Iron fertilization

Iron fertilization is the intentional introduction of iron to iron-poor areas of the ocean surface to stimulate phytoplankton production. This is intended to enhance biological productivity and/or accelerate carbon dioxide (CO
2
) sequestration from the atmosphere.

Iron is a trace element necessary for photosynthesis in plants. It is highly insoluble in sea water and in a variety of locations is the limiting nutrient for phytoplankton growth. Large algal blooms can be created by supplying iron to iron-deficient ocean waters. These blooms can nourish other organisms.

Multiple ocean labs, scientists and businesses have explored fertilization. Beginning in 1993, thirteen research teams completed ocean trials demonstrating that phytoplankton blooms can be stimulated by iron augmentation.[1] Controversy remains over the effectiveness of atmospheric CO
2
sequestration and ecological effects.[2] The most recent open ocean trials of ocean iron fertilization were in 2009 (January to March) in the South Atlantic by project Lohafex, and in July 2012 in the North Pacific off the coast of British Columbia, Canada, by the Haida Salmon Restoration Corporation (HSRC).[3]

Fertilization occurs naturally when upwellings bring nutrient-rich water to the surface, as occurs when ocean currents meet an ocean bank or a sea mount. This form of fertilization produces the world's largest marine habitats. Fertilization can also occur when weather carries wind blown dust long distances over the ocean, or iron-rich minerals are carried into the ocean by glaciers,[4] rivers and icebergs.[5]

Phytoplankton SoAtlantic 20060215
An oceanic phytoplankton bloom in the South Atlantic Ocean, off the coast of Argentina covering an area about 300 by 50 miles (500 by 80 km)

History

Consideration of iron's importance to phytoplankton growth and photosynthesis dates to the 1930s when English biologist Joseph Hart speculated that the ocean's great "desolate zones" (areas apparently rich in nutrients, but lacking in plankton activity or other sea life) might be iron-deficient.[6] Little scientific discussion was recorded until the 1980s, when oceanographer John Martin renewed controversy on the topic with his marine water nutrient analyses. His studies supported Hart's hypothesis. These "desolate" regions came to be called "High Nutrient, Low Chlorophyll" (HNLC) zones.[6]

John Gribbin was the first scientist to publicly suggest that climate change could be reduced by adding large amounts of soluble iron to the oceans.[7] Martin's 1988 quip four months later at Woods Hole Oceanographic Institution, "Give me a half a tanker of iron and I will give you another ice age",[6][8] drove a decade of research.

The findings suggested that iron deficiency was limiting ocean productivity and offered an approach to mitigating climate change as well. Perhaps the most dramatic support for Martin's hypothesis came with the 1991 eruption of Mount Pinatubo in the Philippines. Environmental scientist Andrew Watson analyzed global data from that eruption and calculated that it deposited approximately 40,000 tons of iron dust into oceans worldwide. This single fertilization event preceded an easily observed global decline in atmospheric CO
2
and a parallel pulsed increase in oxygen levels.[9]

The parties to the London Dumping Convention adopted a non-binding resolution in 2008 on fertilization (labeled LC-LP.1(2008)). The resolution states that ocean fertilization activities, other than legitimate scientific research, "should be considered as contrary to the aims of the Convention and Protocol and do not currently qualify for any exemption from the definition of dumping".[10] An Assessment Framework for Scientific Research Involving Ocean Fertilization, regulating the dumping of wastes at sea (labeled LC-LP.2(2010)) was adopted by the Contracting Parties to the Convention in October 2010 (LC 32/LP 5).[11]

Methods

There are two ways of performing artificial iron fertilization: ship based direct into the ocean and atmospheric deployment[12].

Ship based deployment

Trials of ocean fertilization using iron sulphate added directly to the surface water from ships are described in detail in the experiment section below.

Atmospheric sourcing

Iron-rich dust rising into the atmosphere is a primary source of ocean iron fertilization[13]. For example, wind blown dust from the Sahara desert fertilizes the Atlantic Ocean[14] and the Amazon rainforest[15]. The naturally occurring iron oxide in atmospheric dust reacts with hydrogen chloride from sea spray to produce iron chloride, which degrades methane and other greenhouse gases, brightens clouds and eventually falls with the rain in low concentration across a wide area of the globe[12]. Unlike ship based deployment, no trials have been performed of increasing the natural level of atmospheric iron. Expanding this atmospheric source of iron could complement ship-based deployment.

Iron Salt Aerosol

One proposed method to boost the atmospheric iron level is Iron Salt Aerosol[12]. By adding Iron(III) chloride into the troposphere, iron salt aerosol could increase natural cooling effects including methane removal, cloud brightening and ocean fertilization, helping to prevent or reverse global warming[12].

