ScienceDaily (Sep. 13, 2008)
The precise timing of the origin of life on Earth and the changes in life during the past 4.5 billion years has been a subject of great controversy for the past century.
The principal indicator of the amount of organic carbon produced by biological activity traditionally used is the ratio of the less abundant isotope of carbon, 13C, to the more abundant isotope, 12C. As plants preferentially incorporate 12C, during periods of high production of organic material the 13C/12C ratio of carbonate material becomes elevated. Using this principle, the history of organic material has been interpreted by geologists using the 13C/12C ratio of carbonates and organics, wherever these materials can be sampled and dated.
While this idea appears to be sound over the last 150 million years or so, prior to this time there are no open oceanic sediment records which record the 13C/12C ratio, and therefore, geologists are forced to use materials associated with carbonate platforms or epicontinental seas.
In order to test whether platform-associated sediments are related to the global carbon cycle, a paper by University of Miami Professor Dr. Peter K. Swart appears in the Proceedings of the National Academy of Sciences. This paper examines changes over the past 10 million years at sites off the Bahamas (Atlantic Ocean), the Maldives (Indian Ocean), and Great Barrier Reef (Pacific Ocean). The variations in the 13C/12C ratio are synchronous at all of the sites studied, but are unrelated to the global change in the 13C/12C ratio.
It appears that records related to carbonate platforms which are often used throughout the early history of the Earth are not good recorders of the 13C/12C ratio in the open oceans. Hence, the work presented suggests that assumptions made previously about changes in the 13C/12C ratios of carbonate sediments in the geological record are incorrect.
"This study is a major step in terms of rethinking how geologists interpret variations in the 13C/12C ratio throughout Earth's history. If the approach does not work over the past 10 million years, then why would it work during older time periods?" said Swart. "As a consequence of our findings, changes in 13C/12C records need to be reevaluated, conclusions regarding changes in the reservoirs of carbon will have to be reassessed, and some of the widely-held ideas regarding the elevation of CO2 during specific periods of the Earth's geological history will have to be adjusted."
The study is funded by the National Science Foundation and the Comparative Sedimentology Laboratory at the University of Miami.WEATHER NOTE
Climate: New spin on ocean's role
New studies of the Southern Ocean are revealing previously unknown features of giant spinning eddies that have a profound influence on marine life and on the world's climate.
These massive swirling structures � the largest are known as gyres - can be thousands of kilometres across and can extend down as deep as 500 metres or more, a research team led by a UNSW mathematician, Dr Gary Froyland, has shown in the latest study published in Physical Review Letters.
"The water in the gyres does not mix well with the rest of the ocean, so for long periods these gyres can trap pollutants, nutrients, drifting plants and animals, and become physical barriers that divert even major ocean currents," Dr Froyland says.
"In effect, they provide a kind of skeleton for global ocean flows. We're only just beginning to get a grip on understanding their size, scale and functions, but we are sure that they have a major effect on marine biology and on the way that heat and carbon are distributed around the planet by the oceans."
One of the best known large-scale gyres in the world's oceans is that associated with the Gulf Stream in the North Atlantic, notes fellow researcher Professor Matthew England, co-director of the UNSW Climate Change Research Centre.MARITIME NOTE
Donjon responds to Ike
Hillside, N.J. headquartered Donjon Marine Co., Inc. has been playing its part in cleaning up after Hurricane Ike.
Donjon, whose services include marine salvage, heavy lift, dredging and related emergency response, was contracted by the U.S. Army Corps of Engineers through the company's salvage and related services contract with the U.S. Navy, Supervisor of Salvage of Diving, to remove and dispose of debris after Ike's trek through Texas.
To date, this debris has included vessels, containers and upland material, such as sections of houses and local storefronts, which accumulated in the Gulf Intracoastal Waterway just outside Galveston, Texas.
Donjon subcontracted this work to various area-based marine service providers for equipment and labor, while Donjon provided onsite project management, logistical and financial support.
The US Coast Guard issued a press release stating that, next Monday, it will formally propose regulations that will, if adopted, require operators of lake carriers to keep records of loading, unloading, and discharges of dry cargo residue. It will also encourage lake carriers to use control measures to reduce the amount of dry cargo residue entering waters of the Great Lakes. Discharges into certain protected and sensitive waters will be prohibited. Comments on the proposal should be submitted by January 15, 2009. (9/25/08).
The Australian Transport Safety Bureau (ATSB) issued the report of its investigation of a collision between a liquefied petroleum gas (LPG) carrier and a fishing vessel on 30 November 2007 off Queensland. Neither vessel was maintaining a proper lookout and the LPG carrier failed to report the collision and made no attempt to contact the damaged fishing vessel. (9/25/08).