[Updated] Could plastic debris, coarse, fine and molecules (polymers), affect oceans characteristics as climate regulator, CO2 sink, albedo, evaporation, …? (by Diego Fdez-Sevilla, PhD)
Citation: Could plastic debris, coarse, fine and molecules (polymers), affect oceans characteristics as climate regulator, CO2 sink, albedo, evaporation, …?. Diego Fdez-Sevilla. PhD 2015. https://diegofdezsevilla.wordpress.com DOI: 10.13140/RG.2.1.1469.6407
(Updated 28/07/2014. Comments added at the bottom. Those comments come from the discussion generated in one or more groups at LinkedIn. My only intention bringing them together is to broader the spectra of profiles adding feedback to the subject.)
Laura Parker has published an article in National Geographic (July 15, 2014) about new discoveries on plastic waste in the oceans “First of Its Kind Map Reveals Extent of Ocean Plastic”.
The article describes the situation about plastic debris in the oceans and introduces new findings from marine ecologist Andres Cozar Cabañas and colleagues.
The work published this month in the Proceedings of the National Academy of Sciences, did find millions of pieces of plastic debris floating in five large subtropical gyres in the world’s oceans. But plastic production has quadrupled since the 1980s, and wind, waves, and sun break all that plastic into tiny bits the size of rice grains. So there should have been a lot more plastic floating on the surface than the scientists found.
“Our observations show that large loads of plastic fragments, with sizes from microns to some millimeters, are unaccounted for in the surface loads,” says Cozar, who teaches at the University of Cadiz in Spain. “But we don’t know what this plastic is doing. The plastic is somewhere—in the ocean life, in the depths, or broken down into fine particles undetectable by nets.”
What effect those plastic fragments will have on the deep ocean—the largest and least explored ecosystem on Earth—is anyone’s guess. “Sadly,” Cozar says, “the accumulation of plastic in the deep ocean would be modifying this enigmatic ecosystem before we can really know it.”
This article got me into thinking about that all the properties attributed to the oceans in climatic regulation are based on the physicochemical properties of seawater. So, considering the important role played by the Oceans in climatic events,
Could plastic debris, coarse, fine and/or molecules (polymers), affect ocean’s functions as climate regulator; CO2 sink, albedo, evaporation, …?
One possible connection affected would come from altering the physical properties of oceans such as albedo and evaporation and I haven´t found information about it yet. I can only guess that the increase in the amount of particles in the column of water would increase albedo, inducing retention of more heat in the water due to refraction. That could lead to increasing temperature, reducing density (involved in upwelling processes) and may be also increasing evaporation. Have I gone too far from making sense? This is just an exercise of free thinking.
The other possible connection affected would come from the synergistic interaction between aquatic biota and the chemistry of the water. Thanks to this balance oceans have the capacity to act as CO2 sinks but, what would happen if plastic degradation reduces the aquatic biota involved in fixing CO2? And here it is what I have found about it (so far):
The North Pacific Garbage Patch, a loose collection of drifting debris that accumulates in the northern Pacific, first drew notice when it was discovered in 1997 by oceanographer and chemist Charles Moore of the Algalita Marine Research Foundation.
Scientists had previously thought plastics broke down only at very high temperatures and over hundreds of years. The researchers behind this study, however, found that plastic breaks down at cooler temperatures than expected, and within a year of the trash hitting the water.
In 2009, a Japan-based team led by researcher Katsuhiko Saido, a chemist with the College of Pharmacy at Nihon University in Japan, collected samples in waters from the U.S., Europe, India, Japan, and elsewhere. All the water samples were found to contain derivatives of polystyrene, a common plastic used in disposable cutlery, Styrofoam, and DVD cases, among other things.
The toxic compounds the team found don’t occur naturally in the ocean, and the researchers thought plastic was the culprit. The scientists later simulated the decomposition of polystyrene in the sea and found that it degraded at temperatures of 86 degrees Fahrenheit (30 degrees Celsius). Left behind in the water were the same compounds detected in the ocean samples, such as styrene trimer, a polystyrene by-product, and bisphenol A, a chemical used in hard plastics such as reusable water bottles and the linings of aluminum cans. Bisphenol A (BPA) has been shown to interfere with the reproductive systems of animals, while styrene monomer is a suspected carcinogen.