Experiments

Martin hypothesized that increasing phytoplankton photosynthesis could slow or even reverse global warming by sequestering CO
2
in the sea. He died shortly thereafter during preparations for Ironex I,[16] a proof of concept research voyage, which was successfully carried out near the Galapagos Islands in 1993 by his colleagues at Moss Landing Marine Laboratories.[6] Thereafter 12 international ocean studies examined the phenomenon:

  • Ironex II, 1995[17]
  • SOIREE (Southern Ocean Iron Release Experiment), 1999[18]
  • EisenEx (Iron Experiment), 2000[19]
  • SEEDS (Subarctic Pacific Iron Experiment for Ecosystem Dynamics Study), 2001[20]
  • SOFeX (Southern Ocean Iron Experiments - North & South), 2002[21][22]
  • SERIES (Subarctic Ecosystem Response to Iron Enrichment Study), 2002[23]
  • SEEDS-II, 2004[24]
  • EIFEX (European Iron Fertilization Experiment),[25] A successful experiment conducted in 2004 in a mesoscale ocean eddy in the South Atlantic resulted in a bloom of diatoms, a large portion of which died and sank to the ocean floor when fertilization ended. In contrast to the LOHAFEX experiment, also conducted in a mesoscale eddy, the ocean in the selected area contained enough dissolved silicon for the diatoms to flourish.[26][27][28]
  • CROZEX (CROZet natural iron bloom and Export experiment), 2005[29]
  • A pilot project planned by Planktos, a U.S. company, was cancelled in 2008 for lack of funding.[30] The company blamed environmental organizations for the failure.[31][32]
  • LOHAFEX (Indian and German Iron Fertilization Experiment), 2009[33][34][35] Despite widespread opposition to LOHAFEX, on 26 January 2009 the German Federal Ministry of Education and Research (BMBF) gave clearance for this fertilization experiment to commence. The experiment was carried out in waters low in silicic acid which was likely to affect sequestration efficacy.[36] A 900 square kilometers (350 sq mi) portion of the southwest Atlantic was fertilized with iron sulfate. A large phytoplankton bloom was triggered. This bloom did not contain diatoms because the site was depleted in silicic acid, an essential nutrient for diatom growth.[36] In the absence of diatoms, a relatively small amount of carbon was sequestered, because other phytoplankton are vulnerable to predation by zooplankton and do not sink rapidly upon death.[36] These poor sequestration results led to suggestions that fertilization is not an effective carbon mitigation strategy in general. However, prior ocean fertilization experiments in high silica locations revealed much higher carbon sequestration rates because of diatom growth. LOHAFEX confirmed sequestration potential depends strongly upon appropriate siting.[36]
  • Haida Salmon Restoration Corporation (HSRC), 2012 - funded by the Old Massett Haida band and managed by Russ George - dumped 100 tonnes of iron sulphate into the Pacific into an eddy 200 nautical miles (370 km) west of the islands of Haida Gwaii. This resulted in increased algae growth over 10,000 square miles (26,000 km2). Critics alleged George's actions violated the United Nations Convention on Biological Diversity (CBD) and the London convention on the dumping of wastes at sea which prohibited such geoengineering experiments.[37][38] On 15 July 2014, the resulting scientific data was made available to the public.[39]

Science

The maximum possible result from iron fertilization, assuming the most favourable conditions and disregarding practical considerations, is 0.29W/m2 of globally averaged negative forcing,[40] offsetting 1/6 of current levels of anthropogenic CO
2
emissions. These benefits have been called into question by research suggesting that fertilization with iron may deplete other essential nutrients in the seawater causing reduced phytoplankton growth elsewhere — in other words, that iron concentrations limit growth more locally than they do on a global scale.[41][42]

Role of iron

About 70% of the world's surface is covered in oceans. The part of these where light can penetrate is inhabited by algae (and other marine life). In some oceans, algae growth and reproduction is limited by the amount of iron. Iron is a vital micronutrient for phytoplankton growth and photosynthesis that has historically been delivered to the pelagic sea by dust storms from arid lands. This Aeolian dust contains 3–5% iron and its deposition has fallen nearly 25% in recent decades.[43]

The Redfield ratio describes the relative atomic concentrations of critical nutrients in plankton biomass and is conventionally written "106 C: 16 N: 1 P." This expresses the fact that one atom of phosphorus and 16 of nitrogen are required to "fix" 106 carbon atoms (or 106 molecules of CO
2
). Research expanded this constant to "106 C: 16 N: 1 P: .001 Fe" signifying that in iron deficient conditions each atom of iron can fix 106,000 atoms of carbon,[44] or on a mass basis, each kilogram of iron can fix 83,000 kg of carbon dioxide. The 2004 EIFEX experiment reported a carbon dioxide to iron export ratio of nearly 3000 to 1. The atomic ratio would be approximately: "3000 C: 58,000 N: 3,600 P: 1 Fe".[45]

Therefore, small amounts of iron (measured by mass parts per trillion) in HNLC zones can trigger large phytoplankton blooms on the order of 100,000 kilograms of plankton per kilogram of iron . The size of the iron particles is critical. Particles of 0.5–1 micrometer or less seem to be ideal both in terms of sink rate and bioavailability. Particles this small are easier for cyanobacteria and other phytoplankton to incorporate and the churning of surface waters keeps them in the euphotic or sunlit biologically active depths without sinking for long periods.

