Metal Stocks in Society â Scientific Synthesis - UNEP

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Metal Stocks in Society – Scientific Synthesisand one for the aggregate of all types of steel(a mixture that is roughly 95 % iron). Geographically,an overwhelming majority of theestimates concern more-developed countries.Ona global basis, top-down estimatesfor in-use stocks exist for only four of theseelements: aluminium, copper, iron, and lead.The per capita stock of iron is largest, asbefits its high rate of flow into use; aluminium’sstock is slightly larger than that ofcopper, and that for lead is significantlylower. (Global values are generated by dividingtotal estimated in-use stock by globalpopulation. The results should not be interpretedas suggesting equivalent per capitain-use stocks around the world; most stocksclearly reside in more-developed countries.)a bottom-up basis. The locales are diverse:Stockholm, Vienna, New Haven, Cape Town,Beijing, and Sydney. There are still too fewbottom-up studies to evaluate the accuracy ofthis approach, although where comparisonsof results can be made, they appear reasonable.At the city level, it is possible to allocatethe stock on a spatial basis, and this hasbeen done for Cape Town and Sydney.Anthropogenic stock estimates exist for fiveprecious metals, as shown in Table 2; mostare for more developed countries. The exceptionis silver, for which a rather poorly documentedglobal estimate exists.Table 2.Extant In-UseMetal StockEstimationsfor PreciousMetals. aMetalNumber ofestimatesPercent ofall estimatesGlobal percapita stockMDC percapita stock bGold 2 1.6 35 – 90Palladium 2 1.6 1 – 4Platinum 2 1.6 1 – 3Rhodium 1 0.8 0.2Silver 2 1.6 110 13LDC percapita stock ca The years of the determinations in Tables 1 – 3 vary, but most are for the period 2000 – 2006. The units of per capita stock arekg of metal in most cases, but g of metal for cadmium, gold, mercury, palladium, platinum, rhodium, and silver. The totalnumber of estimates is 124.b The more-developed countries (MDC) used in this calculation are Australia, Canada, the European Union EU15, Norway,Switzerland, Japan, New Zealand, and the United States (altogether about 860 million people in 2005).c The less-developed countries (LDC) used in this calculation consist of all countries except those in the “more-developed”category (altogether about 5620 million people in 2005).18Few stock estimates are available on a regionalbasis - only aluminium for Europe,copper for North America and Europe, andstainless steel for several. The stock evaluationsare all quite recent, and appear reasonablyreliable. On a country basis, data existfor Japan, USA, Australia, and several Europeancountries.Urban-level evaluations have been performedfor several metals and several cities, all onFor the “specialty metals” (those used inmore modest quantities than the major engineeringmetals, particular for unique physicalor chemical properties), Table 3 gives the anthropogenicstock estimates. Twelve differentmetals are listed, none with more than threedeterminations. The only global estimate inthis group is for cadmium; it is seriously outof date and cannot be regarded with confidence.In a recent unpublished presentation,Halada (2008) described a top-down esti-
Metal Stocks in Society – Scientific Synthesismate of in-use stocks for some 20 elementsin Japan; he found that the Japanese in-usestocks of gold, indium, silver, tin, and tantalumwere 10 – 20 % of estimated virgin reservesof those metals, indicating the importanceof enhanced reserach efforts for theseless-abundant metals.For the more-developed countries, there issufficient information in Table 1 to computean average person’s allocation of in-usemetal stock. Doing so demonstrates thedependence of modern lifestyles on a substantialstock of metal, a perspective especiallyuseful because few individuals areaware of their share of metals in infrastructuressuch as communications, rail networks,and power generation and distributionsystems, as well as in their personal homesand vehicles. The average more-developedcountry citizen’s in-use metal stock is betweenten and fifteen metric tons. Of thisamount, five metals – iron, aluminium,copper, zinc, and manganese, make up morethan 98 %.One feature of the limited data is that thereappear to be significant differences atpresent in the per capita in-use stock of themore-developed and less-developed countries.Additionally, when measured at differentspatial levels suburban residents appearto have larger per capita in-use stock thando urban or especially rural residents, althoughthis is an observation that needs inputfrom future research on in-use stock variations.Given the obvious wealth discrepancies,these results seem qualitatively reasonable,but much work remains to be done tobetter understand stocks from a spatial (orspatial analytical level) perspective. An additionalfactor is that taking into account an entirenation may increase the per capita in-usestock due to infrastructure and other in-usefinal goods that occur only in sparsely populatedareas. Such final goods may includeships, large trucks, heavy industrial equipment,offshore drilling equipment, railways,military hardware, and aircraft.Table 3.. Extant In-UseMetal StockEstimationsfor SpecialtyMetals. aMetalNumber ofestimatesPercent ofall estimatesGlobal percapita stockMDC percapita stock bAntimony 1 0.8 1Cadmium 3 2.5 40 80Chromium 3 2.5 7 – 50Cobalt 1 0.8 1Magnesium 1 0.8 5Manganese 1 0.8 100Mercury 1 0.8 10LDC percapita stock cMolybdenum1 0.8 3Nickel 3 2.5 2 – 4Tin 2 1.6 3Titanium 1 0.8 13Tungsten 1 0.8 119a/b/c see table 2
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Metal Stocks in Society â Scientific Synthesis - UNEP