Friday, October 3, 2008

Microplastics in the ocean

Are 'microplastics' marine pollutants?
Experts start to ask if tiny particles might be clogging ocean food chain

By Jessica Marshall
Discovery Channel

We've all heard about sea turtles, dolphins or seabirds dying from entanglement in six-pack rings, plastic bags or other detritus - or from bellies full of mistakenly swallowed plastic. But some marine researchers are concerned about the effect that much smaller bits of plastic may be having on the seas.

So-called "microplastics" may concentrate pollutants, be ingestible by the ocean's tiny denizens - from zooplankton to filter feeders like clams and mussels - and move up the food chain.

A group of scientists gathered this month to identify what's known about this problem and where more research is needed.

"We know that stuff breaks down, and as it breaks down, it forms smaller and smaller pieces of plastic," said workshop organizer Joel Baker of the University of Washington, Tacoma. "But there's another story, and that is that there are some processes that either purposefully or inadvertently create microplastic particles in their own right."

One such source is nurdles, the little plastic pellets used as the raw material that's molded or extruded into plastic products. A growing source is tiny plastic spheres - less than a millimeter across, and in some cases just microns in diameter - used in new industrial abrasives or in cosmetics as exfoliants, Baker said.

"Because they're used as abrasives, presumably they're pretty hard and pretty resilient to breakup," he said. "The general rule of thumb is, if it doesn't break down pretty quickly, it ends up in the ocean. We don't have any way of monitoring for them. We have no idea, really, if they're having any impact on any organisms."

Estimates of exactly how many particles are in the ocean give a wide range.

"You tend to have numbers that are much less than one per cubic meter," Baker said. "But if you do that in terms of the number of pieces per square kilometer of sea surface, it's tens of thousands."

Amphipods, lugworms, barnacles and mussels take up microplastic in aquarium experiments. Fish and birds in the wild have been found with microplastic pieces in their bodies. But the extent and effect of this ingestion is not yet known.

Plastic specks in the oceans appear to adsorb poorly water-soluble pollutants, such as polychlorinated biphenyls (PCBs), and persistant pesticides like DDT. This might give creatures that ingest pellets a superdose of toxins that can accumulate up the food chain.

"There's some indication that when the animal ingests those, they not only get the physical damage to the gut, but those pollutants can desorb into the animal," said workshop participant Douglas Helton of the National Oceanic and Atmospheric Administration's Marine Debris Program, in Silver Spring, Md.

On the other hand, the pellets might act like pollutant sponges that mop up the contaminants and sequester them out of harm's way, Baker said. One study presented at the meeting suggested that the amount of pollutant accumulated by one type of marine worm decreased when more plastic was added to sediment in an aquarium, suggesting the latter mechanism may work in that case.

One of the outcomes of the workshop was to identify areas where the greatest effects are likely to be seen. "There are probably areas where it floats on the surface, and those are lagoons and marshes," Baker said. "The other place is coastal urban sediments, where it has settled to the bottom."

These are good starting points for additional research, because if microplastics are causing problems, such locations should show the effects most directly, he added.

In the meantime, taking steps to reduce plastic debris - large and small - is a good idea, Helton said. "I don't think there's any right amount of plastic to dump in the ocean."

(c) 2008 Discovery Channel

Wednesday, October 1, 2008

New York Times: No More Plastic Bags

September 30, 2008
No More Plastic Bags

Westport, Conn., this month became the latest of a handful of communities to ban some plastic bags. The bags, which have only a brief, useful life, can survive forever in landfills and are of enormous concern to not only environmentalists but local officials who are running out of places to put their trash.

Westport’s ordinance will take effect in six months and applies to bags dispensed at checkout counters. Others, like dry cleaning bags, will be exempted. The aim is to reduce litter and encourage customers to tote their groceries in reusable cloth bags.

The town’s stand is laudable but will have only a limited effect on what is, after all, a statewide problem. The Connecticut Legislature rebuffed a proposed statewide ban last year. Massachusetts and Maine considered similar bans and also backed down.

Americans use and dispose of at least 100 billion bags every year. Although the plastics industry points out that plastic grocery bags are made more from natural gas than petroleum, natural gas is not a renewable resource and contributes to global warming. And about only 5 percent of all plastic bags are recycled nationwide. The rest end up in the trash, hanging in trees or floating in water where they menace marine life.

There are other possible remedies, including a constructive idea that has taken hold in Ireland. In 2002, Ireland became the first country in the world to impose a tax on plastic bags. Use of the bags dropped by 90 percent, and proceeds from the tax went to environmental causes.

If Ireland is any guide, tax laws may have greater impact on human behavior than recycling laws. Tax law could also be written to apply to an entire state, thus eliminating the need for town-by-town bans.