MARINE DEBRIS - Marine Pollution: What Everyone Needs to Know - page 44

very difficult to measure once they are small enough to pass
through the nets typically used to collect them. Their impacts
on the marine environment and food webs are still poorly
understood. These tiny particles are known to be eaten by
various animals and to get into the food chain. Due to its low
density, plastic waste is readily transported long distances
and concentrates in gyres, which are systems of rotating ocean
currents. We don't know how long plastic remains in the
ocean. Current research suggests that most commonly used
plastics will never fully degrade. Because most of the plastic in
the ocean is in very small fragments, there is no practical way
to clean it up. One would have to filter enormous amounts of
water to collect a relatively small amount of plastic.
How is debris in the ocean measured?
The most common way to measure floating plastic in the ocean
is to collect it using very fine-meshed nets towed at the ocean
surface from a ship. These nets collect planktonic organisms,
as well as plastic and any other floating debris, which is sorted
to pick, count, and preserve all plastic samples collected dur-
ing the tow. However, a lot of the debris floats below the sur-
face and is not collected by towing nets at the surface.
How much is there?
Annual cleanups pick up millions of pounds, mostly plastic,
from beaches, although most beaches around the world are not
cleaned up. We don't know how much trash is out there because
no one monitors it carefully. There are also large quantities of
small debris mixed in the sand or within the water column.
The Ocean Conservancy, a Washington, DC-based environ-
mental organization that organizes cleanups, released its 2012
list of trash collected during its International Coastal Cleanup.
More than 10 million pounds of debris was collected by volun-
teers globally, with over 769,000 pounds from California alone.