1 . Human activity is changing the surface and temperature of the planet. But new research shows it is also changing the sound of the Earth’s oceans and seas. Scientists say the changes in the sounds of our oceans, seas, and other waterways affect many marine animals (海洋生物) —from very small shrimp to huge whales.
Sound travels “very far underwater,” Francis Juanes told the Associated Press. Juanes is an ecologist at the University of Victoria in Canada. “For fish,” he explained,“sound is probably a better way to sense their environment than light.”
Sounds help fish and other marine animals survive. They use sounds to communicate with each other. Sounds also help some ocean animals find food and avoid their hunters. Many ocean animals use sounds to find good places to mate.
However, increased noise from humans is making it harder for these animals to hear each other. The noise is corning from shipping traffic, motorized fishing ships, underwater oil and gas exploration, offshore construction and other noisy human activities. “For many marine animals, their attempts to communicate are being blocked by sounds that humans have introduced,” said Juanes.
Experts at NOAA say that effects of noise on marine mammals are not well understood. However, some studies suggest that noise may cause hearing loss. The stress from human noise might also affect the immune (免疫) system—an animal’s natural defense system.
“When people think of threats facing the ocean,” said Joe Roman, a marine ecologist at the University of Vermont, “we often think of climate change, plastics, and overfishing. But noise pollution is another vital thing we need to be monitoring.” “If you make something for the ocean,” Joe Roman suggested,“think about how to make it quieter. In theory (理论),you can reduce or turn off sound immediately. It’s not like plastics or climate change, which are much harder to get rid of.”
1. Why is sound important for ocean animals?| A．It makes them travel far in the sea. |
| B．It guides them to find their mates. |
| C．It helps them locate food and avoid danger. |
| D．It keeps them stay away from offshore construction. |
| A．prevented | B．destroyed | C．caused | D．monitored |
| A．Marine animals are being monitored. |
| B．People pay equal attention to noise pollution. |
| C．Noise pollution is theoretically easier to deal with. |
| D．Plastics is the most serious threat for ocean animals. |
| A．Sound Is Important to Ocean Life. | B．The Future of Oceans Exploration. |
| C．The Changes in the Sounds of Oceans. | D．Humans Are Making Oceans Too Noisy. |
2 . The fertile land of the Nile delta is being eroded (侵蚀) along Egypt’s Mediterranean coast at an astonishing rate, in some parts estimated at 100 metres per year. In the past, land washed away from the coastline by the currents of the Mediterranean Sea used to be replaced by sediment (沉淀物) brought down to the delta by the River Nile, but this is no longer happening.
Up to now, people have blamed this loss of delta land on the two large Aswan dams in the south of Egypt, which hold back almost all of the sediment that used to flow down the river. Before the dams were built, the Nile flowed freely carrying huge quantities of sediment. But when the Aswan dams were constructed to provide electricity and irrigation, and to protect the huge population centre of Cairo from annual flooding and drought, most of the sediment with its natural fertilizer accumulated up above the dam in the southern upstream half of Lake Nasser, instead of passing down to the della.
Now, however, there turns out to be more to the story. It appears that the sediment-free water picks up sand as it erodes the river bed and banks on the 800-kilometre trip to Cairo. Daniel Jean Stanley of the Smithsonian Institute noticed that water samples taken in Cairo indicated that the river sometimes carries more than 850 grams of sediment per cubic metre of water — almost half of what it carried before the dams were built.
International environmental organizations are beginning to pay closer attention to the region, partly because of the problems of erosion and pollution of the Nile delta, but mainly because they fear the impact this situation could have on the whole Mediterranean coastal ecosystem.
But there are no easy solutions. In the immediate future, Stanley believes that one solution would be to make artificial floods to flush out the delta waterways, in the same way that natural floods did before the construction of the dams. He says, however, that in the long term an alternative process such as desalination (脱盐) may have to be used to increase the amount of water available.
1. What stopped the sediment coming down to the delta?| A．The Mediterranean Sea. | B．The River Nile. |
| C．The Aswan dams. | D．Lake Nasser. |
| A．To flush out the river beds. |
| B．To offer electricity and protection. |
| C．To make the water in the River Nile clean. |
| D．To keep the soil in the region nearby nutrient-rich. |
| A．There is no need to worry about the delta. |
| B．The methods of measurement need improving. |
| C．Whether the situation is good or not remains to be seen. |
| D．The dams’ consequences are beyond people’s expectation. |
| A．Difficulties to be settled. |
| B．Rewards for the challenge. |
| C．Severe influence of the situation. |
| D．Possible solutions to the problem. |
