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25 August 2013 - 30 August 2013
Dates: 25-30 August 2013
Location: Florence – Italy
For further information: http://goldschmidt.info/2013/index
GEOTRACES Relevant Special Sessions:
This session aims at focusing on chemical weathering processes not taking place in the soils but in deeper aquifers, in floodplains, in estuaries and in marine sediments. It is of particular importance to evaluate the diversity of processes at play and their quantitative importance. Is our view of the global chemical weathering picture or global carbon cycle significantly modified when these marginal weathering environments are taken into account?
Marine sediments are the ultimate sink for many constituents in seawater, but this flux is significantly moderated at the seafloor before burial. Solute exchange between marine sediments and the overlying water column is occurring throughout the ocean basins. Elemental mass fluxes operate in both directions, often with profound effects on the local or global seawater chemistry. Rates of exchange are sensitive to various internal and external forcing mechanisms that operate on seasonal to geological time scales. In the shelf seas the benthic boundary layer communicates with the surface ocean through upwelling and mixing, thus providing a feedback between primary productivity and benthic respiration. Seafloor exchange in the deep ocean can contribute significantly in terms of the element’s global mass balance. Microbial processes are important drivers for many of these exchange processes in shallow and deep-sea sediments.
Technical innovations have led to improved quantification of these fluxes in the modern ocean, while development of novel paleo-proxies provide new insight into changes in the nature and rate of benthic-pelagic exchange over longer time scales. This session invites contributions that examine the process regulating benthic exchange, as well as techniques to quantify these fluxes on a variety of time scales.
Important physical, chemical, and biological processes in the ocean occur over a wide range of timescales from seconds up to millennia. Geochemical tracers provide tools to assess the rates and timescales of these processes. For example radiocarbon, nuclear bomb test products and long-lived U-series isotopes have been used to look at oceanic overturning circulation rates. Radiogenic thorium has been used to quantify fluxes of particles (and carbon) through the water column and to the seafloor, and radium has been used examine the extent of lateral advection from the continents to the ocean interior. These and other traditional and novel approaches provide insight into ocean mixing and biogeochemical cycling processes central to the ocean’s interaction with the Earth system as a whole. In this session we welcome contributions that use geochemical approaches to examining the rates of oceanic processes both in the modern ocean and in the past. Invited speakers – Bob Anderson and Pieter Van Beek.
Isotopic tracers are a powerful tool for studying the balance between physical circulation and biogeochemical processes that govern the cycling of elements within the global ocean. While the impact of the large-scale circulation on the marine distribution of radiogenic isotopes has long been recognized, the recent increase in measurements of stable isotopes in seawater has made it also possible to observe interactions between circulation and stable isotope distributions. This session aims to bring together these two fields by encouraging contributions pertaining to stable isotope constraints on the cycling of globally important macro- and micronutrients (e.g. nitrate δ15N, nitrate δ18O, δ30Si, δ56Fe, δ114Cd), as well as isotopic proxies that trace ocean circulation pathways (e.g. εNd). To this end, we explicitly solicit contributions from both the modeling and observational communities. While this session emphasizes isotopic tracers, other data (e.g. trace elements) that elucidate the interactions between physical circulation and biogeochemical processes governing marine elemental distributions in the modern or past ocean are also welcome.
Recent advances in analytical chemistry and molecular biological techniques indicate that trace metal micronutrients play an important role in regulating the species composition and physiological rate processes of the marine microbial community. Fully understanding the marine carbon and nitrogen cycles is thus intimately tied to our efforts to determine the distribution, chemical speciation and resulting bioavailability of trace metals to the marine biota. New and fruitful collaborations between chemical oceanographers and microbial physiologists are being achieved through, for example, high spatial resolution data as obtained via the ongoing international GEOTRACES program (www.geotraces.org). We invite submissions to this session which highlight trace metal-biota interactions and the complex interlacing of geochemical, physiological and ecological maps which shape the tempo and mode of carbon and nitrogen transformations in the ocean.