【自然科学-生物】
Plastic rubbish smells good to turtles
（517字 精读 必做篇）
Turtles have an unfortunate habit of devouring plastic objects floating in the sea. These then get snared in their alimentary canals, cannot be broken down by the animals’ digestive enzymes and may ultimately kill them. It is widely assumed that this penchant for plastics is a matter of mistaken identity. Drifting plastic bags, for instance, look similar to jellyfish, which many types of turtles love to eat. Yet lots of plastic objects that end up inside turtles have no resemblance to jellyfish. Joseph Pfaller of the University of Florida therefore suspects that something more complicated is going on. As he writes in Current Biology, he thinks that the odour of marine micro-organisms which colonise floating plastic objects induces turtles to feed.
The idea that the smell of plastic flotsam might lure animals to their doom first emerged in 2016. Researchers at the University of California, Davis, noticed that certain chemicals, notably dimethyl sulphide, which are released into the air by micro-organism-colonised plastics, are those which many seabirds sniff to track down food. These chemicals mark good places to hunt because they indicate an abundance of the algae and bacteria that lie at the bottom of marine food chains. The researchers also found that birds which pursue their food in this way are five or six times more likely to eat plastic than those which do not.
Since turtles are known to break the surface periodically and sniff the air when navigating towards their feeding areas, Dr Pfaller theorised that they are following these same chemicals, and are likewise fooled into thinking that floating plastic objects are edible.
To test that idea, he and his colleagues set up an experiment involving loggerhead turtles, a species frequently killed by plastic. They arranged for 15 of the animals, each around five months old, to be exposed, in random order, to four odours delivered through a pipe to the air above an experimental arena. The odours were: the vapour from deionised water; the smell of turtle-feeding pellets made of shrimp and fish meal; the smell of a clean plastic bottle chopped up into ten pieces; and the smell of a similarly chopped bottle that had been kept in the ocean for five weeks to allow algae and bacteria to grow on it.
Two of the smells proved far more attractive to the animals than the others. When sniffing both the odour of food pellets and that of five-week-old bottles turtles kept their nostrils out of the water more than three times as long, and took twice as many breaths as they did when what was on offer was the smell of fresh bottle-plastic or deionised-water vapour. On the face of it, then, the turtles were responding to the smell of old bottles as if it were the smell of food.
Though they have not yet tested whether dimethyl sulphide is the culprit, Dr Pfaller and his colleagues think it is the most likely candidate. In an unpolluted ocean, pretty well anything which had this smell would be edible—or, at least, harmless. Unfortunately, five-week-old plastic bottles and their like are not.
Source: The Economist
【自然科学-环境】
As People Stay Home, Earth Turns Wilder and Cleaner
（582字 5分26秒 精听 必做篇）
先做精听再核对原文哦~
Wednesday marked the 50th anniversary of Earth Day. American Gaylord Nelson launched the first Earth Day in 1970. His aim was to urge local action and increase people’s understanding of our planet and its environment.
The creation of Earth Day is widely considered to be the beginning of the modern environmental movement.
As climate activists marked the event this year, an unplanned experiment is changing the planet.
Many people continue to stay at home to stop the spread of the new coronavirus.
As a result, people are making less pollution, and the air has become cleaner.
Smog stopped covering New Delhi, one of the world’s most polluted cities.
Nitrogen dioxide pollution in the northeastern United States has dropped 30 percent. Air pollution levels in Rome have dropped 49 percent compared to a year ago. Stars seem more visible at night.
People have also reported seeing wild animals in unusual places. Coyotes have been observed walking in downtown Chicago and near San Francisco’s Golden Gate Bridge. A puma was seen in the streets of Santiago, Chile. Goats entered a town in Wales and showed no interest in leaving.
When people stay home, the Earth becomes cleaner and wilder.
Stuart Pimm is a scientist at Duke University in the United States. He says the stay-at-home orders worldwide are “giving us this quite extraordinary insight into just how much of a mess we humans are making our beautiful planet.”
Pimm told The Associated Press that the situation is providing a chance to “see how much better it can be.”
Scientists, stuck at home like the rest of us, say they are interested in studying unexpected changes in plants, insects, weather, noise and light pollution.
Researchers have been observing sharp drops in traditional air pollutants, such as nitrogen dioxide, smog and tiny particles. These kinds of pollutants kill up to 7 million people a year worldwide, said Dan Greenbaum, president of the Health Effects Institute.