Atmospheric deposition is an important iron source. Satellite images and data (such as PODLER, MODIS, MSIR)[46][47][48] combined with back-trajectory analyses identified natural sources of iron–containing dust. Iron-bearing dusts erode from soil and are transported by wind. Although most dust sources are situated in the Northern Hemisphere, the largest dust sources are located in northern and southern Africa, North America, central Asia and Australia.[49]

Heterogeneous chemical reactions in the atmosphere modify the speciation of iron in dust and may affect the bioavailability of deposited iron. The soluble form of iron is much higher in aerosols than in soil (~0.5%).[49][50][51] Several photo-chemical interactions with dissolved organic acids increase iron solubility in aerosols.[52][53] Among these, photochemical reduction of oxalate-bound Fe(III) from iron-containing minerals is important. The organic ligand forms a surface complex with the Fe (III) metal center of an iron-containing mineral (such as hematite or goethite). On exposure to solar radiation the complex is converted to an excited energy state in which the ligand, acting as bridge and an electron donor, supplies an electron to Fe(III) producing soluble Fe(II).[54][55][56] Consistent with this, studies documented a distinct diel variation in the concentrations of Fe (II) and Fe(III) in which daytime Fe(II) concentrations exceed those of Fe(III).[57][58][59][60]

Volcanic ash as an iron source

Volcanic ash has a significant role in supplying the world’s oceans with iron.[61] Volcanic ash is composed of glass shards, pyrogenic minerals, lithic particles and other forms of ash that release nutrients at different rates depending on structure and the type of reaction caused by contact with water.[62]

Increases of biogenic opal in the sediment record are associated with increased iron accumulation over the last million years.[63] In August 2008, an eruption in the Aleutian Islands deposited ash in the nutrient-limited Northeast Pacific. This ash and iron deposition resulted in one of the largest phytoplankton blooms observed in the subarctic.[64]

Carbon sequestration

CO2 pump hg
Air-sea exchange of CO
2

Previous instances of biological carbon sequestration triggered major climatic changes, lowering the temperature of the planet, such as the Azolla event. Plankton that generate calcium or silicon carbonate skeletons, such as diatoms, coccolithophores and foraminifera, account for most direct sequestration. When these organisms die their carbonate skeletons sink relatively quickly and form a major component of the carbon-rich deep sea precipitation known as marine snow. Marine snow also includes fish fecal pellets and other organic detritus, and steadily falls thousands of meters below active plankton blooms.[65]

Of the carbon-rich biomass generated by plankton blooms, half (or more) is generally consumed by grazing organisms (zooplankton, krill, small fish, etc.) but 20 to 30% sinks below 200 meters (660 ft) into the colder water strata below the thermocline. Much of this fixed carbon continues into the abyss, but a substantial percentage is redissolved and remineralized. At this depth, however, this carbon is now suspended in deep currents and effectively isolated from the atmosphere for centuries. (The surface to benthic cycling time for the ocean is approximately 4,000 years.)

Analysis and quantification

Evaluation of the biological effects and verification of the amount of carbon actually sequestered by any particular bloom involves a variety of measurements, combining ship-borne and remote sampling, submarine filtration traps, tracking buoy spectroscopy and satellite telemetry. Unpredictable ocean currents can remove experimental iron patches from the pelagic zone, invalidating the experiment.

The potential of fertilization to tackle global warming is illustrated by the following figures. If phytoplankton converted all the nitrate and phosphate present in the surface mixed layer across the entire Antarctic circumpolar current into organic carbon, the resulting carbon dioxide deficit could be compensated by uptake from the atmosphere amounting to about 0.8 to 1.4 gigatonnes of carbon per year.[66] This quantity is comparable in magnitude to annual anthropogenic fossil fuels combustion of approximately 6 gigatonnes. The Antarctic circumpolar current region is one of several in which iron fertilization could be conducted—the Galapagos islands area another potentially suitable location.

Dimethyl sulfide and clouds

CLAW hypothesis graphic 1 AYool
Schematic diagram of the CLAW hypothesis (Charlson et al., 1987)[67]

Some species of plankton produce dimethyl sulfide (DMS), a portion of which enters the atmosphere where it is oxidized by hydroxyl radicals (OH), atomic chlorine (Cl) and bromine monoxide (BrO) to form sulfate particles, and potentially increase cloud cover. This may increase the albedo of the planet and so cause cooling—this proposed mechanism is central to the CLAW hypothesis.[67] This is one of the examples used by James Lovelock to illustrate his Gaia hypothesis.[68]

During SOFeX, DMS concentrations increased by a factor of four inside the fertilized patch. Widescale iron fertilization of the Southern Ocean could lead to significant sulfur-triggered cooling in addition to that due to the CO
2
uptake and that due to the ocean's albedo increase, however the amount of cooling by this particular effect is very uncertain.[69]

Financial opportunities

Beginning with the Kyoto Protocol, several countries and the European Union established carbon offset markets which trade certified emission reduction credits (CERs) and other types of carbon credit instruments. In 2007 CERs sold for approximately €15–20/ton COe
2
.[70] Iron fertilization is relatively inexpensive compared to scrubbing, direct injection and other industrial approaches, and can theoretically sequester for less than €5/ton CO
2
, creating a substantial return.[71] In August, 2010, Russia established a minimum price of €10/ton for offsets to reduce uncertainty for offset providers.[72] Scientists have reported a 6–12% decline in global plankton production since 1980.[43][73] A full-scale plankton restoration program could regenerate approximately 3–5 billion tons of sequestration capacity worth €50-100 billion in carbon offset value. However, a 2013 study indicates the cost versus benefits of iron fertilization puts it behind carbon capture and storage and carbon taxes.[74]

Ocean privatization could additionally create the possibility of profits through increased fish stocks.

Sequestration definitions

Carbon is not considered "sequestered" unless it settles to the ocean floor where it may remain for millions of years. Most of the carbon that sinks beneath plankton blooms is dissolved and remineralized well above the seafloor and eventually (days to centuries) returns to the atmosphere, negating the original benefit.[75]

Advocates argue that modern climate scientists and Kyoto Protocol policy makers define sequestration over much shorter time frames. For example, trees and grasslands are viewed as important carbon sinks. Forest biomass sequesters carbon for decades, but carbon that sinks below the marine thermocline (100–200 meters) is removed from the atmosphere for hundreds of years, whether it is remineralized or not. Since deep ocean currents take so long to resurface, their carbon content is effectively sequestered by the criterion in use today.

