Abstract: An operating enterprise in northern China was selected as a case study to explore the pollution detection probability of soil and soil gas monitoring in operating enterprises,spatial distribution patterns,the applicability of the J&E and J&E-DED models,the relationship between measured and model-calculated concentrations,and the sensitivity of site parameters to the models.The results showed that:The pollution detection probability of soil monitoring at the case site was 58.2%,while that of soil gas monitoring was 91.1%,indicating that soil gas monitoring is more sensitive to the detection of benzene-series compounds and more effective in revealing pollution presence.The spatial distribution of benzene-series compounds in soil and soil gas at the case site exhibited some differences,with soil gas distribution being more susceptible to factors such as preferential underground pathways,surface cover layers,and biodegradation conditions in the subsurface.When the benzene concentration in soil was below 34 mg/kg and the toluene concentration was below 170 mg/kg,the J&E-DED model was more applicable,whereas the J&E model was more suitable beyond these thresholds.For ethylbenzene,m&p-xylene,and o-xylene,the J&E-DED model was generally more applicable.As soil concentrations increased,the difference between the two models' calculated concentrations decreased.When concentrations reached approximately 30 mg/kg,the concentrations calculated by the J&E and J&E-DED models were of the same order of magnitude.When concentrations increased to 10000 mg/kg or even higher,the J&E-DED model's calculated concentrations remained lower than those of the J&E model,with their ratios stabilizing at approximately 0.77,0.65,and 0.66.The measured soil gas BTEX concentrations represented a combination of the in-situ soil gas concentration at the sampling point and the contribution from lateral migration of soil gas from nearby sources.In many cases,measured concentrations exceeded modeled concentrations by several orders of magnitude.However,under high soil concentration conditions,for ethylbenzene,m,p-xylene,and o-xylene,which have higher octanol-water partition coefficients,modeled concentrations could be 2 to 4 orders of magnitude higher than measured concentrations.The J&E model was more sensitive to the organic carbon-water partition coefficient (K_oc) and soil organic carbon content (f_oc),while the J&E-DED model was primarily sensitive to soil organic carbon content (f_oc) and exhibited lower sensitivity to other site parameters.