Science can be wonderfully serendipitous. Any number of terse journal articles would seem to dispute this, but a refreshingly readable (and open access!) new article in the American Geophysical Union’s journal Earth’s Future showcases the fact that one can go searching for diatoms and instead find… plastic. Okay, this is no cause for celebration, as the problem of plastic in the oceans has been well-documented (including on this very blog here, here, and here). It is a rather poignant serendipity, then, that scientists intending to consider diatoms in sea ice instead found enough plastic to justify its own journal article.
The story began when researchers from Dartmouth College and the University of Plymouth (UK) received ice cores collected from the Arctic during NSF research cruises in 2005 and 2010. The research team was planning to analyze the cores to determine whether sea ice could be a suitable habitat for diatoms. Accordingly, they sliced, melted, and filtered a section of core, only to realize that there were no fewer than 24 bits of rayon and plastic among the phytoplankton. At this, the scientists may have assumed they screwed up and had contaminated the cores, because their subsequent analyses included acetone rinses, replacement syringes, and “extreme care” in handling samples. Any suspected synthetic fragments found were analyzed with Fourier transform infrared (FTIR) stereoscopy.
The researchers’ diligence should convince readers that their findings were no accident: they identified between 38 and 234 synthetic particles per cubic meter of ice. The synthetic particles included, in order of prevalence, rayon, polyester, nylon, propylene, and small quantities of polystyrene, acrylic, and polyethylene. The small size of these fragments- no more than 2 mm- gives them the common name of microplastics. (Technically, rayon isn’t a plastic, but researchers included it because it’s man-made.) These tiny plastic scraps have the dubious distinction of being the first microplastics identified in the Arctic. Frankly, I’m shocked that it took this long, as it’s been no secret that macroscopic plastic litter is bobbing around the Arctic Ocean. Furthermore, the researchers explained that a result like this is not unexpected, since the microplastic equilibrium is lopsided. We’ve been producing more and more plastic waste, but a number of studies have found no corresponding increase in surficial plastic abundances, suggesting an unidentified sink. Sea ice, sadly, could be one of those sinks for microplastics.
The plastic found in the Arctic ice cores likely drifted over from the Pacific, but microplastics are being generated by human activities worldwide. Rayon, for example, is found in clothing and can enter the oceans via sewage that includes laundry discharge. In some ways, sea ice is doing us a favor by trapping our microplastics, precluding their consumption by marine organisms and subsequent toxic influence. But as climate change melts sea ice, those particles will be released, to the tune of more than 1 trillion bits of microplastic over the next decade from the Arctic alone, based on the lowest concentrations found by the research team. If you were hoping for a Good News Friday then, you’re in the wrong place, because when plastic pollution and climate change collide, we may be facing much more zemblanity than serendipity in the near future.
Check out the original article here: http://onlinelibrary.wiley.com/doi/10.1002/2014EF000240/full
Obbard RW, Sadri S, Wong YQ, Khitun AA, Baker I, and Thompson RC. 2014. “Global warming releases microplastic legacy frozen in Arctic Sea ice.” Earth’s Future.
Cover image from http://phys.org/news/2013-12-microplastics-marine-worms-sick.html