科学家在美国南达科塔州发现地球上最纯净的水

来源：中国科技网 2015年08月31日　14:35

[导读] ：美国科学家在南达科塔州风洞国家公园的最低点发现了一系列的湖泊，这里没有动物活动，甚至连最容易发现的微生物都不存在，这里有地球上最纯净的水。

中国科技网8月31日报道（张微 编译）黑山下数百英尺的地方，一队科学家和研究人员蜿蜒穿过黑暗、狭窄而且寂静的古代岩石走廊，到达了他们的目的地：这里有地球上最纯净的水。

美国国家公园管理局的科学家在微生物学家黑兹尔 巴顿的带领下，偶然地来到了南达科塔州风洞国家公园的最低点，研究一系列的地下湖泊，这些湖泊是上世纪60年代发现的，这里没有动物活动，甚至连最容易发现的微生物都不存在。

但是，来自阿克伦大学的巴顿发现，湖水中存在细菌——尽管很少。她正在分析六年的数据，希望能够破译细菌是如何生存的，以及回答多细胞生物出现之前细菌如何相互作用的问题，也许能够发现新的抗生物质来源。

“这就有可能回答生物学上的很多问题，而这些问题在其他地方是找不到答案的，因为那些地方生物构成存在复杂的层级关系。”她说。

为了收集样品，穿越洞穴的经历是必须的：即使最擅长洞穴探险的人也要花费超过两个小时的时间才能到达最近的水域Calcite湖。根据国家公园管理局的科学家马克欧姆的说法，“对于没有经验的人来说这根本不是路，”他经常随巴顿一起进行研究，按照他的计算，这条路线他们已经走了超过50次了。

这是一件很安静的事情。穿越洞穴的人通常只能听到他们自己的声音，脚步的刮擦声以及他们挤过洞穴裂缝最窄处(只有7英寸宽)的咕隆声，他们的设备重量很轻以便于携带和应对艰难的路程。

巴顿今年44岁，是居住在美国的英国人，当她还在科罗拉多读研究生的时候就开始洞穴研究，周末去洞穴探险后来还做了一个洞穴的纹身。她因为洞穴探险者而闻名，还出现在好几部电影的电视纪录片中。

在她第一次探险中，巴顿只带了几升湖水回来研究水的特征。在她的一个学生设计的过滤系统的帮助下，现在微生物学家能够过滤数百升洞穴水，这些水中细菌浓度异乎寻常的低。

因为在湖泊的生态系统中，生命体数量很少，所以生物必须进行生存斗争。因此，细菌的捕食特性能够帮助科学家寻找新的抗生物质，巴顿说。其他的路线都已经进行过研究，因为这个非常原因，他们将研究地点转向奇异的世界，如大而深的洞穴。

巴顿和她的同事正在仔细探察洞穴。因为这个洞穴有着原始的自然环境，探险家和科学家们必须要采取非常措施，以确保他们不污染风洞湖及其周边地区：他们不能携带容易粉碎的食品，而且尿液都封存在瓶子里。

在地面上，美国国家公园管理局一直关注土地的情况。好几次，官员们都提出了反对意见，反对研究团队试图从麦迪逊含水层(湖泊的最上层)抽取更多的水，因为担心湖泊干涸。

“在过去5年里，我们才刚刚发现这里，知道我们拥有了这个资源...，而且我们不想看到这些资源在自然过程中消失了，”国家公园管理局的物理学家罗德 霍罗克斯说。

巴顿希望她的工作能够在今年年底结束。她已经向美国能源部的联合基因组研究所提交了一些调查结果，她说，科学家们要求她发送样品，以便他们能准确地确定在湖泊中生物是什么。

同时，风洞的湖泊可能很快就会成为科学研究的温床。

“一旦这个新闻发布出去，”她说，“这里将到处都是跑来做研究的人。”

英文原文：

Far below South Dakota, a cave holds pure, promising water

Hundreds of feet beneath the Black Hills, a team of scientists and researchers snake through dark, narrow and silent corridors of ancient rock to reach their goal: what is thought to be some of the purest water on Earth.

The crew of National Park Service scientists that's anchored by microbiologist Hazel Barton travels sporadically to the lowest reaches of South Dakota's Wind Cave National Park to study a series of underground lakes, which were discovered in the 1960s and aren't home to any animal life or even easily detectable microscopic organisms.

But Barton, from the University of Akron, has discovered there is bacteria—albeit scant—in the lakes. She's beginning to analyze about six years of data and hopes to decipher how the bacteria survives, answer questions about how it interacted before multicellular organisms came along and perhaps find new sources of antibiotics.

"It has the potential to answer a lot of questions that we have in biology that you can't answer anywhere else because you have levels of complexity," she said.

To gather the necessary samples, caving experience is crucial: It takes more than two hours for even the most adept cavers to reach Calcite Lake, the nearest body of water. "It's certainly not a route for the inexperienced," according to park service scientist Marc Ohms, who often joins Barton and, by his count, has made over 50 trips.

It's a quiet affair. Cavers typically hear only their voices, the scraping of feet and some grunting as they squeeze through crevasses—the narrowest is about 7 inches wide—with equipment that's light enough to carry and durable enough to survive the journey.

Barton, a 44-year-old British transplant, began caving here when she was a graduate student in Colorado, making weekend trips and later getting a tattoo of the cave. She has a reputation as an adventurous caver and has been featured in several film and television documentaries.

During her first excursions, Barton brought only a few liters of lake water back to study its properties. But with the help of a filtration system designed by one of her students, the microbiologist now filters hundreds of liters of cave water, which hosts an unusually low concentration of bacteria.

Because there are so few living things in the lakes' ecosystem, the organisms have to fight for survival. Thus, the bacteria's predatory characteristics could help scientists find new antibiotics, Barton said. Having exhausted other routes, they're turning to exotic environments like big, deep caves for that very reason.

Barton and her fellow cavers are doing so carefully. Because of its pristine nature, cavers and scientists have to take special precautions to make sure they don't contaminate Wind Cave lakes and surrounding areas: They don't bring crumble-prone foods, and they urinate in bottles.

Above ground, the National Park Service has been concerned about development on the land. Several times, officials have objected to proposals from groups wanting to draw more water from the Madison Aquifer—of which the lakes are the top—for fear that the lakes could be permanently drained.

"We just don't know what we have down here. We just now discovered in the last five years that we have this resource ... and we don't want to see these natural processes eliminated," said Rod Horrocks, a physical scientist with the park service.

Barton hopes to have her work wrapped up by the end of the year. Already, she's presented some of her findings to the U.S. Department of Energy's Joint Genome Institute, where she said scientists asked her to send samples so that they could determine exactly what organisms are in the lakes.

In the meantime, Wind Cave's lakes could soon become a hotbed for scientific research—if you can squeeze down there.

"As soon as the word gets out," she said, "I imagine people are going to be jumping all over the place to try and do research."