1 . A shark attacked a 14-year-old girl near a Florida beach on Saturday, though a surfer tried to save her. The surfer pulled the girl from bloody water and frightened the shark away with his fists（拳头）.

Can sharks really smell blood in the water? Yes. Sharks have a good sense of smell, and blood happens to be a very attractive smell. Sharks also use sight and hearing to discover their food. In particular, hungry sharks like to hear the sounds which are made by swimming fish. They also look for something bright. Attacks on people can sometimes be a case of mistaken recognition. Sometimes, a shark could confuse shining stones for food.

The sharks’ eyes, ears, and nose are all near their mouth. But sharks also search for their food with sensory receptors（感受器）. These receptors can feel any movement in the water. When a shark gets very close to a food, it can use electroreceptive organs（电觉器官）, which sit the wall of little holes on the shark’s nose. Living things in salty seawater produce a weak electrical field（电磁场）that the shark can feel at a short distance, so it allows the shark to find out creatures that bury themselves in the sea floor. Muscle（肌肉）movements also produce little electrical fields that a shark can feel.

The surfer who tried to save the girl said he protected himself by frightening away the shark with his fists. Is that a good idea? Some experts think frightening away a shark with fists should only be the last choice. It won’t be wise for you to stay still in water. Swimming away rapidly seems to be a better choice. If you can’t swim away right away, hit the shark on the face or nose—where it has a high concentration of sensory receptors like humans—to drive off your attacker and give you enough time to escape. When you are beside a shark’s face, try sticking your finger in its eyes.

3 . In British Bristol, 70 English women at once entered into legal "marriage" with dozens of trees in protest (反对，抗议) against their being cut down. They "married" the trees in an attempt (试图) to prevent them from being cleared for construction (建造) of residential buildings worth £55 million in the forest. The British construction company has applied for the construction of 166 houses in Bristol, including luxury (奢华的) cottages. At the same time, the townspeople were especially angry at the fact that the application did not show the exact number of trees that are planned to be cut down. So, in order to attract the attention of the government, the activists organized an unusual wedding ceremony to save the forest.

The event took place at a park on Spike Island. The women who went there, dressed in wedding dresses, held photographs of the "suitors" in their hands. The celebration itself took place according to the classic storyline—with groomsmen and wedding vows (誓词). The organizer was John Tarleton, a professor at the Bristol Veterinary School, According to him, this action was supposed to suggest that tees are partners of people throughout their life.

The idea to hold such a ceremony came from Siobhan Kierans, who admitted that she came up with it by the story of women from the environmental movement Chipko, who chained (链在一起) themselves to trees in the 1970s to save them from destruction by logging companies.

The protesters said that Bristol needs trees more than luxury private housing. One of the "brides", Suzan Hackett, said, "To get married to a tree is a real honor. It's not a show. It's highly significant (important) and symbolic."

5 . Sugar cane (甘蔗) contains around 10% sugar. But that means it contains around 90% non-sugar — the material known as bagasse (甘蔗渣) which remains once the sugar-bearing juice has been squeezed out of the cane. World production of cane sugar was 185m tonnes in 2017. That results in a lot of bagasse.

At the moment, most of this is burned. Often, it fuels local generators, so it is not wasted. But Zhu Hongli, a mechanical engineer at Northeastern University in Boston thinks it can be put to better use. "With a bit of improvement bagasse makes an excellent replacement for the plastic used for disposable food containers such as coffee cups," says Dr. Zhu.

Dr. Zhu is not the first person to have this idea. But previous attempts tended not to survive contact with liquids. She thought she could overcome that by combining the bagasse pulp (浆状物) with another biodegradable (可生物降解的) material. She discovered that the main reason past efforts failed is that bagasse is composed of short fibres which are unable to give resilience (韧性) to the finished product. She therefore sought to insert a suitably long-fibred substance.

Bamboo seemed to fit the bill. It grows quickly, degrades readily and has appropriately long fibres. When the researchers mixed a small amount of bamboo pulp into bagasse, they found that the short and long fibres combined with each other closely.

To put their new material through its paces, Dr. Zhu and her colleagues fist poured hot oil onto it and found that their invention showed resistance to oil. They also found that when they made a cup out of the stuff and filled it with water heated almost to the boiling point, the cup remained good for more than two hours. Though this is not as long as a plastic cup would last it is long enough for all practical purposes. Moreover, the new material is twice as strong as the plastic used to make cups, and is definitely biodegradable. When Dr. Zhu buried a cup made out of it in the ground, half of it rotted away within two months.

10 . Off the coast of Formentera, an island, lives seagrass that stretches 15 kilometres. The seagrass, covering several hectares, is made up of a single organism. The grasses are also long-lived, for tens or hundreds of thousands of years. Along with two other kinds of coastal ecosystems—mangrove swamps（红树沼泽）and tidal marshes, seagrass meadows are particularly good at taking carbon dioxide from the air.

This role was highlighted in a report, which was published on March 2nd by UNESCO, on blue carbon—the carbon taken in by Earth's oceanic and coastal ecosystems. In total around 33 billion tons of carbon dioxide, about three-quarters of the world's emissions（排放）in 2019, are locked away in the planet's blue carbon sinks（碳汇）. Research by Carlos Duarte, the report's author and a marine ecologist, has shown that one hectare of seagrass can suck as much carbon dioxide each year as 15 hectares of rainforest.

One reason that blue—carbon ecosystems make such effective sinks is that underwater forests are thicker than the land-based woods. They can also trap floating pieces and organic matter, which settles on the sea floor and can double the amount of carbon stored away. They have another advantage, too. Climate change is leading to more wildfires around the world. As forests burn, their carbon stocks are released back into the atmosphere. Unlike forests on land, blue-carbon ecosystems do not burn.

Blue-carbon ecosystems may not be fired, but they remain affected to other sorts of disasters. In May 2020 hurricane Amphan destroyed 1,200 square kilometres of mangrove forest. A marine（海洋的）heatwave in Australian waters in 2010 and 2011 damaged around one third of the world's largest seagrass meadow in Shark Bay. “Mangrove forests can weaken or control waves and provide natural barriers to storm surges. Protecting and expanding them, then, appears to be a must,” said a marine biologist.