VOA标准英语2012--Study: Ocean Acidity Exceeds Natural Norms

Study: Ocean Acidity¹ Exceeds Natural Norms

New research suggests an overload² of carbon dioxide in the oceans is posing a serious threat to marine³ life, food security and tourism.
While most CO2 emissions⁴ from automobiles⁵, buildings and factories go into the atmosphere, one-third ends up in the oceans, changing ocean chemistry and making seawater more acid.
A study in Nature Climate Change tracks ocean acidity over 21,000 years of climate history. Tobias Friedrich, co-author and post-doctoral fellow at the University of Hawaii International Pacific Research Center says the record shows natural increases in CO2 concentrations in the atmosphere over time and differences from region to region.
“This, of course, also had an effect on acidity levels in the ocean, and then (we) compared this naturally occurring increase in atmospheric⁶ carbon dioxide concentrations with man-man emissions over the last two-hundred years.”
The scientists used computer models with data from ice and ocean sediment⁷ cores to simulate ocean conditions, back to the ice age and forward to the end of the 21st century.
When Earth started to warm 17,000 years ago, at the end of the last ice age, atmospheric CO2 began to rise. Over the next 6,000 years, it grew from 190 parts per million to 280 parts per million.
Marine systems had time to adjust.
Axel Timmerman is a professor of oceanography at the University of Hawaii International Pacific Research Center and co-author of the study. He says the past 200 years paint a much different picture.
“Starting with the pre-industrial revolution, anthropogenic emissions increased so much that the oceans suddenly started to take up huge amounts of carbon.”
CO2 concentration in the atmosphere now stands at 392 parts per million. Timmerman says the study, which also includes 30 years of observational data, finds dangerously high levels of ocean acidification in certain regions.
“Such as the coral triangle, the western tropic of the Pacific and the Caribbean exceed the naturally occurring levels by factors of up to thirty in a few spots.”
Timmerman says this is happening at an accelerated pace. “The rate of change is about two orders of magnitude faster than what occurred during the last glacial period about 20 to 15,000 years ago.”
While ocean acidification could have been detected much earlier, scientists only began to monitor it a few decades ago. As seawater becomes more acid, carbonate - the mineral many sehllfish and corals use to form their shells and skeletons - is reduced.
Coupled with pollution and warming temperatures, it is a serious threat to ocean life. Axel Timmerman says his study gives decision-makers another tool for assessing that threat and evaluating the steps they can take to mitigate⁸ it.

1 acidity   

n.酸度，酸性

参考例句：

• This plant prefers alkaline soil,though it will readily tolerate some acidity.这种植物在酸性土壤中也能生存，但硷性土壤更加适宜。
• Gastric acidity would not prevent the organism from passing into the gut.胃的酸度不能防止细菌进入肠道。

2 overload   

vt.使超载；n.超载

参考例句：

• Don't overload the boat or it will sink.别超载，否则船会沉。
• Large meals overload the digestive system.吃得太饱会加重消化系统的负担。

3 marine   

adj.海的；海生的；航海的；海事的；n.水兵

参考例句：

• Marine creatures are those which live in the sea. 海洋生物是生存在海里的生物。
• When the war broke out,he volunteered for the Marine Corps.战争爆发时，他自愿参加了海军陆战队。

4 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。

5 automobiles   

n.汽车( automobile的名词复数 )

参考例句：

• When automobiles become popular,the use of the horse and buggy passed away. 汽车普及后，就不再使用马和马车了。 来自《简明英汉词典》
• Automobiles speed in an endless stream along the boulevard. 宽阔的林荫道上，汽车川流不息。 来自《现代汉英综合大词典》

6 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。

7 sediment   

n.沉淀，沉渣，沉积(物)

参考例句：

• The sediment settled and the water was clear.杂质沉淀后，水变清了。
• Sediment begins to choke the channel's opening.沉积物开始淤塞河道口。

8 mitigate   

vt.（使）减轻，（使）缓和

参考例句：

• The government is trying to mitigate the effects of inflation.政府正试图缓和通货膨胀的影响。
• Governments should endeavour to mitigate distress.政府应努力缓解贫困问题。