July 9, 2013


Iron Is the Key -- Iron Ion Replenishment for Sustainable Oceans

Keywords: Ecosystems / Biodiversity Environmental Technology Newsletter 

JFS Newsletter No.130 (June 2013)

Adverse Effects of the Iron Deficiency in our Oceans

The Earth we live on is called the water planet because about 70 percent of its surface is covered with water. The oceans account for about 97 percent of this area, covering a total area of 360 million square kilometers at an average depth of 3,795 meters.

Seaweed and seagrass beds found in brackish waters and coastal areas are among the most important marine environments for living things. Seaweed beds serve as shelter and spawning grounds to various marine species, and they also function to purify water and maintain its oxygen supply by absorbing carbon dioxide through photosynthesis in seaweed and phytoplankton.

However, although Japan is surrounded by the sea, a phenomenon involving the massive loss of areas with seaweed and seagrass beds, called "isoyake" (literally "burned rocky shore" in Japanese), has taken place nationwide since the mid-Meiji period (1868-1912), causing negative impacts on fisheries. In recent years, areas where seaweed beds have vanished are increasing and expanding and thus accelerating a situation that could be described as "desertification of the oceans."

This phenomenon is thought to result from multiple factors that are moreover complexly intertwined, such as feeding damage caused by seaweed-eating species like sea urchins, decreased nutrient salt levels caused by reduced water flows from streams and rivers due to dam construction, as well as by typhoons, torrential rains, and freshwater inflow and mudflows from deforested areas upstream.

Under these circumstances, a new technique for supplying iron ions to the sea is attracting attention as a way to prevent the decline of seaweed beds. Iron ions function as a vital catalyst for every living organism on Earth because they activate the necessary enzymes when nutrients are ingested. Experiments in adding ferrous substances to oceans at various sites around the world started around 1990, and have verified that iron is also an essential trace element for phytoplankton.

Plants utilize iron in the form of ferrous ion (Fe2+). Iron tends to be easily oxidized and becomes red rust. After being oxidized, iron is precipitated in the poorly water-soluble form of ferric ions (trivalent iron; Fe3+), which plants cannot utilize. Taking a look at the natural world, on the forest floor in broadleaf forests with rich leaf mold, a humic substance called fulvic acid combines with ferrous iron contained in the soil and forms an iron-fulvic acid complex. This iron complex produced in upstream forests is transported by rivers to the sea and supplied to seaweed and phytoplankton.

However, the iron supply chain between upstream and marine ecosystems has not been functioning very well in recent decades due to various obstructive factors such as dam construction and river improvement works, and an increase in artificial forests of conifers that are not appropriately managed. These ecosystems are thus thought to have become iron deficient. Therefore, efforts are ongoing to support an alternative iron supply to the sea in the absence of an iron supply from forests.

Making Full Use of Daily-life Wisdom

Throughout Japan, people engaging in fishery and forestry are working together to plant broadleaf trees in the mountains, aiming to create nutrient-rich seas. Moreover, a unique activity in which iron ions are supplied artificially to the sea by using discarded disposable hand warmers is showing good results.

Japan's Toyama Bay: Working to Restore the Links between Forests, Rivers, and the Sea

The hand or body warmer is a pocketable tool for keeping warm. Japanese people formerly used a heated stone wrapped in cloth to keep warm since before the Edo period (1603-1868). In the Meiji period, another method was invented, in which a lighted fuel stick made from powdered charcoal and ashes was placed in a metal case that was put into a pouch. Subsequent methods evolved using a heat source employing the chemical principle that vaporized benzene generates heat when reacting with a platinum catalyst. Later hand warmers of the 1970s utilized the exothermic oxidation of iron powder, and innovative disposable hand warmer products first appeared on the market. They have been bestsellers ever since due to their convenience.

The idea of supplying iron ions from disposable hand warmers was developed by Mikio Sugimoto, a citizen scientist who lives in Ube City, Yamaguchi Prefecture. Since he found out about the function of iron in water about 35 years ago, he has been researching how to restore water environments on his own. He introduces himself as a farmer ("hyakusho" in Japanese, which is written "one hundred names" in kanji characters), proudly regarding farming as an occupation informed by hundreds of collected pieces of wisdom.

While engaged in farming, Sugimoto gradually began to feel that current farming practices dependent on chemical fertilizers and pesticides were imposing intolerable burdens on the water environment, for example by causing eutrophication. In the meantime, local sayings and daily life wisdom alerted him to the possibility that regular use of iron tools and products such as knives, sickles and spades helped purify water and revitalize the flora and fauna.

Some examples of local sayings include: no bad smells emanate from drains under fish stores, sushi restaurants and Japanese restaurants, where iron knife sharpening is a daily task; good fishing grounds with flourishing seaweed can be found around unexploded bombs sunk in the Seto Inland Sea off the coast of Ube City, which was attacked by air raids in the end of the World War II; shijimi clams (fresh water clams) are abundant under old iron bridges; and the practice of farmers who add red soil to supply iron and minerals to farm lands.

