Why are the seas salty?

海水为什么是咸的?

CrowdScience

科技

2024-06-15

31 分钟
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单集简介 ...

Listener Julie lives close to the coast in New Zealand and wants to know why the water that washes up on the beach isn't fresh. How exactly does all that salt get into the world's oceans? In India, a country where salt became symbolic of much more than well-seasoned food, host Chhavi Sachdev visits coastal salt farms and a research institute dedicated to studying all things saline, to better understand our relationship with salty seas. The team also ventures to a very briny lake on the other side of the globe in Salt Lake City, Utah, to learn how salt makes its way into water bodies. Speaking to an expert in deep sea exploration, we learn how hydrothermal vents may play a role in regulating ocean saltiness, and how much the field still has to explore. Meanwhile, listener Will wants to know how much melting ice sheets are affecting ocean salinity. But ice melt isn’t the only thing affecting salt levels when it comes to the impacts of climate change. And... how many teaspoons of salt are in a kilogram of sea water anyway? We do the rigorous science to answer all these salient saline questions. Featuring: Deepika - small scale salt farmer Mark Radwin - PhD candidate in geology and geophysics at the University of Utah Brenda Bowen - Geology & Geophysics, Atmospheric Sciences, University of Utah Chris German - Geology & Geophysics, Woods Hole Oceanographic Institution Prasan Khemka - Chandan Salt Works Paul Durack - Lawrence Livermore National Laboratory Bhoomi Andharia - Central Salt & Marine Chemicals Research Institute Presenter: Chhavi Sachdev Producer: Sam Baker Editor: Cathy Edwards Production Coordinator: Liz Tuohy Studio Manager: Sarah Hockley (Photo: Shiv Salt Works, Bhavnagar, Gujarat in India. Credit: Chhavi Sachdev, BBC)

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  • Namaskar.

  • Namaskar.

  • Deepika.

  • Deepika, nice to meet you.

  • I'm Chavi Sachdev and you're listening to Crowd Science from the BBC World Service.

  • Deepika is a salt farmer here on the outskirts of Bhavanagar, a town in the state of Gujarat on the west coast of India.

  • We are standing in the blazing heat amidst five different sized fields of saltwater.

  • This is her salt farm and it covers 10 acres.

  • Can you tell me what, what your process is?

  • She wakes up at about 3:34 in the morning, early in the morning.

  • Okay.

  • So they aim to finish by 9:00 because it's too hot after 9 to be outside and they feel really hot when they get heat stroke and faint.

  • So they start, she's telling me that it takes her at least four hours, sometimes four and a half hours to rake the salt in these pans.

  • So how long does the whole process take to turn seawater into salt?

  • 10 days to just to crystallize it and then the water is pumped out and then the next one takes 10 days.