Sentences with phrase «tonnes of ballast water»

The 70,000 or so vessels that would be covered by the treaty transport more than 7 billion tonnes of ballast water round the world each year, says David Smith, head of technical services at the Plymouth Marine Laboratory in the UK.

At any one time, an estimated 7 billion tonnes of ballast water is crossing the oceans — almost all of it carrying seeds, spores, eggs, larvae, bacteria and plankton native to wherever the water was loaded.