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:
Key findings:
● 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:
See all that plastic garbage floating around tangling up the porpoises and sea turtles and albatrosses?
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.”
Thus:
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:
http://www.nature.com/news/2011/110328/full/news.2011.191.html
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.
# # # # #
The ocean degradation of plastic does create nano-sized particles. Some research has been done trying to extrapolate effect on living cells. There is considerable more that has been published, including more recently, if anyone interested.
“… photo-oxidation functionalizes the surface of plastics to render them with different charge polarities …adsorption of (20 nm) nanosized plastic (polystyrene) … favor positively charged over negatively charged plastic beads … to cellulose … of … Chlorella and Scenedesmus … hindered algal photosynthesis, possibly through the physical blockage of light and air flow by the nanoparticles ….” Edited quote from (2010) “Physical Adsorption of Charged Plastic Nanoparticles Affects Algal Photosynthesis”; J. Phys. Chem. C, 114, by Bhattacharya, et.al. Clemson U. Laboratory of Single-Molecule Biophysics & Polymer Physics & Center for Optical Materials Science & Engineering Technologies
(2013) “Polystyrene Nanoparticles Perturb Lipid Membranes”, J. Phys. Chem. Lett., 2014, Rossi et.al Université Paris Diderot, Sorbonne suggests “… nanoparticles permeate … lipid membranes … alter … structure … reduce molecular diffusion … affects … organization by stabilizing raft-like domains ….”
(2014) “Nanoplastic Affects Growth of S. obliquus and Reproduction of D. magna” , Environ. Sci. Technol., 48 (20) conclude ” … reduced population growth & reduced chlorophyll concentrations … Daphnia … reduced body size & … alterations in reproduction … body size of neonates were lower … number of neonate malformations … rose … effects … observed between 0.22 and 103 mg nano-PS/L. Malformations … from 30 mg of nano-PS/L onward….”
Reply to gringojay ==> This research generally is concerned with the nano-plastics that are used in cleaning agents — manufactured for that purpose. They are very small.
What Cózar et al. found was that as the ocean breaks down pelagic plastics, they don’t end up as ka-gillions of nano-particles, but actually disappear altogether — eaten up by bacteria and other micro-critters.
It is not entirely clear yet what happens when the manufactured particles are smaller than microbes….
The is concern that nano-plastics will or might cause harm, it has been shown tpo maybe happen in the lab, but if Cózar et al. is correct, such tiny particles are probably being eaten in the natural environment.
(2015) “Marine Anthropogenic Litter” edited by Bergmann, Gutow & Klages full 456 page free text is available on-line as a pdf. My edited quotes follow:
“… microparticles … (European Union/USA adopted 5-mm upper bound for categorization of microplastics within the Marine Strategy Framework Directive) … = …primary’ microplastics, produced either for indirect use as precursors (nurdles or virgin resin pellets) for the production of polymer consumer products … in cosmetics/ scrubs/abrasives & (ii) ‘secondary’ microplastics … from … breakdown of larger plastic … normally float at the sea surface …(as) … less dense than sea-water … buoyancy & specific gravity … may change … results in … distribution across … sea surface/deeper water column/seabed/beaches/sea ice … sediments …of the deep sea … Arctic sea ice … (at)… 2 orders of magnitude higher than … contaminated surface waters … encounters … by marine species = ~ 10 % with microplastics (as per Secretariat of the Convention on Biological Diversity and Scientific and Technical Advisory Panel GEF) …
For those interested pg 249 Table 10.1 has data for different Pacific micro-plastic densities, pg. 253 Table 10.3 has Atlantic densities, pg. 256 Table 10.5 has Med/European densities & good extensive details from pg 263 Table 10.8 (lab data) to end of Table 10.9 (field data) page 274.
