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The paper looks to be "Effects of Microplastics in Soil Ecosystems: Above and Below Ground" by Bas Boots, Connor William Russell, and Dannielle Senga Green. Th
by nkurz 7y ago
The paper looks to be "Effects of Microplastics in Soil Ecosystems: Above and Below Ground" by Bas Boots, Connor William Russell, and Dannielle Senga Green.
The abstract is here: https://pubs.acs.org/doi/10.1021/acs.est.9b03304 https://pubs.acs.org/doi/10.1021/acs.est.9b03304
And the full paper here:
https://sci-hub.tw/10.1021/acs.est.9b03304 https://sci-hub.tw/10.1021/acs.est.9b03304
After a quick skim, it looks like a well written paper with a small dataset. They took 40 1.2L plastic pots and filled them with 1kg of local soil. In 10 of the pots, they then added 1 g of PLA microplastic; in another 10 they added 1 g of HDPE microplastic; in another 10 they added 10 mg of acrylic and nylon fibers collected from a washing machine; and in the last 10 they added nothing.
In half of the pots (5) from each of the 4 categories, they then planted ryegrass. Then they added 2 earthworms to each of the 40 pots, waited for a month, and then measured the results. They found (Figure 3) that the 10 earthworms in the 5 unplanted control (no plastic) gained about 5% weight, that the 10 earthworms in the 5 planted HDPE containers lost about 5% of their weight, and all the rest had no significant change.
Overall, it seems like a solid paper, with all the information one would need for a replication attempt. Nicely, they report the average weights for the two each of the individual pots, but unfortunately they don't seem to report the intra-pot variation of the individual worms, which would be helpful to know in assessing the likelihood of replication.
The Guardian article, though, which mentions only the two "significant" results and ignores the 6 results that showed no particular difference, seems more intent on generically sowing fear than on informing the public about recent scientific results. I guess it's better to have a soft-science article like this than another "did you see what the idiot tweeted", but sometimes I'm not sure.
ps. Did you know that in much of the northern US, all of the native earthworms were killed by the glaciers, and that practically all the current earthworms in these areas are invasives? The northern hardwood forests evolved without these earthworms, and may in fact be harmed by their presence: http://theconversation.com/silent-partners-are-earthworms-creating-pathways-for-invasive-plants-77848 http://theconversation.com/silent-partners-are-earthworms-cr.... I wonder if the same true for England (where the study was done) since it was also mostly glaciated?
- Forge36 7y agoThank you for sharing a source on how earthworms are invasive (I'd heard the claim, but not a source). I remember a Park ranger talking about flowers in Minnesota which didn't grow as well because of earthworms and were thus Endangered. I wonder how these flowers would do if Plastics were added to their soil. I can't recall the name of the flower, but that the reason they couldn't flourish was that Earthworms were eating the nutrients they needed to grow. I found two sources https://kstp.com/news/u-of-m-researchers-find-earthworms-are-threatening-minnesota-state-flower-lady-slipper-/5431231/ https://kstp.com/news/u-of-m-researchers-find-earthworms-are... And https://www.sciencedaily.com/releases/2000/09/000904130558.htm https://www.sciencedaily.com/releases/2000/09/000904130558.h... I don't believe this is the same flower (I feel like I'd remember the state flower). So the impact of earthworms is interesting, as I'd never heard of a way (or suggestion to) treat and remove earthworms from an ecosystem.
- userbinator 7y agoyou know that in much of the northern US, all of the native earthworms were killed by the glaciers, and that practically all the current earthworms in these areas are invasives? That made me think of an alternative title for this article: "Microplastics are an effective solution to invasive earthworm control." ...that is, if a 5% difference in some of the results is even considered significant.
- autokad 7y agoand fighting climate change. Earth worms release more green house gasses than cows that politicians seem to like going on about.
- JulianMorrison 7y agoThey are part of the natural carbon cycle without which plants would pile up like they did in the carboniferous. Plants are only temporary carbon sequestration. The actual sequestration is in the standing-wave of growing, living, dying, decomposing material.
- autokad 7y agoyou are wrong. in north america, forests sequester layers of methane in burred layers of rotted material that are supposed to keep building up. however, the arrival of the earth worm has been releasing those layers of methane into the atmosphere and destroying forest layers.
- refurb 7y ago1 g per 1 kg is 1 Part per thousand. How does that compare to what is seen in nature that seems like an incredibly high plastic load. Reminds me of other studies that say “X causes problems” and then you learned they force fed rats 1000x any reasonable exposure doesn't necessarily tell you a lot.