Iron fertilization

Iron fertilization describes deliberate fertilization of surface waters of certain areas of the oceans, with the aim to promote the growth of algae. Relevant it is mainly related to the removal of carbon dioxide from the atmosphere. In particular, the iron fertilization and its impact on marine ecosystems are investigated experimentally at the time and controversial.

The basic idea

There are numerous scientific studies over the past decades in the field of earth sciences have shown that algal growth in certain parts of the oceans - the so-called HNLC regions - by the addition of iron can be significantly accelerated as micronutrient. As part of the current attempts to avoid unnecessary carbon emissions or carbon dioxide to escape to the atmosphere, an attempt is made to withdraw carbon dioxide through photosynthesis the most important global producers of biomass, the algae, the atmosphere. Several such tests have already been carried out and the limiting effect of micronutrients iron could be sufficiently confirmed.

Methods

When CO2 sequestration, there are different approaches. So, the idea is to promote the growth of algae by the introduction of iron sulphate, so that they escape in the context of an artificially induced algal bloom CO2 by photosynthesis of the atmosphere. Such experiments have been and are, inter alia, performed by the Alfred Wegener Institute (AWI ), see:

• Eisenfertilizationsexperiment LOHAFEX the German -Indian Partnership for Observation of the Global Oceans ( POGO ).
• Iron experiment EisenEx the AWI in November 2000
• CROZEX ( Crozet natural iron, algal blooms and EXport experiment )

However, recent research results have shown that the incorporation of ferrous sulfate has a much smaller effect on CO2 reduction than expected, since the export production of phytoplankton is only one to three percent.

By far the greater part of the algal biomass additionally produced is immediately reprocessed by higher trophic levels, ie it is converted into biomass of algae -feeding organisms and thus contributes nothing directly to a reduction in the carbon dioxide content in the atmosphere. Later, however, when the fish dies or all of algae -feeding organisms, they sink to the ocean floor, where they form a natural carbon sink for CO2. The time delay between the mass -produced algae in the sea and the process to storage on the seabed is regarded as negligible, since the creatures in the sea next to their life cycle also have their natural digestive processes.

Shipping

Thousands of tons of iron are introduced by emissions from cargo ships in the North Pacific each year. This is shipping to (according to the Japanese Institute for Marine Research and Technology JAMSTEC ), the largest source of iron compounds in this region. However, this is legal and does not violate the geoengineering moratorium of the United Nations, as it happens unintentionally.

Public debate in January and February 2009

Regarding possible effects of a large-scale iron fertilization on the ecosystems of the oceans, there is a controversial discussion. Proponents of ocean fertilization argue that introduced by fertilising substances such as iron sulfate also occur under natural conditions in the seas through which the natural mixing of water layers is simulated. Prof. Andrew J. Watson of the University of East Anglia is of the view that iron fertilization, if it is performed correctly, CO2 for centuries there conveyed ( to the sea floor ) where there is also a natural way finally arrives ( " ... the Ultimately it would place did end up anyway " ). Opponents such as Stephan Lutter of the nature conservation organization WWF, however, worry about a significant change in an intervention in the ecosystem. This he sees as a threat to biodiversity. The Federal Ministry for the Environment, Nature Conservation and Nuclear Safety ( BMU) is ocean fertilization experiments to critical because " the indirect consequences for marine ecosystems are difficult to estimate ." The BMU and the German Federal Ministry of Education and Research agree that " iron fertilization may be an instrument of climate policy ". The IPCC has, however, found in the fourth assessment report that none of the expected adverse effects in the experiments performed were found.