The ocean is full of plastic. Discarded straws, bags, water bottles, and fishing lines are just a few of the sources of plastic that end up in the open ocean. Since 60% of most plastics produced are less dense than seawater, these pieces are carried along by ocean currents. Those plastics that don’t end up sinking or washing ashore, can eventually enter oceanic gyres. An ocean gyre is a large system of circular ocean currents influenced by global wind patterns and the earth’s rotation. The strength of these systems pull debris and serve as a conduit for transporting plastic thousands of miles across the ocean. The Great Pacific Garbage Patch is one such accumulation of trash found far out in an isolated section of the Pacific Ocean. The eastern section of the North Pacific Subtropical Gyre contains a high volume of buoyant plastics.
Researchers have come up with a more accurate method for quantifying how much garbage is actually circulating in the GPGP. Using a combination of surface trawl samples to estimate small plastic volume and aerial imagery to calculate estimates of debris larger than 0.5 m, the researchers have determined that the GPGP is four to sixteen times larger than previously estimated. Researchers estimate that at least 79 (45–129) thousand tons of ocean plastic are floating inside an area of 1.6 million km2. The researchers found that this number was sixteen times higher when compared to a study that used net trawl data only and four times higher than a study which used net trawl data combined with visual boat surveys. While these microplastics account for 94% of the estimated 1.8 (1.1–3.6) trillion pieces of debris floating in the GPGP, they account for only 8% of the mass.
Researchers also determined that compared to historical data collected from surface net tows (1970–2015), the accumulation of plastic debris in the GPGP is growing exponentially.
Lebreton, L., Slat, B., Ferrari, F., Sainte-Rose, B., Aitken, J., Marthouse, R., … Reisser, J. (2018). Evidence that the Great Pacific Garbage Patch is rapidly accumulating plastic. Scientific Reports, 8(1), 4666. https://doi.org/10.1038/s41598-018-22939-w