Geography
Lead
In the context of Geography, "lead" refers to a naturally occurring element that is commonly found in the Earth's crust. It is a heavy metal with various industrial uses, including in batteries, construction materials, and as a component in some types of gasoline. However, lead is also known for its toxic properties and can have harmful effects on human health and the environment.
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4 Key excerpts on "Lead"
eBook - ePubEnvironmental Forensics
Contaminant Specific Guide
- Robert D. Morrison, Brian L. Murphy(Authors)
- 2010(Publication Date)
- Academic Press(Publisher)
Elemental Lead is rarely found in nature. Lead is present in ores such as galena (cubic Lead sulfide, PbS), anglesite (rhombic Lead sulfate, PbSO 4), cerussite (rhombic Lead carbonate, PbCO 3), minim (a form of Lead oxide with formula Pb 3 O 4), and other minerals. Galena is the most important source. Lead also accumulates with Zn and Cd, Fe and other metals in ore deposits. Lead occurs in rocks as a discrete mineral, or as the major portion of the metal in the earth’s crust. It replaces K, Sr, Ba and even Ca and Na in the mineral lattice of silicate minerals. Among silicate minerals, potassium feldspars and micas are notable for their affinity to accumulate Pb; therefore, granitic rocks tend to have higher levels than basaltic ones (Table 4.2.2). Lead ranks about 36th in natural abundance among elements in the earth’s crust with an average crustal abundance of 16 ppm, and is the most abundant of the heavy elements with an atomic number >60 (Marshal and Fairbridge, 1999). Lead in surface water run-off originates from chemical weathering, municipal and industrial water discharges, and from atmospheric deposition. The concentration of Lead in natural waters is much lower than would be expected from the inputs because of adsorption of the element onto particulate matter (clay minerals, oxides and hydroxides of aluminum, iron and manganese). The adsorption decreases with lowering pH of the water. Under reducing conditions Lead precipitates as highly insoluble sulfide. During production (mining, roasting, refining), use (antiknock agents, tetramethylLead, batteries, pigments, ceramics, plastics, glasses), recycling, and disposal, Lead enters the environment. Estimates of the emissions of individual sources of Lead indicate that atmosphere is the major initial recipient and that contributions from the anthropogenic sources are at least 1–2 orders of magnitude greater than natural sources
eBook - ePubLead
Chemistry, Analytical Aspects, Environmental Impact and Health Effects
- José S. Casas, José Sordo(Authors)
- 2011(Publication Date)
- Elsevier Science(Publisher)
Chapter 1An overview of the historical importance, occurrence, isolation, properties and applications of Lead
José S. Casas and José Sordo, Departamento de Química Inorgánica, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.Publisher Summary
This chapter provides an overview of the historical importance, occurrence, isolation, properties, and applications of Lead. Lead and its derivatives are widely used, and world trade in this metal, either impure or refined, as well as in its minerals and compounds, has extensively increased in recent years. The large amount of the produced metal, the high economic value of its trade, and the fact that its production and transformation employs a large number of people, all make Lead an extremely important metal. Although Lead can be found in the nature as a pure element, this is extremely rare and it is usually present in deposits with different origins. In these sources, it is combined with other elements—such as sulfur and oxygen—in a variety of minerals that have a wide range of compositions. Lead ores in deposits are usually present in other minerals and rocks. These ores cannot be smelted immediately after they have been mined, so the first step in the production process is to concentrate the ore to obtain a higher concentration of Lead.1 HISTORICAL IMPORTANCE
Nowadays Lead and its derivatives have a very widespread use and world trade in this metal, either impure or refined, as well as in its minerals and compounds has been extensively developed. The large amount of the metal that is produced, the high economic value of its trade and the fact that its production and transformation employs a large number of people, all make Lead an extremely important material. This situation is not new and there is evidence of the use of Lead from very early times, well before the time of the Roman Empire [1