This report summarized reports that ” …decreased feeding … following ingestion … by zooplankton … mussels (Mytilus edulis) and oysters (Crassostrea virginica) take up 100 nm … (yet) … bioavailability … (&) … mussels reduced their filter-feeding activity in response to 100 mg/L 30 nm … 2-generation toxicity … (if) chronic … ingestion by copepods (Tigriopus japonicus)… mortality of nauplii and copepodites for 50 nm … at … 12.5 mg/L (F0 generation) & 1.25 mg/L (next generation) … effects … in the early development of sea urchin (Paracentrotus lividus) embryos, with EC50 values of 3.85 and 2.61 mg/L @ur momisugly 24 and 48 h post fertilization … sorption of 39.4 nm … to … chorion of medaka (Oryzias latipes) eggs/uptake into yolk & gallbladder during embryonic development, whereas adults accumulated the NPs mainly in the gills and intestine yet also in the brain, testis, liver and blood … suggest(s) … capable of passing the blood–brain barrier … acute (24 h) toxicity to medaka eggs was zero and 35.6 % for 1 and 30 mg/L , respectively … toxicity increased with higher salinity … 25 nm … transported through … food chain from green algae (Scenedesmus sp.), through water fleas(Daphnia magna) to carp (Carassius carassius) and other fishes, and affected lipid metabolism and behaviour of the fish … 55 and 110 nm … on algae (Pseudokirchneriella subcapitata), crustaceans (Thamnocephalus platyurus; Daphnia magna), bacteria (Vibrio fischeri) and rainbow trout (Oncorhynchus mykiss) cell lines … effects … in vivo species … EC50 values between 0.54 and 5.2 mg/L … (&) … EC50 … cytotoxicity … ~60 and 87 mg/L … 70 nm … reduced … growth of algae (Scenedesmus obliquus) … malformed offspring of Daphnia at … 32 mg/L … effects on Daphnia … with and without fish (Perca fluviatilis) kairomones in the water and the effect of the kairomones appeared to be stronger in the presence of 1.8 mg/L nanoplastic …. suggest(ing) … interfere with …chemical communication among species ….”
Based on the referenced Tables’ data it does not seem to me that the amount of marine micro-organisms that are breaking down these nano-particles (NP) are keeping up with the level of NP.
Incidentally, I also see that : “Several studies … showed beneficial effects of microplastic ingestion by reducing bioaccumulation due to sorption of chemicals to the plastic ….” For brevity am not replicating that & interested readers should look for that to get editors’ references.
Thanks, gringojay. You are concerned about the effects of nanoparticles.
Let me note that the ocean is a soup of big particles of stuff, small particles of stuff, and nanoparticles of stuff, all the way down to the molecular size. These include a huge variety of both organic and inorganic materials, metameterials, and compounds. In general, if there is energy that can be released by breaking those particles of any size down, there are tiny creatures in the ocean doing so. And energy is indeed released by breaking down plastics.
As a result, while you wouldn’t want to feed spoonfuls of plastic nanoparticles to the heir to your fortune, in the ocean things just get eaten.
Could a big dose of plastic nanoparticles obstruct sunlight or algal breathing or the like in some small local area? Sure, and that’s why they’ve now been banned in things like toothpaste and such. We don’t want to be adding them to our rivers and wetlands and sewage plants.
But for the plastic that is floating around in the ocean, I just don’t see the danger … and as Kip points out in this article, the science bears me out. There is no slow rain of indigestible plastic particles in the deep ocean—it all gets eaten.
w.
Before going further I want to make clear that maritime studies of nano-particles are not always
only referring to micro-plastics. That distinction made, some times a metal ion based
nano-particles can be picked-up (so to speak) by plastics. One researcher described concern that this is a kind of “Trojan horse” vector allowing them to dispersal with risks (delivery of metal ion) & benefits (tie metal ion up).
