Factors Controlling Deoxygenation of "Floodwater" Overlying an Acid Sulfate Soil: Experimental Modeling

(整期优先)网络出版时间:2003-04-14
/ 1
Anincubationexperimentwasconductedtosimulatetheeffectoffloodingonwaterdeoxygenationinacidsulfatesoilfloodplainsystems.Theoriginallyoxygenated'floodwater'couldbedeoxygenatedimmediatelyfollowing'flooding'anditislikelythatthiswascausedmainlybydecompositionoforganicdebrisfromtheinundatedplants.Deoxygenationeventuallyledtothedepletionofdissolvedoxygen(DO)inthe'floodwater'anditishighlypossiblethatthisresultedinthetransformationsofferricFetoferrousFe,sulfatetohydrogensulfide,andorganicnitrogentoammonia(ammonification).Theaccumulationofthesereducedsubstancesallowsthe'floodwater'todevelopDO-consumingcapacity(DOCC).Whenthe'floodwater'ismixedwiththeintroducedoxygenatedwater,apartfromthedilutioneffects,thereducedsubstancescontainedinthe'floodwater'oxidizetofurtherconsumeDOcarriedbytheintroducedwater.However,itappearsthattheDOdropinthemixedwatercanonlylastforafewhoursifnoadditionalDO-depleted'floodwater'isadded.EntryofatmosphericoxygenintothewatercanraisetheDOlevelofthemixedwaterandlowerwaterpHthroughtheoxidationofthereducedsubstances.