Oceans and plastic

Whilst far from perfect myself, I really want to help my boys to understand their impact on the planet and how they can make good choices to protect the environment. We've talked about how we reuse things by buying things other people have already used (particularly plastic toys) and we pass on things we've finished with to others who can use them. We've also talked about recycling, and we made new multicoloured wax crayons from our broken bits rather than throwing them away. One environmental issue that my son has seen a lot about in places we visited before lockdown (notably London Zoo and the Horniman Museum) is the issue of plastic in our seas.  

Our oceans contain a huge amount of plastic, all waste from human activity. Estimates vary, but it seems there's 5-10 million tonnes of plastic entering our seas each year, some as large pieces and others as smaller 'microplastics'. It takes a long time to break down and can cause damage to sea creatures as well as ending up in our food chain. This is a problem that has become far greater during my years as a consumer of plastic products, and it's something that we could drastically reduce if people collectively used less single-use plastic, recycled more efficiently and were more careful with preventing litter. There are other good reasons to use less plastic too, including oil - from which it is made - being a finite resource. I thought we could try an experiment to enable us to talk about the effect of plastic pollution in our seas and how we can make better choices about packaging. We actually did this a few weeks ago, but as I've finally managed to finish writing this blog entry and it's Earth Day on Wednesday 22nd April, it seemed like a good time to post it as people may be looking for activities about our environment.

My idea was to create a 'sea in a jar' and observe what happened to different packaging. I wasn't sure how well it would work, but decided to give it a go with the small boy as I thought we could both learn something from it. The 'sea in a jar' is an approximation to the real thing as we're not going to use any living creatures and the things we put in don't fully match the more composition of the oceans, but it was the best I could think of with household and garden items!

We talked about the different types of packaging we could find in our house.  I cut samples of 9 different materials, with two pieces of each (one to go in the jar and one to keep as a reference).  These included different types of paper and cardboard, different types of plastic, biodegradable cornstarch packaging and juice carton (Tetrapak).  There are other things you could try e.g. wet wipes, but we went with what we found quickly, mostly in the kitchen and our recycling box.

Jar, sand, gravel, salt, water and packaging samples

We haven't been to the seaside since last June and I wasn't sure how much my son remembered (sadly I suspect it will be a while before he can experience the sea again given our lockdown). I asked him if he thought the sea was salty and he didn't know. So I explained that it was, and we weighed out 10g of salt and added it to 250ml of water, which approximately matches the salinity of the sea. He shook the jar to mix it and asked if he could taste it. As it was all clean and edible at this point, I said that he could - he declared it to be disgusting! 

Adding components of the pretend sea into the jar

As materials in the sea can be worn down by sand and rocks, we also added a tablespoon of sand (from our sand timer experiment) and a tablespoon of gravel (washed with boiling water in case it had any bacteria that could survive a wet and salty environment).  We had a play with shaking the jar and saw that in our pretend waves these moved around, but then settled at the bottom when the waves (shaking!) stopped.

Putting packaging in the jar

My 3 year old put one set of packaging pieces in the jar and gave it a good shake. I put it on the windowsill where he could see it but neither he nor his little brother could reach and put the other set of packaging pieces on a shelf. We then had a look an hour later, and the small boy wanted to take the packaging out and have a closer look. The paper looked soggy, with the newspaper going so you could see the print through from the other side, but otherwise there wasn't much change. We put them back in and gave the jar another shake. 

Simulating the movement of the sea

We had another look a few hours later, and the paper was starting to rip. More interestingly the corrugated cardboard was separating into three layers, with the middle being a longer piece that forms a zig-zag pattern. My son found this intriguing and we talked about how it makes the cardboard strong. 

A day later - the paper is in small pieces and the corrugated cardboard in 3 layers

We had a look a day later, then about a week, and then about weekly for a month. We shook the jar when we remembered, sometimes a few times a day, and sometimes not for several days. The paper was in such tiny pieces by the end that we couldn't find it amongst the sand and stones. The corrugated cardboard had also broken down into tiny fragments, but the egg box cardboard was still largely intact. The juice carton had separated into three layers, two of which seem to contain plastic. The plastics looked just like the pieces that hadn't been in the jar, although the print on the bagel wrapper was a little scuffed in places. The one I was most interested in was the cornstarch packaging which also looked unchanged. This is meant to be rapidly biodegradable, but I think that's under aerobic conditions in compost rather than submerged in the sea, so I don't know how much better than conventional plastic it actually is for our oceans.

Finding the packaging pieces after a month

So what did we learn? We found that paper breaks down quickly in a sea-like environment, and as it's made of fibres from trees, I suspect it doesn't cause many problems. Plastic, however, stays intact. It does eventually break down into smaller fragments but these can be eaten by sea creatures. So why does the supermarket sell the bread we buy in a paper bag but the bagels in plastic? I don't know. If they had bagels wrapped in paper, my son thinks we should buy those instead. It's a lot faster to grow more trees to make paper than to make oil, so it seems logical from that perspective too.

Samples that haven't been in the jar on the left, and those that had on the right

We have changed to using refillable water bottles and have used mostly cloth nappies and reuseable wipes. But we still buy plenty of things contained in single use plastic. By talking about the choices we make when buying and disposing of things and referring back to this activity, hopefully I can help my son learn which options are better for the environment so that when he makes decisions for himself he will factor this in.