Spring 2014 GEOC Sessions
247th National Meeting
Dallas, TX: March 16-20
Modeling the interface: mineralogy, environment and energy applications.
Organizers: Paolo Raiteri, Andrey Kalinichev, Peter Zapol, Stephen Parker
Chemical processes occurring at the solid liquid interface are critical for the stability and performance of materials. Particles exchange and chemical reactions occurring at the interface are indeed responsible for the dissolution/growth of the material as well as for the incorporation of contaminants and ultimately determine the properties of the material. Computer simulations and experiments are tackling this problem from opposite directions and the constant progress of technology is rapidly closing the gap between them making a truly atomistic understanding of the solid liquid interface morphology and reactivity a reality. This session will focus on the recent advances in the area of interface science between water and natural and man-made materials. Both computational and experimental papers are welcome.
1) Ab initio studies of chemical reactions at the interface
2) Molecular dynamics of water-solid interfaces
3) Interaction of solvated species with mineral surfaces
4) Structure and composition of reactive interface
5) Chemical reactions at the interface in the presence of defects and
Geochemical Processes at Mineral-Water Interfaces: From Atomic-Scale Observations to Field-Scale Phenomena
Organizers: Francesco Bellucci, Anastasia G. Ilgen, Sebastien Kerisit, Sang Soo Lee
Mineral-water interfacial chemistry exerts a significant control over the composition of natural environments. This symposium will consider research presentations that highlight recent experimental results on geochemical processes at mineral-water interfaces, including interface structure and reactivity, ion adsorption-desorption rate and mechanisms, chemical and biological controls on mineral nucleation, growth and dissolution, surface-mediated redox reactions, and the effects of organic matter and biota on surface reactivity. Presentations will be focused on fundamental studies of the mechanisms controlling surface and interfacial chemistry, as well as advances in experimental design and technical development for interrogating mineral-water interfaces.
Geochemistry of Nuclear Waste Storage and Disposition
Organizers: Eric M. Pierce, Louise J. Criscenti, and Joseph V. Ryan
Nuclear power, a carbon free source of electricity generation, represents one solution to the looming energy crisis and the potential impact of CO2 on climate change. Currently, nuclear energy represents ~10 to 15% of the net electricity generation in the United States. With the projected increase in US total primary energy consumption and the desire to reduce CO2 emission from fossil fuels (e.g., coal); nuclear power offers an attractive solution. However, for the US to realize a nuclear power renaissance requires closure of the nuclear fuel cycle. A key aspect to closing the nuclear fuel cycle is the storage and disposition of nuclear waste in geologic systems. For example, the ability to predict the behavior of waste forms (e.g., mineral and glass) over geological time scales constitutes one the main scientific challenges for evaluating the long-term impacts of nuclear waste storage on public health and environmental resources.
This symposium will focus on the geochemistry of nuclear waste storage and disposition. We invite paper submissions that highlight geochemical issues associated with solid-fluid interactions and govern the long-term weathering of mineral and glass waste forms.
Geochemistry and Reactive Transport in Shale Nanopores
Organizers: Louise Criscenti, Thomas Dewers, Young-Shin Jun, Yifeng Wang, Hongkyu Yoon
Shales have become increasingly highlighted in our search for unconventional gas and oil resources, storage of CO2, and disposal of nuclear waste. Complex nanopore structures and surface properties pose a challenge in understanding the coupled multiphysics involved in non-Darcy fluid flow and reactive transport within this important rock type. In addition, a better understanding of geochemical and environmental reactions is essential to designing safer energy-related subsurface operation strategies, predicting their performance, and assessing potential risks. This session seeks contributions with a focus on water/shale/gas interactions, geochemical tracers (isotopes, organics, metals), and water chemistry for understanding the mechanisms and processes involved in generation, migration, trapping, and recovering of these resources in unconventional low-permeability systems. We welcome imaging, experiments, and modeling contributions from the molecular to the continuum scale. Topics of interest include, but are not limited to, reactive transport, mineral-brine interactions, the properties of water, adsorption, osmotic effects, and nanopore and brine chemistry related to shale gas extraction and geologic storage of CO2 and nuclear waste disposal in shale.
Advances in understanding the environmental geochemistry of manganese (Mn) oxides
Organizers: Xionghan Feng, Wei Li, Mengqiang Zhu
Manganese oxides (Mn-oxides) are critical environmental minerals that play a significant role in adsorption, co-precipitation and redox reactions in the earth’s near surface environment, affecting biogeochemical cycling of numerous nutrients (e.g., P and N) and contaminants (e.g., As, Cr, Pb and phenols). However, there are still many missing knowledge in terms of the environmental geochemistry of Mn-oxides, such as the biogenic formation mechanisms, the detailed crystal structure of nanocrystalline phases, electron transfer routes in redox reactions, adsorption mechanism of contaminants at the surface, physiochemical factors controlling the contents of structural Mn(III) and vacant sites that largely determine Mn oxide reactivity, and the mysterious role of Mn(III) in the above processes as well.
In this proposed symposium, we invite papers that can advance the current understandings of the role that Mn-oxides play in biogeochemical processes from either experimental or modeling perspectives. Topics within this theme may include, but are not limited to: 1) formation mechanisms and phase transformation of Mn-oxides of both biotic and abiotic origin; 2) application of experimental (e.g., X-ray spectroscopic and scattering, and electron paramagnetic resonance) or modeling approaches (e.g., molecular dynamics and quantum chemical calculations) in understanding the structure of nanocrystalline Mn-oxides; 3) biogeochemical coupling of Mn with other redox-sensitive elements (e.g., N and Cr) in soil and aquatic environment; 4) surface reactivity of Mn-oxides towards heavy metals and other environmentally-relevant substances (e.g., dissolved organic matter); and 5) applications of Mn-oxides or Mn-bearing materials in soil remediation, water treatment, and air purification.
Biogeochemistry in support of climate-land modeling
One of the significant challenges facing climate modeling today is the representation of molecular-scale processes. State-of-the-art climate-land models utilize grid sizes of a few tens of km. In contrast, molecular-scale processes occur within pores and at interfaces having dimensions of a few tens of micrometers or smaller. This leaves a 9 orders-of-magnitude "scaling gap" between explicit spatial model representation and process dynamics. Incorporation of molecular-scale process knowledge into climate models is limited by the complexity of soil organic matter (SOM), subsurface materials, and of geochemical and microbiological reaction networks, as well as by limitations in model upscaling schemes, and computational power. Omission of molecular-scale processes from climate-land models, however, is undesirable. For example, transformation of SOM into greenhouse gasses (GHGs) such as carbon dioxide and methane occurs at the molecular scale within soil and sediment pores. The physical, geochemical, and biological characteristics of these environments, through time and across landscapes, profoundly influence the pathways and rates of GHG production. In this fashion, molecular-scale processes dictate whether or not a landscape will be a source or sink of GHGs and the extent of their emissions or uptake.
George Aiken (USGS)
Jon Chorover (University of Arizona)
Raoul-Marie Couture (Waterloo)
David Lipson (San Diego State)
Satish Myneni (Princeton University)
Geochemistry Poster Session
Organizer: Andrew Stack