Guest Essay by Kip Hansen
Images such as this appear on the Internet and in the Main Stream Media, alongside of almost every article or report about the pollution of the Earth’s oceans with plastics of all kinds. The image is usually associated with the words “Great Pacific Garbage Patch” in the text of the article. The implication by association is that the image is a photograph of said ‘garbage patch’.
This clip from the Guardian shows a typical example:
The Guardian is atypical in that it states, in the caption, that the photo is of Manila Bay, Philippines – garbage forced by the wind into a raft near shore after a tropical storm washed all the trash from the city streets and slums into the bay. I’ve seen similar scenes in the Rio Ozama in Santo Domingo, this one at the “yacht marina” on the eastern shore just below the swing bridge:
There are low-lying slums upriver – tropical storms or even simple heavy rainfalls wash trash off the streets and into the river – hurricanes wash entire neighborhoods into the river. There appears to be a door-less cheap refrigerator floating amongst the other debris.
There is a lot of plastic trash and debris going to the world’s oceans. It used to be dumped intentionally – New York City barged its municipal trash out to sea and tipped it in for years and years, as recently as 1992.
There is no longer any country or municipality known to be disposing of municipal trash and garbage at sea today. Most trash and garbage is fairly readily decomposed in the natural environment and in modern landfills. Plastics, however, are less prone to biodegradation – and some types of plastic are very resistant. As the two photos above illustrate, Manilla Bay and Rio Ozama, lots of plastic ends up in the sea.
Dr. Jenna R. Jambeck is one of the world’s leading experts on trash – and specifically on plastics entering the oceans. Her group at the Environmental Engineering College of Engineering, University of Georgia has published many papers on the problem, most recently “Plastic waste inputs from land into the ocean” (summary here – full .pdf here). From the summary:
● The amount of plastic waste entering the oceans from land each year exceeds 4.8 million tons (Mt), and may be as high as 12.7 Mt – or nearly one to three orders of magnitude greater than the reported mass of plastic in high-concentration ocean gyres.
● Quantities of plastic entering the ocean are growing rapidly with the global increase in population and plastics use, with the potential for cumulative inputs of plastic waste into the ocean as high as 250 Mt by 2025.
● Discharges of plastic are spread around the globe from the 192 countries with coastal borders considered in the study, but the largest quantities are estimated to be coming from a relatively small number of countries in Asia and other middle income, rapidly developing countries. The top 20 countries account for 83% of the mismanaged plastic waste available to enter the ocean.
● Reducing the amount of mismanaged waste by 50% in these top 20 countries would result in a nearly 40% decline in inputs of plastic to the ocean.
One rightly wonders about their estimated range of plastic waste entering the seas – given as 4.8 to 12.7 million tons. The reason for that spread is that after a massive amount of calculating plastic production by all nations, plastic manufacturing by all nations, percentage of plastic in the nations waste stream, and the amount of waste that does not end up proper landfills – all this to arrive at an amount of plastic “on the loose” – their “mismanaged plastic waste available to enter the ocean” – Jambeck and team simply guess that 15% of that plastic potentially ends up in the oceans.
Now that’s a lot of plastic and it certainly doesn’t belong in the oceans – any of it, really. But we must be pragmatic – some stuff always gets away from us even when we have efficient waste collection systems and enforced recycling. I admit – I’m guilty – I have had plastic items blow or wash off the deck of my venerable old motor sailing catamaran, the Golden Dawn: the occasional five-gallon bucket, a plastic drinking glass, a plastic washbasin, my favorite deck chair (dang!) – if this happens at anchor, we run out in the dinghy and fetch it back but if we are underway, under sail, it is often impractical to double back for a small item.
Here is a photo of the real Pacific Ocean Garbage Patch:
Neither do I.
Don’t be surprised. In my travels at sea (1/2 of my adult lifetime on the briny deep – well, at least actually living aboard a ship or boat), my experience is that seeing something floating in the open ocean is rare – rare enough that it always calls for at least an investigation through binoculars, and if the item looks interesting, we might make a course change, if possible, to check it out. The most common items are things that have fallen off fishing boats – buckets – gallon jugs – buoys and floats of different types (which are recovered if possible for their usefulness). I have never come across any tangles of floats and nets which can be dangerous, especially if under motor power, as they can wrap around shafts and props, in our 13,000 miles of voyaging in the Golden Dawn. There are pictures of these tangles on the web – and I have seen a small one caught on the sea side of a barrier reef, but have never seen one in the open ocean.
