WEEKLY OCEAN NEWS

DATASTREME OCEAN WEEK FOUR: 16-20 February 2004

• Overhaul of national ocean policies and management needed -- A press conference at the recent AAAS meeting in Seattle, WA was the site for a meeting of members of the U.S. Commission on Ocean Policy and the Pew Oceans Commission where the results of their findings concerning the nation's oceans and policies needed to protect them. [EurekAlert!]
• Fish identification guide made available -- NOAA Fisheries and the Rhode Island Sea Grant Program recently announced the public release of a book entitled "Guide to Sharks, Tunas & Billfishes of the U.S. Atlantic & Gulf of Mexico". [NOAA News]
• New devices used to track fish -- Scientists from a several laboratories, marine refuges and universities recently reported on how new acoustic tags and underwater listening devices can track the daily activity of various fish, thereby providing added knowledge needed to design effective conservation measures. [EurekAlert!] In a related report, a scientist at Stanford University described the electronic tags used to track tuna. [EurekAlert!]
• Tracking atmospheric carbon to beneath the ocean floor -- An earth science professor at Rice University recently reported on his analysis of clathrate hydrates located just beneath the ocean floor. He suggests that these ice-like substances formed from water, methane and other gases by various biological and geological processes represent an enormous pool of carbon in the form of methane. [Rice University]
• Coral reefs threatened by climatic change and pollution -- In a report authored by scientists at the National Center for Atmospheric Research, the Kansas Geological Survey and Dauphin Island Sea Lab, a warning has been issued that warns that changes in the surface temperature and chemistry of the oceans will continue to damage coral reefs, biologically vital and economically important ecosystems. [EurekAlert!] Harbor Branch scientists suggest that pollution from such sources as sewage and agricultural runoff, is the main cause of the coral-smothering spread of seaweed on many reefs. [EurekAlert!]
• A new stage reached by the Hudson River Estuary -- Based on analysis of sediment accumulation, geologists at Lamont-Doherty Earth Observatory and Queens College have found that the stretch of the Hudson River called the Hudson River Estuary has reached what they consider as middle age. [The Earth Institute at Columbia University]
• The "iron fertilization" experiment still unproven -- A Duke University scientist reported that the decade-long small scale "iron fertilization" experiment whereby iron particles were broadcast across ocean waters in an attempt to promote increased photosynthesis by marine phytoplankton have not demonstratively produced the significant reduction in the absorption of atmospheric carbon dioxide needed to alleviate global warming. [EurekAlert!]
• Global and US Hazards/Climate Extremes -- A review and analysis of the global impacts of various weather-related events, including drought, floods and storms during the current month. [NCDC]
• Earthweek -- Diary of the Planet [earthweek.com] Requires Adobe Acrobat Reader.

Concept of the Week: Minerals from the Ocean Floor

Mineral resources extracted from Earth's crust (e.g., metals, non-metallic minerals) are considered nonrenewable because in the context of human history, the geological processes that generate them occur at such slow rates. For all practical purposes, the supply of these resources is fixed and finite. Most mineral resources are extracted from deposits on land; very little is mined from the sea floor. However, as future demand for mineral resources increases-especially for those critical or strategic minerals in limited supply-and if economic conditions permit, more of these resources will likely come from the seabed. These potential seabed resources originate either on land or on the ocean floor.

Today, the only seabed mineral resources that are exploited include certain metals, gemstones, and sand and gravel. Most of these resources are products of weathering and erosion of continental rock and sediment and transported in suspension to the sea by rivers along with other lithogenous particles. Metals and gemstones are sorted and concentrated by ocean circulation in coastal or submarine sediment deposits (known as placer deposits). Although hundreds of such deposits are known from around the world, very few are actually being exploited. Today, dredging of placer deposits usually takes place in shallow waters just offshore, yielding tin (Thailand and Indonesia), gold (Alaska, New Zealand, and the Philippines), and diamonds (Namibia and South Africa). Worldwide, sand and gravel is the most widely recovered marine resource and is used for construction purposes and beach nourishment (Chapter 8). Rivers also deliver minerals in solution to the sea including manganese ( which forms manganese nodules via biochemical cycling) and phosphorite (which precipitates from ocean water over continental shelves.) Neither of these seabed resources is currently being mined.

