Researchers discover more plastic than expected in the ocean

During a recent expedition, KAUST researchers studied the distribution of microplastics in the open ocean around the planet.

"These are the times of dreamy quietude, when beholding the tranquil beauty and brilliancy of the ocean's skin, one forgets the tiger heart that pants beneath it; and would not willingly remember, that this velvet paw but conceals a remorseless fang."

Perhaps the following interview with Dr. Xabier Irigoien, Director of the Red Sea Center at King Abdullah University of Science and Technology (KAUST), isn't quite as dramatic as Herman Melville's "Moby Dick," but it is true that the world's oceans are not as beautiful, nor as clean as they once were. Irigoien's finding during his research team's expedition were recently published in a paper, "Plastic Debris in the Open Ocean," in Proceedings of the National Academy of Science (PNAS).

We recently sat down with Dr. Irigoien for a face-to-face interview. Candid and insightful, he detailed the findings of the expedition's research, spoke of what worries him and talked about what's next in the global battle to clean up our oceans.

Researchers found that smaller-sized plastics (the micro plastics) are disappearing.

Dr. Irigoien, could you please give a brief synopsis of this latest research?

This is a paper where we studied the distribution of microplastics in the open ocean around the planet. This was done with an expedition crew that went around the planet collecting samples. There are two main messages in the findings we got. The first is that there is plastic everywhere. There are microplastics as far away from dry land as one can travel. The second finding is that much less plastic was found than what should be there. We know the amount of plastics that are produced, and how much is entering the ocean. This means the plastics are either sinking or going into the food chain of ocean species.

So that's the crux of it? You have a pretty good bead on the quantity of plastics that are leaving dry land and going out into the oceans. You're expecting to find a certain quantity, but that quantity is not there. Then, it's a question of where it has gone, and is it then harmful in some fashion?

Yes. The exact estimation of how much plastic is going out into the oceans is not absolutely precise, but we are finding 100 times less plastic than expected. So even if the outgoing plastic estimation is slightly off, the discrepancy between what plastic is being found is a lot less…a lot less. So, the plastic is entering the ocean, and then breaking down into microplastics – but then much of it is disappearing.

The exact estimation of how much plastic is going out into the oceans is not absolutely precise, but KAUST researchers found 100 times less plastic than expected.

Another interesting observation is that for the larger-sized plastic materials, we are finding the expected amounts. But for the smaller-sized plastics (the micro plastics) - they are disappearing. There is a range of smaller sizes that are disappearing. In 88 percent of the water samples we pulled from the world's oceans, we found plastics.

That is a significant percentage. To clarify, when you're referring to plastics, you are talking about trash? Trash that is dumped by humans – via barges and so forth -that then travels into the open ocean?

Yes, it's coming out from the rivers, from the coast, wherever.

OK. So let's just take a plastic milk container, for example. When you're referring to microplastics, you're talking about something that, when traveling out into the open ocean, it is being deteriorated by salt water, so it ends up being in tiny pieces?

Yes, what happens is the weathering effect. You have the sun, the salt, the water – so the plastic starts breaking down. Any large piece will break into smaller pieces. Those smaller pieces break down to even smaller sizes, and so on - eventually to sizes less than one millimeter. We found that in the centimeter sized ranges, there is the amount of plastics that we expected. When we looked for sizes in the one to two millimeter range, we found that they are, and have been, disappearing. And our main hypothesis is that they are being eaten by fish.

Are there studies and/or groups who have actually caught fish and checked their digestive systems to see if plastics are present?

There are studies looking at fish in the open ocean, and they have found that yes, they do eat the plastics. There are a limited number of these studies, but they do find that the fish do have plastics in their stomachs.

Is there a risk of these microplastics getting back into human water supplies?

No. Although the microplastics are very tiny, they are still much larger than anything that could pass through water treatment facilities. But, the real concern would be the plastics that enter the food chain, when fish eat them.

Was there anything that surprised you in these findings?

The fact that there are plastics everywhere. Perhaps that was naïve on our part. You're used to going to the open ocean and seeing clean, clear water everywhere so you don't expect to find as much as we did. The other surprise is that so much plastic is missing, is unaccounted for. The question then is where has it gone?

What's the next step in the research?

The next step is to find out where the microplastics are going, with certainty. Our main hypotheses are that they are being eaten or that they sink.

The next step is to find out where the microplastics are going. KAUST researcher's say their main hypotheses is that they are being eaten or that they sink.

What's the most important message for the average person on the street?

Plastics have been around for a long time, and they are a large part of our daily lives. Eliminating plastics from our lives is not practical. But the issue of the management of the plastic trash, any trash, is something that needs to be addressed.

So, you're out in a boat, enjoying this beautiful paradise that is the open ocean. It's full of life – sea life. And then you find out that we've been dumping so much trash, that this trash is now virtually everywhere in the Earth's oceans. Does what we've done make you feel bad?

Yes. It definitely makes you feel sad. I want to have a good life. I also want my children to have that good life, to leave them a good planet. This wasn't an issue two thousand years ago. What will be the issue if this continues? We do have the technology, the management tools to reduce this issue now, without compromising our use of plastics in our lives.

How do we take that challenge on?

There are countries that do a good job now with management. What we need to do is copy that, and apply it to the areas that don't do a good job.

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- by Will Clark, KAUST News