Returning specifically to micro-plastics, there certainly is data that some of these are reaching the ocean depths. Atlantic & Mediterranean top layer sediments from 1,176 to 4,844 m … (locations = Porcupine Abyssal Plain, Congo Canyon, Nile Deep Sea Fan & S. Atlantic sector) … led one group to (quote): “… tentatively …conclude … microplastics … average … 0.5 microplastics per 25 cm2 in the top cm of sediment …(while) … highest concentration … (of 11 samples was) … in the sediment of the Porcupine Abyssal Plain (avg. 1 particle/25 cm2) … (samples) … size across at widest… = … 75-161 um … pigments … = … copper phthalocyanine, polychloro copper phthalocyanine & permanent red … reach the sea floor as marine snow … a biologically enhanced aggregation of small particles … (which) … contain phytoplankton, organic debris & clay particles … adhered (by) … action of extracellular polymeric material exuded by … cells …sinking rates … marine snow … = … 1 – 368 m d -1 … (so) even … polyethylene & polypropylene … can be transported to the sea floor …”
Above edited quote from (2013) “Microplastic pollution in deep-sea sediments”, Environmental Pollution 182; 495-499 & a free full pdf with their data charts for latitudes & longitudes is available online. Authors note that microplastics’ size is categorized by different authors from 1 – 5 mm & ” … <1 mm accounted for 65% of all marine debris items collected on beaches in the Tamar Estuary (U.K.) … worldwide (continental region) … 8 – 621,000 particles/Kg in sediments …. (&) … 3 – 102,000 particles/cubic mt. water …."
Reply to grinojay ==> I have this definition of micro-plastics in my notes (but have lost the exact reference — could finds it but will only if you insist):
“Microplastics are plastic particles smaller than 5.0 mm in size (Arthur et al. 2009). The lower bound (size) of the microplastics is not defined; however, it is common practice to use the mesh size (333µm or 0.33mm) of the neuston nets used to collect the samples (Arthur et al. 2009). There are two main ways microplastics are formed and enter a body of water : pri mary and secondary microplastics (Arthur et al. 2009). Primary microplastics consist of manufactured raw plastic material, such as virgin plastic pellets, scrubbers, and microbeads (Browne et al. 2007, Arthur et al. 2009) that enter the ocean via runoff from land (Andrady 2011). Secondary microplastic introductions occur when larger plastic items (meso – and macro – plastics) enter a beach or ocean and undergo mechanical, photo (oxidative) and/ or biological degradation (Thompson et al. 2004, Browne et al. 2007, Cooper and Corcoran 2010, Andrady 2011). This degradation breaks the larger pieces into progressively smaller plastic fragments which eventually become undetectable to the naked eye. ”
One must be careful not to confuse micro-plastics in the ocean and on the beach with “nano-plastics” or “plastic nano-particles” .
Jambeck and Cózar (and others) state that the vast majority of all plastics in the oceans consist of micro-plastics, dispersed in the water column, nearly all invisible to the naked eye from a boat.
Nano’s and another problem altogether — in the air, in the water, in our food, in our cosmetics and in our cleaning agents.
Came across this related article about Adidas making trainers out of recycled ocean plastic.
http://www.dezeen.com/2015/07/08/adidas-parley-sports-shoe-alexander-taylor-recycled-ocean-plastic/
Reply to Bloke ==> As usual, the devil is in the details — a vessel of Sea Shephard tracked illegal fishing vessels and retrieved one or more wayward poly fishing nets, and reused that plastic in a publicity stunt to make one (?) pair of shoes.
@Cray:
“Rabbits ate my Toyota Camry’s main wiring harness when it was parked for a month as I was trying to sell it. My wife did some research on a mechanics forum and one “expert” made a brilliant comment. He said a rabbit couldn’t be the culprit since rabbits are vegitarians. 🙂 Is copper wiring a vegetable?”
Lol, no, but it does look a lot like the roots that might cause obstruction in a burrow, and in any case is about the right size for a bun to wear down his/her ever-growing teeth on. The electrical wires in our house are for the most part hidden &/or shielded just so Professor Lapin won’t accidentally get a bigger energy boost than he was counting on in his daily explorations of the abode.
