By Eric Lindstrom
Plastic bottle floating by the ship.
A 1960’s movie classic, “The Graduate” (1967), contains a scene where the young Benjamin Braddock (Dustin Hoffman) is given advice about his future by the worldly Mr. McGuire (Walter Brooke):
Mr. McGuire: I want to say one word to you. Just one word.
Benjamin: Yes, sir.
Mr. McGuire: Are you listening?
Benjamin: Yes, I am.
Mr. McGuire: Plastics.
A report from the World Economic Forum earlier this year estimates that the weight of plastic in the ocean will equal the weigh of fish by 2050. According to the report the worldwide use of plastic has increased 20-fold in the past 50 years and is expected to double again in the next 20 years.
Ocean pollution by plastic has been worrisome for years, but the global prevalence of plastic in the ocean and the full impact of its consequences are more recently appreciated. Plastic breaks down at sea into “microplastics” that are now part of the floating plankton – the base of the food web in the ocean. So, plastic is increasingly found in the stomachs of marine organisms. Recent estimates put the amount of plastic floating in the world’s oceans at more than 5.25 trillion pieces weighing more than 268,000 metric tons. That translates to as much as 100,000 pieces per square kilometer in some areas of the ocean. This is a new ocean habitat know as the plastisphere.
The plastisphere is a new waterfront mobile home for marine microorganisms. It potentially provides a floating home for microbes to take long tours of the ocean that were heretofore impossible. The ecological implications of this new globalization of the ocean microbial biota have yet to be determined.
Zooplankton and fish consume microplastics as they forage the plankton. Scientists think that nearly every bird that feeds at sea has a burden from the plastisphere as they forage the small fish. Given the rapidly increasing tonnage of plastic joining the plastisphere and the plastisphere invasion of the marine food chain, we too will be doing battle with the plastisphere, if not already.
Marine debris is not all plastic and has many sources. However, dumping from ships at sea is NOT the major source. Dumping at sea has been highly regulated for more than 30 years. The major source of plastics and other debris in the ocean is from land sources and river runoff.
Dan Clark with two of his nearly 50 bottles of samples for investigation of ocean microplastics.
In SPURS-2 we are very far from land – 7.5 days transit by ship from the Hawaiian Islands. Yet, still, we spy plastic bottles, shoes, fishing gear, and other unidentifiable debris at the surface of the ocean every day. We also have evidence that microplastics exist here. A UV filter, part of the water intake to one of R/V Revelle’s new thermosalinograph systems (Underway Salinity Profiling System) inadvertently acts as a microplastics sampler. Floating plastics, fibers and ocean detritus accumulate in the UV filter chamber that used to sterilize the saltwater sample prior to salinity sensing. The debris in the filter must be cleaned frequently to keep the system in working order and prevent bioaccumulation in salinity sensor. This thermosalinograph system was not designed for studying ocean debris, but it is a plenty worrisome observation. Dan Clark from University of Washington’s Applied Physics Laboratory is keeping the daily samples for analysis after SPURS-2. This a nice example of citizen science undertaken through the curiosity and personal initiative of Dan over and above his many other duties. Now he just has to figure out how to deal with the unusual sampling protocol!
The ocean is actually quite forgiving as a disposal site for human detritus in moderation, except plastic. Organics can be recycled by marine life, wood is disposed of quickly by boring worms, metals can be corroded by seawater, but plastic cannot be dissolved or digested. It is only humans who create and produce plastic goods. It is only humans who can dispose of plastic properly. Plastic MUST be recycled or disposed in landfills. Plastic has no business being in the ocean. We can only hope that the plastisphere we have created can be tamed and that it does not spawn deadly new microbes by virtue of its existence.
So, next time you are using a plastic good, make sure its afterlife is not in the plastisphere of the ocean. Benjamin’s retort to Mr. McGuire should have been “Yes. Mr. McGuire. Plastics are the future. If we can find proper ways to dispose of them!”
By Eric Lindstrom
The R/V Knorr, in the beautiful Sargasso Sea.
One of the things that we worry about on the ship, as part of our daily routine, is trash. Nothing goes over the side unless it is biodegradable. We have separate trash cans for plastics, foils, and other such material that would pollute the ocean. There are cans with paper liners for food scraps and paper waste. We keep the deck clean and our eyes open for any loose cable tie or anything else that could be washed overboard. It’s our duty to pick these things up and dispose of them properly.
It may be surprising to some of you how much plastic is already in the ocean. It’s both amazing and depressing. If one stands by the ship’s rail and watches the water go by, as one wants to do in an idle moment, it is quite shocking to realize that more man-made objects can be observed than natural ones (like fish). A 2005 report from the U.N. Environment Program estimated that, on average, more than 13,000 visible pieces of plastic litter were floating on any square kilometer of ocean.
A piece of plastic debris floating near the Knorr.
Given the fact that plastic takes so long to break down, it should come as no surprise that this problem is still getting worse by the year, despite decades of effort to reduce the sources of pollution.
As a physical oceanographer, I know that the major ocean basins have gyre circulations at mid-latitude. The water moves in a great loop around the center of the ocean basins in the northern and southern hemispheres. Surface waters tend to converge toward the center of these gyres and trash of all sorts concentrates in these spots, far away from the coasts of the continents. In the North Pacific, there is the so-called “Great Garbage Patch” between California and Hawaii. Similar, but less well-known patches occupy dynamically similar regions in the other oceans. Nikolai Maximenko at University of Hawaii, a NASA-funded physical oceanographer studying the Pacific circulation, uses satellite and drifter data to understand this surface circulation in great detail. He made news with his analysis of the fate of tsunami debris from the 2011 Japan disaster.
Here in the Sargasso Sea, we have yet to see some giant patch of garbage (well, except for my desk in the upper lab!), but plastic does abound. I thought that I should testify as to my personal experience of observing so much plastic along our path. It’s more than I remember seeing 30 years ago, when I last sailed for an extended period in the Sargasso Sea. Its certainly not a scientific observation, but it reminds me that we are the creators and users of these materials and we should be the stewards of their disposal as well. So, pick up and recycle any loose plastic you see! It could wind up in the ocean.