다를 바

다를 바

結果 (中文) 1:

不同的

結果 (中文) 2:

不一样

結果 (中文) 3:

natural attenuation(NA)has become an accepted remediation strategy for a variety of contaminants including petroleum hydrocarbons()the success of NA as a remediation strategy depends on a thorough understanding of attenuation processes including the fate of degradation productsprevious studies at a crude oil spill site near bemid Ji，Minnesota have documented the progression of oil degradation through a series of terminingmethanogenesis along with significant CH4 concentrations were noted in the ground water at the site by 1987 and in the vadose zone by 1985(BAE decectdata from 2002 to 2003 indicate significant attenuation of the dissolved CH4 plume；however，the mechanism of attenuation is unknown(Amos et al .，2005)。previous studies of the fate of methane at the bemid Ji site used wells with screen lengths measuring 0.15 to 1.5m，with the longer screens generallydata from wells were useful in capturing plume scale processes but did not provide sufficient detail to capture the sharp redox gradients near the watturemany studies at this and other sites have shown that plume fringes are highly reactive zones where introduction of electron acceptors occurs and demonthe water table can be an especially reactive zone where O2，nutrients，and other TEAPs enter the ground water from both vadose zone gases andin a modeling study of the bemid Ji site，Amos and Mayer(2006)showed that entrapment of gas bubbles near the water table could result in enterprisethis result is consistent with laboratory column and numerical modeling studies that demonstrate enhanced O2 transport into anaerobic ground watersthe objective of the current study was to investigate the mechanism of CH4 attenuation in the groundwater at the bemid Ji site through the use of high REEthe use of direct-push profiling allows for greater spatial resolution and broader coverage in sampling than can be accomplished with the existingSpecifically，the study examined whether CH4 oxidation is occurring in the saturated zone near the water table，and the potential for aerobicmultivariate analysis provides a means of reducing the data to reveal the underlying governing processes that potentially control geochemical varartsPreviously，factor analyses and/or cluster analyses have been used to interpret spatial and temporal trends in geochemical data(Leesuk and Lee(1999)suggest that applying cluster analysis to factor scores can prevent the inclusion of trivial or unnecessary factors andthat approach is used here to reveal the spatial distribution of groundwater with similar geochemical characteristics。this approach was also used by Lee et al .(2001)to decipher major geochemical zones in a petroleum hydrocarbon contaminated aquifer