Iron seeding and algae blooms

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A study published in the current issue of the journal Nature says that fertilization of the ocean with iron compounds has induced algae blooms that are accompanied by considerable CO2 drawdown in the ocean surface layer.

German researchers conducted the study over a five-week period in the iron-deficient Antarctic Ocean at a spot where a vertically coherent eddy formed a 60km (37 mi) container-like test area. Four weeks after sprinkling several tons of iron sulfate in the area, an algae bloom peaked and was soon followed by mass mortality that formed a rapidly sinking aggregate of dead algae, taking with it the CO2 sucked from the atmosphere, which should remain on the ocean floor for “many centuries”.

However, this hardly means that SWRO facilities that use ferric sulfate or ferric chloride as a pretreatment coagulant will be allowed to discharge backwash water without further treatment.

Other researchers have expressed concern about the possible side effects of the technology in such a poorly understood field. They questioned the amount of CO2 that would be sequestered, and wondered how disrupted marine ecosystems might be through drastic changes in phytoplankton.

Volume 48
Issue 29

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As a guest you can read up to 3 full articles before a subscription is required. You can read 2 more articles for free.