Alan Shiller 1. I would be interested in participating in shore-based analysis of samples following the cruises. I have a long-standing interest in the distributions/geochemistry of several elements including Ga, V, and Mn. 2. I hope that the implementation folks will give some thought to the possibility of H 2 O 2 analyses in near surface waters during these cruises. This (as well as other reactive oxygen intermediates) could be a useful interpretive tool particularly for redox-active trace elements. 3. I would be especially interested in a Pacific section that comes out of the Sea of Okhotsk. I suspect this marginal sea has an important impact on the NW Pacific.

Billy Moore - Section I propose 16 stations for the GEOTRACES track across the Atlantic to collect radium samples that would be used to determine the inventory of 228 Ra and 226 Ra in the upper 1000 m of the water column. The stations should be spaced roughly every 4 degrees of longitude across the ocean. Samples could be collected by in situ pumping through Mn-fiber canisters at 10 different depths or by combining most of the water from a single rosette cast to 1000 m depth (about 300 liters) into a single sample. The in situ pumping would provide details of the distribution in the water column and an opportunity to collect large volume particulate samples at the same time. The rosette cast would be a fast way to collect the essential data and could provide limited water samples (10% of each bottle) for other projects. Since the supply of 228 Ra is closely linked to the supply of submarine groundwater discharge (SGD) (Moore, Sarmiento and Key, 2008), changes in 228 Ra would imply changes in SGD fluxes.

Billy Moore - Process Study I propose that we initiate Process Studies at each end of the GEOTRACES N. Atlantic track, i.e. the coastal waters of Massachusetts and northern Spain. These studies should be directed to determining fluxes of TEI’s from the continent to the ocean (or in certain cases, e.g. uranium, from the ocean to the continent). The needs for such studies are well documented in the GEOTRACES Science Plan. The best way to plan these Process Studies would be to convene a separate international workshop directed to these specific sites. The workshop would be charged with developing the strategy for implementing the studies, selecting key TEI’s and other parameters to measure, identifying scientists willing to undertake these studies, setting a time frame, and investigating funding opportunities in addition to the usual GEOTRACES sources.

Landing-Measures Aerosols I propose to deploy aerosol and rain sampling equipment on these cruises (either me or some combination of collaborators). All of this equipment would be mounted on the 02 or 03 decks, as far forward as possible. We would collect daily aerosol samples and event rain samples so we would not need any wire time, and the ship tracks are not all that critical. We would need some lab space for filter handling and rain sample processing. I could make do with a regular 6'x4' table in a lab space where I could hang a HEPA clean air blower from ceiling unistrut tracks. We would need at least one berth, and perhaps 2, depending on how much shipboard processing needs to be done. The aerosol handling takes less than 3 hours per day, so whoever goes from my group would also be available to help with rosette operations and subsampling in the GEOTRACES van.

Biological Response Pigments (Stan Hooker) FRRF? …

Large Volume Samples Halfnium isotopes - Water mass tracer. “ Enough global stations should be sampled for Hf isotopes to yield a solid picture of the behavior of Hf isotopes along the global conveyor belt. ” Fallout (bomb test) isotopes were sampled during GEOSECS. “ Enough global stations should be sampled for fallout isotopes to yield a solid picture of their evolution over the 3 decades since GEOSECS. ”

Lamborg - Mercury 1) Margins – Hg methylation on the shelf/slope is an important area of research, and integration of open ocean sampling with that closer to shore and particular cross-shelf would be very powerful. The issue of cross-shelf transport is also an important one for a number of elements, and inclusion of such ship tracks in conjunction with the application of radiochemical and other tracers would be an exciting addition to GEOTRACES. 2) Hydrothermal Influences – As I’ve recently found, hydrothermal systems could be large sources of Hg and methylated forms of Hg especially. The impact of this source on the wider ocean is difficult to assess based on vent fluid sampling alone, and therefore I feel that selection of cruise tracks near known hydrothermal systems as well as the dedication of ship time to plenty of associated deep water and plume sampling be considered.

Lamborg - Mercury 2/2 3) Oxygen Minimum Zones – Though relative oddities in the ocean, oxygen minimum zones could be locations of very dynamic Hg species cycling. Furthermore, such zones could be growing the ocean due to macronutrient runoff, making this research area particularly relevant to themes regarding a changing ocean. My person interests lie in the OMZ of the Arabian Sea near India, and I therefore suggest that ship tracks in that location be included in the Indian Ocean cruises and at a time that best facilitates the observation of this phenomenon. 4) Particle Dynamics – The flux of Hg from the surface ocean to the deep is a central aspect of this metal, and most others, cycling. Particle sampling and study often gets neglected, and I therefore request access to and adequate wire time for in-situ pump sampling, and perhaps even drifting sediment trap studies to be made available. 5) Air-Sea Exchange – Hg is an unusually volatile metal, and its air-sea exchange is a large and highly influential term in the Hg cycle. Thus, I request that sampling towers/space and meteorological support be made available for those of us studying volatile species so that we can adequately fold this aspect of biogeochemistry into our budgets.

Peuker-Ehrenbrink - Osmium GEOTRACES offers a unique opportunity and ideal programmatic framework for resolving the significant first order questions about the marine chemistry of Os. 1: Does Os behave as a conservative element in seawater? 2: Is the 187 Os/ 188 Os ratio of Os dissolved in seawater homogeneous given the precision of isotope ratio analyses? The Atlantic Ocean, specifically the central Atlantic that is influenced by Saharan dust inputs, is ideally suited for investigating the affects of atmospheric deposition on the Os chemistry of seawater. Cruise tracks in the western North Atlantic (e.g., Labrador Sea; a cruise track from Iceland to East Greenland) are ideally suited to investigate spatial homogeneity in 187 Os/ 188 Os due to the contrasting Os isotope composition of the adjacent land masses. Ideally, Os studies should be carried out in conjunction with neodymium isotope studies.

Sedwick - Time series Many TEI’s, particularly bioactive elements with episodic input functions (dust, rivers, ice) -- e.g., Fe, Co, Al -- exhibit extreme temporal variability on seasonal or shorter timescales. Time-series data from BATS suggest that there is as much as an order-of- magnitude increase in dissolved Fe concentration in the surface mixed layer over a period of 1-2 months following dust input. To place GEOTRACES Section results into context, I advocate that sections be designed to pass through existing (or new) stations where ongoing and additional time-series measurements and process studies might be encouraged - e.g., stations BATS, TENATSO etc. in the Atlantic. Such observations would also be augmented by the intercalibration cruises proposed for some of these stations (BATS, SAFe).