By Sarah “Steve” Mosko
You’d think that finding far less plastic pollution on the ocean’s surface than scientists expected would be something to cheer about. The reality, however, is that this is likely bad news, for both the ocean food web and humans eating at the top. Ingestion of tiny plastic debris by sea creatures likely explains the plastics’ disappearance and exposes a worrisome entry point for risky chemicals into the food web.
Except for a transient slowdown during the recent economic recession, global plastics consumption has risen steadily since plastic materials were introduced in the 1950s and subsequently incorporated into nearly every facet of modern life. Annual global consumption is already about 300 million tons with no foreseeable leveling off as markets expand in the Asia-Pacific region and new applications are conceived every day.
Land-based sources are responsible for the lion’s share of plastic waste entering the oceans: littering, wind-blown trash escaping from trash cans and landfills, and storm drain runoff when the capacity of water treatment plants is exceeded. Furthermore, recent studies reveal an alarming worldwide marine buildup of microplastics (defined as a millimeter or less) from two other previously unrecognized sources. Spherical plastic microbeads, no more than a half millimeter, are manufactured into skin care products and designed to be washed down the drain but escape water treatment plants not equipped to capture them. Plastic microfibers from laundering polyester fabrics find their way to the ocean via the same route.
Given that plastics do not biodegrade within any meaningful human time-scale, it’s been assumed that the quantity of plastic pollution measured over time on the surface waters of the ocean will mirror global plastics production and hence should be rising. However, regional sampling over time indicates that plastic debris in surface waters has been rather static since the 1980s.