[The cable shielding is plastic, and he’s a living creature that doesn’t seem to mind chewing on it, so that’s all on-topic right…?]
Reply to Smokey ==> The topic did come up (way) above — so I think you’re covered.
In my experience, with small farm equipment, it is usually field mice that take up residence “under the hood” during the winter because it is dry, out of the wind, and safe from the barn cats. We normally checked the engine compartment for mouse nests, cleaned them out, and checked the wiring and hoses before the first start-up in the spring.
Kip Hansen December 19, 2015 at 10:31 am
Well … yes and no, as in many things. You guys are both right.
The first issue is whether the density of sea water increases with depth. It does, although not in a simple manner. In the surface mixed layer (top few hundred meters depending on location) there is little change in density with depth. Then there is the “pycnocline” where the density increases rapidly with depth. This same depth zone is also where the temperature and salinity change rapidly with depth. Finally, in the deep oceans, once again there is little change of density with depth.
http://ocp.ldeo.columbia.edu/climatekidscorner/ocean_stratification.jpg
Figure S1. The grey area at the surface is the mixed layer.
The density of the ocean is controlled by three things—temperature, pressure, and salinity. Of the three, the temperature has the biggest effect. HOWEVER, you can see in the images above that in the upper “mixed layer” of the ocean the temperature and the salinity don’t vary much with depth because as the name implies, the waters in that top 100 metres or so are pretty well mixed. As a result, there is very little pressure gradient in the mixed layer, only a tiny change on the order of a part per thousand or so from the surface to the bottom of the mixed layer.
As a result, while Kip is correct that the plastic bits are found below the surface and not just floating on top, there is not enough change in the density of the mixed layer for plastic particles to differentiate by density.
Instead, what happens is that floating particles accrete heavier things until they get to an almost-neutrally-buoyant state where they would just barely float in perfectly still water. At that point, the mixing action of the mixed layer is stronger than the tendency of the particle to float. As a result, the particle of plastic-plus-heavier-stuff gets swallowed up and sucked under in the vertical descending currents that form nightly when the mixed layer overturns. These currents mix the surface waters downwards. Because the downwards currents occur in relatively small concentrated columns of descending water, they are moving downwards faster than the corresponding upwelling currents in the larger areas between.
As a result, the nearly neutrally buoyant plastic particles are first mixed downwards and then mixed throughout the mixed layer. Faster downwelling currents take them down into deeper waters, and then they slowly make their way back to the surface with the slower upwelling currents … lather, rinse, and repeat in the endless wash cycle.
So yes, Kip, you are right that we do find plastic throughout the mixed layer and not just at the surface. And you are right that the density increases with depth … but density doesn’t increase fast enough with depth to allow stratification of the mixed layer by density.
As a result, you are wrong about the reason we find plastic particles below the surface—they are physically mixed throughout the mixed layer as soon as the upward force of their buoyancy becomes less than the downward force of the nightly overturning action of the oceanic washing machine.
In other words, I’d say that both you and dbstealey are correct in this matter.
My best regards to you both,
w.
Let me add that the nightly spontaneous reorganization of the circulation of the upper ocean is a form of Rayleigh-Benard circulation, which is another emergent thermoregulatory phenomenon which helps to constrain the global temperature by increasing night-time heat loss from the ocean.
http://wattsupwiththat.files.wordpress.com/2011/08/tropical-diurnal-after-midnite.jpg
See my post about the diurnal oceanic changes here.
w.
Reply to w. ==> “but density doesn’t increase fast enough with depth to allow stratification of the mixed layer by density.” — I don’t think so either.
But each particle does achieve its own s.g., and thus finds itself, in a general sense, in a depth range at which it is neutrally buoyant — which was the point. There are easily discernible changes on buoyancy in the first 30 – 60 feet pf the ocean, as you know from diving. Our plastic-plus-friends ends up moving about in a range determined by s.g., up and down, around and around, with the currents.
