Time: Monday, April 10, 2016 17：30 -18：30
Venue: Conference Building, No.8 room, Tianjin University, 92 Weijin Road
Title:Behavior of Minerals at Near-Surface Conditions: Interfacial Geochemistry
Speaker: Dr. Hui Henry Teng from the George Washington University
Abstract
The field of interfacial geochemistry is developed over the past three decades at the advent of surface sensitive techniques and in situ observation capabilities. The main scope of this field concerns the behavior change of minerals at near earth surface conditions where atmosphere, hydrosphere, biosphere, and lithosphere meet and interact with each other. The wide geochemical relevance of this field ranges from chemical and biochemical weathering, mineral transformation, soil formation, environmental processes, and ecological evolution. In this presentation, I will provide a high-level overview of this field covering the driving force of mineral behavior change, reaction sites at interfaces, and scientific approaches used to explore the interfacial processes. I will present three case studies highlighting the application of interfacial geochemistry studies to geological problems. The first is the surface process of feldspar weathering. Synchrotron radiation and in situ Atomic Force Microscopy data will be presented to illustrate that feldspar dissolution at different pH conditions is controlled by different physiochemical aspects of the mineral-water interface. The second case deals with cellular dissolution of serpentine by fungi. Bio-analytical, FIB-HRTEM, and AFM data will be combined to explore the cell-mineral interaction and the incentives for the microbes to decompose the mineral phase. The last example gives a sneak peek of the long-held dolomite problem that has puzzled geoscience for many decades. Non-aqueous reactions and in situ AFM observations provide strong evidence arguing against the widely-accepted cation hydration theory for the inability of magnesite and dolomite to mineralize at ambient surface conditions. The presentation will be concluded by a short discussion on the outlook of this field in hope to stimulate interests of students to pursue research in this field.