Dr. Jambeck and I corresponded by email about plastic at sea and she related to me that on a recent voyage from Lanzarote (in the Canary Islands off the shore of Africa) to Martinique (one of the Windward Islands of the Caribbean), a trip of 3,200 miles, they recorded sighting 15 floating items – “mostly buckets and buoys, with at least one bottle too”. That’s one item every 215 miles or so. One wishes the highways and byways of America were so clean.
So where is all that plastic? Where is the Great Pacific Garbage Patch?
From NOAA’s Ocean Service — Office of Response and Restoration we have this page:
“The NOAA Marine Debris Program’s Carey Morishige takes down two myths floating around with the rest of the debris about the garbage patches in a recent post on the Marine Debris Blog:
1. There is no “garbage patch,” a name which conjures images of a floating landfill in the middle of the ocean, with miles of bobbing plastic bottles and rogue yogurt cups. Morishige explains this misnomer:
“While it’s true that these areas have a higher concentration of plastic than other parts of the ocean, much of the debris found in these areas are small bits of plastic (microplastics) that are suspended throughout the water column. A comparison I like to use is that the debris is more like flecks of pepper floating throughout a bowl of soup, rather than a skim of fat that accumulates (or sits) on the surface.”
2. There are many “garbage patches,” and by that, we mean that trash congregates to various degrees in numerous parts of the Pacific and the rest of the ocean. These natural gathering points appear where rotating currents, winds, and other ocean features converge to accumulate marine debris, as well as plankton, seaweed, and other sea life.”
Note the scale on the right. The jar is about 2 inches in diameter, and the plastic bits fill it up to about 2 inches high. It took a lot of sieving the Great Pacific Garbage Patch to collect that much.
This agrees with my own impromptu research on our beach-side walks along Cape Canaveral Beach, Florida. This is what we find washed up:
This sample was taken from a one-mile stretch of beach that is not raked or cleaned by the county, over a period of two days of careful searching from just above the high water line to the low water line. On the right is what we identified as “Tourist Trash” – left by recent beach goers. On the left is the Flotsom and Jetsom – stuff that has been floating on the sea and been washed ashore.
It is an interesting mix, and if you look carefully, you’ll recognize the similarities to the bits and bobs found in NOAA’s jar above. We have a lot of little bits of plastic of no particular shape. We don’t have bottles, cups, plastic cutlery or very much that is recognizable. There is something (red) that looks like a six-pack holder, some bits if plastic rope reduced to threads, an o-ring and the remains of a plastic zip-lock bag. For size, the o-ring is about 1 inch in diameter.
Jenna Jambeck summarizes it saying that the amount of plastic estimated to be washing into the oceans is “one to three orders of magnitude greater than the reported mass of plastic in high-concentration ocean gyres”. That means that 10 to 1,000 times more plastic is going into the oceans than can be found.
So, the Big Question about the Great Pacific Garbage Patch – all the Garbage Patches – is:
“Where is all that plastic?”
Here’s the headlines:
Science Magazine: “Ninety-nine percent of the ocean’s plastic is missing”
National Geographic: “Ocean Garbage Patch Not Growing—Where’s “Missing” Plastic?”
Here’s the data, in graphic form:
Original Caption: “Fig. S6. Size distributions of plastic fragments by ocean basin. Size distributions were built with the plastic items collected along the circumnavigation: 1565 in North Pacific Ocean, 1043 items in North Atlantic Ocean, 259 items in South Pacific Ocean, 3339 items in South Atlantic Ocean, and 1153 items in Indian Ocean. The gap in the plastic size distributions below 1 mm was present in all ocean basins. Dashed vertical line [lime green for visibility – kh] corresponds to 1 mm size limits.”
What are we looking at here? The graphic shows “Abundance of Plastic (items)” – the number of bits of plastic – found by ocean by size of item. The image is a bit confusing as to the Log Length (mm) and Length (mm) – the scale at the bottom gives the sizes in millimeters. The lime-green line is at 1 mm. The largest item recorded is 158 mm (about six inches). The bulk of items found fall in the 25 mm down to fractional mm range. That size range, in items you can hold in your hand, is from the diameter of a US quarter dollar (24.26 mm) down thru the thickness of a US dime (1.36 mm) to the thickness of a sheet of common 20 lb. copy paper (0.1 mm).
