Plastics are globally distributed, and present in significant levels as marine pollution in every ocean on the planet (Eriksen et. al. 2014). They tend to collect in higher concentrations in the sub-tropical gyres of the world's oceans (Moore 2001, Eriksen 2013). A gyre is a large system of circulating ocean currents. Their whirling pattern causes a higher density of ocean debris to collect, including plastics (Moore 2001, Eriksen 2013). Many of you may have heard of the Great Pacific Garbage Patch, plastic island, trash island, or garbage island. These terms are all referring to two gigantic patches of marine debris, one on either side of the gyre in the northern Pacific Ocean. So there isn't literally an island that you could walk around on, it's just a massive concentration of trash in the ocean.
Ocean Gyres. This image shows the five major ocean gyres. They act like giant whirlpools, collecting higher quantities of plastics.
Imagery by NOAA
In 2014 Eriksen et al published a paper modeling the amount of plastic in the world's oceans, by count and by weight. They conducted wide scale sampling of surface plastics in every ocean, and then used a statistical model to determine the most probable distribution of plastics throughout the sea. These models took into account oceanic circulation and currents, as well as the size and weight of the plastic pieces.
Based on their model, they conservatively estimated:
"at least 5.25 trillion plastic particles weighing 268,940 tons are currently floating at sea."
How much is that?
5.25 trillion seconds is equal to 166,000 years - 166,000 years ago homo sapiens had just started to wear clothing (Toups et al 2010, Wu et al 2012)
268,940 tons is 10 times the weight of The Statue of Liberty and 20 times the weight of the Eiffel Tower!
Here are the maps they generated to show the distribution of those plastics:
Above: Model results for global plastic count density in four size classes. (Eriksen et. al. 2014)
The numbers in the lower left of each picture indicate the size class of plastic being looked at, the bar on the right indicates the projected count density. Red is a higher plastic count, blue is lower.
Above: Model results for global plastic weight density in four size classes. (Eriksen et. al. 2014)
The numbers in the lower left of each picture indicate the size of plastic being looked at, the bar on the right indicates the projected weight density. Red is a higher plastic weight, blue is lower.
The implications of this study are that plastics are globally pervasive in marine environments. This plastic soup is unavoidable for marine life, and could have incredibly drastic effects on the health of marine ecosystems.