Weighing the plastic in the ocean is difficult. The most comprehensive study has a new estimate: 268,000 tonnes. While it can seem like the oceans are infinite, plastic is killing wildlife. Filter feeders, like whales, can’t avoid ingesting the garbage. Birds, like the albatross, are dying because they mistake plastic for shrimp, can’t digest it, and can’t pass it. When they die, their bodies decay and leave behind piles of plastic. Ever sadder, they sometimes feed it to their young. (See Journey to Midway for an excellent documentary.) Fish have the same issues. Even tiny aquatic life mistakes bits of plastic and microbeads as other tiny aquatic life. The pieces like old lighters make up less than 10% of the total. It is also estimated that the 268,000 tonnes are only 30% of the total because it is estimated that 70% of trash sinks.
(Click on the graph for the link.)