Debate

While ocean iron fertilization could represent a potent means to slow global warming current debate raises a variety of concerns.

Precautionary principle

The precautionary principle (PP) states that if an action or policy has a suspected risk of causing harm, in the absence of scientific consensus, the burden of proof that it is not harmful falls on those who would take the action. The side effects of large-scale iron fertilization are not yet quantified. Creating phytoplankton blooms in iron-poor areas is like watering the desert: in effect it changes one type of ecosystem into another. The argument can be applied in reverse, by considering emissions to be the action and remediation an attempt to partially offset the damage.

Fertilization advocates respond that algal blooms have occurred naturally for millions of years with no observed ill effects. The Azolla event occurred around 49 million years ago and accomplished what fertilization is intended to achieve (but on a larger scale).

20th-century phytoplankton decline

While advocates argue that iron addition would help to reverse a supposed decline in phytoplankton, this decline may not be real. One study reported a decline in ocean productivity comparing the 1979–1986 and 1997–2000 periods,[76] but two others found increases in phytoplankton.[77][78] A 2010 study of oceanic transparency since 1899 and in situ chlorophyll measurements concluded that oceanic phytoplankton medians decreased by ~1% per year over that century.[79]

Ecological issues

Algal blooms

La-Jolla-Red-Tide.780
A "red tide" off the coast of La Jolla, San Diego, California.

Critics are concerned that fertilization will create harmful algal blooms (HAB). The species that respond most strongly to fertilization vary by location and other factors and could possibly include species that cause red tides and other toxic phenomena. These factors affect only near-shore waters, although they show that increased phytoplankton populations are not universally benign.[80]

Most species of phytoplankton are harmless or beneficial, given that they constitute the base of the marine food chain. Fertilization increases phytoplankton only in the open oceans (far from shore) where iron deficiency is substantial. Most coastal waters are replete with iron and adding more has no useful effect.[81]

A 2010 study of iron fertilization in an oceanic high-nitrate, low-chlorophyll environment, however, found that fertilized Pseudo-nitzschia diatom spp., which are generally nontoxic in the open ocean, began producing toxic levels of domoic acid. Even short-lived blooms containing such toxins could have detrimental effects on marine food webs.[82]

Deep water oxygen levels

When organic bloom detritus sinks into the abyss, a significant fraction is devoured by bacteria, other microorganisms and deep sea animals that also consume oxygen. A large enough bloom could render certain regions beneath it anoxic and threaten other benthic species. However this would entail the removal of oxygen from thousands of cubic km of benthic water beneath a bloom and so seems unlikely.

The largest plankton replenishment projects under consideration are less than 10% the size of most natural wind-fed blooms. In the wake of major dust storms, natural blooms have been studied since the beginning of the 20th century and no such deep water dieoffs have been reported.[83]

Ecosystem effects

Depending upon the composition and timing of delivery, iron infusions could preferentially favor certain species and alter surface ecosystems to unknown effect. Population explosions of jellyfish, that disturb the food chain impacting whale populations or fisheries is unlikely as iron fertilization experiments that are conducted in high-nutrient, low-chlorophyll waters favor the growth of larger diatoms over small flagellates. This has been shown to lead to increased abundance of fish and whales over jellyfish.[84] A 2010 study showed that iron enrichment stimulates toxic diatom production in high-nitrate, low-chlorophyll areas[85] which, the authors argue, raises "serious concerns over the net benefit and sustainability of large-scale iron fertilizations". Nitrogen released by cetaceans and iron chelate are a significant benefit to the marine food chain in addition to sequestering carbon for long periods of time.[86]

However, CO
2
-induced surface water heating and rising carbonic acidity are shifting population distributions for phytoplankton, zooplankton and many other populations. Optimal fertilization could potentially help restore lost/threatened ecosystem services.

Ocean Acidification

A 2009 study tested the potential of iron fertilization to reduce both atmospheric CO2 and ocean acidity using a global ocean carbon model. The study showed that an optimized regime of micronutrient introduction would reduce the predicted increase of atmospheric CO2 by more than 20 percent. Unfortunately, the impact on ocean acidification would be split, with a decrease in acidification in surface waters but an increase in acidification in the deep ocean.[87]

See also

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Further reading

Secretariat of the Convention on Biological Diversity (2009). Scientific Synthesis of the Impacts of Ocean Fertilization on Marine Biodiversity. Montreal, Technical Series No. 45, 53 pages

Technique

Context

Debate

Bio-geoengineering

Bio-geoengineering is a form of climate engineering which seeks to use or modify plants or other living things to modify the Earth's climate.Bio-energy with carbon storage, afforestation projects, and ocean nourishment (including iron fertilization) could be considered examples of bio-geoengineering.Biogenic aerosols can be grown to replace those beneficial aerosols lost as the result of the death of 50% of Earth's boreal forests. Agricultural production of atmospheric aerosols called "monoterpenes" is possible if crops that are rich in monoterpenes are grown.

