There's a lot of plastic floating around in the ocean these days, but did you know one of the biggest causes isn’t straws or shopping bags? Those get a lot of attention, but they’re not the real heavyweight. It’s actually something millions of people use every single day: car tires. 🚗
The problem isn't whole tires ending up in the water. Instead, as we travel in cars, tiny pieces of rubber shred off our tires and scatter on the roads. The more our tires wear down, the more little bits get released. When it rains, all those tiny pieces wash into storm drains, flow into rivers, and eventually end up in the ocean.
These tiny particles are called microplastics, and since they're flowing along with our water, they're practically everywhere. We don't know what the long-term effects of so much plastic exposure will be on our environment, but it makes sense to try and stop the spread whenever we can.
Here’s some good news: scientists are experimenting with a surprisingly simple solution called biochar. 🌱 If you burn rice husks in a low-oxygen environment, you get a porous material that can attract and trap chemicals and plastic particles to its surface. Mix it with wood chips, stuff it into giant filter socks, and set those socks across the ends of storm drains. Suddenly, you can trap up to 90% of the tire bits before they hit waterways!
Image: biochar sample
Will we start seeing biochar filter socks tucked into drains along busy highways? It's too soon to tell, but the early results are promising. The next challenge is figuring out what to do with the filter socks once they’re full.
Microplastics are hard to capture because they’re so tiny. The graph below shows how the size of microplastics compare to more familiar objects:
If I brought this graph to my classroom, here are some questions I would have to go along with it.
💡Based on the graph, which of the following objects are the same size range as microplastics: the width of graphite for a mechanical pencil, a housefly, the height of a dime, or grain of salt?
💡According to the graph, what is the smallest length of a microplastic? What object is similar in size?
💡Biochar is best at absorbing nanoplastics and microplastics. Based on the graph, what size are these plastic particles? What sort of equipment would we need to use to study what is trapped by the filter?
