With the weather heating up in Beijing, my wife and I were happy to find a swimming pool not far from home. But it wasn’t just the weather. Her heart’s desire for years has been to learn how to swim. 

北京的天越来越热，我和妻子在离家不远的地方找到了一个游泳池，觉得很高兴。不单单是因为天气炎热，而是因为她多年来心心念念的就是学会游泳。

Good hubby that I am, I wanted to help. 

作为一个好丈夫，我当然想要帮她实现这个愿望。

Learning to swim is a bit scary for anyone, regardless of age. My wife, who is in her 50s, was no exception. In the beginning, she thrashed around like a wet chicken and gulped water like a beer-swigging sailor on shore leave.

对任何年龄段的人来说，学习游泳都是一件有点可怕的事情。我妻子当然也不例外，她已经50多岁了。一开始，她只能像一只落汤鸡一样在水里四处扑腾，大口大口地喝泳池里的水，就跟刚到岸的水手狂喝啤酒一样。

I’m sympathetic, since she has low body fat and — unlike me — sinks like a stone. (In my youth I, too sank like a stone, but over the years I’ve become more … shall we say … buoyant.) But mostly her problem was panic.

跟我不同，她体脂太低，在水里就像石头一样，很容易沉下去，对此我深表同情。我年轻时，也曾像石头一样容易沉入水中，但这些年来我越来越……我们应该说……浮力越来越大。但她最主要的问题是恐慌。

Two lessons from a Chinese instructor settled her down. On the deck, she practiced proper kicking technique: Crouch, spread, pull together. Crouch, spread, pull together. In the water, the instructor calmly taught her how to put her face down — and breathe only after coming out. The lessons did wonders.

随后，在一位中国游泳教练的指导下上了两堂课，她就平静了下来。在岸上，她练习了正确的脚法：收、翻、蹬夹。在水中，教练耐心地教她如何把脸低下来，当脸抬出水面后再呼吸。课程很有效。

After that, I got her to swim underwater. Now she can breaststroke the length of the pool, kicking and breathing rhythmically, and only occasionally reverting to the chicken thrash. 

随后，我让她下水练习游泳。现在，她能够采用蛙泳游完整个泳池，并且有节奏地踢腿和控制呼吸，偶尔才会在水里胡乱扑腾。

I have now pronounced her pool-safe. The amount of water she has ingested has decreased markedly over the last two weeks. 

我对她说泳池很安全。在过去的两周里，她喝的水已经明显变少了。

But it’s the swallowing that gets a swimmer to thinking: What’s in this stuff?

但正是不断从泳池中喝水的过程让游泳者开始思考：游泳池的水里都有什么?

Swimming pool water has a distinctive odor, a chemical byproduct of chlorine interacting with body oils, sweat and urine. Yes, urine. Some bad-mannered people actually pee in pools around the world.

游泳池的水有一种独特的气味，它是由氯与人的油脂、汗水和尿液混合在一起所产生的化学物质的浓烈味道。是的，这里面有尿液。实际上，世界各地的游泳池里都有低素质的人在里面撒尿。

The amount of pee has been difficult to measure until now. Xing-Fang Li of the University of Alberta explained in February how her team did it. Instead of trying to measure pee directly, they measured the level of an artificial sweetener — acesulfame potassium, or Ace-K — which is carried in most people’s urine, including in China. It’s found in many foods, such as yogurt. It’s not metabolized. In other words, it goes right through you, thereby providing a urine yardstick.

目前为止，尿液具体含量一直难以测量。今年2月，加拿大阿尔伯塔大学的李兴芳教授向外界解释了她的团队如何测量泳池中的尿量。研究团队没有直接测量尿液，而是测量了一种名叫乙酰磺胺酸钾（或者简短地称为Ace-K）的人造甜味剂含量。这种甜味剂在大多数人的尿液中存在，其中也包括中国人。它来源于许多食物，比如酸奶，但是它在人体内不代谢。换句话说，它通过人体然后排入泳池，从而提供了一个尿液衡量标准。

Li’s team collected water samples from public pools, hotel hot tubs and recreation venues and tested for Ace-K. Result: An 833-cubic-meter pool contains about 0.08 cubic meters of pee.

李兴芳的团队从公共泳池、酒店热水浴缸和娱乐场所收集了液体样本，并对其中的Ace-K含量进行了检测。结果显示，一个833立方厘米的水池含有大约0.08立方米的尿液。

Other products of the body pose a problem, too. Li advises a one-minute shower before entering a pool to remove much of the perspiration residue and oils that might react with chlorine to form the harmful byproducts.

人体的其他产物也会对泳池水质造成危害。李兴芳建议，游泳者在进入游泳池前应该先淋浴。即使在入水中前冲洗一分钟，也可以清除大部分能与氯反应的汗液和油脂。

When I was a kid — long before the advent of artificial sweeteners — you’d get thrown out if you didn’t shower first, but at the Beijing pool, I notice that many swimmers don’t bother. Instead, they sit on the edge of the pool and perform a little ritual of splashing water on their bodies before plunging in. For them, it’s literally bathing.

当我还是个孩子的时候，距人工甜味剂出现还早得很，如果游泳前不洗澡，就会被踢出泳池，但在北京的泳池里，我注意到很多游泳者完全不介意这个问题。相反地，他们在跳进水里之前，就坐在泳池边缘往身上泼点水。对他们来说，这就是洗澡了。

I want my wife to continue swimming, so I’m not telling her any of this.

我希望我妻子能够继续游泳，所以我不会把这些事告诉她。

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