VOA常速英语2013--非洲大陆的灰尘飘向美国（在线收听）

Africa Kicks-up A Lot of Dust 非洲大陆的灰尘飘向美国

Bits and pieces of the African continent are falling on the United States and surrounding regions much of the year. Scientists say large amounts of African dust may be having major effects on the hurricane season, ocean organisms and human health.

一些非洲大陆落后于美国以及周围地区好多年，科学家说大量的非洲灰尘或许会对飓风季、海洋生物、人类健康产生巨大影响。

African dust particles become airborne during storms and travel anywhere from 7,000 to 10,000 kilometers to reach the U.S.  Scientists can now distinguish between domestic dust particles and those from Africa.

非洲尘粒会暴风中漂浮到7000到10000千米的高空，最后到达美国。科学家现在可以将国内的尘粒与来自非洲的区分开来。

Joseph Prospero studies dust. He’s professor emeritus at the University of Miami Rosenstiel School of Marine and Atmospheric Sciences. Prospero said dust is important for a number of reasons, including its effect on climate.

Joseph Prospero在研究尘粒，他是迈阿密罗森斯蒂尔学院海洋与大气科学的荣誉教授，Prospero说灰尘很重要有许多因素促成的，包括他对大气的影响。

“The very fact that you can see dust in the atmosphere means that the dust is interacting with solar radiation, scatters and absorbs solar radiation. So, anything that affects the distribution of solar radiation on the Earth’s surface – whether it’s at the surface itself or in the atmosphere – will affect climate,” he said.

“一个非常因素，是大气中的可见尘埃，这意味着灰尘会与阳光的辐射，散射相互作用，并且吸收太阳辐射。任何影响地球表面太阳辐射分配的东西—无论是在他自身表面还是在大气层中--都会影响气候。”他说。

Dust will also reduce the amount of sunlight reaching the ocean. That’s a big deal, especially for those who live in the usual paths of hurricanes.

灰尘也会减少到达海洋的阳光，这是一件大事，特别是对于那些生活在飓风线路上的人。

“The surface oceans will be somewhat cooler than they would be in the absence of dust. This is something of considerable interest because this region of the Atlantic is where we see tropical cyclones and hurricanes develop. And the fact that we have so much dust means you have cooler sea surface temperatures and the cooler sear surface temperatures mean less water vapor getting into the atmosphere. And water vapor is an essential component that drives tropical cyclones and hurricanes,” he said.

“海洋表面将会比没有灰尘时更冷。这个是很有趣的，因为在大西洋区域产生了热带气旋和飓风。事实上非常多的尘埃意味着我们拥有较冷的海面温度，较低的海表温度意味着更少的水蒸气进入大气层中，水蒸气是推动热带气旋和飓风的必须元件。”他说。

So, that’s a benefit of African dust for those who fear their houses will be damaged by such storms.

所以，非洲灰尘对害怕房子被暴风摧毁的人来说是有益的。

Prospero said, “Until recently – the last few weeks – this year has been unusually dusty and we’ve had remarkably few tropical cyclones and hurricanes.

Prospero说，“直到最近--前几个星期--这一年是不寻常的雾霾天气，而且我们经历了一些异常的热带气旋和飓风。

Dust also affects climate by depositing in the ocean.

灰尘也会通过沉积在大西洋中来影响气候。

“Dust carries with it a lot of elements and one that’s [of] particular interest is iron, which in many regions, ocean regions, is a limiting nutrient. Phytoplankton – marine organisms – need iron in order to photosynthesize. It’s an essential micronutrient. Therefore, if there’s not enough iron, then you have less biological activity, which, of course, affects the carbon cycle. Anything that affects the carbon cycle will affect climate by modulating the amount of CO2 in the atmosphere,” he said.

“灰尘带着许多元素，其中一个特别的元素是铁，在一些区域，太平洋区域，是一种限制性的营养。浮游植物—海洋生物—需要铁元素促进光合作用。它是一种必须的微量元素。因此，如果没有足够的铁元素，必将导致较少的生物活动，当然，这会影响碳循环。任何影响碳循环的东西都会影响气候，通过调制大气层中二氧化碳的量，”他说

Now, lest you think that African dust only has benefits, think again. It also ends up in people’s lungs – a problem for those with asthma, for example.

现在，免得你以为非洲灰尘只有好处，再想想。例如他最后会跑到人们的肺中—对哮喘病人来说，这是个问题。

“[In] one of our studies we’ve shown that in the Caribbean region the concentrations of dust are so high that they often exceed the World Health Organization’s 24 hour standard for the concentration of particles,” said Prospero.

“在我们的一个研究中已表明在加勒比区域，灰尘的浓度如此的高以至于他们经常超过世界卫生组织的24小时标准颗粒浓度，”Proepero说

Recently, average concentrations of dust particles that could be inhaled more than doubled over Houston, Texas – all due to a major Saharan dust intrusion.

最近，陈尘粒的平均浓度于休斯顿德克萨斯的两倍。--这归因于一场撒哈拉灰尘的侵扰。

“With satellites we can see that that dust cloud extended from Central America – it was against the mountains of Central America – across all of Texas and up into northern Oklahoma. The satellite images lost the dust in a large area of cloud,” he said.

通过卫星我们可以看到尘粒延伸到了中美洲—在中美洲的山区-越过了德州到达了被俄克拉哈马州。卫星图像显示灰尘消失在大片的云中，”他说

Prospero said there was a time when scientists did not pay much attention to atmospheric dust. That’s changed.

Proepero说有一段时间科学家不太注重大气灰尘，现在改变了。

“When I first started this work in the mid-late 1960s, no one cared about dust and there were very few publications. And now, it’s phenomenal. Every year, there are literally hundreds and hundreds of publications about dust. I mean not only African dust, I mean there’s Asian dust. The other huge area of dust activity is in Asia.  Dust is ubiquitous and there hasn’t been much attention paid to it.”

“当我20世纪60年代中后期开始这项工作的时候，没有人关心灰尘，出版物非常的少。现在，它是众所周知的。每年差不多有成百上千的关于灰尘的出版物，我说的不仅仅是非洲的灰尘，也包括亚洲的灰尘。灰尘非常的普及并且没有得到足够的重视。”

Prospero -- and colleagues at the University of Houston and the Arizona State University -- published their findings in the journal of Environmental Science and Technology. But there’s much they don’t know because the interaction of dust with the atmosphere is very complex and not well understood.

Prospro—以及他在休斯敦大学和亚利桑那州大学的同事—在环境科学与技术的刊物上出版了他们所发现的东西。但是也有许多他们不知道的东西，因为灰尘与大气层的作用非常复杂不容易很好的理解。

For example, North Africa is expected to get drier and produce more dust. But computer models don’t agree on what that means in the long-term for climate and human health.

例如，南非将会变得更干燥，产生更多的灰尘。Prospero说它将会一直产生更多的灰尘。

In case you’re wondering, Africa is not expected to blow away. Prospero says it’ll just keep producing more and more dust.