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Somehow, it's almost winter again here in Montana, and that means icy roads.
蒙大纳的冬天又要到了，这意味着路面要结冰了。
In the United States, the most common way of battling slippery streets is with road salt.
在美国，除冰盐是应对湿滑路面的最常用方法。
But although it does make things safer, salt can also have long-term effects on cars, roads, and the rest of the environment.
但虽然这样可以让路面更加安全，但是盐对汽车、路面和其他环境都有着长期的影响。
So a few cities around the world have thought of new, creative ways of keeping snowy roads safe.
因此世界上的一些城市想到了一些创新式的方法保护雪天路面安全。
Here are three of them, including lab-made pee.
以下是其中三种方法，包括实验室制造的尿液。
There are a few kinds of road salt, but the most common is sodium chloride,
除冰盐有几种类型，但是最常用的是氯化钠，
which we usually call "table salt", even though about ten times more of it ends up on streets than tables.
通常被称为“食用盐”，虽然洒在路面上的盐是餐桌用盐的约10倍。
When it's spread on a road, the salt mixes with the water in snow or ice, creating a solution known as brine.
当被撒在路面上时，盐和雪与冰中的水相混合，形成一种被称为盐水的溶液。
Brine freezes at 5 to 10°C colder than fresh water, because the salt blocks water molecules from easily joining together into a frozen crystal.
盐水的冰点比淡水低5到10摄氏度，因为盐阻碍了水分子形成凝固晶体。
That keeps roads ice-free at lower temperatures, and makes ice melt sooner once the weather warms up.
这样即便在更低的温度下，路面也不会结冰，并且一旦温度上升，冰会立刻融化。
With less ice, cars get more traction, so it's no surprise that plowed and salted roads have 50 to 90% fewer accidents than their untreated counterparts.
冰更少，汽车就有更多牵引力，因此相比未经过处理的路面，撒盐路面上车祸率减少了50%到90%。
But states can run out of salt during especially bad winters. And even if they don't, salt is pretty corrosive.
但是在尤为糟糕的天气中，盐是会用完的。即便没用完，盐也是具有相当的腐蚀性。
If it's not rinsed off the bottom of a car, it can eat away at the metal, which eventually leads to expensive or dangerous problems.
如果不对汽车底部进行清理，盐就会腐蚀金属，最终导致高昂的代价或危险的问题。
Salt on roads and sidewalks can also irritate our skin and our pets', it can wreck our clothing, and it can be toxic for animals who eat it.
路面和人行道上的盐也会刺激人类的皮肤和我们宠物的皮肤，毁坏我们的衣服，吃掉这些盐的动物也会中毒。
Once it washes away, it can damage ecosystems and corrode metal pipes, as well.
一旦被冲洗掉，它会破坏生态系统，也会腐蚀金属管道。
Salt can even corrode underground electrical cables, ultimately releasing flammable gases and causing sparks.
盐甚至可以腐蚀地面电线，最终释放可燃气体并造成火花。
In New York City and elsewhere, that leads to exploding manhole covers in the winter. Which sounds more than a little alarming.
在纽约和其他地方，这会导致冬季井盖爆炸。这听起来有点恐怖。
Although it's usually mixed with road salt, one common alternative to salt is sand because it gives cars more traction.
虽然通常是和除冰盐相混合，但普遍可以用沙替换盐，因为沙可以给汽车更多牵引力
But sand clogs sewers, and is expensive to clean up. Plus, it doesn't actually melt ice.
但是沙会堵塞下水道，而且也很贵，另外，沙子并不能融化冰。
Which brings us to synthetic, lab-grade pee, or, really, a white component of urine known as urea.
所以就有了人造的实验室级的尿液，尿液的一种白色化合物，俗称尿素。
Urea lowers water's freezing point like salt does, and it's not as corrosive or as immediately harmful to animals.
尿素降低水的冰点，就像盐一样，但没那么具有腐蚀性且对动物伤害小。
As a bonus, it's also a pretty common fertilizer, so it can help some winter-hearty plants grow as it washes off the road.
作为奖励，它还是一种相当常见的肥料，因此当路面的尿素被冲洗之后，它可以帮助一些喜冬的植物成长。
Today, urea is a common ingredient in what are called "pet-friendly de-icers", but it might not be the best large-scale solution to the salt problem.
如今，尿素是“宠物除冰器”的一种常见材料，但是它或许并不是替代盐的大范围解决方法。
Even if some urea fertilizes your lawn, it can also run off into rivers,
虽然一些尿素可以滋润你的草坪，但它也会流入河流之中，
where it gets processed by bacteria and eventually robs the water of oxygen that other organisms need to live.
