氧化还原条件对红枫湖沉积物磷释放影响的微尺度分析
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2020-03-14 10:36:37
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.,.LakeSci.(湖泊科学),2016,28(1):68—74D0I10.18307/2016.0108⑥2016byJournalofSciences氧化还原条件对红枫湖沉积物磷释放影响的微尺度分析徐洋,陈敬安,王敬富,罗婧(1:贵州大学资源与环境工程学院,贵阳550025)(2:中国科学院地球化学研究所环境地球化学国家重点实验室,贵阳550002)摘要:选取贵州红枫湖为研究对象,在实验室条件下模拟了自然、好氧和厌氧条件下沉积物内源磷的释放过程,联合应用微电极技术和沉积物磷形态分析对沉积物一水界面开展了微尺度观测与研究.结果表明,厌氧条件下红枫湖沉积物总磷含量显著降低,且主要是NaOH提取态磷(NaOH—P)和残渣态磷(rest—P)含量降低所致,厌氧条件下沉积物孔隙水中磷酸盐浓度明显升高,而好氧条件下沉积物孔隙水磷酸盐浓度显著降低,反映厌氧条件显著促进了红枫湖沉积物磷释放.厌氧条件下沉积物内部溶解氧浓度下降、硫还原活动增强可能是导致NaOH—P释放的主要原因.0,浓度的降低加速了沉积物还原作用并产生大量HS,进而与二价铁离子形成硫化亚铁沉淀,最终导致Na0H.P(Fe.P)释放到孔隙水中.好氧条件向厌氧条件的转换可通过改变沉积物内部pH值分布和微生物活动促使rest.P释放:厌氧条件下,厌氧微生物不仅可以消耗硫酸根产生HS,导致pH值降低,还可消耗有机质,将有机磷转变为无机磷.上述研究结果表明,沉积物一水界面氧化还原环境可影响沉积物氧渗透深度、pH值分布、微生物活动、硫循环以及有机质降解过程,进而控制沉积物磷的形态转化与释放.联合应用微电极技术和沉积物磷形态分析对湖泊沉积物一水界面开展微尺度观测研究是揭示沉积物内源磷释放机制与控制因素的有效途径.关键词:氧化还原环境;微电极;微尺度;沉积物内源磷;红枫湖Themicro·-scaleinvestigationontheefectofredoxconditiononthereleaseofthesedi·-mentphosphorusinLakeHongfengXUYang.CHENJing’an.WANGJingfu&LUOJing(1:CollegeofResourcesandEnvironmentalEngineering,GuizhouUniversity,Guiyang550025,P.R.China)(2:StateKeyLaboratoryofEnvironmentalGeochemistry,InstituteofGeochemistry,ChineseAcademyofSciences,Guiyang550002,P.R.China)Abstract:Inthispaper,LakeHongfeng,locatedinGuizhouProvince,waschosentostudythereleaseprocessofthesedimentphosphorusunderthenatural,aerobicandanaerobicconditions.Microscaleobservationofthephysicalandchemicalprope~iesofsediment-waterinterfacebymicroeleetrodetechnologywasused.togetherwitbtraditionalP—speciationanalysis,toexploretheP-re-leasingmechanisms.Theresultsshowedthatunderanaerobicconditions,thetotalcontentofphosphorusinthesedimentinLakeHongfengdecreasedsignificantly,whichwasmainlycausedbythereductionofNaOH—Pandrest—P,indicatingthattheaerobicconditionpromotedthephosphorusreleasefromsediments.Theconcentrationofphosphateintheporewaterofsedimentincreasedgreatlyunderanaerobiccondition.andthetrendwascontrarytothatunderaerobiccondition.Undertheanaerobiccondition,con-centration0fdissolvedoxygendecreasedandsulfatereductionwasenhanced.whichreleasedNaOH—Pfromthesediment.
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