from Christina Cilento…
In terms of soil/plant content, I used to work on climate policy in agriculture, so I have some potentially relevant content for the garden club folks in my presentation! I also have the picture of the microplastics in the plant, and then the below:
I mention that research on microplastics in soil doesn't seem to be as developed as studies of microplastics in the ocean, but research is now coming out estimating that microplastic contamination in agricultural soils may be even greater than microplastics in the ocean. Here's a UN report on this point https://www.unep.org/news-and-stories/story/plastic-planet-how-tiny-plastic-particles-are-polluting-our-soil
I highlight that microplastics in soil are potentially disrupting soil's ability to act as a carbon sink (absorb carbon from the atmosphere). So not only is the production of plastics contributing to direct emissions, but plastic contamination in the natural environment may be preventing tiny soil microorganisms from eating up the carbon that we do release into the atmosphere. The research is pretty new on this one (and a quick Google search reveals that I likely need to update my sources since there were some papers published early this year on this), but here are some articles that might be helpful to drive home this point: https://www.sciencedirect.com/science/article/abs/pii/S004896972302733X and https://www.sciencedirect.com/science/article/abs/pii/S0959652622051320#
I describe microplastics as big magnets that attract other pollutants and toxins and mention research on what this means for our food. There's one study I mention that compares how wheat plants uptake cadmium in the presence of microplastics, vs. with no microplastics. The study found that the wheat plants watered with a solution that contained microplastics ended up absorbing 1.5x as much cadmium in their leaves than those watered with regular tap water. Here's the study:
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwiNoIz8so37AhWGkIkEHUedDqUQFnoECA0QAQ&url=https%3A%2F%2Fscisoc.confex.com%2Fscisoc%2F2020am%2Fmediafile%2FHandout%2FPaper125118%2FASAPosterPhoenixVirtualMeeting2020.pdf&usg=AOvVaw1A6m6sFjYze1IL6KuLNfaG
All of these links are kind of technical, but the bottom line is --
soils are a vastly understudied hotbed of microplastics and may be a greater destination for microplastic pollution than the ocean;
we rely heavily on soils to absorb carbon from the atmosphere, and emerging research is showing that microplastics in soils may be preventing soils from doing just that, which takes away a critical tool in the fight against climate change;
microplastics attract other pollutants, and research has shown that plants watered with microplastics end up channeling more toxins (like heavy metals) into our food. Here's the link to my presentation if it's useful, but not all these points have full slides.
Controlled-release fertilizers as a major concern
A growing number of fertilizers are now coming encapsulated in little microplastic pearls designed to release the fertilizer slowly over time. But then of course the microplastics stay in the soil forever and contribute to all the problems I highlighted above. Here's an article on that dynamic https://cen.acs.org/environment/pesticides/Stop-delivering-agrochemicals-microplastics-group/100/i19 based on this report https://www.ciel.org/reports/microplastics-in-agrochemicals/.