Carbon sequestration

Carbon sequestration is the process involved in carbon capture and the long-term storage of atmospheric carbon dioxide or other forms of carbon to mitigate or defer global warming. It has been proposed as a way to slow the atmospheric and marine accumulation of greenhouse gases, which are released by burning fossil fuels.Carbon dioxide (CO2) is naturally captured from the atmosphere through biological, chemical, and physical processes. Artificial processes have been devised to produce similar effects, including large-scale, artificial capture and sequestration of industrially produced CO2 using subsurface saline aquifers, reservoirs, ocean water, aging oil fields, or other carbon sinks.

Climate engineering

Climate engineering or climate intervention, commonly referred to as geoengineering, is the deliberate and large-scale intervention in the Earth's climate system, usually with the aim of mitigating the adverse effects of global warming. Climate engineering is an umbrella term for measures that mainly fall into two categories: greenhouse gas removal and solar radiation management. Greenhouse gas removal approaches, of which carbon dioxide removal represents the most prominent subcategory addresses the cause of global warming by removing greenhouse gases from the atmosphere. Solar radiation management attempts to offset effects of greenhouse gases by causing the Earth to absorb less solar radiation.

Climate engineering approaches are sometimes viewed as additional potential options for limiting climate change or its impacts, alongside mitigation and adaptation. There is substantial agreement among scientists that climate engineering cannot substitute for climate change mitigation. Some approaches might be used as accompanying measures to sharp cuts in greenhouse gas emissions. Given that all types of measures for addressing climate change have economic, political, or physical limitations, some climate engineering approaches might eventually be used as part of an ensemble of measures, which can be referred to as climate restoration. Research on costs, benefits, and various types of risks of most climate engineering approaches is at an early stage and their understanding needs to improve to judge their adequacy and feasibility.Almost all research into solar radiation management has to date consisted of computer modelling or laboratory tests, and an attempt to move to outdoor experimentation has proven controversial. Some carbon dioxide removal practices, such as afforestation, ecosystem restoration and bio-energy with carbon capture and storage projects, are underway to a limited extent. Their scalability to effectively affect global climate is, however, debated. Ocean iron fertilization has been investigated in small-scale research trials. These experiments have proven controversial. The World Wildlife Fund has criticized these activities.Most experts and major reports advise against relying on climate engineering techniques as a main solution to global warming, in part due to the large uncertainties over effectiveness and side effects. However, most experts also argue that the risks of such interventions must be seen in the context of risks of dangerous global warming. Interventions at large scale may run a greater risk of disrupting natural systems resulting in a dilemma that those approaches that could prove highly (cost-)effective in addressing extreme climate risk, might themselves cause substantial risk. Some have suggested that the concept of engineering the climate presents a moral hazard because it could reduce political and public pressure for emissions reduction, which could exacerbate overall climate risks; others assert that the threat of climate engineering could spur emissions cuts.

Some are in favour of a moratorium on out-of-doors testing and deployment of solar radiation management (SRM).The United Nations is involved in discussions regarding some aspects of the topic.

High-nutrient, low-chlorophyll regions

High-nutrient, low-chlorophyll (HNLC) regions are regions of the ocean where the abundance of phytoplankton is low and fairly constant despite the availability of macronutrients. Phytoplankton rely on a suite of nutrients for cellular function. Macronutrients (e.g., nitrate, phosphate, silicic acid) are generally available in higher quantities in surface ocean waters, and are the typical components of common garden fertilizers. Micronutrients (e.g., iron, zinc, cobalt) are generally available in lower quantities and include trace metals. Macronutrients are typically available in millimolar concentrations, while micronutrients are generally available in micro- to nanomolar concentrations. In general, nitrogen tends to be a limiting ocean nutrient, but in HNLC regions it is never significantly depleted. Instead, these regions tend to be limited by low concentrations of metabolizable iron. Iron is a critical phytoplankton micronutrient necessary for enzyme catalysis and electron transport.Between the 1930s and '80s, it was hypothesized that iron is a limiting ocean micronutrient, but there were not sufficient methods to reliably detect iron in seawater to confirm this hypothesis. In 1989, high concentrations of iron-rich sediments in nearshore coastal waters off the Gulf of Alaska were detected. However, offshore waters had lower iron concentrations and lower productivity despite macronutrient availability for phytoplankton growth. This pattern was observed in other oceanic regions and led to the naming of three major HNLC zones: the North Pacific Ocean, the Equatorial Pacific Ocean, and the Southern Ocean.The discovery of HNLC regions has fostered scientific debate about the ethics and efficacy of iron fertilization experiments which attempt to draw down atmospheric carbon dioxide by stimulating surface-level photosynthesis. It has also led to the development of hypotheses such as grazing control which poses that HNLC regions are formed, in part, from the grazing of phytoplankton (e.g. dinoflagellates, ciliates) by smaller organisms (e.g. protists).

Iron cycle

The iron cycle (Fe) is the biogeochemical cycle of iron through the atmosphere, hydrosphere, biosphere and lithosphere. While Fe is highly abundant in the Earth's crust, it is less common in oxygenated surface waters. Iron is a key micronutrient in primary productivity, and a limiting nutrient in High-Nutrient, Low-Chlorophyll (HNLC) regions of the ocean. A critical component of the iron cycle is aeolian dust, which is transported from the Earth's land via the atmosphere to the ocean.

