Welcome to GEOTRACES
GEOTRACES is an international programme which aims to improve the understanding of biogeochemical cycles and large-scale distribution of trace elements and their isotopes in the marine environment. Scientists from approximately 35 nations have been involved in the programme, which is designed to study all major ocean basins over the next decade.
GEOTRACES Sections. For more information please click here. In red: Planned Sections. In yellow: Completed Sections. In black: Sections completed as GEOTRACES contribution to the IPY. Download the map.
What is controlling the copper isotopic composition in oceanic waters?
- Published on Friday, 19 December 2014 14:23
Takano and co-workers (2014, see reference below) strongly suggest that the isotopic composition of dissolved copper (δ65Cu) in surface seawater is mainly controlled by supply from rivers, the atmosphere and deep seawater. This is the conclusion of a study involving six vertical profiles of copper (Cu) concentration and isotopes measured in the Indian (1) and North Pacific (5). The finding contradicts preceding interpretations suggesting a strong role of the biological activity in δ65Cu fractionation.
At depth, δ65Cu values are becoming heavier with the age of deep seawater, likely due to preferential scavenging of the light isotope (63Cu). The authors built a box-model to quantify the oceanic budgets of both Cu concentrations and δ65Cu. Unbalance in this model suggests that Cu fluxes from continental shelf sediment might affect Cu distribution in the open ocean.
Figure: A box-model of Cu in the ocean based on both Cu concentration and isotopic composition. Click here to view the figure larger.
AGU Fall 2014 - GEOTRACES Special Sessions
- Published on Monday, 23 June 2014 13:14
American Geophysical Union Fall 2014 Meeting
15-19 December - San Francisco, CA, USA
Trace Element and Isotope Cycling in the Coastal Environment – 40 Years of Innovations
Conveners: Greg Cutter and Pete Sedwick
Trace metals and isotopes in the Eastern Tropical South Pacific: Results of the 2013 US GEOTRACES Zonal Transect and complimentary studies
Conveners: Jim Moffett, Chris German and Martin Frank
Productivity Proxies: New Developments and Records
Conveners: Fatima Abrantes, Bob Anderson and Heather Stoll
Biogeochemical cycling of silicon in coastal transition zones
Conveners: Claudia Ehlert, Patricia Grasse, Daniel J Conley and Mark A Brzezinski
The Biogeochemical Cycling of Mercury in the Coastal and Open Ocean
Conveners: Robert P Mason and Arthur Russell Flegal
Past Ocean Dynamics
Conveners: Joerg Albert Lippold, Luke Skinner and Sam Jaccard
See GEOTRACES full session abstract list.
GEOTRACES Japanese Cruise in the South Pacific Ocean
- Published on Monday, 01 December 2014 08:45
The latest Japanese GEOTRACES cruise (KH-14-6) of R/V Hakuho Maru will depart on Tuesday 2nd December from Tokyo (Japan) with the aim of establishing the first meridional profiles of GEOTRACES trace elements and isotopes (TEIs) in the South Pacific. On board of the cruise 52 Japanese scientists, technicians, and students, including 6 graduate students from other countries (China, Korea, Brunei, and Austria) will sail along ~170°W in the southern Pacific (GEOTRACES GP19 section).
This cruise will allow extracting important information on the biogeochemical cycles of TEIs and their roles in marine ecosystems, associated with the northward Antarctic Bottom Water which plays a key role in dynamic deepwater convection. In addition, data from this cruise will be compared with data obtained from a similar cruise held in 2004-2005, revealing any decadal changes in physical, chemical and biological parameters in the western Pacific.
Another important target of the cruise will be to study the submarine hydrothermal activity in the Mariana arc-backarc zone as a significant source of trace metals from lithosphere to seawater.
The cruise will consist of 4 legs: leg-1 (from Tokyo to Wellington), leg-2 (from Wellington to Auckland), leg-3 (from Auckland to Majuro), and leg-4 (from Majuro to Tokyo). It will return port on 26th February 2015.
Figure. KH-14-6 cruise track. Click here to view the figure larger.
PI : Toshitaka Gamo (University of Tokyo)
Seasonal iron supply in the Southern Ocean is dominated by winter mixing
- Published on Monday, 24 November 2014 10:06
An international team of researchers analysed the available dissolved iron data taken from all previous studies of the Southern Ocean, together with satellite images taken of the area, to quantify the amount of iron supplied to the surface waters of the Southern Ocean. They found that in contrast to the processes that supply so-called macronutrients in the tropics, seasonal iron supply is dominated by winter mixing with little iron input afterwards. This is because the vertical profile of iron is distinct from other nutrients, with subsurface reserves located much deeper in the water column and therefore only accessible by the deeper mixing that occurs in winter. This means that after this input pulse, intense iron recycling by the 'ferrous wheel' is necessary to sustain biological activity. This unique aspect of iron cycling is yet to be explained but places important constraints on how climate models represent the iron distribution and how changes in ocean physics impact iron limitation.
Figure. This diagram represents the seasonal variability in Southern Ocean iron (Fe) cycling.
Click here to view the figure larger.
- Why is the deep ocean zinc isotopic signature so heavy?
- Present day neodymium isotopic composition of the Caribbean Sea deep waters questions the paleo-application of this tracer in restricted basins
- UK GEOTRACES Process Study in the Celtic Sea
- The sources of the water soluble organic matter contained in the aerosols over the Atlantic ocean decoded
- Overview of the dissolved iron, manganese and aluminium distributions along the North Atlantic GEOTRACES GA03 section