###### Abstract
One shortcoming, for example, is that their resolution is not fine enough to reflect plume fringes of the intrinsic biodegradation and their limiting factors of electron acceptors from the surrounding subsurface environment [36]. A substantial problem is the negligence of various hydrogeological variables and attenuation processes that may occur in subsurface environments (e.g., advection, dispersion, mixing). The resulting first-order rate constants thus describe bulk attenuation rather than local in situ biodegradation kinetics [37]. Another reactive model used for the in situ quantification of biodegradation is Michaelis-Menten (MM) kinetics, also known as Monod, no-growth kinetics, which presents the situations that the initial cell number is much greater than that could be produced using the substrate present at time zero [16; 38]. The MM model originates from biochemistry and is generally applied for enzyme kinetics in the quasi-stationary state. It relates the maximum turnover rate of one specific enzyme to the present substrate concentration (single compound) in the medium. The MM model requires that the amount of enzyme remains constant during the experiment and is not particularly useful for in-site simulation. Mass flux reflecting the contaminant mass loss through the control planes (CPs) perpendicular to the groundwater flow direction is often calculated to quantify the natural attenuation of petroleum hydrocarbons [39; 40; 41]. The 2D method and 3D mass balance approach for determining plume mass loss [42] have been used to estimate the natural attenuation. The 3D mass balance approach is more accurate but needs more monitoring information. Due to aquifer heterogeneity, the resulting plume delineation is strongly influenced by the positioning and number of monitoring wells [43; 44; 45]. In the application of the method, a few issues need to be addressed. Firstly, it is important to choose appropriate CPs and determine their lengths by the TPH concentration in groundwater, which can be an easy way but is actually sometimes not accurate. When enough monitoring wells are not available at the site, a pumping well is needed [41]. Secondly, the vertical distribution of TPH is to be delineated, and the mass quantity of plume compounds transformed between synoptic sampling events is estimated on the basis of dissolved phase concentrations, sorption characteristics, and groundwater flux [46; 47]. Although the assumption of sorption ideality is often applied, laboratory and field experiments can often provide evidence of the solute behavior that deviates from ideality. Thirdly, it is hard to calculate the TPH fluxes at each CP at various times under the presence of microbial degradation [48]. Therefore, many assumptions are to be made generally during the assessment. In this article, a study for the quantitative assessment of an organic contaminant plume at the typical petroleum contaminated site in NE China under a framework of the government core funding program (863) for clean and novel science and technology in the resources and environment section is reported. Extensive field surveys focusing on geology, hydrogeology, geochemistry, and fractions of the petroleum contaminants were carried out systematically in order to understand the contaminant hydrogeological processes and potential in situ remediation with enhanced monitored natural attenuation (e-MNA), air/bio sparging (AS/BS), and/or permeable reactive barriers (PRB). With the support of much monitoring data from the field samplings, a series of lab-based bench-scale experiments were conducted to understand the fate and transport mechanism of the petroleum contamination from land surface to shallow groundwater according to this site condition. The mathematical, statistical model, Mann-Kendall test, and mass flux were reported in this study.