Sunday, March 13, 2016

Rubber duckies serving science (Plastic 1)

Having a young grandchild now, I am pulling out my children’s toys, boxed away for over 15 years, for a new round of use. Among the Brio train sets, Legos, stuffed animals, dolls, Bobo Fett’s space ship, and Teenage Mutant Ninja Turtles are a variety of bath toys. The tub toys include these simple floating animals that I bought in the mid to late-1980’s.

Three remaining tub toys from my original set of four.
In September 1994, I was surprised to see these tub toys on the front page (photo below) of the American Geophysical Union newsletter Eos (abstract:

The featured Eos tub toys had enjoyed a more cosmopolitan cruise venue than a bath tub, with about 29,000 of them floating across the Pacific to the northwest coast of North America (Gulf of Alaska) after the shipping container transporting them from their Asian birthplace fell off the ship during a storm in January 1992 and broke open. The full Eos article described their service to science tracking ocean currents. The authors, Curtis Ebbesmeyer and W. James Ingraham, modeled possible routes from "deployment" to landfall and predicted subsequent trajectories of duckies, etc that did not wash up on beaches.

Parameters affecting the pathway include, of course, ocean currents, plus "windage": the air resistance or effect of the wind on a moving object. Air currents had a greater effect on the early movement of the tub toys since they are light and ride high in the water. On the other hand, the Nike sneakers in the Eos photo above, from a shipment lost in the Central Pacific in 1990, usually floated upside down with the sole barely above the surface of the water. The higher windage of the tub toys increased their speed across the Pacific after initial entry into the sea, compared to models for objects with lower windage.

The Eos authors discussed the several types of planned and serendipitous ocean current trackers: messages-in-a-bottle (MIB), flotsam, scientific drift bottles. About 2% of planned scientific drift releases are recovered, so the ~400 tub toys recovered from November 1992-August 1993, and an equal amount reported subsequently, are the same order of magnitude. However, the absolute number found was large since typical scientific drift bottle releases at that time were usually only 500-1000 objects. For flotsam to be useful, their point of entry into the ocean must be known so that they aren't confused with other shoreline trash. The Nike shoes had unique identification numbers. The tub toys had no numbers, but from the rather sudden appearance of all four plastic animal types on beaches along the SE coast of Alaska, coupled with reports of the spill, confirmed the shipping flotsam connection.

Computer models projected that, after 2 years, some tub toys still at sea would enter the Bering Sea. Computer modeling of trajectories in earlier years (back to 1946) showed that due to interannual variability in currents, drift objects initially traveling eastward from the central north Pacific reached a turning point close to the west coast of North America, and then could go north, like the 1992 toys, and either circle counterclock-wise around an eastern sub-orbit of the Subarctic Gyre or continue west to the Bering Sea; go south and then float clockwise west towards Hawaii, or not turn at all and head straight on for the coast. The Eos authors speculated that some tub toys could eventually reach the North Atlantic though a combination of ocean water and pack ice transport into the Arctic Sea through the Bering Strait or traverse the Bering Sea and head south towards Japan. Historic examples since the late 19th century of shipwreck debris or planned bottle/container releases support both these long-term travel pathways (

With additional co-authors, Ebbesmeyer and Ingraham did a follow-up Eos article in January 2, 2007 ( or on the toys and other cargo and natural flotsam looking at long-term trajectories. The speed of tub toys travel had eventually decreased, after initial passage to Alaska, due to decreased windage as the toys aged and leaked, barely floating above the surface. Computer simulations were combined with flotsam reports from western Canada and southern Alaska. In that period, the authors found toys had completed up to four round-trips on various sub-orbits of the Subarctic Gyre.
Subarctic Gyre and locations of various flotsam releases and finds (Ebbesmeyer and others, 2007).
Flotsam study, of both planned and accidental releases, is the research focus of the Eos articles' lead author, Curtis Ebbesmeyer ( For tracking specific flotsam debris, he uses reports from beachcombers (including which he founded), and solicited information using local media, and beachcomber and lighthouse keeper networks and associations, an example of organized citizen science data collection (another citizen science example:

So WHY am I discussing PLASTIC in this blog? The current feedstock for plastic is petroleum (mostly in Europe) or natural gas (US manufacture), so it has a natural geologic carbon base. Plastic, and “synthetic” fibers such as rayon or nylon, are synthetic meaning that they are not naturally-occurring organic polymers (long chains of repeating organic units) (  Even in its anthropogenically transformed manufactured state, plastic remains part of the global carbon cycle, for better or worse.

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