Last post I talked about the impact of Ocean acidulation on marine animals and food net. How do we mitigate this?
Most potential methods used to mitigate ocean acidification are controversial. There is no known effective way to prevent the pH value of ocean continue decreasing as the carbon dioxide concentration of the atmosphere is increasing constantly.
On the one hand, long term scale of the value of ocean pH is mainly controlled by the input of eroded (or dissolved) rocks which give negative and positive ions. On the other hand, on short term scale, the ocean pH value if affected by the dissolved weak acid or alkali, for example, carbonate acid and borate. As I mentioned before, the increase of atmospheric carbonate acid accelerated the production of carbonate acid in the ocean.
Recently, there are several geo-engineer projects are proposed. One of them is “Iron fertilization”. It is the introduction of iron into the upper ocean in order to stimulate phytoplankton blooms. Schiermeier (2012) stated that “Each atom of added iron pulled at least 13,000 atoms of carbon out of the atmosphere by encouraging algal growth which, through photosynthesis, captures carbon.” Moreover, diatom contributes to about 40 per cent of all oceanic Carbon sequestration (Jones, 2012).
The most recent open ocean trial of ocean iron fertilization was conducted from January to March 2009 in the South Atlantic. Another one, in July 2012, iron fertilization was carried out in the ocean off western Canada by the Haida Salmon Restoration Corporation (Tollefson, 2012).
Ocean iron fertilisation seems to be an effective method to mitigate ocean acidification. However, some scientists suggested that massive ocean iron fertilization might cause toxic algal blooms or deplete oxygen levels in the middle of the water column.
Reference:
Aumont, O.; Bopp, L. (2006) Globalizing results from the ocean in situ iron fertilization studies. Global Biogeochem Cycles
Tollefson, J. (2012). Ocean-fertilization project off Canada sparks furore. Nature 490 (7421)
Schiermeier, Q.(2012). Dumping iron at sea does sink carbon
Jones, V. (2012). Global Biogeochemical Cycles. Global environmental change lecture powerpoint.
Cao, L.; Caldeira, K.(2010) Can ocean iron fertilization mitigate
ocean acidification?