Iron exists in a range of oxidation states from -2 to +7; however, on Earth it is predominantly in its +2 or +3 redox state. The cycling of iron between its +2 and +3 oxidation states is referred to as the iron cycle. This process can be entirely abiotic or facilitated by microorganisms. Some examples of this include the rusting of iron-bearing metals (in this case, Fe2+ is abiotically oxidized to Fe3+) by oxygen, and the abiotic reduction of Fe3+ to Fe2+ by iron-sulfide minerals or the biological cycling of Fe2+-oxidizing microbes.Iron is an essential micro-nutrient for almost every life form, and is a primary redox-active metal on Earth. Due to the high reactivity of Fe2+ with oxygen and low solubility of Fe3+, iron is a limiting nutrient in most regions of the world. Thus, the iron cycle is intrinsically linked to the cycling of other biologically-important elements.

John Martin (oceanographer)

John Martin (February 27, 1935 – June 18, 1993), was an oceanographer.

Born in Old Lyme, Connecticut, he is best known for his research on the role of iron as a phytoplankton micronutrient, and its significance for so-called "High-Nutrient, Low Chlorophyll" regions of the oceans. He is also known for advocating the use of iron fertilization to enhance oceanic primary production to act as a sink for fossil fuel carbon dioxide.

John Martin died from prostate cancer at the age of 58.

Lohafex

LOHAFEX was an Ocean Iron Fertilization experiment jointly planned by the Council of Scientific Industrial Research (CSIR), India, and Helmholtz Foundation, Germany. The experiment followed a Memorandum of Understanding signed on 30 October 2007 by Dr. T. Ramaswami, Director General, CSIR, and Dr. Juergen Mlynek, President, Helmholtz Foundation, Germany, on Cooperation in Marine Sciences, during the visit of the German Chancellor, Frau Angela Merkel to India. The experiment was conducted mainly by CSIR-National Institute of Oceanography (NIO), Goa, and Alfred-Wegener Institute (AWI) of Polar and Marine Research, Bremerhaven, with participation of scientists from Chile, France, Spain and UK. The German Research Vessel POLARSTERN was utilized for the experiment on her ANT XXV/3 cruise. It was jointly led by Wajih Naqvi of CSIR-NIO and Victor Smetacek of AWI. Weekly reports of the expedition were published on the website of AWI.A cyclonic eddy centred on 48 deg S, 16 deg E was selected for fertilization. The experiment began on India's Republic Day (26 January 2009). Ten tonnes of ferrous sulphate dissolved in seawater was spread over an area of 300 square kilometers, and the patch created was monitored for 38 days to investigate the effects of iron addition on marine biogeochemistry and ecosystem. Another iron addition of similar magnitude was done two weeks later. It was expected that iron addition would trigger algal bloom leading to sequestration of carbon dioxide from the atmosphere.

The ship left Cape Town 7 January 2009. The expedition ended after 70 days on 17 March 2009 in Punta Arenas, Chile.

Following protests from several NGOs, the German Government ordered a halt of the experiment. The environmentalists feared damage to marine ecosystem by an artificial algal bloom. The critics argued that long-term effects of ocean fertilization would not be detectable during short-term observation. Other critics feared the entry into large-scale manipulation of ecosystems with these large geo-engineering experiments. The German Government sent the proposal for scientific and legal reviews that were supportive of the project and the experiment was allowed to continue.

LOHAFEX was not the first experiment of its kind. In 2000 and 2004, comparable amounts of iron sulfate were discharged from the same ship ( EisenEx experiment). 10 to 20 percent of the algal bloom died off and sank to the sea floor. This removed carbon from the atmosphere, which is the intended carbon 'sink'.

As expected iron fertilization led to development of a bloom during LOHAFEX, but the chlorophyll increase within the fertilized patch, an indicator of biomass, was smaller than in previous experiments. The algal bloom also stimulated the growth of zooplankton that feed on them. The zooplankton in turn are consumed by higher organisms. Thus, ocean fertilization with iron also contributes to the carbon-fixing marine biomass of fish species which have been removed from the ocean by over-fishing.

Mid-Pleistocene Transition

The Mid-Pleistocene Transition (MPT), also known as the Mid-Pleistocene Revolution (MPR), is a fundamental change in the behaviour of glacial cycles during the Quaternary glaciations. The transition happened approximately 1.25–0.7 million years ago, in the Pleistocene epoch. Before the MPT, the glacial cycles were dominated by a 41,000 year periodicity with low-amplitude, thin ice sheets and a linear relationship to the Milankovitch forcing from axial tilt. After the MPT there have been strongly asymmetric cycles with long-duration cooling of the climate and build-up of thick ice sheets, followed by a fast change from extreme glacial conditions to a warm interglacial. The cycle lengths have varied, with an average length of approximately 100,000 years.The Mid-Pleistocene Transition was long a problem to explain, as described in the article 100,000-year problem. The MPT can now be reproduced by numerical models that include a decreasing level of atmospheric carbon dioxide and gradual removal of regoliths from northern hemisphere areas that have been subject to glacial processes during the Quaternary. The reduction in CO2 may be related to changes in volcanic outgassing, burial of ocean sediments, carbonate weathering or iron fertilization of oceans from glacially induced dust. Before the Quaternary, northern North America and northern Eurasia are believed to have been covered by thick layers of regoliths, which have been removed over large areas by subsequent glaciations. Ice with its base on regolith at the pressure melting point will slide with relative ease, which limits the thickness of the ice sheet. Later glaciations were increasingly based on core areas with thick ice sheets strongly coupled to bare bedrock.

