Non-degradable particles threaten the food chain

PUBLISHED : Friday, 13 November, 2009, 12:00am
UPDATED : Friday, 13 November, 2009, 12:00am

Litter and waste that finds its way into Hong Kong's marine or coastal environment is not only an aesthetic problem, it is also an economic and health problem.

Discarded plastic bottles, supermarket bags and other plastic items that end up in the sea might look unsightly but they also pose a bigger problem for humans. A number of recent studies have shown that over time, tidal movement and erosion grinds plastic waste into tiny non-degradable particles. These are then eaten by small fish and passed along the food chain until the potentially harmful particles are consumed by humans.

Scientists believe that less visible waste, such as sewage sludge, a mixture of organic matter containing viruses and bacteria, synthetic organic chemicals and toxic metal compounds contribute to 'red tide', a combination of algal blooms that can release dangerous levels of toxins into the water. These toxins can kill fish and accumulate in the fatty tissues of shellfish, which are then eaten by humans. Hong Kong experienced a massive 'red tide' in 1998 that killed various species of farmed fish and caused substantial economic loss and ecological damage.

According to the Algalita Marine Research Foundation, 60 to 80 per cent of marine debris in the world's oceans comes from land, either directly washed in during rainstorms, deliberately dumped as waste or discharged via outfall pipes or accidentally blown into the sea.

Supporting this theory, James Wong, a member of Friends of Sai Kung, who are actively involved in local environmental issues, believes rubbish blown from the Junk Bay landfill site is one of the contributors to trash that also washes up on the shore on the southeastern side of Hong Kong.

'When the wind is blowing in a southwesterly direction, not only is there a noxious smell several kilometres offshore, plastic wrappers and plastic bags are picked up by the wind from the landfill and blown into the sea,' said Wong. Each year the government spends million of dollars on removing plastic and household waste from costal waters and shoreline.

Globally, it is estimated 150,000 to 450,000 marine birds are killed by routine releases of oil from tankers. In addition, thousands of the seabirds die every year after eating rubbish they mistake for food. Plastic waste blocks up their digestive systems and poisons them. Seals and sea lions starve after being muzzled by six-pack rings or entangled by nets.

Six-pack holders will not decompose for 400 years.

With an estimated 100 million tonnes of plastic waste floating in our oceans, it is not surprising that 143 various marine species have been identified when entangled in these plastic flotillas.

However, Hong Kong might be able contribute a solution to combatting the rising tides of floating debris. Hong Kong-based Mint Urban Technologies has begun producing plastic food-service products that have a self-terminating additive that gives the products a life cycle of one or two years before they start to degrade.

Unlike conventional plastic or bio-plastics - these new plastics are able to fully degrade in sunshine, on water surfaces, underwater and anywhere there is oxygen. The technology has historically been used in plastic bags, but is now being perfected for hard plastic products such as utensils and coffee cup lids.

The new plastics leave behind no fragments or eco toxicity.

'The problem is we are simply not capturing plastic waste,' said Marc Miller, director of Mint Hong Kong. 'We need intelligent plastic solutions that accelerate the degradation of litter - and to resolve eco-toxicity issues on land and at sea, not only from a beautification aspect but also to protect marine life.'