1ESM 202Industrial Ecology, Life Cycle Assessment & Biogeochemistry2Lead Lead (Pb) is a nonessential, toxic “heavy metal” Soft metal in the elemental form (quite dense: 11.3 g/cm3) Important constituent of ~200 minerals, with an average concentration of ~ 1.6 g Pb per 100 kg soil (i.e. relatively rare) Natural releases from weathering of rocks, volcanic activity and radioactive decay3Lead Oxidation States Present as lead oxide and lead salts Three oxidation states:Pb0(elemental form), Pb2+, Pb4+ In organic compounds, lead can form up to four Pb-C bonds In terms of biogeochemical cycles, inorganic lead is the predominant form, although organic lead compounds may be significant on a local scale4Lead Use Given its properties, lead is one of the easiest metals to mine as PbS (galena), and smelting (transform from PbS to Pb0) requires only moderate temperatures More than 7000 years of use in human activities:Egyptians used it for weights, anchors, cooking utensils, piping, solder, pottery glaze,…High lead content found in remains of Roman “aristocrats” - due to lead in cooking utensils?5Lead Use Use of lead compounds greatly accelerated in the last 2 centuriestetraethyl lead (Eth4Pb) in gasoline, as an anti-knocking agent (octane booster) Eth4Pb is still used in many developing countries and in parts of Europe, since regulations are not as stringent Urban concentrations can be several thousand times higher than preindustrial6Lead7Lead Emissions8.6-54.1Total0.001-5.0Sea-salt spray to land0.1-1.6Vegetation0.5-6.8Forest fires0.4-16Volcanogenic3-31Windblown dust109g/yrNatural EmissionsSource: SCOPE 31 (1987)8Lead Emissions354Total5.9Miscellaneous0.1Phosphate fertilizers4.5Wood combustion7.4Industrial applications of lead50Iron and steel production0.8Secondary non-ferrous metal production85Primary non-ferrous metal production14Coal Combustion8.9Waste incineration177Gasoline and other fuel combustion109g/yrAnthropogenic EmissionsSource: Nriagu (1979)9Lead10Lead Production & Use11US Lead Production12Industrial Ecology of Lead13Industrial Ecology of Lead14Extraction of Materials15Recovery of Metals16Lead In 1973, gasoline averaged 2-3 grams/gallon of tetraethyl lead, (used since the 1920's) By 1986, lead content of 0.1 gram/gallon was the federal maximum in USA Approximately 4 million tons of lead are refined annually globally Most emissions from mining, smelting, vehicle emissions and industrial emissions from transformation of lead17Lead Also used to produce different alloys such as bronze and brass - common in bathroom and kitchen fixtures Most common source of lead exposure for children in the United States is from deteriorating lead-based paint and leaded dust in older homes Most common source of high-dose lead exposure for adults is occupational (selected industries)18Lead in Blood1976-19801988-199119Lead in Blood20Lead Lead poisoning in young children can produce permanent damage to the brain and may cause reduced intelligence and behavioral problems Lead poisoning can also have an effect on pregnant women, reducing a baby's birth weight, and causing premature birth It can also interfere with the formation of red blood cells21Lead Particle lifetime in the atmosphere depends on particle size, with particles greater than ~ 10 µm being deposited rapidly near the source (tens of meters) Small particles (less than 1 µm) can remain for a long time in the atmosphere, transported long distances before they increase their size or are removed from the atmosphere22Lead In aquatic systems, lead can form precipitates with carbonates (PbCO3) and sulfides (PbS) and thus be removed to sediments Some Pb-hydroxide complexes are also formed, but tend to redissolve easily- pH dependent Microbial activity is known to alkylate (methyl and higher alkanes) Pb to form organic lead compounds which can then be taken up by plants and animals23Lead Plants take up lead from water usually in ionic form (Pb2+) or in methylated form Submerged macrophytes tend to have highest lead concentrations - species and pH specific Terrestrial plants do not pickup significant amounts of lead from soils (usually bound) and foliar uptake of deposited lead is small Aquatic animals take up lead via ingestion of water and food, through gills and skin adsorption24Lead Inorganic lead exchanges with calcium in bones, accumulating to high concentrations Organic lead can be accumulated in fatty tissues - more toxic than inorganic lead Bioconcentration is not significant for lead: some studies show decreasing concentration as you go up in trophic levels - depends on exposure routes and availability of highly concentrated sources25Lead26Industrial Ecologyand Biogeochemistry27 28Life Cycle Analysis29Evaluating Impacts3031 32Life Cycle Analysis33Life Cycle Analysis34Life Cycle Analysis35Life Cycle Analysis36Life Cycle Analysis37Life Cycle Analysis38Life Cycle Analysis39Life Cycle Analysis40Life Cycle Analysis41IE = LCA + BGC Industrial Ecology is a powerful tool for preparing information for public debate Life-Cycle Analysis is intimately tied to an understanding of Biogeochemistry Like in BGC, you must Develop a conceptual modelMake assumptionsEvaluate fluxes (sources and sinks)Understand effects (damages) and