Kip Hansen December 19, 2015 at 2:04 pm Edit
Thanks, Kip, but I fear that I don’t know anything of the sort. First, in the top hundred metres of the ocean the density doesn’t change more than a tenth of one percent.
Second, as a diver I can assure folks that there is no way to sense a change in density of that amount. Yes, there is a change in pressure that you can discern in the first 30-60 feet, but there’s no way that you can detect the infinitesimal change in density over that range.
All the best, and thanks for an interesting thread,
w.
Reply to w. ==> “There are easily discernible changes on buoyancy…”
You never had to adjust your BC, from surface to 60 feet?
Kip Hansen December 20, 2015 at 4:05 pm
Thanks, Kim. Of course I do … but as I pointed out, that is an example of a difference in pressure, not a difference in density.
To a first approximation water is an incompressible fluid. For example, from the graph I posted above the change in density from 1000 metres depth to 4000 metres depth is an increase of about 2%. Two percent in three thousand metres is two thirds of a percent per thousand metres, or .006% per ten metres.
So if I go down sixty feet, about 20 metres, that would be a density change of one hundredth of one percent.
Again I say, things don’t settle in the ocean to a certain density. Particularly in the mixed layer, the density gradient is far too small for that.
And I say again, there is no way that a human can perceive the water density change of a hundredth of a percent by diving down sixty feet. The pressure change is very clearly perceptible … but the water hardly compresses at all.
w.
What about the buoyancy of the critters ?
A question probably well covered upthread.
Reply to w. ==> Willis, You are absolutely correct about the density issue.
I have been using the wrong word there. It is the pressure effects on buoyancy that cause buoyancy to change for objects at different levels. There are other incidental issues — temperature layers, salinity layers, etc, along with the general list of chaotic behaviors incident to all fluid dynamic systems, causing up, down, and all around currents of all types, some cyclic, some seeming random — many long term which result in the gyres in the first place.
Buoyancy does change at depth — and particles do “seek” a depth at which they are neutrally buoyant. They don’t do it for very long….as stuff grows on the particles the can pretty quickly become too heavy to float at any level and head for the deep deep. That my understanding from Cózar, which makes pretty interesting reading.
Cózar mentions that this sinking, which should seem inevitable, is not found in the data — when they do bottom mud cores of areas with lots of 5 mm to 1 mm bits in surface layers, they do not find lots of bits in the mud below.
What they acutally find instaead is that surface bits break down into smaller and smaller pieces, each already colonized by bacteria and other microbes, eating away, until the size becomes so small that they are simply consumed.
In short…
Anything more compressible than water becomes less buoyant with depth, due to increasing water pressure.
The buoyancy of anything else remains essentially unchanged for the first 100 meters of depth, due to constant water density.
Good article, Kip, thank you! You did a great job of dispelling the myth of what the real garbage patch is, while not ignoring the need for more research on possible toxins entering the water via the microbial decomposition process, or the need for us to reduce our consumption of plastics.
reply to Michael Jankowski ==> You are correct that by 1992, most sludge was being dumped…. the NY Times link gives the history?
“Congress banned the practice in 1988, after a summer in which tons of medical waste washed up on beaches and thousands of dolphins died mysteriously along the Atlantic Coast. Although government officials insisted there was no connection between the medical debris and ocean dumping much farther out to sea, environmentalists had a strong election-year issue and few politicians were eager to oppose a ban. “
Kip, at least one of your found articles, the o-ring, doesn’t float. Did you try putting the plastic bits into a bucket of seawater to see how buoyant they are?
Reply to verdeviewer ==> If I still had the sample finds I would try it and see. Unfortunately, the samples are long gone. All that stuff was found at or near the high water line — the assumption is that it floated before getting there. I do not know that it was “an o-ring” — just used that as a name to call it for readers to have something to size the remainder — I could have called it “the little back ring”…
Kip,
So it goes. I can see why you wouldn’t be inclined to save that “treasure.”
Thanks for a thought-provoking article.
