Why are the seas salty?

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)