U.S. JGOFS SMP IRON WORKSHOP 17-19 June 2002 Moss Landing, CA

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Results from this workshop are now available as an article written for Eos: "Workshop highlights role of iron dynamics in the carbon cycle", by Kenneth S. Johnson, J. Keith Moore and Walker O. Smith (posted 12 August 2002)
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A more detailed report is also available:
view article in html
download or view article as MS Word file
download or view article as PDF file

Our focus in the original meeting proposal to JGOFS was to synthesize recent field and lab work, fertilization experiments, and modeling efforts in regards to the marine iron cycle, and to promote interactions between modelers and observationalists.

The goals for the meeting can be summarized as:

1. To synthesize recent results from observational work and modeling efforts.
2. To examine how models are currently incorporating iron dynamics, and to determine whether there is new information that could be used to improve parameterizations/representations in the models.
3. To identify critical gaps in our knowledge of the marine iron cycle that are hampering modeling efforts, and to provide suggestions for future research.

PRESENTATIONS

- your powerpoint or other presentation can be linked here -

REFERENCES

PW Boyd (in press?). The role of iron in the biogeochemistry of the Southern Ocean and Equatorial Pacific: a comparison of in situ iron enrichments. DSR II Special Issue on the Southern Ocean. PW Boyd, GA Jackson and AM Waite (in press). Are mesoscale perturbation experiments in polar waters prone to physical artefacts? Evidence from algal aggregation modelling studies. Geophys. Res. Letters. ABSTRACT: The exceptional longevity (>50 d) of a phytoplankton bloom following the mesoscale iron-enrichment of Antarctic polar waters (SOIREE) considerably exceeded that reported for naturally-occurring blooms (15-20 d) in this region. During SOIREE, SF6-labelled waters increased from 50 km2 to > 1100 km2, and the greatest algal loss term was lateral advection (0.1 d-1), akin to "cell-washout" required to maintain laboratory algal chemostats. To test whether such advective losses could delay the onset of mass sedimentation, a published algal aggregation model was employed. It successfully simulated temporal trends in the onset of mass sedimentation during the tropical IronEx II bloom, yet suggested no such event during SOIREE. However, when an iron-enrichment of 100 km length-scale (i.e. characterised by low lateral advection) was mimicked for SOIREE, a marked increase in algal aggregate size occurred after day 15, indicative of the onset of mass sedimentation. Thus, careful interpretation of results is essential - especially for the fate of algal carbon - from such experiments. In particular for polar waters where the ratio of net algal growth to advective losses is low (2, SOIREE), compared to tropical waters (6, IronEx II), suggesting that the understanding of polar experiments will require the proper compensation for artefacts.

COMMENTS

Abiotic Iron Scavenging? by J. Keith Moore We have incorporated a somewhat simplified version of the ecosystem model we described in a recent DSR special issue into the 3D global ocean model at NCAR. In this 3D work it has become apparent that the non-biotic removal of iron is a crucial issue about which we know relatively little. The biological uptake can keep surface concentrations of dissolved iron at reasonable concentrations in most regions, but much of this iron is then dumped in the 100-500m range as sinking biogenic particles remineralize. Thus, there has to be a strong abiotic scavenging of dissolved iron at these depths to prevent a buildup of dissolved iron due to the large amounts of iron entering surface waters from dust deposition each year. Some questions I have for the workshop include: What processes control the rates of abiotic iron scavenging? Model efforts to date have tied scavenging rates to particle concentration (i.e. sum of all biota POC) or to sinking POC flux, or some combination of both. How do scavenging rates vary as a function of depth? There must be fairly high scavenging of dissolved iron at shallow to intermediate depths (< ~500m), but much lower losses in the deep ocean. What is the role of ligands in controlling scavenging rates? Clearly the binding of iron to ligands is a key process in determining scavenging rates. However, do we know enough about the dynamics of the ligands (sources, sinks, etc..) to attempt to incorporate into ecosystem models? PDF versions of our papers describing the ecoystem model are available online at the JGOFS SMP website: http://usjgofs.whoi.edu/mzweb/preprints.html I will also bring hard copies to the workshop

Airports:
The Monterey Airport (the closest airport to MBARI) is approximately 20 minutes south of Moss Landing. AmericaWest and United Airlines fly into Monterey Airport  The San Jose Airport is approximately 1.5 hours north of MBARI. Many major carriers fly into San Jose Airport.

Hotels:
PLEASE NOTE: The rate and room block listed below is only available until MAY 17th. Please make your reservation early and please mention IRON WORKSHOP or JGOFS IRON WORKSHOP. If you have problems with hotel reservations, please feel free to contact the hotel sales rep (Mary Carrieri) directly or Cyndi Stubbs at MBARI.

We have rooms blocked as follows:

Hotel	Telephone	Rate*	Description
Hilton Hotel 1000 Aguijito Road Monterey Monterey Hilton web page	831-373-6141 Mention: Iron Workshop or JGOFS Iron Workshop Mary Carrieri, Sales Manager	$99/night and $94 for Fed government	Free shuttle service from the airport. Full service hotel with restaurant on property.

Transportation:
Shuttle service from the San Jose and San Francisco airports:
There is a shuttle service that leaves roughly every hour. Please make a reservation with Monterey Salinas Airbus 831-883-2871
This shuttle has daily (almost hourly) departures from San Jose and San Francisco to Monterey.

Carpooling between Hotel and MBARI:
Rental cars and carpooling from the hotel is recommended for daily transportation to and from MBARI. As the agenda begins at 8:30 for a breakfast at MBARI, and the drive is ~20 min., those who need rides and those who can provide rides should meet in the hotel lobby at ~8:00-8:05 am on Monday.
Taxis are very expensive; there is no convenient bus service.

How to get to MBARI:
Please check the following web page: http://www.mbari.org/about/directions/directions.html

Pacific Forum Room - A variety of high-end AV equipment is available. Please contact Cyndi Stubbs ahead of time in order to reserve this equipment.

While on site, MBARI will provide:

• The following meals:
• Morning continental breakfast
• Buffet lunch
• First day welcome reception
• A message board for any messages for the workshop.

Other:

• Information about the local area is available including maps and items of interest, upon advance request
• MBARI is a non-smoking institute
• We strive to keep paper use to a minimum
• MBARI is not a conference center, we are a private research facility and cannot provide full conference service support. Please contact Cyndi Stubbs ahead of time for any specialized needs.

JGOFS Iron Workshop
June 17-19, 2002
MBARI
Cyndi Stubbs (831-775-1773)