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.
Join GEOTRACES webinar series!
- Published on Friday, 17 April 2015 20:55
A 4-part webinar series presenting GEOTRACES research begins on April 30th!
It will focus on trace elements and what they can tell us about biogeochemical processes, the carbon cycle, and climate. Nine scientists, each studying a unique facet of ocean chemistry, will share their work and the importance of researching these rare and vital "clues" from the ocean.
How do key micronutrients get to the middle of the ocean? Why should (or shouldn't) we fertilize the ocean?
What are oxygen minimum zones? How might they affect life?
How are hydrothermal vent fluids created and how do they move through the ocean?
These topics (and more!) will be covered via presentations from scientists using interactive concept maps, brimming with images, videos and other resources available for use after the series concludes.
The presenters are: Ben Twining, Phoebe Lam, Kristen Buck, Kathy Barbeau, Claire Parker, Carl Lamborg, Dan Ohnemus, Brandy Toner and Jess Fitzsimmons.
- An Introduction to GEOTRACES - Thursday, April 30 - 7 pm ET / 4 pm PT
- Nutrients in the Open Ocean - Tuesday, May 5, 2015 - 4pm ET / 1pm PT
- The "Near" Shore - Thursday, May 7 - 7pm ET / 4pm PT
- Hydrothermal Vents and Megaplumes - Tuesday, May 12 - 7 pm ET / 4pm PT
The webinar series is organized by Ben Twining and hosted by the COSEE-OS office at University of Maine. This webinar series is free to attend but registration is required to participate. A computer with a working audio system and internet connection are needed to attend. Webinars and all of the materials presented will be archived online.
GEOTRACES Webinar Series Information:
GEOTRACES Webinar Series Registration:
Two GEOTRACES works question the present ocean chemical elements budgets
- Published on Thursday, 09 April 2015 09:24
New revelations on the land-ocean flux of chemical elements are presented in two different papers highlighting the value of the ocean isotopic data. Both works reveal that the present quantification of the oceanic cycle of the chemical elements need to be revisited...a big question to dig in!
When radiogenic and trace metal isotopes suggest that the land-ocean flux of elements have to be revisited
An extensive review of our present understanding and quantification of the oceanic budgets of the elements is proposed by Jeandel & Oelkers (2015, see reference below). Thanks to the international GEOTRACES programme (among others) isotopic data are currently acquired in the ocean and in its tributaries (rivers, estuaries...). Isotopes provide additional constraints to the oceanic budgets of the chemical species, and often reveal that these budgets are imbalanced. While this was already demonstrated for radiogenic Sr and Nd isotopes, recent data on Mo, Zn, Ni, Fe isotopes show that their budgets are also imbalanced. Since the processes yielding this disequilibrium are not clear yet, the possibility of an under-estimated input term has to be considered. The authors suggest that the term that would close the ocean isotope budgets could be, as for Nd and Sr, the dissolution of particles of terrigeneous origin.
Figure: Dissolved Si budget of the Mediterranean Sea, in 1010 mol/year (Ribera d'Alcala et al., 2003; Durrieu de Madron et al., 2009; Jeandel et Oelkers, 2015). It is estimated that 28.8 to 42.4 x 1010 mol/year of Si are released from the Mediterranean Sea to the Atlantic Ocean, but only 5.1 to 12.7 x 1010 mol/year are returned. It is not possible to balance this flux by considering dissolved river and atmospheric inputs alone. The authors suggest it requires the input from the dissolution of continentally derived particulates.
GEOTRACES Japanese Cruise in the South Pacific Ocean - Short report
- Published on Friday, 03 April 2015 13:27
The KH-14-6 cruise, nicknamed as "GRUS Expedition", has been conducted between December 2, 2014, and February 26, 2015, in the Pacific Ocean including the Antarctic Sea. The main purpose of the cruise is to establish the 2-dimensional profiles of trace elements and isotopes along the 170°W line (see figure below).
The cruise consisted of four legs, the leg-II (8 stations from GR-7 to GR-14) and the leg-III (7 stations from GR-15 to GR-21) of which were assigned for the GEOTRACES program. Water samples were collected from surface to near bottom by using a clean CTD Carousel Multi Sampling system (24 Niskin-X (12L) bottles) attached at the end of a Ti-armored cable. We occupied two stations, GR-6 (30°S, 174°E) in Leg-I and GR-13 (32°30'S, 170°W) in Leg-II for the purpose of inter-comparison with the data obtained by a previous Australian GEOTRACES cruise.
Figure: Track chart of the cruise KH-14-6 cruise. Click here to view the figure larger.
Chief scientist: Toshitaka Gamo, University of Tokyo
A new method to measure lead isotopes in the ocean with an outstanding precision
- Published on Friday, 06 March 2015 15:55
A new method for the determination of seawater lead (Pb) isotope compositions and concentrations was developed, which combines and optimizes previously published protocols for the separation and isotopic analysis of this element. It involves 1 to 2 L of seawater, double spike, magnesium hydroxide coprecipitation, anion exchange chromatography and thermal ionization mass spectrometry. Ratios involving the minor 204Pb isotope are a factor of five more precise than previously published data, yielding uncertainties better than ±3‰. Results are presented on GEOTRACES intercalibration samples and a first depth profile from the eastern South Atlantic Ocean.
Figure: Methodology to separate and analyse Pb isotopes and concentrations from seawater samples using a 207Pb-204Pb double spike and thermal ionisation mass spectrometry (TIMS). Click here to view the figure larger.
- How to constrain the biogeochemical cycle of cobalt in the surface Western Atlantic Ocean?
- New neodymium data in the North East Atlantic Ocean allow progressing on the behaviour of this geochemical tracer
- 5 minutes to improve Ocean Research
- What drives the silicon budget in the Bay of Bengal? The isotope composition clues...
- How iron isotopes offer a new window on the oceanic biogeochemical cycling of iron