By Marcus Ericksen, Research Director, 5 Gyres
Earlier this week Mayor Garcetti of Los Angeles released 20,000 black balls with a cry “Balls Away!” bringing the total to 96 million plastic balls covering Los Angeles reservoirs. They’re like the ones you might see at Chucky Cheese- you know, those dirty little pits of multi-colored plastic balls that smell like kids. Those may be gross, but Garcetti’s balls have a higher purpose.
The pros, as the mayor explained, are that they reduce evaporation by up to 300,000,000 gallons per year when all Los Angeles reservoirs are covered, and will reduce algal growth in the reservoirs. Also, the black balls restrict UV light, reducing harmful reactions between chlorine and bromide that form Bromate, another nasty chemical that is apparently difficult to filter out. There is no question, access to clean tap water is much healthier all around than relying on bottled water.
The cons are that plastic degrades in UV light, especially a dark color like black, which absorbs light rather than deflects it, as white does. The color accelerates degradation, as well as the heat on the sunny side, known as "thermal loading". These conditions set the stage for chemical oxidation. The LADWP claims that the balls do not leach any chemicals and should last 10 years. They state, "at some point they will lose their structural integrity and could split at the seams"
Lets be clear, this IS chemical degradation.
According to one study (Hakkarainen and Albertsson, 2004) “More that 200 different degradation products including alkanes, alkenes, ketones, aldehydes, alcohols, carboxylic acids, dicarboxylic acids, lactones and esters have been identified in thermo- and photo-oxidized polyethylene.” What’s missing here is information about the city’s system of water ‘polishing’. Is it filtration, reverse osmosis, or chlorine treatment? We know from our studies of plastic marine pollution that microplastic particles in the nano- and micro- range (<1oum) are appearing in zooplankton, which tells us that degraded plastic can be smaller than many water filter systems.
Many of us have questions - not just in LA, but across the country. We plan to follow up with the city, and will report back when we have some answers:
What do you know about plastic degradation? How do you cleanse our water. Had any benign alternatives been considered? Hate to be a ball-buster, but as an organization based in Los Angeles, we know enough to raise concern.
Hakkarainen, M. & Albertsson, A. (2004) Environmental Degradation of Polyethylene. Advanced Polymer Science 169: 177-199.