Tourists have been warned not to take sand and seashells from beaches in Sardinia, an Italian island in the Mediterranean Sea. More than 40 people,
2 . Plastic—Eating Worm
Humans produce more than 300 million tons of plastic every year. Almost half of that ends up in landfills(垃圾填埋场) , and up to 12 million tons pollute the oceans. So far there is no effective way to get rid of it, but a new study suggests an answer may lie in the stomachs of some hungry worms(幼虫).
Researchers in Spain and England found that the worms of the greater wax moth(大蜡螟) can break down polyethylene(聚乙烯), which accounts for 40% of plastics.
That is to say, part of plastics can be consumed by this kind of worms. The team left 100 wax worms on a plastic shopping bag for 12 hours, and the worms consumed and broke down about 92 milligrams, or almost 3% of it. To confirm that the worms' chewing alone was not responsible for the polyethylene breakdown, the researchers made some worms into paste(糊状物)and applied it to plastic films. 14 hours later the films had lost 13% of their mass—apparently broken down by enzymes(酶)from the worms' stomachs. Their findings were published in Current Biology.
Federica Bertocchini, co—author of the study, says the worms' ability to break down their everyday food—beeswax—also allows them to break down plastic." Wax is a complex mixture, but the basic bond in polyethylene, the carbon—carbon bond, is there as well," she explains. "The wax worm developed a method or system to break this bond."
Jennifer Debruyn, a microbiologist at the University of Tennessee, who was not involved in the study, says it is not surprising that such worms can break down polyethylene. But compared with previous studies, she finds the speed of breaking down in this one exciting. The next step, DeBruyn says, will be to identify where the enzyme comes from. Is it an enzyme produced by the worm itself or by its gut microbes(肠道微生物)?
Bertocchini agrees and hopes her team's findings might one day help make use of the enzyme to break down plastics in landfills. But she expects using the chemical in some kind of industrial process—not simply "millions of worms thrown on top of the plastic."
1. What can we learn about the worms in the study?| A．They take plastics as their everyday food. |
| B．They can consume plastics. |
| C．They end up in landfills. |
| D．They are new creatures. |
| A．prove the research findings |
| B．discover other kinds of worms |
| C．increase the breakdown speed |
| D．find out the source of the enzyme |
| A．help to raise worms |
| B．help make plastic bags |
| C．be used to clean the oceans |
| D．be produced in factories in future |
| A．To propose new means to keep eco—balance. |
| B．To present a way to break down plastics. |
| C．To introduce the diet of a special worm. |
| D．To explain a study method on worms. |
3 . For decades,Americans have been sorting their trash believing that most plastic could be recycled.But the truth is that the vast majority of all plastic produced can't be or won't be recycled.In 40 years,less than 10% of plastic has been recycled.
A news programme Frontline,by NPR and the PBS,found that oil and gas companies- the makers of plastic-have known that all along,even as they spent millions of dollars telling the American public the opposite.The plastics industry officials said the industry is providing money for new technology that they believe will get recycling plastic up to scale.The goal,they said,is to recycle 100% of the plastic they make in 5 years.
But the more plastic is recycled,the less money the industry will make by selling new plastic.And those profits have become increasingly important.Companies have told shareholders（股东）that profits from using oil and gas for transport are expected to decline in coming years with the increasing use of electric cars.The industry leaders expect oil and gas demands from the chemical industry will be much greater than the demand from the transport side in the coming decade.Plastic production overall is now expected to rise three times by 2050,and once again,the industry is spending money on advertisements and public relations to promote plastic recycling.
Plastic is now more common than it's ever been and harder to recycle.Gas prices remain at historic lows,making new plastic cheaper than recycled plastic.And the industry now produces many more different-and more complex-kinds of plastics that are more costly to sort and in many cases can't be recycled at all.Efforts to reduce plastic use are mounting nationwide,but any plan to slow the growth of plastic will face an industry with billions of dollars of future profits to lose.
1. What do we know about the goal of 100%plastic recycling?| A．It's modest. |
| B．It's achievable. |
| C．It's urgent. |
| D．It's unreal. |
| A．By selling electric cars. |
| B．By adding emphasis on recycling. |
| C．By increasing plastic production. |
| D．By meeting the needs of transport. |
| A．Increasing. |
| B．Working. |
| C．Failing. |
| D．Decreasing. |
| A．Should Plastic Be Recycled? |
| B．Can Plastic Waste Be Handled? |
| C．Recycle Plastic or Sell More? |
| D．Plastic Products or Substitutes? |
