Science Results : Daily Update

Daily Update | Current SEA Research

June 13, 2010

By Giora Proskurowski

Last night, while attempting to double jibe around to get in position (hove to) for a neuston station the wind died on us and we were forced to start the main engine. Since then we've been motoring east at about 7 knots, stopping every 6 hours or so to do a surface net tow.

Our hauls of plastic have been fairly consistent, and we've tallied about ~70 pieces per net tow, which works out to a surface concentration of around 50,000 pieces per square kilometer. These values are well within the range that we've found in this region before, but do not represent the super high values that define the center of the accumulation zone.

Assuming that each plastic piece weighs less than a 0.1 g, this means that within the area that we can see from the deck of our ship (about 4.5 nautical miles) there are almost 800 pounds of tiny plastic fragments floating in the surface waters. It is extremely important to realize that the plastic fragments are small enough that you cannot easily observe them from the deck of the ship. Thus, we do not generally know if we're pulling up a net full of plastic or not. This makes for exciting – and troubling – first glances at the sample as we empty the contents of the net from cod-end jar (the collection vessel at the end of the net) into a bucket.

Although we hope that the wind returns so that we can return to sailing, getting east right now is a primary goal of this expedition, and motoring in relatively calm seas is a fairly painless way to achieve this.