2010年3月16日

The iron hypothesis

iron hypothesis—fertilizing the sea with iron—was first put to the test on the open ocean in 1993. According to Martin's iron hypothesis, seeding the ocean surface with iron should make microscopic marine organisms like diatoms multiply dramatically, which might in turn cool the planet. The big question is: Should this type of "global engineering" be done?
Since 1993, these 12 small-scale open ocean experiments (red dots) have shown that iron additions do indeed result in phytoplankton blooms, thereby drawing carbon dioxide out of the atmosphere and into the ocean.  
  Twelve small experiments have shown that blooms of phytoplankton consistently result from intentional addition of iron to the ocean. But the efficacy and ecological impacts of iron fertilization remain uncertain, particularly with larger-scale experiments. If and when a new round of experiments is begun, these questions will be first on the list:
  • How long will carbon be sequestered in the ocean?
  • How deep is deep enough to accomplish this?
  • How can sequestration efficiency be increased?
  • How does the ocean food web change during and after a bloom?
  • Which phytoplankton and grazers raise sequestration efficiency?
  • Which parts of the ocean are best for iron fertilization?
  • What size and what shaped patch should be fertilized?
  • How often and how continually should iron be added?
  • What kinds of currents and surface conditions give the best results?
  • How can the amount and fate of carbon from a bloom be verified?
  • How could effects downstream of experiments be detected?
  • How could the production of other greenhouse gases be monitored?
References:
http://www.whoi.edu/oceanus/viewArticle.do?id=34167&sectionid=1000
http://www.palomar.edu/oceanography/iron.htm
http://www.nature.com/nature/journal/v331/n6154/ris/331341a0.ris
http://en.wikipedia.org/wiki/Iron_Hypothesis