Signs of Fall 4: Make Mine Plastic

Photo by jdxyw, Flickr

The family friend who leaned in to young Ben (Dustin Hoffman) at the party in the movie “The Graduate” and whispered the single word of advice that would lead to Ben’s future success and happiness (“plastics”) was well-meaning, I am sure. That the word carried a whole matrix of connotations (synthetic, cheap, superficial, fake, non-natural) was not the fault of the man giving the advice or even of the material he was advocating.  Plastic is something we all use, something upon which we all rely, and something that our society is making in absolutely unbelievable quantities.

Plastics are human manufactured materials. They were invented 110 years ago (the first plastic was “bakelite” invented by Leo Baekeland in New York in 1907). Plastics are large polymers of repeating organic subunits with very high molecular weights and, depending on the specific building block subunits, a wide range of properties and uses. Most of the organic building blocks of plastics come from petroleum or natural gas, but there is a great deal of research into and commercial interest in the use of renewable organic materials (cellulose etc.) to make these polymers.

Photo from Grendz,com

Roland Geyer (University of California, Santa Barbara) in a paper in Science Advances (July 19, 2017) estimates that since the invention of bakelite we have produced 8.3 billion tons of plastics. That is enough plastic, according to Geyer, to cover the entire country of Argentina ankle deep in plastic materials. Geyer also notes that almost all of this plastic is non-degradable and will, along with all of the rapidly accelerating yearly production of new plastics, be with us for hundreds of years. We are conducting an unintentional, global experiment in which we are wrapping the Earth in plastics.

National Geographic explored the Geyer article and noted that 91% of all plastics are not recycled. Most ends up in landfills but many millions of tons a year pollute our oceans, land masses, and food webs.

Photo by JJHarrison, Wikimedia Commons

Sea birds and many other marine vertebrates consume floating plastics in large, and often fatal, quantities. Matthew Savoca and his research group at University of California, Davis analyzed floating ocean plastics (Science Advances, November, 2016). They found that the floating plastics were covered with algae and that these algae were being consumed by zooplankta called krill. Further, when these tiny krill ate the algae, the algae released a distress chemical called dimethyl sulfide at levels detectable by seabirds and, probably, other marine vertebrates. These animals were attracted to the dimethyl sulfide because it indicated the presence of the krill and, maybe, the myriad of other organisms that feed upon the krill! So, the seabirds were attracted to and preferentially consumed the floating bits of ocean plastic!

In a related paper published by Jennifer Lowers of the University of Tasmania (Proceedings of the National Academy of Sciences (May, 2017)), another consequence of floating oceanic plastic debris was examined. Henderson Island is an uninhabited, “desert” island in the middle of the Pacific Ocean that is over 3000 miles from any industrial center or large town. Henderson Island’s shoreline, though, is covered with 17 tons of plastic debris. Turtles get caught in tangles of plastic lines and cords, crabs use plastic containers as homes and refuges, and debris is layered all the way up to the high tide line. It is the highest density of plastic pollution found anywhere in the world. All of this plastic debris has arrived at Henderson by the floatation delivery system of the converging currents of the central Pacific  The magnitude of this “pristine” island’s level of plastic pollution reflects the ever-building plastic content of our befouled oceans.

Photo by Mypix, Wikimedia Commons

A recent article in The Scientist (June 1, 2017) further illustrates the blessing and the curse of plastics. In the northcentral and northwest regions of China agricultural production has been historically inhibited by the very dry and relatively cool climate. Over the past thirty years, though, great increases in crop production has come about because of the use of plastic film soil mulching. China currently utilizes 80% of the world’s plastic sheet, field mulching (Photo is from a field on the Isle of Wight, U.K.). Long, white sheets of thin plastic spread across planted fields help to increase soil moisture and temperature and, thus, increase the growth of a wide variety of crop plants. Every year fields equal in size to half of the area of the state of California are covered in the “white revolution” wrapping of plastic. Remarkable increases in yield and moisture efficiency have been seen in maize, wheat, cotton and potatoes throughout this formerly unproductive region.

Unfortunately, though, there are costs of using so much plastic in these fields. The sheets are very difficult to recover after crop harvesting. The thin plastic tears and fragments and ends up becoming incorporated into the soil itself. This “white pollution” changes the physical and chemical properties of the soil and alters the soil microflora, micro and macro-fauna and the growth potentials of the crops subsequently planted in plastic laden soil.

The synthesis of many plastics involves the use of a diverse array of toxic chemicals, and a finished plastic frequently contains detectable levels of these toxins. Plastics, then, that accumulate as pollutants in soil and water systems slowly release these chemicals into their ecosystems and can represent micro-pollution sources that will persist for centuries.

Plastics also attract a wide array of fat-soluble, non-degradable toxic chemicals that enter ecosystems from a variety of other sources. Dioxins, PCB’s, DDT’s, and PAH’s have all been found adhering to the surfaces of floating, marine, plastic pollutants. These toxins, because of their hydrophobic natures accumulate in the tissues of any organism unlucky enough to consume them. These “bioaccumulated” chemicals are passed up food chains in ever increasingly large concentrations. “Higher order” consumers, then, (large fish, sea birds, etc.) will bear the brunt of negative impacts of these powerful, toxic pollutants.

So, whisper or shout the word “plastics!” To rework a phrase, they are “the answer to and the cause of so many of our problems!”