Over the past several decades, development of the plate tectonics concept has inspired interest in another source of marine mineral deposits: geological processes taking place at submarine plate boundaries (Chapter 2). Ocean basins include sites where mineral deposits form (a process called mineralization) rather than simply being on the receiving end of terrestrial minerals delivered by rivers. Along plate boundaries (including spreading centers and subduction zones) and at hydrothermal vents, magma, oceanic crust, and seawater interact, exchanging heat and chemicals and producing hydrothermal mineral deposits. Magma from Earth's interior heats the seawater that circulates through the fractures in the ocean crust. Hot seawater dissolves metals from the magma and crust, with those metals reacting with sulfur in the seawater to precipitate as sulfide minerals on the ocean floor. These hydrothermal deposits are potential sources of copper, zinc, silver, gold, and other metals. This type of mineralization is also a slow process-taking at least tens of thousands of years-so that hydrothermal mineral resources are also nonrenewable.

As is the case for seabed placer deposits, future development of hydrothermal mineral deposits depends on favorable economic conditions as well as consideration of potential environmental impacts. In any event, hydrothermal sulfide metals associated with subduction zones (e.g., in the western Pacific) are economically more promising for several reasons: a greater percentage of precious metals, occurrence at shallower ocean depths (1000 to 2000 m), and location within the 370-km (200-nautical mi) jurisdiction of coastal nations.

1. The origin of placer deposits of metals and gemstones on the continental shelf is [(rivers)(hydrothermal vents)].
2. For all practical purposes, seabed mineral resources are [(renewable)(nonrenewable)].

• 16 February 1832...The HMS Beagle with Charles Darwin onboard reached St-Pauls (1ºN, 29ºW).
• 16 February 1993...The Haitian passenger ferry Neptune sank, sending 1,215 Haitians to their deaths. Coast Guard units participated in the search and rescue operation but found no survivors. They then assisted in recovering the bodies of those killed. (USCG Historian's Office)
• 17 February 1836...The HMS Beagle and Charles Darwin left Tasmania.
• 18 February 1828...More than 100 vessels were destroyed in a storm at Gibraltar.
• 18 February 1846...A General order was issued by the Secretary of the US Department of Navy "on Port and Starboard", in which the term "port" replaced "larboard". (Naval Historical Center)
• 19 February 1473...Nicolaus Copernicus, the father of modern astronomy, was born in Torun in north central Poland. He was the first modern European scientist to propose that the Earth and other planets revolve around the Sun. (The History Channel)
• 19 February 1845...The Lighthouse Establishment was transferred to the Revenue Marine Bureau. Metal buoys were first put into service. They were riveted iron barrels that replaced the older wooden stave construction. (USCG Historian's Office)
• 19 February 1972...A vicious coastal storm dumped 10 to 20 inches of snow over interior sections of the mid-Atlantic and Northeast states and caused some of the worst coastal damage this century in New England. Storm surges up to 4.5 feet and winds gusting over 80 mph along coastal Rhode Island, Massachusetts, New Hampshire, and Maine resulted in extensive property damage and tremendous beach erosion. Twenty-seven houses were destroyed and 3000 damaged in Massachusetts alone. (Intellicast)
• 20 February 1823...English Captain James Weddell and the brig Jane reached 74º 15' S, or 940 mi (1520 km) from the South Pole. His voyage was farther south than anyone had ventured until the 1850s, as it was 214 miles south of the latitude that Captain James Cook had reached.
• 20 February 1856...The John Rutledge, an American steamer that sailed from Liverpool, England for New York, hit an iceberg in the North Atlantic. Most of the 155 people on board were lost.
• 21 February 1835 The HMS Beagle, along with Charles Darwin left Valdivia, Chile.
• 21 February 1907...During an exceptionally heavy gale, the British-owned mail ship Berlin hit dangerous shoals and broke up while attempting to navigate around the Hook of Holland in the English Channel. Only 14 on board survived, while 127 were killed or drowned.
• 22-26 February 1995...Cyclone Bobby slammed into the Western Australia coast causing widespread flooding. Some areas reported up to 12 inches of rain from the storm. (The Weather Doctor)

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Prepared by AMS DSOcean Central Staff and Edward J. Hopkins, Ph.D., email hopkins@meteor.wisc.edu
© Copyright, 2004, The American Meteorological Society.