The Pacific Trash Vortex and the paradox it is creating



by LORENZO CIOTTI

The Pacific Trash Vortex and the paradox it is creating

The Pacific Trash Vortex is a region of floating plastic waste accumulation located in the Pacific Ocean. The Algalita Marine Research Foundation and the United States Navy estimate the combined amount of plastic alone in the area at a total of 3 million tons.

American oceanographer Charles Moore believes the area could contain up to 100 million tons of debris. The accumulation was formed starting from the 80s, due to the incessant pollution by man and by the action of the ocean current called the North Pacific Subtropical Gyre, endowed with a particular clockwise spiral movement, the center of this vortex is a relatively stationary region of the Pacific Ocean, which allows floating waste to aggregate with each other in the first layers of the ocean surface.

The existence of the Great Pacific Garbage Patch was foretold in a paper published in 1988 by the US National Oceanic and Atmospheric Administration. The predictions were based on results obtained by several Alaska-based researchers who, between 1985 and 1988, measured the aggregations of plastic materials in the north Pacific Ocean.

These surveys found high concentrations of marine debris accumulated in regions dominated by sea currents. Based on research carried out in the Sea of Japan, the researchers hypothesized that similar conditions should occur in other portions of the Pacific Ocean, where the prevailing currents favored the development of relatively stable water masses.

The researchers specifically pointed to the North Pacific as the convergence zone of the Subtropical Vortex. While floating biological waste undergoes spontaneous biodegradation, an enormous amount of non-biodegradable materials such as plastics and marine debris is accumulating in this ocean area.

Instead of biodegrading, plastic photodegrades, it disintegrates into smaller and smaller pieces up to the size of the polymers that compose it; nevertheless, the latter remain plastic and their biodegradation is still very difficult.

The floating of the plastic particles, which have a hydrostatic behavior similar to that of plankton, induces their ingestion by planctophagous animals, and this causes the introduction of plastic into the food chain. In some seawater samples taken in 2001, the ratio of the amount of plastic to that of zooplankton, the area's dominant animal life, was more than six parts plastic for every part zooplankton.

The island constitutes a new ecosystem where plastic is colonized by about a thousand different types of heterotrophic, autotrophic, predatory and symbiont organisms, including diatoms and bacteria, some of which apparently are capable of degrading plastic material and hydrocarbons.

Potentially pathogenic agents are also found in it, such as bacteria of the genus vibrio. The effects for the environment have not yet been studied in depth and appear difficult to evaluate given the extension of the phenomenon and the associated time scales, but they are probably important.

Above all, we think of the high concentrations of PCBs that can enter the food chain given that the plastic filaments are difficult to distinguish from plankton and therefore ingested by marine organisms, but also of the ability of microplastics to provide support to the proliferation of microbial colonies of pathogens.