如果你没看过美国自由女神像的老照片，你大概以为自由女神像一直都是绿色的吧。其实，最初的女神像是古铜色的，那她是怎么一步一步变成绿色的呢？一起来了解其中奥妙。

New York's iconic, blue-green statue of liberty wasn't always green.
纽约的标志性蓝绿色自由女神像并不一直都是绿色的。

When the statue was gifted to the US from France in 1885, she was actually a shiny copper color.
1885年法国把这座女神像送给美国时，她实际上是亮闪闪的古铜色。

A new video reveals the chemical reactions involving oxygen and even air pollution that led to her color change from copper to liberty green.
最近有个视频揭示了氧气和空气污染是如何与女神像发生化学反应，把古铜色变成绿色的。

The statue of liberty was a gift from France to the US as a way of commemorating the US's fight for independence, as well as their own aspiration for democracy.
法国将这座自由女神像送给美国作为礼物，是为了纪念美国的独立战争，以及法国自己对民主的渴望。

A video, published by the American Chemical Society, explains that the 305-foot (93 meter) statue was built over nine years in sections of copper skin on top of an iron skeleton.
由美国化学学会发布的这个视频解释了这座花费九年造成的高达305英尺（93米）的雕像是如何在铁质框架上包上一层铜。

According to the National Park Service, the statue is made of thirty tons of copper - enough to make 435 million pennies.
美国国家公园管理局称，自由女神像由30吨铜打造而成，这些铜足以制造4.35亿枚美分硬币。

'In her first few decades in the Big Apple, the statue slowly turned from that shiny copper color to a dull brown and the, finally, to the blue-green, or as they'd say back in France, 'verdigris' we see today,' said the video's narrator.
该视频的解说员说：“在自由女神像入驻纽约市的头几十年，女神像慢慢地从闪亮的古铜色变成了暗淡的棕色，最后变成了我们今天看到的蓝绿色，或者法国人所谓的‘铜绿色’。”

When it changed color, some officials suggested restoring her back to her original color, but after the public protested against this decision, she was left the way she is.
自由女神像最初变色时，一些官员建议将其还原成最初的颜色，但是公众对这个决定表示抗议，于是女神像的这个颜色就保留了下来。

The statue's color change was as a result of oxidation reactions between copper and the air.
自由女神像变色是铜和空气氧化反应的结果。

But it was more than one reaction - the color change is due to about 30 years worth of different reactions leading to a mixture of greenish minerals.
但是这种变色不只缘于一种化学反应，而是三十年间多种不同的化学反应相混合才导致了这种绿色。

Oxidation reactions happen when an atom loses an electron to another atom.
当一个原子的一个电子转移给了另一个原子，这时就发生了氧化反应。

In the case of the statue of liberty, her color change was bound to happen due to oxygen in the atmosphere that is 'hungry' for electrons.
自由女神像的颜色变化是必然会发生的，因为周围空气中的氧气“渴求”电子。

On top of this, elements of New York City's polluted air added to the color change too.
除此以外，纽约市空气中的污染物质也促成了颜色的变化。

The first chemical reaction of the color change involved copper giving up electrons to electron-hungry oxygen in the atmosphere.
和颜色变化有关的第一个化学反应是铜将电子转移给了周围渴求电子的氧气。

This led to a mineral called cuprite - which is pinkish red.
这种化学反应的结果是生成一种叫作赤铜矿的矿物质，赤铜矿呈肉红色。

Then, cuprite loses even more electrons to oxygen, forming a new mineral called tenorite, which is blackish in color.
赤铜矿失掉更多电子给氧气，从而形成了名为黑铜矿的新矿物质，黑铜矿颜色发黑。

The black color of tenorite explains why the statue got darker over time, forming a dark brown color.
黑铜矿的黑色解释了为什么女神像这些年来颜色越来越暗，呈现出深棕色。

Then, further chemical reactions occurred when sulfur in the atmosphere reacts with water.
接下来，当周围空气中的硫与水接触时，又发生了进一步的化学反应。

Sulfur comes from natural processes such as volcanic eruptions, but also from man-made emissions from boats, cars, airplanes and factories.
硫来自火山喷发等自然过程，但船舶、汽车、飞机和工厂的人为排放也会产生硫。

When sulfur dioxide in the atmosphere reacts with water, it produces sulfuric acid.
当空气中的二氧化硫与水发生反应时，就会产生硫酸。

Sulfuric acid forms green minerals with copper oxides, so the sulfuric acid in the atmosphere made the state green over time.
硫酸和氧化铜发生反应，生成了绿色的矿物质，就这样，随着时间的流逝，周围空气中的硫酸将自由女神像变成了绿色。

Added to that, chloride from the sea spray surrounding Ellis Island where the statue is located made the statue even greener.
此外，自由女神像所在的埃利斯岛四周海浪中的氯化物让女神像的颜色变得更绿。

The statue stayed this way for over 100 years because the exposed copper is now oxidized and stable, but the statue wouldn't be the same anywhere else.
自由女神像就这样保持了100多年，因为暴露在空气中的铜已经被氧化，化学性质稳定下来，但这尊女神像如果放在其他任何地方都不会是这个颜色。