Hi again Kip, – You report “… the size becomes so small that they are simply consumed.” This is not supported by actual data take from the depth of 4,843 meters of the Porcupine Abyssal Plain (48 degrees 49.77 N x 16 degrees 28.90 W ) where a 76 um x 125 um plastic was brought up. This is not an isolated finding since 2 other’s came up in bottom samples from 2 different Porcupine Abyssal Plain locations nearby of 4,842 depth, one piece measured 44um x 83 um & the other 137 um x 161 um.
I am wondering what microbes, or kind of microbes, might be at that depth which can eventually fully eliminate the plastic molecular structure. This is a genuine question I have not figured out.
Reply to gringojay ==> See the graph of recovered floating bits, which fails to continue to double and redouble. Cozar et al. report that the data doesn’t find the missing 99% in the bottom mud — not that they don’t find ANY plastic, but that they don’t find the number or quantity of bits that would be expected if they are simply sinking to the bottom.
Thanks for reminding us that almost nothing is universal — not all the bits break down smaller and smaller and are consumed, just what seems, with present data, to be the vast majority. We know for sure that at least three bits made it to the bottom.
As for the microbes at the bottom, I don’t think we know very much about that … but the recovered three bits mentioned by you would be a place for the microbiologists to start looking.
Cozer’s team have their own uncertainty (quote): ” … fragments ingested by small fish … transferred to larger predators … sink with the bodies of dead fish … or … defecated … mesopelagic fish … evacuate … viscous feces that assume spheroid shapes … sinking at high
velocities (around 1,000 m·d−1)…. microplastic fragments could also reach the bottom via defecation ….”
Cozer also cites (2013) “Microplastic particles in sediments of Lagoon of Venice, Italy: First observations on occurrence, spatial patterns and identification”. Of course this is not open ocean, but indicates they are forming. Quote: “… Microplastics (10 polymers) were found in all samples (10 sites)… abundances (of max. 1mm pieces) varied from 2175 – 672 kg−1 d.w. … 82% … = … polyethylene & polypropylene … 93% … = … 30–500 μm ….”
(2015) “Characterisation of microplastics and toxic chemicals extracted from microplastic samples from the North Pacific Gyre” ( between latitude 34835.4680 –31844.0020 N and longitude 12283.4170 –152812.5910 W.); published in Environ. Chem. 12, 611–617 is available as free full pdf text on-line if interested. (Quote): ” … Microscopic plastics were detected on 10 of 12 GF/F filters … mass … ranged from 0.132 to 1.184 g … filaments … = … main microplastic
particles detected with an average of 1 – 3 fibres -1L of seawater ….”
Reply to gringojay ==> Yes, there is a lot of interesting data out there, and still scads of uncertainty.
The most interesting to me in the Rios Mendoza and Jones paper [ pdf ] is that they find mostly fibers and filaments…not little bits and pieces — “main microplastic particles detected with an average of 1 – 3 fibres -1L of seawater ….”. Once expects to see the solid plastics reduced to tiny micro-bits, but they find fibers and filaments.
Where the heck do all those filaments and fibers come from? Some, maybe, from plastic nets and ropes, but I suspect plastic-based cloth — clothing — degrading. Can’t be polyesters — s.g. 1.38->1.4. Polyprop for ropes and nets are pretty thick, crude fibers.
I just don’t know.
Hi Kip, – You noticed (below) that in samples from the ocean water column it was fiber micro-plastics found by Medoza’s team & then suggest these are unlikely from poly-propylene fibers. In contrast those from 4,000+ mt. sea bed were not fibers, but “little bits & pieces.”
Which indicates there are at least 2 distinct micro-plastic issues. 1st category is that plastic undergoing UV light absorption (excited electrons become reactive allowing alterations) & subsequent oxidation (a factor of time & temperature changes acting on the polymer) that gets the molecular weight down. My surmise is that in the water column & Venice lagoon (unlike deep sea bed) there is enough temperature to allow oxidation down to fibers.
