A team of researchers set off from the southern California city of Los Angeles to the Hawaiian islands on a mission to collect data in the Pacific Ocean which might help find routes taken by millions of tonnes of plastic dumped into the seas each year.

Members of Plastic Change, an international organization based in Denmark that aims to raise awareness the consequences of the increasing plastic pollution of the oceans, are set to collect data and measure levels of micro-plastics floating in the water.

Micro-plastics are particles from larger items made brittle by sunlight and pounded to pieces by waves, bitten by sharks and other fish or otherwise torn apart.

Wind and sea currents gather plastic debris in the so-called gyres — big patches of debris, spun by currents and floating in the oceans and seas.

Tip of the iceberg

In their research, the team uses Manta Trawl, a net system designed to help measure levels of micro-plastics on the surface of the water. The researchers also collect water from different depths to measure levels of micro-plastics in the ocean.

Kristian Syberg, an environmental biologist, says that the patches of micro-plastics seen on the surface of the water are only the tip of the iceberg and that their research may help to track down the rest.

"There are several hypothesis of where the remaining part of the plastic can be. It can be different at different depths in the water column. Some of it might have sunk to the ocean floor; some might have entered the food chain," Syberg said.

 'The ocean works like a blender and it's blending the plastic down to these smaller pieces.' - Henrik Beha Pedersen, founder of Plastic Change

Henrik Beha Pedersen, founder of Plastic Change and leader of the expedition, says the amount of plastics in the ocean is likely to double within the next ten years and some of the debris will return to land.

Collecting samples of debris washed out on the beach, Pedersen says, "Look at this. It's all pieces of micro-plastic. It's washed ashore here. The ocean works like a blender and it's blending the plastic down to these smaller pieces."

A problem for wildlife and human health 

Megan Lamson, program manager of Hawaii Wildlife Fund — a non-profit organization dedicated to the preservation of the islands' wildlife — says volunteers come to the beaches for regular clean-ups.

"When heaps and heaps of marine debris wash ashore or are entangled in our reefs, that's a problem for the marine wild life and it's a problem for human health. So our best bet is to reduce this problem or to prevent future entanglement, just to come down here and get as much debris off the beach as possible," she said.

Items found on the beach prove the ocean pollution is a truly global issue, says Lamson, holding one such piece of debris: "I think it's from Korea. It resembles the floats that are from there." 

Experts have sounded the alarm over how plastic pollution kills huge numbers of seabirds and marine mammals and destroys ocean ecosystems.

Some plastic objects like discarded fishing nets, kill by entangling dolphins, sea turtles and other animals. Pieces of plastic frequently get stuck in the throats and digestive tracts of marine animals.