Now, one can see a bit of colored plastic that is 25 mm square – the size of a quarter. But they found very few quarter-sized bits, even combining all the oceans. The numbers don’t start ramping-up until one gets as small as 10-13 mm – for comparison, a dime is 17 mm – so, smaller than a dime. The real peak of bits found is in the 4 to 5 mm to 1 mm size range (1 mm is about the thickness of a CD or DVD).
Why does the graph look like this? Mainly it is that as plastic items degrade from the UV in the sunlight, from submersion in salt water, and wave action – breaking into bits, over and over – the bits get smaller and smaller. Thus, we see a rapid doubling and redoubling of the number of bits. Until….?
Until the size gets to about 1mm – then they rapidly decrease and virtually disappear.
This is not because they can’t sieve them out of the water – they have
hardily tired tried very hard with smaller and smaller sieves and searching under microscopes for those littler bits. They just aren’t there.
That is the chief finding of Cózar et. al. What should have happened is that the numbers should have kept doubling and re-doubling. And they didn’t. The littler bits just disappear.
This is what is meant by the headlines: “Ninety-nine percent of the ocean’s plastic is missing” and “Ocean Garbage Patch Not Growing—Where’s “Missing” Plastic?”
“Where is all that plastic?” – Part II
I always ask my wife: “Do you want the quick, easy answer? or the real answer?” Over the years she has tended towards getting the real answer, much to her credit, even though she know that it usually takes much longer.
I’ll give you the quick and easy first: The plastic gets eaten.
That is the simple and straightforward physical fact. Something is eating those littler and littler bits of plastic. Once the bits get smaller than 1 mm – they get eaten up by the denizens of the deep.
I’m sure you all have seen the sad pictures of the poor albatross babies, laying there, a bag of dried bones and the remains of a stomach full of soda bottle caps.
Just to clarify, I’ve counted about a dozen different pictures of dead albatross chicks from Midway on the internet, some of them look to be several seasons old. Midway Atoll is the winter home of nearly a million nesting albatrosses. Roughly 450,000 pairs wedge their way into a scant 2½ square miles of land surface. Not very many albatross chicks are dying from being fed plastic. In a Darwinian sense, mother albatrosses who feed chicks too much plastic don’t get to pass on their genes, thus improving the species.
We are not talking about this kind of “eating”. Nor the eating done by the occasional misguided sea turtle thinking a floating plastic bag is a jellyfish. Nor the visible bits gobbled up by every type of sea bird and fish that snaps at anything that moves. A lot of that goes on and biologists are finding plastic in the digestive tracts of lots of different species. There is, as yet, no evidence that the plastic is harming any of these birds and animals – with the exception of those obviously choking or getting clogged up by something they shouldn’t have tried to get down.
Aside: I have watched a cormorant struggle for an hour to regurgitate “a fish too large” – he got it into his throat, but couldn’t get it any further. I thought he was going to die, but after an hour, by hooking the bottom half of his beak on a board on the dock and pushing forward with his body to force his beak open further than he could normally open it, he got the fish out – and gave up on it, happy, I suppose, to have survived. So, birds do eat things they can’t handle – some of it plastic, I would think.
So, who or what is doing the eating?
One hypothesis put forward is that the fish that normally eat zooplankton are eating the similarly sized bits of plastic. It is quite certain that some little fishes eat little bits of plastic:
“Zooplanktivorous predators represent an abundant trophic guild in the ocean, and it is known that accidental ingestion of plastic occurs during their feeding activity. The reported incidence of plastic in stomachs of epipelagic zooplanktivorous fish ranges from 1 to 29%, and in stomachs of small mesopelagic fish from 9 to 35%. The most frequent plastic size ingested by fish in all these studies was between 0.5 and 5 mm, matching the predominant size of plastic debris where global losses occur in our assessment. Also, these plastic sizes are commonly found in predators of zooplanktivorous fish.” (Cózar et. al – source)
Cózar speculates that this ingested plastic would be defecated and return to the surface. Some would be semi-permanently encased in feces and, with the addition of pelagic lifeforms (tiny barnacles, sea worms, and the like) sink to the bottom of the sea. Some of the fishes, with plastic now in their digestive tracks would themselves be eaten by larger fish which would now carry the plastic load and accumulate it – or not – again, defecating it out, either to float back to the surface or sink to the bottom. There is no data available on how much in either case.
