富氧-缺氧过程对氧气分布及交换过程影响

中国环境科学2015，35(5)：1495-1501ChinaEnvironmentaIScience富氧一缺氧过程对氧气分布及交换过程影响古小治，张启超，一，孙淑霎。，一，陈开宁(1．中国科学院南京地理与湖泊研究所，湖泊与环境国家重点实验室，江苏南京210008；2．中国科学院大学，北京100049)摘要：为考察底层水体不同的氧动态对水土界面氧气交换过程影响，采用Unisence的微电极测试系统考察底层水体不同的复氧一缺氧环境(物理微曝空气供氧、添加过氧化剂的化学供氧及物理微曝氮气)中，沉积物一水界面氧气的分布及其传输机制，并评估不同富氧与厌氧过程对表层沉积物有机碳的矿化过程的影响．结果表明水体处极度厌氧状况，控制溶解氧分布和交换的水底扩散边界层(DBL)厚度明显变薄(一般在O．2,-0．4mm)且溶解氧衰变相对较缓．但底层水体溶解氧丰富甚至处于过饱和状态，DBL层的厚度(一般在0．4--0．7ram)相对较厚且氧气变化迅速(JP<0．05)．增加水体氧气供给的条件下，水体与沉积物间溶解氧交换过程加快，溶解氧交换通量由(4．87~0．92)增加至(5．31+0．66)及(17．14~3．15)mmolO2m2·d)交换速率，最高提升252％，温度升高氧气交换速率可增加15％，温度效应明显．关键词：氧气；交换；扩散边界层；有机碳矿化；沉积物中图分类号：X52，X144文献标识码：A文章编号：1000—6923(2015)05—1495—07Influenceofanaerobicandaerobicprocessesonbottomoxygendynamicandexchangeprocessacrosssediment-waterinterface．GUXiao．Zhi，ZHANGQi．chao，-，SUNShu．yun，CHENKai．ning(1．StateKeyLaboratoryofLakeScienceandEnvironment，NanjingInstituteofGeographyandLimnology,ChineseAcademyofScience，Nanjing210008，China；2．GraduateUniversityofChineseAcademyofScience，Beijing100049，China)．ChinaEnvironmentalScience，2015，35(5)：1495～1501Abstract：Toquantifyimpactsofoxygendistributiondynamiconexchangeprocessbetweensurfacesedimentandoverlyingwater，weemployedO2penetratingmicroelectrodesystem(UnisenceLtd．，Denmark)toobtainmultiplehighresolutionmicroprofilesofin-situ02，calculatedO2exchangerateusingFickFirstLaw．Besides，wealsoinvestigatedtheinfluenceofanaerobicandaerobicprocesses(microaerationairbubbles，microaerationnitrogenbubbles，injectionCaO2suspensionintosurfacesediments)onmineralizationofsoilorganicmatter．Inthepresentstudy，theresultsshowedthatdiffusiveboundarylayer(DBL)thicknesscontainingsignificantchemicalgradients，whichgreatlylimitedoxygenexchangebetweenbotomwaterandtopsoil，isdependentonoxygenlevelsinthebenthicoverlyingwater．Inanaerobicconditionsbymeansofnitrogenmicrobubbles，DBLrangedfrom0．2to0．4millimetersinthickness．However，DBLthicknessincreaseddramaticallybetween0．4-0．7mmrP<0．05)comparedtotreatmentswithbubblingairorinjectionCaO2suspensionintosurfacesediments．Also，02exchangewasaccelera