Cleaner air has been most noticeable in India and China. On April 3, people living in Jalandhar, a city in north India’s Punjab, woke up to a sight not seen for many years: snow-covered Himalayan mountains more than 160 kilometers away.
Cleaner air means stronger lungs for asthmatics, especially children, said Mary Prunicki. She is a doctor and director of air pollution and health research at the Stanford University School of Medicine in California. She noted that early studies have linked coronavirus severity to people with weak lungs and those living in more polluted areas.
In Australia, police shared a video of a kangaroo on social media. It showed the animal jumping around a mostly empty neighborhood in downtown Adelaide.
Several wild jackals recently occupied a city park in Tel Aviv, Israel.
We are not being invaded, Duke’s Stuart Pimm noted. The wildlife has always been there, but many animals only come out when people are not around.
Human activity usually makes it difficult for sea turtles to leave their eggs on sandy coastlines. Nesting turtles need to be undisturbed. After they come out of their eggs, baby turtles might have problems finding their way to the water because of bright lights, said David Godfrey. He is executive director of the Sea Turtle Conservancy.
But with lights mostly off and people in their homes, the sea turtle nesting seems much better this year -- from India to Costa Rica to Florida, Godfrey said.
“There’s some silver lining for wildlife in what otherwise is a fairly catastrophic time for humans,” he added.
Source: VOA
【自然科学-环境】
The northern-hemisphere winter of 2019-20 was the warmest ever on land
（441字 精读 选做篇）
The most commonly cited risks of climate change are natural disasters: fiercer wildfires and hurricanes, bigger floods and longer droughts. But one of the most striking recent effects of global warming has been unusually mild weather in many parts of the world.
The northern-hemisphere winter that ended on March 20th was the second-warmest since records began, and the warmest ever on land. The anomaly was biggest in Europe and Asia, where average temperatures from December to February were 3.2°C (5.8°F) and 3.1°C above the average from 1951-80, and 0.8°C and 0.7°C above those continents’ previous record highs. After a normal autumn, temperatures stayed close to their November levels for months. In Boston, where daily lows in January tend to hover around -6°C, the average minimum this January was 0°C; for Tokyo the figures were 0°C and 5°C. By local standards, the balmiest winter of all was in Russia. Moscow’s average daily low in January was -2°C, far from the customary -13°C.
The winter-that-wasn’t of 2019-20 is not yet a new normal. The main factor determining the severity of northern winters is the “Arctic oscillation”: the relative pressure of Arctic and sub-tropical air. When pressure is higher in the Arctic, cold air from the North Pole pushes south, bringing harsh, dry winters to many places. When pressure is higher towards the sub-tropics, warm air pushes northwards, hemming in cold air around the pole. These two patterns flip back and forth irregularly.
For reasons that are not yet clear, pressure in the sub-tropics this year was much stronger than in the Arctic. And researchers have not yet determined how rising temperatures affect the Arctic oscillation. Until a few years ago, climate models tended to show pressure in the Arctic strengthening, reducing the amount of warming during winter at temperate northern latitudes. The latest models find the reverse.
However, climate change is still responsible for anomalies like this one. At the average global temperature in 1950, a winter this mild was all but impossible. In today’s climate, such reprieves from the cold should occur once every 11 years. And if global warming continues on its current trajectory, winters like this year’s could become standard within a few decades.
Mild winters offer benefits. Heating is cheaper, flu seasons are shorter and fewer people die overall. But problems mount as well. Without hard frosts, pests can survive and multiply to attack crops more harshly. Warmer winters are usually wetter, changing snowfall patterns. This can shrink the snowpack that supplies rivers, and cause floods. Even people who bemoan frigid winters may miss them if they vanish.
Source: The Economist
【笔记格式要求】
精读笔记格式要求：
1.总结文章中心大意
2.总结分论点或每段段落大意
3.摘抄印象深刻或者觉得优美的句子
4.总结文章中的生词
5.记录阅读时间、总结时间、总时间
精听笔记格式要求：
1.逐句听写整篇文章
2.对照原文修改听写稿，标记出错原因
3.总结文章中心大意
4.总结精听过程中的生词
5.记录听写时间、总结时间、总时间
这里也给大家两点学习小建议哦~
精读：如遇到读不懂的复杂句，建议找出句子主干，分析句子成分，也可以尝试翻译句子来帮助理解~
精听：建议每句不要反复纠结听，如果听 5 遍都没听出来，那就跳过，等完成后再回听总结原因，时间宝贵，不要过于执着哦~
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发表于 2020-5-12 22:33:01
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