Geochemical and Hydrological Reactivity of Heavy Metals in Soils - Chapter 6

Silicon-Töông hữu cơ trong môi trường và trong sinh vật Hiện nay, có trong địa hóa học và văn học khoa học đất một tầm quan trọng lớn trên ý nghĩa môi trường tương tác giữa các loài vô cơ, khoáng sản bề mặt, các phân tử hữu cơ và vi khuẩn. Nhấn mạnh đã có mặt trên chelation các chất dinh dưỡng kim loại nặng từ các khoáng sản khoáng sản hữu cơ trung gian giải thể, và đính kèm vi khuẩn bề mặt khoáng sản. Trong chương này, tôi tập trung trên oxy sau khi kim đồng, silicon, đó là nguyên tố phổ biến. | 6 Silicon-Organic Interactions in the Environment and in Organisms Nita Sahai CONTENTS Introduction Phospholipid-Oxide Surface Interactions Differential Effect of Oxides on Cell Membrane Structure Molecular Composition of Cell Membranes Phospholipid Adhesion to Oxides Thermodynamic Basis for the Membranolytic Potential of Oxides Crystal Chemistry and Interfacial Solvation Effect of Exchange-Free Energy Effect of Adsorption Entropy Model Interpretation Model Prediction for Behavior of Stishovite Relevance to Cell Attachment Role of Dissolved Si-Organic Complexes in Biology Approach to Studying Putative Si-Organic Complexes Rationale for Using MO Calculations Computational Details Computational Results and Interpretation Si-Polyalcohol Complexes Si-Amino Acid Complexes Relevance to Biological Silicon Uptake Summary References 2003 by CRC Press LLC INTRODUCTION Currently there is in the geochemical and soil science literature a great emphasis on the environmental significance of interactions between inorganic species mineral surfaces organic molecules and microbes. Much of the emphasis has been on the chelation of heavy metal nutrients from minerals by organically mediated mineral dissolution and on bacterial attachment to mineral surfaces. In this chapter I focus on a metalloid silicon which is the most abundant element after oxygen in the Earth s crust. I summarize results of theoretical studies for silicon-organic interactions where the silicon exists in the solid phase as quartz or amorphous silica and where the silicon is dissolved in aqueous solution. The studies are motivated by a desire to understand silicon-organic interactions in the natural environment and in organisms. PHOSPHOLIPID-OXIDE SURFACE INTERACTIONS Interactions of amphiphilic molecules with oxide surfaces can serve as a model to understand cell attachment at mineral surfaces an .