Plastic pollution threatens water bodies around the world

In two separate studies, scientists in the United States and Italy found widespread plastic pollution in coral reefs and freshwater lakes around the world. Coral reef-related studies have found that the vast majority of plastic is large debris, most of which come from fisheries, especially in deep-water corals. Freshwater lake and reservoir studies found that all of the assessed water bodies were contaminated with microplastics. The study was recently published in Nature.

Human-caused plastic pollution is an emerging threat to water systems. While this is a problem on a global scale, pollution levels are highly influenced by regional and local factors, meaning that comprehensive databases are needed to properly inform mitigation and management policies.

Hudson Pinheiro of the California Academy of Sciences and colleagues surveyed 84 coral reef sites around the world, including the Pacific, Atlantic and Indian Ocean basins, studying large plastics and other debris larger than 5 centimeters in coral reefs. They studied shallow water with a depth of less than 30 meters and deep-water coral reefs with a depth of 30~150 meters. The researchers found fragments in 77 of the 84 locations, with large plastics accounting for 88 percent of the debris found. Levels of large plastics are highest in deep-water coral reefs. In most survey areas, fishing vessels were found to be the main source of plastic, such as threads and discarded nets.

In another independent study, Veronica Nava of the University of Milano Bicocca and colleagues sampled surface water from 38 lakes and reservoirs in 23 countries, mainly concentrated in the Northern Hemisphere. They found microplastics (greater than 250 microns) at all sampling sites. Plastic pollution concentrations are greatest in lakes and reservoirs close to densely populated human settlements and large surface areas. Lakes with a small surface area have a higher proportion of polyester, while larger, deeper lakes are mainly polypropylene and polyethylene. Textile fibers, an identified major source of plastic pollution, are also found in remote areas where humans rarely have access.

Together, the two studies demonstrate widespread contamination of water bodies by plastic debris and highlight the urgent need for coordinated, systematic monitoring of plastic pollution.

At a depth of 70 meters in Cape Verde, fishing lines become entangled with tree corals and break them. Image courtesy of Luiz Rocha

Off the coast of Brazil, one of the most remote islands in the world, the large longline at a depth of 80 meters in the São Paulo Islands. Plastic is everywhere, even in the most remote places sampled by researchers. Image courtesy of Luiz Rocha

(Source: Feng Weiwei, China Science News)

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