1 . Flower scents (香味) help pollinators (传粉者) locate their favorite plants. Scientists have established that air pollutants change those scents, throwing off the tracking abilities of such beneficial insects as honeybees. But new lab experiments are the first to confirm that one pollinator, the tobacco hawkmoth, can quickly learn that a pollution-changed scent comes from the jasmine tobacco flower that the insect likes.
Chemical ecologist Markus Knaden and colleagues focused on one pollutant-ozone, the main element in smog. In the lab, his team blew an ozone-changed scent from a tiny tube into a tunnel, with a moth (飞蛾) awaiting at the far end of the tunnel. Usually, when the moth smells the unchanged scent, it flies upwind and uses its long, skinny mouthparts to probe the tube the way that it would a flower. The researchers expected that the changed scent might throw the moth off a little. But the insect wasn’t attracted at all.
In addition to scent, tobacco hawkmoths track flowers visually, so Knaden’s team used the feature, along with a sweet snack, to train the moth to be attracted to a pollution-changed scent. The researchers wrapped a brightly-colored artificial flower around the tube to trick the moth back across the tunnel, despite the unfamiliar scent. And the team added sugar water to the artificial flower. After a moth was given four minutes to taste the sweet stuff, it was attracted to the new smell when sent into the tunnel 15 minutes later, even when neither the sugar water nor the visual signal of the artificial flower was present.
This study focused on only one moth species, but Knaden’s team is now working on planning experiments with other pollinators that are easier to follow than tobacco hawknoths. While he guesses honeybees might also be as adaptable as the moth was, that won’t be true of every pollinator. “The situation can become very bad for insects that are not as clever or cannot see that well. I don’t want the take-home message to be that pollution is not a problem.”
1. What does the underlined word “probe” in paragraph 2 mean?| A．Surround. | B．Favour. | C．Access. | D．Examine. |
| A．not all moths were attracted to ozone-changed scent as expected |
| B．the current research conducted by Knaden is pioneering and wide-ranging |
| C．not all pollinators are adaptable to human-driven changes to their environment |
| D．the moth didn’t like the new smell without sugar water and artificial flower |
| A．Positive. | B．Cautious. | C．Unclear. | D．Critical. |
| A．A moth can be rid of the tracking ability to locate its favourite plants. |
| B．A moth is able to establish a relationship between pollution and scents. |
| C．A moth may outsmart smog by learning to like pollution-changed scent. |
| D．A moth is born with an ability to adapt to the changes in the environment. |
2 . Airborne dust is normally seen as an environmental problem, but the lack of it is making air pollution over China considerably worse.
A new study suggests less dust means more solar radiation hits the land surface, which reduces wind speed. That lack of wind in turn leads to an accumulation of air pollution over heavily populated parts of China. The researchers found that reduced dust levels cause a 13% increase in human-made pollution in the region.
Hundreds of millions of people across China continue to be impacted by air pollution from factories and coal-fired power plants. Studies suggest that the dirty air contributes to 1.6 million deaths a year, about 17% of all mortalities. But this new research says that the human-induced pollution is being made worse or better by naturally occurring dust that blows in from the Gobi desert. Using models to simulate 150 years of wind and dust patterns in the region, the researchers found that the dust deflects significant amounts of sunlight. Without it, more heat from the Sun hits the land. Differences in the temperatures between land and sea cause the winds to blow. Without the dust, the land warms up more and that changes the temperature differential with the sea leading to weaker breezes - and more air pollution.
"There are two dust sources. One is the Gobi and the other is the highlands of north-west China, but we found the Gobi had much more influence," said lead author Yang Yang, from the Pacific Northwest National Laboratory in Washington State, US. "Less dust in the atmosphere causes more solar radiation to reach the surface. It weakens the temperature difference between the land and the sea and impacts the circulation of the winds and causes a stagnation over eastern China and that causes an accumulation of air pollution."
Another study has recently shown a link between declining Arctic sea ice and a major air pollution event in China in 2013. The authors of the new study believe that both theories could be true.
"Our study has the same mechanism: the weakening of winds causes more pollution, and what is behind this needs to be studied," said Yang Yang, "We have two views on this kind of weakening of wind. They found the sea ice, we found the dust-wind interaction can also lead to weakening of the wind. I think both of them are important."
The researchers believe that the study may inform broader questions about how natural and human-created aerosols interact.
Many parts of the world, in addition to China, are now suffering from increased levels of air pollution and understanding how dust, winds and emissions work together may help limit some of the worst impacts of dirty air.
One of the key lessons from this study is that the absence of dusty conditions could mean the air you are breathing is worse for you, not better.
1. According to the new study, the formation of air pollution over heavily populated parts of China is due to ________.| A．the accumulation of dust | B．the lack of temperature |
| C．the high level of living standards | D．the shortage of wind |
①the worse circulation of the winds
②more heat from the sun
③lessening temperature between the land and the sea
④less dust
⑤a worse stagnation
| A．④①③②⑤ | B．①④②⑤③ |
| C．④②③①⑤ | D．①⑤②④③ |
| A．Millions of people die of diseases caused by dirty air every year in China. |
| B．The theory of the consequences caused by declining Arctic sea ice is less scientific. |
| C．The new study must invite questions about how natural and human-created aerosols interact. |
| D．The absence of dusty conditions means a more healthier environment. |