OIF

OIF may refer to:

Ocean iron fertilization, the intentional introduction of iron to the upper ocean to stimulate a phytoplankton bloom

Office for Intellectual Freedom, a department of the American Library Association

Operation Iraqi Freedom, the United States' code-name for the Iraq War from 2003–2010

Optical Internetworking Forum, a non-profit industry organization founded in 1998

Organisation internationale de la Francophonie, an international organization representing Francophonic and Francophilic countries and regions

Ocean acidification

Ocean acidification is the ongoing decrease in the pH of the Earth's oceans, caused by the uptake of carbon dioxide (CO2) from the atmosphere. Seawater is slightly basic (meaning pH > 7), and ocean acidification involves a shift towards pH-neutral conditions rather than a transition to acidic conditions (pH < 7). An estimated 30–40% of the carbon dioxide from human activity released into the atmosphere dissolves into oceans, rivers and lakes. To achieve chemical equilibrium, some of it reacts with the water to form carbonic acid. Some of the resulting carbonic acid molecules dissociate into a bicarbonate ion and a hydrogen ion, thus increasing ocean acidity (H+ ion concentration). Between 1751 and 1996, surface ocean pH is estimated to have decreased from approximately 8.25 to 8.14, representing an increase of almost 30% in H+ ion concentration in the world's oceans. Earth System Models project that, by around 2008, ocean acidity exceeded historical analogues and, in combination with other ocean biogeochemical changes, could undermine the functioning of marine ecosystems and disrupt the provision of many goods and services associated with the ocean beginning as early as 2100.Increasing acidity is thought to have a range of potentially harmful consequences for marine organisms, such as depressing metabolic rates and immune responses in some organisms, and causing coral bleaching. By increasing the presence of free hydrogen ions, the additional carbonic acid that forms in the oceans ultimately results in the conversion of carbonate ions into bicarbonate ions. Ocean alkalinity (roughly equal to [HCO3−] + 2[CO32−]) is not changed by the process, or may increase over long time periods due to carbonate dissolution. This net decrease in the amount of carbonate ions available may make it more difficult for marine calcifying organisms, such as coral and some plankton, to form biogenic calcium carbonate, and such structures become vulnerable to dissolution. Ongoing acidification of the oceans may threaten future food chains linked with the oceans. As members of the InterAcademy Panel, 105 science academies have issued a statement on ocean acidification recommending that by 2050, global CO2 emissions be reduced by at least 50% compared to the 1990 level.While ongoing ocean acidification is at least partially anthropogenic in origin, it has occurred previously in Earth's history. The most notable example is the Paleocene-Eocene Thermal Maximum (PETM), which occurred approximately 56 million years ago when massive amounts of carbon entered the ocean and atmosphere, and led to the dissolution of carbonate sediments in all ocean basins.

Ocean acidification has been compared to anthropogenic climate change and called the "evil twin of global warming" and "the other CO2 problem". Freshwater bodies also appear to be acidifying, although this is a more complex and less obvious phenomenon.

Ocean fertilization

Ocean fertilization or ocean nourishment is a type of climate engineering based on the purposeful introduction of nutrients to the upper ocean to increase marine food production and to remove carbon dioxide from the atmosphere. A number of techniques, including fertilization by iron, urea and phosphorus have been proposed.

Ocean storage of carbon dioxide

Ocean storage of carbon dioxide (CO2) is a method of carbon sequestration. The concept of storing carbon dioxide in the ocean was first proposed by Italian physicist Cesare Marchetti in his 1976 paper "On Geoengineering and the carbon dioxide Problem." Since then, the concept of sequestering atmospheric carbon dioxide in the world's oceans has been investigated by scientists, engineers, and environmental activists. 39,000 GtC (gigatonnes of carbon) currently reside in the oceans while only 750 GtC are in the atmosphere. Of the 1300 Gt carbon dioxide from anthropogenic emissions over the last 200 years, about 38% of that has already gone into the oceans. Carbon dioxide is currently emitted at 10 GtC per year and the oceans currently absorb 2.4 Gt carbon dioxide per year. The ocean is an enormous carbon sink with the capacity to hold thousands more gigatons of carbon dioxide. Ocean sequestration has the potential to decrease atmospheric carbon dioxide concentrations according to some scientists.

Oceanic carbon cycle

The oceanic carbon cycle (or marine carbon cycle) is composed of processes that exchange carbon between various pools within the ocean as well as between the atmosphere, Earth interior, and the seafloor. Carbon is an element that is essential to all living things; the human body is made up of approximately 18% carbon. The carbon cycle is a result of many interacting forces across multiple time and space scales that circulates carbon around the planet, ensuring that carbon is available globally. The Oceanic carbon cycle is a central process to the global carbon cycle and contains both inorganic carbon (carbon not associated with a living thing, such as carbon dioxide) and organic carbon (carbon that is, or has been, incorporated into a living thing). Part of the marine carbon cycle transforms carbon between non-living and living matter.

Three main processes (or pumps) that make up the marine carbon cycle bring atmospheric carbon dioxide (CO2) into the ocean interior and distribute it through the oceans. These three pumps are: (1) the solubility pump, (2) the carbonate pump, and (3) the biological pump. The total active pool of carbon at the Earth's surface for durations of less than 10,000 years is roughly 40,000 gigatons C (Gt C, a gigaton is one billion tons, or the weight of approximately 6 million blue whales), and about 95% (~38,000 Gt C) is stored in the ocean, mostly as dissolved inorganic carbon. The speciation of dissolved inorganic carbon in the marine carbon cycle is a primary controller of acid-base chemistry in the oceans.