Supplying Ferrous Ions Using Familiar Materials

Sugimoto's goal of drawing out nature's power through the ecological food chain led to the idea of employing disposable hand warmers to supply ferrous ions by applying the iron-charcoal balls they contain.

Disposable warmers generate heat when iron powder reacts with air and rusts. To stimulate heat generation, the warmer is composed of water, salt, activated charcoal, and water retention agents together with iron powder. By the time the warmer completes its primary function of heat generation, the iron powder and activated charcoal have cohered and solidified. This block of apparently useless junk can be used to reactivate water environments filled with lives.

This is possible because, even though the solidified content inside used warmers is covered with oxidized iron, there remains some un-oxidized iron in the core. Placing the un-oxidized iron in water activates electrical corrosion, creating a battery that employs the potential electrical difference between iron and carbon, with water acting as the medium for electrolysis. As the result of the electron flow from iron to carbon, the iron discharges Fe2+, which dissolves in water. And, rejuvenated by the presence of the Fe2+, phytoplankton activates photosynthesis. At the same time, when Fe2+ combines with phosphorus in water, they transform into iron phosphate. This solidifies phosphorus and prevents eutrophication, a cause of abnormal growths of blue-green algae and red tide algal blooms. Moreover, the activated charcoal contained in the warmer contributes to water purification.

Using the same principle, iron-charcoal balls can be made of the iron powder taken out of used disposable warmers mixed with starch such as cooked rice and shaped into balls about five centimeters in diameter, which are baked. Because most iron in used warmers is already oxidized, they discharge lower levels of Fe2+. Sugimoto worked to make improvements, and started using charcoal obtained by burning forest thinnings or bamboo and waste iron powder obtained from local factories.

The simplest way to utilize disposable warmers after use is to pack as many used warmers as possible into a rough-mesh bag and just throw the bag into water bodies such as murky rivers. Results depend on the location; throwing disposable warmers into seawater begins to show results such as less sludge and restored seaweed growth in about three months. After six months, revitalized benthos such as shellfish, crabs and algae appear in the area. When thrown into freshwater, the bags are pulled out after a few months. The leftover contents of the warmers can be mixed with soil in planters and farmlands so that eutrophic substances absorbed by the activated carbon can function as fertilizer and enhance the propagation of bacteria in soil.

Working to Revive Local Seas

Sugimoto launched experimental restoration of algae beds using iron-charcoal balls at nearby waterfronts such as rivers that were emitting foul odors due to inflows of domestic wastewater, and later cooperated with local fishermen in his hometown of Ube City to spread about two tons of iron-charcoal balls over a 10-kilometer long swath of the seabed four kilometers offshore in the Seto Inland Sea. Seaweed beds there which had been in decline were restored -- large amounts of fish and shellfish including geoduck clams and razor clams, octopuses, shrimps, flatfish, and Japanese whiting were restored over two years' time, resulting in the biggest catches on record.

In 2008, about a ton of iron-charcoal balls were scattered on the seabed about 50 meters off a breakwater in the fishing port of Abu Town, Yamaguchi Prefecture. Two years later in 2010, seaweed beds had grown to about one to two meters high and young turban shells and whitebait had appeared. Four years later in 2012, the sea was found to have been restored to rich biodiversity, with shells, sea cucumbers, sea urchins, etc. On the other hand, there were no signs of restoration in areas where iron-charcoal balls had not been scattered.

As an extracurricular club activity at a fisheries high school directed by Sugimoto, a research project was launched in 2006 to restore the local sea in Nagato City, Yamaguchi Prefecture with iron-charcoal balls made by students. In December 2008, the research project received the second best prize for excellence at the national research conference for fisheries and marine high school students. Later, it evolved into a joint project involving public, private and academic sectors, with the Nagato city government, local fishery cooperatives, and the city board of education working to restore barren seafloors using iron-charcoal balls, while raising environmental awareness among local citizens. In 2010, the project team received the first prize at the same national research conference.

Efforts for ocean revitalization under Sugimoto's direction and/or with his advice have borne fruit in various places, including the prefectures of Niigata, Hiroshima, Shimane and Ehime, making progress in seafloor restoration with used disposable warmers and iron-charcoal balls.

During the last 50 years, the world's catches of fish have drastically increased. The regeneration capacity of fishery stocks has deteriorated due to overfishing and environmental degradation, pushing an increasing number of species on the verge of exhaustion. As the country with the sixth largest fish catch, the greatest volume of marine product imports, and the sixth highest seafood consumption per capita in the world, how can Japan contribute to a more sustainable use of marine resources in the future?

A minute amount of iron can tell us something about the mysterious cycle of life. We need to restore forests from their present derelict state so that they can provide iron ions to the sea again. Until then, we can hope that awareness of the need to enrich the marine environment will increase as each one of us learns about the complex connections between land and marine ecosystems through the action of supplying iron ions to the sea on behalf of presently incapacitated forests.

Note: Ferrous ion elution substance is patented by Mikio Sugimoto
Patent Number: 5258171
Mikio Sugimoto's website

Written by Kazumi Yagi