and a piston corer, a long, heavy tube that takes longer sediment samples.
"Basically, we go to the seafloor with a heavy device that has long tubes that can be filled with sediment and go back in time, hopefully several hundred years, to the Little Ice Age," says Irina Polovodova Asteman.
On the back deck, a team of researchers is hard at work slicing up sediment cores and putting the samples into jars.
"We slice the cores because the sediments with the different layers act as an archive. So by dating the sediments, we know when these particles got there. Now we want to see how the concentration of the pollutants increases with increased production or decreases due to the increased awareness of plastic pollution,’ says Karin Mattsson, marine chemist at the University of Gothenburg.
Because the plastic production industry is relatively new, the researchers believe we still have a lot to learn about the impact of microplastics in the marine environment.
"Microplastics are a kind of end product of modern society that will be around for a long time to come. It is therefore important to know how plastics 'behave' and what the toxic consequences are. We also need to find societal solutions that can mitigate the effects. What are the most obvious and effective measures to take?",
says Martin Hassellöv, cutting another sediment core on the aft deck of the R/V Skagerak.
Text: Agnes Faxén
