密歇根新闻广播 为什么环境改善进展缓慢

 

Air quality has gotten better in the U.S. over the last several decades.

But more recently, nitrogen oxide¹ and carbon monoxide emissions² have not been decreasing the way people expected.

Brian McDonald is an atmospheric³ scientist at the University of Colorado-Boulder, and an author of a study in the Proceedings⁴ of the National Academy of Sciences. He says data collected by ground monitoring and satellites have shown nitrogen oxide (NOx) emissions coming down quite quickly during the years 2000-2010.

"That's largely attributed to controlling emissions from power plants and passenger vehicles. And so, as you control those sources, there's less low-hanging fruit and so other sources become relatively⁵ more important," he says.

Those same monitors showed a significant slowdown in reduction of nitrogen oxides and carbon monoxide between 2011-2015.

Both carbon monoxide and nitrogen oxides contribute to ground-level ozone⁶. That's bad for us to breathe in.

"Many areas of the U.S., especially urban areas, violate the National Ambient Air Quality standard under the Clean Air Act, for ozone," says McDonald. "One of the ways to reduce ozone is to reduce the pollutants⁷ that potentially contribute to that."

McDonald says there are multiple factors that could be leading to this slowdown.

"One is, as the power plant and automobile⁸ emissions have come down, the sources of NOx from things like industrial, residential⁹ and commercial boilers¹⁰... there's also what are called off-road vehicles or diesel¹¹ generators¹² that are used in off the roadways-things like construction equipment… so those sources are becoming relatively more important," he says.

He says heavy duty diesel trucks are another factor.

"Diesel trucks have been getting cleaner, because there have been new regulations on trucks to put (on) after-treatment control technologies to reduce NOx," he says. "But I think they're still a maturing technology and so there's still gains to be made at controlling NOx from the trucks."

1 oxide   

n.氧化物

参考例句：

• Oxide is usually seen in our daily life.在我们的日常生活中氧化物很常见。
• How can you get rid of this oxide coating?你们该怎样除去这些氧化皮？

2 emissions   

排放物( emission的名词复数 )； 散发物（尤指气体）

参考例句：

• Most scientists accept that climate change is linked to carbon emissions. 大多数科学家都相信气候变化与排放的含碳气体有关。
• Dangerous emissions radiate from plutonium. 危险的辐射物从钚放散出来。

3 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。

4 proceedings   

n.进程，过程，议程；诉讼(程序)；公报

参考例句：

• He was released on bail pending committal proceedings. 他交保获释正在候审。
• to initiate legal proceedings against sb 对某人提起诉讼

5 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

6 ozone   

n.臭氧，新鲜空气

参考例句：

• The ozone layer is a protective layer around the planet Earth.臭氧层是地球的保护层。
• The capacity of ozone can adjust according of requirement.臭氧的产量可根据需要或调节。

7 pollutants   

污染物质（尤指工业废物）( pollutant的名词复数 )

参考例句：

• Pollutants are constantly being released into the atmosphere. 污染物质正在不断地被排放到大气中去。
• The 1987 Amendments limit 301(g) discharges to a few well-studied nonconventional pollutants. 1987年的修正案把第301条（g）的普通排放限制施加在一些认真研究过的几种非常规污染物上。 来自英汉非文学 - 环境法 - 环境法

8 automobile   

n.汽车，机动车

参考例句：

• He is repairing the brake lever of an automobile.他正在修理汽车的刹车杆。
• The automobile slowed down to go around the curves in the road.汽车在路上转弯时放慢了速度。

9 residential   

adj.提供住宿的；居住的；住宅的

参考例句：

• The mayor inspected the residential section of the city.市长视察了该市的住宅区。
• The residential blocks were integrated with the rest of the college.住宿区与学院其他部分结合在了一起。

10 boilers   

锅炉，烧水器，水壶( boiler的名词复数 )

参考例句：

• Even then the boilers often burst or came apart at the seams. 甚至那时的锅炉也经常从焊接处爆炸或裂开。 来自英汉非文学 - 科学史
• The clean coal is sent to a crusher and the boilers. 干净的煤送入破碎机和锅炉。

11 diesel   

n.柴油发动机，内燃机

参考例句：

• We experimented with diesel engines to drive the pumps.我们试着用柴油机来带动水泵。
• My tractor operates on diesel oil.我的那台拖拉机用柴油开动。

12 generators   

n.发电机，发生器( generator的名词复数 )；电力公司

参考例句：

• The factory's emergency generators were used during the power cut. 工厂应急发电机在停电期间用上了。
• Power can be fed from wind generators into the electricity grid system. 电力可以从风力发电机流入输电网。 来自《简明英汉词典》