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)：1495~1501ChinaEnvironmentalScience富氧-缺氧过程对氧气分布及交换过程影响古小治1,张启超1,2,孙淑雲1,2,陈开宁1*(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-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-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0.2~0.4mm)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0.4~0.7mm)相对较厚且氧气变化迅速(P<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)mmolO2/(m2·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-zhi1,ZHANGQi-chao1,2,SUNShu-yun1,2,CHENKai-ning1*(1.StateKeyLaboratoryofLakeScienceandEnvironment,NanjingInstituteofGeographyandLimnology,ChineseAcademyofScience,Nanjing210008,China；2.GraduateUniversityofChineseAcademyofScience,Beijing100049,China).ChinaEnvironmentalScience,2015,35(5)：1495~1501Abstract：Toquantifyimpactsofoxygendistributiondynamiconexchangeprocessbetweensurfacesedimentandoverlyingwater,weemployedO2penetratingmicroelectrodesystem(UnisenceLtd.,Denmark)toobtainmultiplehighresolutionmicroprofilesofin-situO2,calculatedO2exchangerateusingFickFirstLaw.Besides,wealsoinvestigatedtheinfluenceofanaerobicandaerobicprocesses(microaerationairbubbles,microaerationnitrogenbubbles,injectionCaO2suspensionintosurfacesediments)onmineralizationofsoilorganicmatter.Inthepresentstudy,theresultsshowedthatdiffusiveboundarylayer(DBL)thicknesscontainingsignificantchemicalgradients,whichgreatlylimitedoxygenexchangebetweenbottomwaterandtopsoil,isdependentonoxygenlevelsinthebenthicoverlyingwater.Inanaerobicconditionsbymeansofnitrogenmicrobubbles,DBLrangedfrom0.2to0.4millimetersinthickness.However,DBLthicknessincreaseddramaticallybetween0.4~0.7mm(P<0.05)comparedtotreatmentswithbubblingairorinjectionCaO2suspensionintosurfacesediments.Also,O2exchangew