Earth’s plants and algae (primary producers) are responsible for the largest annual carbon fluxes. Although the amount of carbon stored in marine biota (~3 Gt C) is very small compared with terrestrial vegetation (~610 GtC), the amount of carbon exchanged (the flux) by these groups is nearly equal – about 50 GtC each. Marine organisms link the carbon and oxygen cycles through processes such as photosynthesis. The marine carbon cycle is also biologically tied to the nitrogen and phosphorus cycles by a near-constant stoichiometric ratio C:N:P of 106:16:1, also known as the Redfield Ketchum Richards (RKR) ratio, which states that organisms tend to take up nitrogen and phosphorus incorporating new organic carbon. Likewise, organic matter decomposed by bacteria releases phosphorus and nitrogen.

Based on the publications of NASA, World Meteorological Association, IPCC, and International Council for the Exploration of the Sea, as well as scientists from NOAA, Woods Hole Oceanographic Institution, Scripps Institution of Oceanography, CSIRO, and Oak Ridge National Laboratory, the human impacts on the marine carbon cycle are significant. Before the Industrial Revolution, the ocean was a net source of CO2 to the atmosphere whereas now the majority of the carbon that enters the ocean comes from atmospheric carbon dioxide (CO2). The burning of fossil fuels and production of cement have changed the balance of carbon dioxide between the atmosphere and oceans, causing acidification of the oceans. Climate change, a result of excess CO2 in the atmosphere, has increased the temperature of the ocean and atmosphere (global warming). The slowed rate of global warming occurring from 2000–2010 may be attributed to an observed increase in upper ocean heat content.

Particle (ecology)

In marine and freshwater ecology, a particle is a small object. Particles can remain in suspension in the ocean or freshwater. However, they eventually settle (rate determined by Stokes' law) and accumulate as sediment. Some can enter the atmosphere through wave action where they can act as cloud condensation nuclei (CCN). Many organisms filter particles out of the water with unique filtration mechanisms (filter feeders). Particles are often associated with high loads of toxins which attach to the surface. As these toxins are passed up the food chain they accumulate in fatty tissue and become increasingly concentrated in predators (see bioaccumulation). Very little is known about the dynamics of particles, especially when they are re-suspended by dredging. They can remain floating in the water and drift over long distances. The decomposition of some particles by bacteria consumes a lot of oxygen and can cause the water to become hypoxic.

Phytoplankton

Phytoplankton are the autotrophic (self-feeding) components of the plankton community and a key part of oceans, seas and freshwater basin ecosystems. The name comes from the Greek words φυτόν (phyton), meaning "plant", and πλανκτός (planktos), meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye. However, when present in high enough numbers, some varieties may be noticeable as colored patches on the water surface due to the presence of chlorophyll within their cells and accessory pigments (such as phycobiliproteins or xanthophylls) in some species.

Plankton

Plankton are the diverse collection of organisms that live in large bodies of water and are unable to swim against a current. The individual organisms constituting plankton are called plankters. They provide a crucial source of food to many large aquatic organisms, such as fish and whales.

These organisms include bacteria, archaea, algae, protozoa and drifting or floating animals that inhabit—for example—the pelagic zone of oceans, seas, or bodies of fresh water. Essentially, plankton are defined by their ecological niche rather than any phylogenetic or taxonomic classification.

Though many planktonic species are microscopic in size, plankton includes organisms over a wide range of sizes, including large organisms such as jellyfish.

Technically the term does not include organisms on the surface of the water, which are called pleuston—or those that swim actively in the water, which are called nekton.

Russ George

Russ George is an American businessman and entrepreneur best known for founding the San Francisco-based firm Planktos Inc. which claims to "restore ecosystems and slow climate change". In 2007 he provided testimony to the House Select Committee on Energy Independence and Global Warming.

Siliceous ooze

Siliceous ooze is a type of biogenic pelagic sediment located on the deep ocean floor. Siliceous oozes are the least common of the deep sea sediments, and make up approximately 15% of the ocean floor. Oozes are defined as sediments which contain at least 30% skeletal remains of pelagic microorganisms. Siliceous oozes are largely composed of the silica based skeletons of microscopic marine organisms such as diatoms and radiolarians. Other components of siliceous oozes near continental margins may include terrestrially derived silica particles and sponge spicules. Siliceous oozes are composed of skeletons made from opal silica Si(O2), as opposed to calcareous oozes, which are made from skeletons of calcium carbonate organisms (i.e. coccolithophores). Silica (Si) is a bioessential element and is efficiently recycled in the marine environment through the silica cycle. Distance from land masses, water depth and ocean fertility are all factors that affect the opal silica content in seawater and the presence of siliceous oozes.

Syed Wajih Ahmad Naqvi

Syed Wajih Ahmad Naqvi is an Indian marine scientist and the former director of the National Institute of Oceanography. His work has concentrated in oceanic water chemistry, biogeochemistry, and chemical interrelations with living organisms. He has also performed research on freshwater ecosystems. He was the Chief Indian Scientist of LOHAFEX, an Ocean Iron Fertilization experiment jointly planned by the Council of Scientific Industrial Research (CSIR), India, and Helmholtz Foundation, Germany.

Aquatic ecosystems

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