VOA慢速英语2015 撒哈拉沙漠的尘土吹到亚马逊雨林

AS IT IS 2015-03-15 Saharan Dust Feeds Amazon Rainforest 撒哈拉沙漠的尘土吹到亚马逊雨林

Large clouds of dust blowing off the Sahara desert can easily be seen from space.

Joseph Prospero is with the University of Miami in the United States. He has studied African dust for many years.

"Atmospheric¹ dust African dust is one of the most prominent² atmospheric features, second only to clouds."

In the 1970s, Joseph Prospero found that a large amount of dust can blow all the way across the Atlantic Ocean. He spoke³ to VOA by Skype.

"We knew there was a lot of dust. I mean it's obvious there's a lot of dust. When it rains in Barbados or even here in Miami during the summer months, you actually get a layer of mud in the bottom of a bucket."

African dust storms can harm air quality across the ocean. But new research shows the storms also can do some good.

Scientists observed Saharan dust by satellite as it blew across the Atlantic.

Hongbin Yu is an atmospheric scientist at the University of Maryland. He found that an average of 28 million metric⁴ tons falls in South America's Amazon River basin each year.

"Yes, it's surprising because of the huge amount of dust and phosphorous."

Phosphorous is a nutrient⁵ that plants need to grow.

Hongbin Yu found that the Amazon receives about 22 thousand metric tons of Saharan dust each year. He says the dust is an important provider of fertilizer⁶.

"The soil has limited phosphorous and it also can be washed out by rain and flooding."

In fact, the phosphorous falling from the sky is about the same as the amount that rivers carry out each year.

The thick rainforest and the desert dust are joined together on one small planet⁷.

Words in This Story

dust - n. pieces of matter so small that they can float in the air

nutrient – n. a substance that plants, animals, and people need to live and grow

fertilizer – n. a substance that helps plants grow

1 atmospheric   

adj.大气的，空气的；大气层的；大气所引起的

参考例句：

• Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
• Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。

2 prominent   

adj.突出的；显著的；杰出的；重要的

参考例句：

• He is prominent in science.他是科学界杰出的人物。
• That school is prominent in baseball.那个学校以棒球著称。

3 spoke   

n.（车轮的）辐条；轮辐；破坏某人的计划；阻挠某人的行动 v.讲，谈（speak的过去式）；说；演说；从某种观点来说

参考例句：

• They sourced the spoke nuts from our company.他们的轮辐螺帽是从我们公司获得的。
• The spokes of a wheel are the bars that connect the outer ring to the centre.辐条是轮子上连接外圈与中心的条棒。

4 metric   

adj.公制的，米制的，十进制的；n.度量标准，公制，米制，十进制

参考例句：

• In the metric system,measurements are made in metres and liters.在公制中，用米和升作计量单位。
• The metric system is fit to all of the world. 公制适用于全世界。

5 nutrient   

adj.营养的，滋养的；n.营养物，营养品

参考例句：

• Magnesium is the nutrient element in plant growth.镁是植物生长的营养要素。
• The roots transmit moisture and nutrient to the trunk and branches.根将水分和养料输送到干和枝。

6 fertilizer   

n.肥料，化肥

参考例句：

• Fertilizer enriches the soil.肥料使土壤肥沃。
• Get some more fertilizer for the garden.给花园再多施些肥料。

7 planet   

n.行星

参考例句：

• Neptune is the furthest planet from the sun. 海王星是离太阳最远的行星。
• Rubbish, however, is only part of the problem of polluting our planet. 然而, 垃圾只是我们这个星球的污染问题的一个方面。