I want to know the answer to the following question:
The presence of what substance in sea water has resulted in low yields when attempting to extract uranium?
All the background I'm provided with is that "An additional 4.6 billion tonnes of uranium are estimated to be in sea water (Japanese scientists in the 1980s showed that extraction of uranium from sea water using ion exchangers was technically feasible).". Is that enough to answer the question?
Answer: no