eBook - PDFHeavy Metals in the Environment
Using Wetlands for Their Removal
- Howard T. Odum(Author)
- 2016(Publication Date)
- CRC Press(Publisher)
Widely distributed in very dilute concentrations in oceans and air, the element converges to become more concentrated in centers of geobiospheric action of land formation and mountain building. The unit labeled economy (our modern civilization) uses rich deposits of fuels as energy for development of the assets of civilization that also require mined materials. BIOGEOCHEMICAL BUDGETS Previous authors have summarized data on the distribution of elements by putting estimates of average flow rates and storage quantities on simplified diagrams of the main features of the geobiosphere. Just as we call the average values of money stored and flowing each month in our BIOGEOCHEMICAL CYCLE OF Lead AND THE ENERGY HIERARCHY 55 Figure 4.5 Main features of the global biogeosphere showing principal mechanisms of interaction affecting circulation of Lead. (a) Units of global energy hierarchy from Figure 4.4; (b) main pathways affecting Lead (Appendix A4). Solar Energy Tide Ocean & Atmosphere Ecosystems Soils Sediment Deposition Continental Sedimentary Rock Mountains Crystalline Rock Civilization (a) Global Hierarchy Sea Water Solar Energy Tide Atmos. Storms Evap. Ecosyst. Weather Land Rain Substrate Runoff Ore Bodies Sedim. Deltas Wetlands River Discharge Economy Fuels Materials Solid Wastes: Air Liquid (b) Main Pathways Affecting Lead Deep Earth Deep Earth Deposition = Symbol for Units of the Earth that Have Storages and Autocatalytic Energy Transformation Processes = Symbol for Source of Energy and Energy and Materials from Outside the System that Has Been Defined = Interaction of Two Different but Necessary Inputs to an Operation 56 HEAVY METALS IN THE ENVIRONMENT: USING WETLANDS FOR THEIR REMOVAL Figure 4.6a-b Main flows of Lead in the geobiosphere (Appendix Table A4.2). (a) Lead circulation before civilization; (b) modern circulation of Lead.
eBook - ePub- Astrid Sigel, Helmut Sigel, Roland K.O. Sigel, Astrid Sigel, Helmut Sigel, Roland K.O. Sigel, Astrid Sigel, Helmut Sigel, Roland K. O. Sigel(Authors)
- 2017(Publication Date)
- De Gruyter(Publisher)
2 Biogeochemistry of Lead. Its Release to the Environment and Chemical Speciation Jay T. Cullen 1 and Jason McAlister 2 1 School of Earth and Ocean Sciences, University of Victoria, Victoria, BC, Canada < [email protected] > 2 Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC, Canada < [email protected] > ABSTRACT 1. INTRODUCTION 2. GEOCHEMISTRY OF Lead 2.1. Chemical Properties 2.2. Abundance in the Continental Crust 3. MOBILIZATION OF Lead 3.1. Natural Sources 3.2. Anthropogenic Sources 4. Lead IN THE ATMOSPHERE 4.1. Sources 4.2. Deposition and Fate 5. Lead IN THE TERRESTRIAL AND FRESHWATER ENVIRONMENT 5.1. Behavior in Soils 5.2. Speciation and Fate in Lakes and Rivers 6. Lead IN OCEAN WATERS 6.1. Distribution 6.2. Speciation 6.3. Biogeochemical Cycling 6.4. Lead Isotopes as Tracers of Ocean Processes 7. SUMMARY AND. CONCLUSIONS ACKNOWLEDGEMENT ABBREVIATIONS AND DEFINITIONS REFERENCES Abstract: Lead (Pb) is a metal that is not essential for life processes and proves acutely toxic to most organisms. Compared to other metals Pb is rather immobile in the environment but still its biogeochemical cycling is greatly perturbed by human activities. In this review we present a summary of information describing the physical and chemical properties of Pb, its distribution in crustal materials, and the processes, both natural and anthropogenic, that contribute to the metal’s mobilization in the biosphere. The relatively high volatility of Pb metal, low melting point, its large ionic radius, and its chemical speciation in aquatic systems contributes to its redistribution by anthropogenic and natural processes. The biogeochemical cycle of Pb is significantly altered by anthropogenic inputs. This alteration began in antiquity but accelerated during the industrial revolution, which sparked increases in both mining activities and fossil fuel combustion
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