经过细菌的加工最终偷走水中的氧气，让其他生物体无法存活。
So, in the last few years, companies have found other ideas, too.
因此，在过去几年中，公司也发现了其他的方法。
For example, they've started marketing de-icers made of beet juice mixed with briny water. The juice is made from sugar in the beets.
例如，他们开始推销甜菜汁混合盐水制成的除冰剂。这种汁液由甜菜中的糖分制成。
And since sugar also lowers water's freezing point, combining beet juice with salt water fights ice more efficiently than salt on its own.
由于糖也可以降低水的冰点，将甜菜汁和盐水相结合除冰比单用盐更有效。
That means it takes less road salt to achieve the same effect.
这意味着用更少的盐实现相同的效果。
Sticky sugar also keeps salt from bouncing off the road, and it can hold it on the streets for a few days, as long as rain doesn't wash it away.
黏糊糊的糖还可以防止盐反弹回路面，可以黏在路面上好几天，只要雨水不把它们给冲走。
It doesn't even paint the town red, like you might expect from a beet, since sugary juice is more like molasses than you might be picturing.
甚至不会把整个镇子涂成红色，就像甜菜汁一样，因为糖汁比你想象的更像糖浆。
It's light-brown instead of beet-red. And while that isn't necessarily the most attractive snow color, its creators say it doesn't leave a stain.
它是浅棕色的而非甜菜红。虽然这并不是最好看的雪色，它的创造者它不会留下污渍。
Beet juice has been used as a de-icer in a couple hundred cities and towns over the last few years, and it's been pretty effective.
过去几年来，有一两百个城市和镇子一直都使用甜菜汁作为他们的除冰器，并且相当高效。
But like urea, it's not perfect, either. Mixing it with brine still means using some salt, which is still a corrosive irritant.
但是和尿素一样，它也不是完美的。和盐水相混合仍然意味着要用到一些盐，因此它仍是一种腐蚀性刺激物。
And once it washes into rivers and streams, it can steal oxygen from the water like urea. So another new option is cheese brine.
一旦被冲刷进小河或溪流中，还是会像尿素一样偷走水中的氧气。所以另一种新的选择是干酪盐水。
It's a combination of water, salt, and the byproduct of certain types of cheese production.
这是水、盐和某种奶酪制品的副产品的结合。
And, like beet juice, it lowers water's freezing point more than salt alone. Although in this case, it's because the brine is super salty, not sugary.
和甜菜汁一样，它能够降低水的冰点，比盐更高效。虽然在此情况下，这盐水超级咸的不是甜的。
Also like beet juice, it stays on the road better than salt does by itself.
还是和甜菜汁一样，它能够比盐更好的保留在路面上。
Companies often give the cheese brine away for free, since it means they won't have to dispose of it.
公司经常免费发放干酪盐水，因为这意味着他们不必处理这些干酪盐水。
And that saves states hundreds of thousands of dollars a year they would have spent on salt.
一年下来也可以为各州节省千万美元。
Cheese brine hasn't gone through a ton of testing, so no one's quite sure if its environmental impact is significantly better than its competitors.
干酪盐水并没有经过大量测试，因此没有确定它是不是比其他方法更环保。
But again, the brine does still have a lot of salt in it, and it can steal oxygen from water supplies like beet juice and urea.
但盐水中还是含有大量的盐，就像甜菜汁和尿素一样会偷走水供应中的氧气。
And in the few counties where it's been tested, some people do report a noticeable odor,
几个国家对其进行了试验，一些人称这种物质有一种明显的气味，
like you might expect after leaving a whole bunch of cheese out for a while.
就像一大块奶酪发霉的味道。
So for now, salt still rules our winter roads, and cities are mostly focusing on methods for using less of it than we have in the past.
所以到目前为止，盐仍掌控着我们的道路，城市中使用的主要方法是使用比以前更少量的盐。
But hopefully a better solution is somewhere over the horizon, and we just haven't seen it yet.
但是希望有一个更好的解决方法，只是我们还没发现而已。
Thanks for watching this episode of SciShow!
感谢收看本期《科学秀》！
If you'd like to learn even more about the science of winter, like why ice is slippery and what watermelon snow is,
如果你想了解更所冬季的科学知识，比如为什么冰是滑滑的，什么是西瓜雪，
you can check out our winter compilation from last year.
请观看我们去年的冬季合辑。
