Wednesday, December 26, 2007

Fifth pathway of carbon fixation

Page 1732 of the Dec. 14 issue of Science contains an article by Thauer titled "A Fifth Pathway of Carbon Fixation." It discusses autotrophs including cyanobacteria and mentions the Calvin cycle, including RuBisCO (ribulose 1,5 bisphosphate carboxylase oxygenase). Reference is made to the article by Berg appearing at page 1782 of the Dec. 14 issue.

The Dec. 14 issue also contains an article by Hoegh-Guldberg et al which discusses the impact of higher CO2 levels on coral reefs (318 Science 1737). The text includes:

Sea temperatures are warmer (+0.7degC), and pH (-0.1 pH units) and carbonate ion concentrations (about 210 micromole per kg) are lower than at any other time during the past 420,000 years.

Many experimental studis have shown a doubling of pre-industrial [Co2] to 560 ppm decreases coral calcification and growth by up to 40% through the inhibition of aragonite formation as carbonate ion concentrations decrease

There is discussion of when "carbonate ion concentrations drop below 200 micromole per kg.


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