Plastic in the Ocean
Plastics make up a large portion of marine debris, the trash that finds its way to the ocean primarily from land sources, polluting water and decimating wildlife populations. Some sources of marine debris are runoff from coastal landfills, litter, sewage overflows, storm-drain discharges and industrial activities. According to a Greenpeace report entitled “Plastic Debris in the World’s Oceans,” of the 6.4 million tons of trash that reach the ocean every year, 60-80% consists of plastics. Plastic bags make up a sizable portion of this garbage. A 1993-94 study of the seafloor around the coasts of Italy, France and Spain published in the Marine Pollution Bulletin found 77% of the debris to be plastic, of which 92.8% were plastic bags. We can greatly ameliorate the problem of marine debris by using reusable bags instead of plastic.
While the amount of trash in the ocean is difficult to quantify, a 2006 study by the United Nations Environment Program estimated an average of 18,000 pieces of floating plastic garbage per square kilometer of ocean. According to Greenpeace, the North Pacific Gyre between Hawaii and California (also known as the “Great Pacific Garbage Patch”) hosts an estimated average of 334,271 pieces of litter per square kilometer, and in some places the density is nearly one million pieces per square kilometer. Most of this floating debris consists of plastic films, plastic fragments and fishing line. According to a 2001 study conducted by the Algalita Marine Research Foundation, plastic fragments in the North Pacific Gyre outweigh surface zooplankton by six times. So much litter converges in the North Pacific Gyre because clockwise ocean currents prevent it from floating back to the mainland.
When plastics find their way to the ocean in such quantities, the effect on marine life is devastating. The biggest problems plastics cause for many species are entanglement, starvation and intoxication from chemicals in the plastic. Ingestion of plastics is particularly destructive for many species of sea turtles, marine birds and mammals because plastics photodegrade, breaking down into microscopic pieces and making it impossible for animals to avoid ingesting them. Animals may also mistake pieces of floating plastic for prey. According to Greenpeace, studies on dead sea turtles in 2002 revealed ingestion of marine debris in 56%-79% of the animals. Ingestion of plastic has also been linked to an increased mortality rate in albatross chick populations. When an animal ingests marine debris such as plastic bags, their digestive tract can become clogged, they may stop eating due to an artificial feeling of fullness, or their bodies may incorporate harmful chemicals from the plastics. Small pieces of plastic can act as sponges for persistent organic pollutants such as PCBs and various pesticides, which can cause cancers and reproductive problems. These effects can transfer to humans who consume marine animals. It is imperative both for our own health and for that of marine life that we reduce our waste, particularly our consumption of plastic, by turning to environmentally sound products such as reusable shopping bags.