American Geophysical Union Fall 2014 Meeting

American Geophysical Union Fall 2014 Meeting
Dates: 15-19 December 2014
Location:  San Francisco, California, USA

Abstract deadline: 6 August 2014

For more information: http://fallmeeting.agu.org/2014/

GEOTRACES sessions:

Trace Element and Isotope Cycling in the Coastal Environment – 40 Years of Innovations
Conveners: Greg Cutter and Pete Sedwick

It could be argued that the first comprehensive treatise on chemical oceanography in coastal environments – estuaries, salt marshes, and shelf waters – was found in the 1975 book “Marine Chemistry in the Coastal Environment.” In the almost 40 years since this publication, tremendous developments in sampling and analytical methods, treating the coastal zone as a coupled atmosphere, water column, and sediment system, and advanced modeling and simulation approaches have radically changed how we view these environments. Now that global investigations like GEOTRACES of trace elements and isotopes are including ocean margins, it is timely to discuss the most recent insights into the biogeochemical functioning of the coastal zone. We are soliciting presentations on the cycling of trace elements and isotopes between the atmosphere (aerosols/dry and wet deposition; gas exchange), water column, and sediments of the diverse coastal regime.

-> In point of fact, this session will be in honor of Dr. Tom Church (who edited the Marine Chemistry in the Coastal Environment book) upon his retirement from the University of Delaware. We will be having a retirement party for Tom the evening of the session as well, so I encourage you to submit an abstract on any aspect of your work that has, whether planned or not, relevance to the broad spectrum of coastal zone research Tom has touched – trace elements, radionuclides, atmospheric deposition, sediments, water column, etc. Then come to the party, which as many of you know from the Hawaii Ocean Sciences Meeting, I’m good at hosting!

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

The second US GEOTRACES sectional cruise was staged in 2013: a zonal transect from the Peruvian Coast to the central South Pacific. It included (1) the Peruvian Oxygen Minimum Zone (OMZ), (2) a vast oligotrophic region of the upper water column, and (3) an extensive hydrothermal plume originating from the East Pacific Rise.  Approximately 25 research groups were involved in the cruise, with samples collected for all key GEOTRACES parameters plus additional redox-sensitive tracers. The objectives were to understand the cycling of trace elements and isotopes in the highly diverse, overlapping regimes surveyed within the transect.  Submissions are invited from participants in the US GEOTRACES program, from other programs in the region (e.g. the German SFB754) with complimentary objectives – including related process studies – and from workers who have become involved in any aspects of data synthesis and modelling after the cruise was completed.

GEOTRACES-related sessions:

Productivity Proxies: New Developments and Records
Conveners: Fatima Abrantes, Bob Anderson and Heather Stoll

The role of the ocean in the global carbon cycle is greatly mediated by microorganisms through primary productivity and C export, the so-called biological pump. Understanding the sensitivity of the process and quantifying C export variability associated with past climatic conditions is fundamental to forecast how primary productivity may respond to the changing conditions generated by a CO2 increase in the atmosphere. To help reconstruct the response of the biological pump to past perturbations in forcing we need reliable, varied and independent proxies for: the oceanic physical state, nutrient availability and utilization, primary production and export, and, burial conditions. Many have been proposed through the years; however, problems with their utilization have also been identified. The plan for this session is to attain an overview of the recent progress in the creation of primary productivity related proxies, as well as recently generated past records.

-> Many of the trace elements and isotopes studied by GEOTRACES have been exploited as proxies of past changes in ocean biological productivity, nutrient utilization and water chemistry. We encourage presentations on the development, testing and application of these proxies.

Biogeochemical cycling of silicon in coastal transition zones
Conveners: Claudia Ehlert, Patricia Grasse, Daniel J Conley and Mark A Brzezinski

This session focuses on the bio(geo)chemical cycling of silicon between sources, sinks and within the dynamic transition zones, associated with the transformation of Si during transport from the freshwater to the marine environment. There are large variations in Si cycling in rivers and in estuaries, in the contributions of groundwater and pore water discharge to Si cycling in coastal regions, and within coastal zones themselves that result in large uncertainties in the global budget of silicon and in whether the silicon cycle in the ocean is in steady state. While this session emphasizes on the silicon cycle, other data (e.g. trace elements like cadmium, zinc, iron, aluminum, etc) that elucidate the main processes and interactions between macro- and micro- nutrients within transition zones are also welcome. We explicitly solicit contributions from both isotope analyses as well as concentration studies with a focus on field study results.

The Biogeochemical Cycling of Mercury in the Coastal and Open Ocean
Conveners: Robert P Mason and Arthur Russell Flegal

The ocean plays an important role in the global mercury cycle being the long-term sink for mercury emitted to the atmosphere, and air-sea exchange influences its residence time in the biosphere. Ocean fish are the major route for human exposure to methylmercury, an important health concern. Many processes are involved in the transformation of inorganic mercury to methylmercury asnd there is still uncertainty concerning the primary locations of its net methylation and bioaccumulation. The focus of this session is therefore presentations concerning mercury inputs into the marine environment, and the factors influencing the transformation (methylation, demethylation, oxidation and reduction), both biotic and abiotic, and fate in coastal and offshore waters, and methylmercury bioaccumulation into the marine food chain. Papers describing new laboratory studies, field investigations and/or modeling in coastal and offshore environments are welcome, as are papers using stable isotope signatures or other innovative approaches, or exploring global change implications.

Past Ocean Dynamics
Conveners: Joerg Albert Lippold, Luke Skinner and Sam Jaccard

The oceans have played a major role in amplifying past climate variability and causing shifts between regional, and perhaps global, climate states. In particular the meridional overturning circulations play an instrumental role in climate variability on a range of time scales, by storing and redistributing heat, fresh water, carbon and nutrients.Trace-element and isotope geochemistry (including radiocarbon) are powerful tools to constrain past changes in the distribution of water masses as well as the dynamics of past ocean circulation However, consensus on the occurrence, intensity and precise timing of past variations in the large-scale overturning circulation rate, for example during past abrupt or glacial-interglacial climate change, remains lacking. For this session we invite contributions addressing past ocean circulation change on millennial to glacial/interglacial timescales. We particularly encourage contributions involving inter-proxy comparisons and/or that integrate proxy data and models toward a quantitative understanding of past ocean circulation dynamics.