Do remember though – higher lifeforms are all built on the basic tube model – like an earthworm – what goes in the mouth comes out the other end after processing. Almost all animals have the ability to pass whatever they take in. Some animals, which eat other animals whole (such as owls), have the ability to the regurgitate undigested contents of their stomachs (cats, too). So whatever plastic goes into these little fishes probably comes out somewhere. In the end (unintended pun), “fishes eating the tiny plastic bits” probably doesn’t account for the missing 99%.
What else could be going on?
Remember the Deepwater Horizon Gulf of Mexico Oil Spill? Scientific American magazine ran this piece: “Meet the Microbes Eating the Gulf Oil Spill”.
Well, meet the microbes eating the ocean’s plastic:
Here is what is apparently happening. As the bits of plastic get reduced in size below the threshold of 1 mm or so, the surface area vs.volume ratio becomes favorable for the microbes to eat the bit up entirely. This is similar to the way crushed ice is more quickly melted than large cubes – and why big icebergs last a long time, but an ice cube in the same ocean, at the same water temperature, disappears very quickly.
Ocean biologists are not sure what this portends. Plastics commonly contain contaminants. Marine microbiologist Tracy Mincer of the Woods Hole Oceanographic Institution in Massachusetts is quoted in Nature saying:
”Plastic-eating bacteria might help explain why the amount of debris in the ocean has levelled off, despite continued pollution. But researchers don’t yet know whether the digestion produces harmless by-products, or whether it might introduce toxins into the food chain.
“To understand if it’s a good thing or not, we have to understand the entire system,” says marine microbiologist Tracy Mincer of the Woods Hole Oceanographic Institution in Massachusetts.
Plastics contain toxins such as phthalates, and also absorb additional toxic chemicals such as persistent organic pollutants from the ocean, says Mark Browne, an ecologist at University College Dublin in Ireland, who was not involved with the project. Those chemicals could leach out into the microscopic animals that eat the bacteria, or broken down microscopic plastic particles could enter cells and release their chemicals there, he says.” (Nature news) .
While there is not, as of yet, any quantitative analysis of how much plastic micro-critters are eating, Cózar’s results indicate that as plastics break into smaller and smaller pieces, they get removed from the environment, by something, very rapidly – so rapidly, in fact, that despite what are believed to be increasing quantities of plastics entering the oceans, the amount of plastic found in the oceans is not increasing.
Take Home Message:
We each need to do all we can to keep every sort of trash and plastic contained and disposed of in a responsible manner – this keeps it out of the oceans (and the rest of the natural environment).
Volunteerism to clean up beaches and reefs is effective and worthwhile.
Responsible boating includes keeping your trash (and especially plastics) under control and disposed of properly ashore.
The “floating rafts of plastic garbage”-version of the Great Pacific Garbage Patch is a pernicious myth that needs to be dispelled at every opportunity.
Have a little more faith in “Nature” – the natural system finds a way to use most everything – in the case of oceanic plastics, as homes and food.
The “missing 99% of the plastic in the oceans” has been eaten, mostly by bacteria and other microbes. These little critters will continue to eat the plastic and if we reduce the amount of plastic going into the oceans, they may eventually eat it all up.
# # # # #
Author’s Comment Policy:
I’ll be happy to answer your questions and give more references if anyone wants them. I have worked on this issue off-and-on for the last year to satisfy my own curiosity.
I will admit that I guessed the outcome years ago – like solving the who-dun-it in a mystery novel – after the Deepwater Horizon finding.
My experience with the sea has taught me that everything gets used for something – once I tried to collect a beer can off a reef, only to have it snatched back out of my hand by the octopus that was using it as a door to his hide-away. Almost any solid object placed in the sea becomes a welcomed home for something. And, almost anything is food for some beast or some plant.
The largest piece of floating debris we ever saw on the open ocean was a full-sized home refrigerator.
And this week in local news: “Thousands of Coffee Cans Wash Up on Florida Beach”.
My best beach-combing find, on the east-facing shore of Big Sand Cay in the Turks, was a six-inch green plastic brontosaurus – which had been at sea for so long that by the time I found it, it had been renamed a “Apatosaurus”. I was informed by a precocious four-year old that it could also be a Brachiosaurus – which has the same shape but is much larger.
# # # # #