In1923VictorMoritzGoldschmidt,thefatherofmoderngeochemistry,proposedthe

geochemicalclassifica-onoftheelements(Goldschmidt,1923;Mason,1992).

TheclassificaAonoftheelements:lithophile(affinityforsilicate),siderophile(affinityfor

iron–nickel),chalcophile(affinityforsulfide),andatmophile(affinityforthe

gaseousstate)

Go l d s c hm i d t i n c l u d ed i n h i sclassificaAon the biophile elements.They are defined as ‘‘those elementsthatare themost typical inorganismsand organ ic mater ia l , o r a reconcentrated in and by living plantsand animals’’ (Bates and Jackson,1984).

Thebiophileelementsalloccuraslithophileand/orchalcophileelements.

Biophileelementsincludecarbon,hydrogen,oxygen,nitrogen,

phosphorus,sulfur,chlorine,iodine,bromine,calcium,magnesium,

potassium,sodium,vanadium,iron,manganese,andcopper.

Arsenic,lead,andmercuryhavegreataffinityto

concentrateinthebiosphere.

Undercertaincondi8onstheywillreachrelaAvelyhighconcentra:onsincoaland

humans.

TheyarebiophilebecauseofsubsAtuAons(leadforcalcium),bioaccumulaAon(arsenicandmercury),andmethylaAon

(mercury).

ResearchindicatesthataddiAonalclassificaAonofthesetradiAonalchalcophile

elementsasbiophileelementsisindispensabletofutureproperunderstanding

anduAlizaAonofarsenic,lead,andmercuryinthemodernindustrial,

developing,andimpoverishedworld.

BiophileelementsThe beauty of Goldschmidt’s classificaAon isthat it is based on the distribuAon of theelements. The siderophile, chalcophile,lithophile, and atmophile elements are welldescribedandlongaccepted(GarreT,2005).

Goldschmidt’soriginallistofmajorbiophileelementswasC,H,O,N,P,S,Cl,andI.HislistofminorbiophileelementswasB,Ca,Mg,K,Na,V,Mn,Fe,andCu.

Biophileelementsare

enrichedinthebiosphere—life,organicwaste,deadremains,andnaturally

processedmaterialsfromthebiosphere(coal,oil,

naturalgas,andkerogen).Themostsignificantbiophileelementsare

carbon,hydrogen,oxygen,nitrogen,phosphorus,and

sulfur.

Goldschmidt (1954) had listedeightmajor (C,H,O,N,P,S,Cl,andI)andnineminor(B,Ca,Mg,K,Na,V,Mn,Fe,andCu)biophileelements.Based on the abundance of elements in humans(Lindh, 2005 ),Na,Mg, K, andCa are included asmajorbiophileelementsandiodineisconsideredaminorbiophile.AddiAonalelementsincludedasminorbiophilearetheessen:almicronutrientelementsFe,Cu,Zn,I,Se,Mn,Mo,Cr,F,andCo.FuncAonalsimilariAesinsize and charge and its ease of subsAtuAon forcalcium in human bones place lead as a minorbiophileelement.

Other minor biophile elements that subsAtuteintobone includeSi,As,Br, Sr, andCd.Anothertype of funcAonal similarity iswhen an elementlocateddirectlybelowanelementontheperiodictablereadily subsAtutesfor it.Forexample,thechalcophile mineral sphalerite, ZnS, has as acommon subsAtute for zinc the elementcadmium(GreenwoodandEarnshaw,1997).Extending this type of funcAonal similarity tobiophile elements adds Rb, Sr, Cd, and Te asbiophile elements because of their easysubsAtuAonforK,Ca,Zn,andSe,respecAvely.

Environmentalgeochemistryandanthropogenicdispersionofarsenic,lead,andmercuryArsenic,AsAt1.8ppmarsenic isthe53rdmostabundantelementintheearth’scrust.Arsenic’stypicalconcentraAoninsoilis5ppm,while its average concentraAon in the UnitedStates coal is 22ppm.Arsenic’s abundance inseawater is 3 ppb. The oxidaAon states ofArsenicareAs5+,As3+,As,As2-, andAs3-.Mostarsenic used in industry is obtained as As2O3from flue dust at lead and copper smelters,though it is also obtained from arsenopyrite,FeAsS,andlollingite,FeAs2.

Arsenicisojenconsideredtheclassicexampleofasubstancethatisverytoxic(Fergusson,1990;Thornton, 1996 ; ATSDR, 2000 ). The toxicity of ingested arsenic varieswith oxida:on state andwhetheritisorganicorinorganic.Reducedformsaremoretoxicthanoxidizedformsandinorganicarsenic ismore toxic thanorganic arsenic. The largesthuman intakeof arsenic is from food (e.g.,seafood). Organic arsenic is of low toxicity. As5+ ismore soluble than As3+ . Inorganic forms ofarsenicoccurringingroundwateraremosttoxic.

Arsenic in groundwater can be a risk because it is both reduced and inorganic andarseniccompoundsreadilydissolveinwater.Drinkingwaterhascausedcasesofchronicand acute arsenic poisoning in Taiwan, ArgenAna, China, andMexico. A tragicmodernepidemic of arsenic poisoning from groundwater is occurring in 17 naAons includingregions of Bangladesh, southern Nepal, China, Vietnam, andWest Bengal and Bihar,India.Shallowtubewellsweredugintheseregionstoprovidedrinkingwaterfreeofthethreatsofdiarrhea,dysentery,typhoid,cholera,andhepaAAscommoninsurfacewater.

Ini:aldifferen:a:onistheformaAonoftheearthandits

separaAonfromthesolarsystem.Primarydifferen:a:onisthe

separaAonofearthintocoreandprimiAvemantle.Secondary

differen:a:onistheformaAonofcrust.Ter:arydifferen:a:onistheprocessofformaAonanddevelopmentofhydrosphereand

biosphere,andlithophileenrichmentofcrustbyplumeandplatetectonicacAvity.

Mercury,HgMercury is a classic chalcophile element occurring most commonly as cinnabar, HgS.NaturaloccurrencesofhighmercuryconcentraAonsarelimitedtoafewareasinthecrustwherehydrothermalprocesseshaveconcentratedcinnabarwithlesseramountsofnaAvemercury. Outside of these mineral deposits mercury is a rare substance; Hg is 68th inabundanceat80ppbintheearth’scrust,whiletheconcentraAoninseawateris0.03ppbHg.OxidaAonstatesofmercuryareHg,Hg+,andHg2+.

The world producAon and United StatesproducAon and consumpAon of mercury from1900to2002.TotalworldproducAonofHgfrom1900 to 2002 is esAmated to be 530,000 tons.United States consumpAon from 1900 to 1997was 130,000 tons. There has been no HgproducAonintheUnitedStatessince1992.DatafromUSGS(2003,2004).

Useofmercury inselectedyears intheUnitedStates(Jasinski,1994;SznopekandGoonan,2000).From1941to1996anesAmated93,000tonsofHgwasusedintheUnitedStates.Majoruseswerefor electrical (18,000 tons, includingbaTeries,wiringdevices and switches, and lighAng), chlorineand causAc soda manufacture (12,500 tons), paint (8400 tons), laboratory and measuring andcontrolinstruments(8700tons),pharmaceuAcal(3400tons),agriculturalchemicals(5500tons)anddental (2700 tons). Recovery by amalgamaAon of gold and silver is part of ‘‘other’’. Before 1978mercuryinbaTerieswasincludedwithinelectrical.