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<br /> <br />~ e <br />tif' '° <br />~. <br />1 '~ <br />. . <br />C D <br />~ \ ~;, ' <br />~. J. <br />.~. <br />tgure 6 -Spatial trmda in: fA) depth m the <br />le (cm); (B) oxygen tlon rate (moles <br />"~ar'7 (~ anlphue ooxeatndon (g!L); and (D <br />detxrirai condutxivity of the water at the w <br />le (µS). <br />stilphids oxidatioa.~2:1 lhwr telatiomhip <br />baweea sttiphata ptodaoed and oxygen cam®ad <br />was observed u lore oxidation rues ~iti'~ ~. At <br />hi~a rssaa, the tarygen oamsuatpdon rtes deviates <br />Emm the sulphas ptvdaaioo caret. The lower; than <br />e:petxed tadpbaae prodo~on ta~aq the <br />complex reutiona tech u Incomplete <br />trsnsiOrmatioa of sulphta species oo tulphsos taay <br />play a tole. 13is a tartaidy oontiareae rvilh <br />labotaoory stnrSet the hive idendded demmeal <br />anlphur when taidadon rues us high (!0). in say <br />tare, the tntygem ~ ~+ li~~Y <br />te6ea dosdy the release etas fbt salp~hate. <br />Oxygen waettmptioa rues aro compared <br />to the tlapth ao the sruer table, the sulphas <br />eoneeatration, and the cooduetivhy mneurmtasa <br />at all 26 tines ~ignre ~. 'Ihe water cha~mittry <br />tneasuremeata were based on water samples <br />eolleaed u the weer table. A ~raeral level in <br />oxidation rate of around 200 moles g m''yeaf` <br />was observed ut ttx southeastern part of the test <br />area and a eradoal detxeaee to the lower limit of <br />ms measurable oxidation rate rowarda north anti <br />oorthwrist. The spatial trtotd in tnJdatioa rates aro <br />conssteat whh du cbanga in the depth to water <br />table with decreasing raw towards the ptmd. The <br />trmda la the water chemistry Am also correlue <br />with the oxidation rates bat are somewha shdted <br />Onwards the pond, wrrapcrodiag m the genera! <br />stmt-satiate Bow diretxfoo. <br />The raulp of this field gaily indicated <br />thu oxygen cottstwption measursmaan provide a <br />reaonabte ettim>noe of oxidation raw m sulphide <br />wllttgs. There was a good agreement between <br />oxygen uptake anti the pmdactioa of sulphate <br />resulting from sttkpbide mineral tpddardon. The <br />' axygea coasampHon method an be rued m measure rates over a range of three ardera of magnitude. <br />a Thies study showed that oxygen consumption races exhibit comiasmt trends in time: and apace. <br />Run of oxidation are affected by tlepr6 0o tits water gble, the preetsee of asoiaure•radinirtg oon- <br />talphide {syesa at the: surfue and the age of exposed nilioga at the surtax. Rates at oxidation deueated <br />by a facmor of 1000 from s well~aiaed areas sad deeper water table ro the edge of the rulings pond. <br />i Placrateat of a 20 ®dtick fixaaad layer produced rate redut:tloot of amore then 200 time. Rues of <br />oxidation of fresh vnwddized tailings wrrs as high as two tlmea the rate observed fn the exiating tailings <br />thu had been exposed ro the oxygen a surface Far about eight pears. <br />1003 <br />