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Heavy Metals in the Environment: Using Wetlands for Their Removal - Chapter 4

Các nguyên tố hóa học như chì lưu thông trong biogeosphere và thông qua các nền kinh tế của nền văn minh. Đó là phong tục chu kỳ hóa chất tổng quan bằng cách làm cho sơ đồ đơn giản của thành phần chủ yếu, đường, và những nơi lưu trữ. Đơn giản hóa như vậy được gọi là hệ thống các mô hình. Trên một số sơ đồ, biểu tượng được sử dụng để hiển thị các mối quan hệ nhân quả. Trên sơ đồ khác giá trị số được đặt trên các con đường để hiển thị trong nháy mắt chảy và. | CHAPTER 4 Biogeochemical Cycle of Lead and the Energy Hierarchy Howard T. Odum CONTENTS Material Cycles in the Hierarchy of the Earth.51 Including Mechanisms in Systems Diagrams.54 Biogeochemical Budgets.54 Emergy of Materials in a Biogeochemical Cycle.58 Emergy per Mass of Lead.59 Transformity the Emergy per Unit Energy.60 The Wetland as a Heavy Metal Filter.60 Ecosystems Diagram Showing Mechanisms.61 Spatial Pattern of Dispersal.62 Frequency Distributions.65 Human Interactions with Lead.67 Evaluation Perspectives.68 Chemical elements such as lead circulate in the biogeosphere and through the economy of civilization. It is customary to overview chemical cycles by making simplified diagrams of principal components pathways and places of storage. Such simplifications are called systems models. On some diagrams symbols are used to show causal relationships. On other diagrams numerical values are placed on the pathways to show at a glance which flows and storages are more important. This chapter uses systems models to overview the principles of heavy metal distribution using the cycle of lead. New perspectives come from relating the elemental cycles to the natural energy hierarchy by which the earth is organized. When people in an organization converge their work to fewer supervisors and these in turn send fewer inputs to even fewer people at the top of the organization we call it a hierarchy. In turn those at the top spread their influence among those back at the lower levels. The biogeosphere processes energy through series of units including the atmosphere oceans continents living organisms industrial processes human beings etc. Each unit transforms input energy into a small amount of higher quality output energy that goes to the next higher level. A 49 2000 by CRC Press LLC 50 HEAVY METALS IN THE ENVIRONMENT USING WETLANDS FOR THEIR REMOVAL Toward Top of the Energy Hierarchy Increasing Quality of Energy Flow Figure 4.1 Diagram of a three-unit system arranged from