Along with Moore, David Barnes, a marine ecologist from the British Antarctic Survey, doesn’t think the Japanese team’s lab results can be applied uniformly across the ocean, however. Water temperatures are typically much cooler than the 86 degrees Fahrenheit in the study, he said. “We’re talking about, effectively, what happens in zones of tropical and some subtropical coasts. And there, the study may be very important,” Barnes said. Moore added, “since those chemicals can potentially cause cancer in humans, simpler life-forms may be more susceptible than we are”.
So, could plastic polymers interfere with the biota involved in fixing CO2 in our oceans? And if so, what kind of impact could we expect from a disturbance in the correct performance of this biota?
Even though I have not found any research aiming to look at the effect of polymers over the oceanic biota responsible of fixing CO2 and the consequent impact in the environment, there are studies showing the connections between the aquatic chemistry of seas and the biota such as temperature and acidification, which give us an idea about the impact we can expect if polymers affect Carbonate fixing biota.
Lead researcher Dr Thomas Mock points out that Phytoplankton, including micro-algae, are responsible for half of the carbon dioxide that is naturally removed from the atmosphere. As well as being vital to climate control, it also creates enough oxygen for every other breath we take, and forms the base of the food chain for fisheries so it is incredibly important for food security.
In 2013, researchers from UEA’s School of Environmental Sciences and the School of Computing Sciences investigated “The impact of temperature on marine phytoplankton resource allocation and metabolism” (microscopic plant-like organisms that rely on photosynthesis to reproduce and grow.)
Previous studies have shown that phytoplankton communities respond to global warming by changes in diversity and productivity. But this study shows that warmer temperatures directly impact the chemical cycles in plankton, which has not been shown before.
Collaborators from the University of Exeter, who are co-authors of this study, developed computer generated models to create a global ecosystem model that took into account world ocean temperatures, 1.5 million plankton DNA sequences taken from samples, and biochemical data.
“We found that temperature plays a critical role in driving the cycling of chemicals in marine micro-algae. It affects these reactions as much as nutrients and light, which was not known before,” said Dr Mock.
“Under warmer temperatures, marine micro-algae do not seem to produce as many ribosomes as under lower temperatures. Ribosomes join up the building blocks of proteins in cells. They are rich in phosphorus and if they are being reduced, this will produce higher ratios of nitrogen compared to phosphorus, increasing the demand for nitrogen in the oceans. “This will eventually lead to a greater prevalence of blue-green algae called cyanobacteria which fix atmospheric nitrogen,” he added.
CO2 in the atmosphere has increased from 278 ppm in pre-industrial times to 390 ppm today. During this time, the amount of CO2 dissolved in the ocean has risen by more than 30%, decreasing the pH of the ocean by 0.11 units. As with CO2 and global warming, there is some lag between cause and effect. That means that, even if all carbon emissions stopped today, we are committed to a further drop of up to 0.1 units.
CO2 dissolves in water to form carbonic acid. (It is worth noting that carbonic acid is what eats out limestone caves from our mountains.) In the oceans, carbonic acid releases hydrogen ions (H+), reducing pH, and bicarbonate ions (HCO3-).
CO2 + H2O => H+ +HCO3– (1)
The additional hydrogen ions released by carbonic acid bind to carbonate ions (CO32-), forming additional HCO3–.
H+ + CO32- => HCO3– (2)
This reduces the concentration of CO32-, making it harder for marine creatures to take up CO32- to form the calcium carbonate needed to build their exoskeletons.
Ca2+ + CO32- => CaCO3 (3)
The two main forms of calcium carbonate used by marine creatures are calcite and aragonite. Decreasing the amount of carbonate ions in the water makes conditions more difficult for both calcite users (phytoplankton, foraminifera and coccolithophore algae), and aragonite users (corals, shellfish, pteropods and heteropods).
Now a report from NOAA scientists found large quantities of water undersaturated in aragoniteare already upwelling close to the Pacific continental shelf from Vancouver to northern California. Although the study only dealt with the area, the authors suggest that other shelf areas may be experiencing similar effects.
For corals like those in Australia’s Great Barrier Reef, the outlook is grim. They are threatened with destruction on two fronts, both caused by CO2 emissions. Not only do increased ocean temperatures bleach coral by forcing them to expel the algae which supplies them with energy (see photo at left), but increased ocean CO2 reduces the availability of aragonite from which reefs are made.
Considering the impact of Temperature and Acidification over aquatic environments, should we add plastic polymers as a threat to the aquatic biota connected with the chemistry of our oceans and, subsequently, with the role that they play in atmospheric processes?
Captain Charles Moore on the seas of plastic