Which means the non-fiber “bits & pieces” (in deep sea bed sediment) did not have enough time to be photo-oxidized in the water column before some carrier helped that bit to sink or they represent different original plastics. Possibly the suspended/shallower sediment fibers & deep seabed bits come from different molecular weight plastics; so that those which sank deep were originally greater in molecular weight & thus less alterable.
Microbes attacking plastic in symbiosis have to do so with some’s extra-cellular de-polymerase enzymes & some’s intra-cellular de-polymerase enzymes. When oxygen is available aerobic microbial degradation of plastic can produce bio-mass, CO2 & H20; which presumably is what occurs in the ocean water column. While in low (anoxic) oxygen availability it is probably anaerobic microbial degradation of plastic which needs to go on; leading to bio-mass, CO2, H2O & methanogenic CH4. None-the-less we are probably not going to see certain plastic polymers degrade 100% since some gets integrated into the bio-mass of microbes & naturally occurring compounds; as per Atlas et.al (1997) in 4th edition of “Microbial Ecology: Fundamentals and Applications”.
Polyethylene’s structure is a chain of long carbon “spine” & microbial degradation of this is not simple to complete; it’s high molecular weight & hydro-phobic feature make it very resilient to microbes. If this is what settled down on the deep sea floor it is far from the chemical, light & thermal actions on it’s polymer parts that managed to get cleaved in abiotic (environmental vs. microbial) degradation.
Polymers cleaved by enzymes wear down the surface polymers & yet the interior polymers are not automatically eroded at the same time or subsequently either; hence on the deep sea bed “bits” not fibers are found. Where abiotic degradation can go on (in the sea water column) that action is capable of going on throughout the plastic oxidizing the polyethylene polymer & hydrolyzing polyesters so that the mechanical attributes of that plastic change; & this then allows mid-stage polymers to be solubilized – which changes that plastic’s mass leading to fibers as the kind of micro-plastic trawled up from the ocean water column.
Reply to gringojay ==> This Opinion piece in the NY Times has some data.
Reply to gringojay ==> This Science news piece from the NY Times on Federal Ban of microbeads. in today’s paper.
Kip have you put any time into collecting some data on how much money is afloat in this ocean plastics trough. Perhaps how many organizations are collecting donations is a start. And how many organizations are pouring funds into the trough. The age old adage “follow the money” seems to apply to this topic. I’d love to chat with you. http://russgeorge.net to find me.
Thanks for this article, finally. I have been debunking the “Garbage Patch” for years, given there were never any satellite photos of this massive thing, no landscape long range photos, and the few boats that went out to “document” or do some other scientifically questionable “study”, never came back loaded to the gills with plastic they had picked up. The same pathetic pictures kept showing up in articles, and the same pictures of harbors were showing up. So, I called bullshit on these articles all the time.
However, we have land on the Southern Yucatan, and for miles along the beaches, there are tons of plastics that wash up constantly – probably the worst I have seen in the world. As you snorkel out (we do a lot of free dive fishing) you can see the micro plastics in the water as the sun shines into it. It is hundreds of times more dense, complete with thousands of shoes and flip flops, jugs, bottles, and some weird stuff. This is all in a very environmentally sensitive area. If the author would like some pictures & locations I would be glad to send some. But I think the conclusions of this article overall is right
Reply to bill Wiltsch ==> You are seeing trash that has been washed into the local waters from the land — a terrible situation in many parts of Latin America. Every time it rains, street trash (and if it rains really hard, entire villages) are washed into the rivers and downstream into the local waters, most of this pushed back close to shore by the wind and waves.
The same, I suspect, as we saw in the Dominican Republic.
Much of the cause of this is a result of poverty — both individual and national — the poor tend not to care or much and the poor nations have not yet sufficient wealth to finance proper collection and disposal of municipal trash.
Local clean-up efforts are often very effective, but must be ongoing.
My wife and I carried net collection bags when snorkeling the DR and VIs and would collect the most offensive materials for disposal.