Compound-specific isotope analysis has been demonstrated to be a powerful tool for the assessment of in situ pollutant degradation. Enrichment factor, an essential and prerequisite parameter, could be determined under simulated control laboratory in advance. However, different microbial community composition and substrate availability may significantly affect the accuracy of simulated enrichment factor. Here, a modified mathematic method of two dimensional is proposed to quantify the extent of pollutant degradation involving the break of carbon and hydrogen bond. In this new model, the laboratory cultures used to determine carbon or hydrogen enrichment factors in advance could be canceled and the key point to assess the extent of biodegradation is only determining the value of Λ_ri (dual C–H isotope slope calculated with a self-modified model) in the field investigation. As a new and convenient method, this math model greatly facilitates the investigation of pollutant degradation extent under field conditions. Two approaches are applied to evaluate the proposed model. With our model, the estimated results based on C isotope are consistent with those measured values, while those based on H isotope are unsatisfactory. This can be attributed to the differences in accuracy of C–H isotope determinations. Overall, enrichment factors and biodegradation rates calculated with the proposed model are comparable with those measured figures.

化合物特异性同位素分析已被证明是评估原位污染物降解的有力工具。富集因子是一个必不可少的前提参数，可以在模拟控制实验室中提前确定。然而，不同的微生物群落组成和底物可用性可能会显着影响模拟富集因子的准确性。在这里，提出了一种改进的二维数学方法来量化涉及碳氢键断裂的污染物降解程度。在这个新模型中，可以取消用于预先确定碳或氢富集因子的实验室培养物，评估生物降解程度的关键只是确定Λri的_值（使用自修改模型计算的双 C-H 同位素斜率）在实地调查中。该数学模型作为一种新的、便捷的方法，极大地方便了野外条件下污染物降解程度的调查。两种方法被用来评估所提出的模型。在我们的模型中，基于 C 同位素的估计结果与那些测量值是一致的，而基于 H 同位素的估计结果并不令人满意。这可归因于 C-H 同位素测定的准确性差异。总体而言，用所提出的模型计算的富集因子和生物降解率与那些测量数据相当。