| DNAPL场地污染通量升尺度预测的敏感性分析 |
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| 引用本文： | 宋美钰,施小清,康学远,吴吉春. DNAPL场地污染通量升尺度预测的敏感性分析[J]. 地质科技通报, 2023, 42(2): 327-335. DOI: 10.19509/j.cnki.dzkq.tb20220262 |
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| 作者姓名： | 宋美钰 施小清 康学远 吴吉春 |
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| 作者单位： | a.南京大学地球科学与工程学院, 南京 210023 |
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| 基金项目： | 国家重点研发计划项目2018YFC1800604国家自然科学基金项目41977157 |
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| 摘 要： | 重非水相液体(DNAPL)污染问题日益严重。为评估DNAPL污染场地的环境风险, 常采用升尺度模型推估DNAPL污染源区溶解相的质量通量(溶解通量)。由于升尺度模型中的参数较多, 调查成本较高, 因此需筛选模型中的关键参数, 指导实际污染场地设计合理的观测数据采集方案。首先对升尺度模型中6个参数(地下水平均流速q、标准化浓度C0/Ceq、离散状DNAPL质量比例GF0、初始时刻离散状DNAPL贡献的通量比例fg、拟合参数β1及β2)开展全局敏感性分析, 识别其中关键参数, 进而采用局部敏感性分析定量化关键参数的变化对通量预测的影响。研究结果表明, 参数q、C0/Ceq、GF0和fg对通量预测有较大影响。q和C0/Ceq在整个衰减过程中敏感性均相对较高, GF0和fg随着衰减过程的进行, 敏感性不断增高, 分别在衰减中后期和后期达到峰值; 对于不同结构的污染源区, q或C0/Ceq增大时, 通量的增幅基本不变。随着污染源区中离散状DNAPL和池状DNAPL间的质量比例(GTP)增大, GF0或fg增大时, 其对通量预测的影响不断增大或减小。因此在预测溶解通量时需将调查成本重点应用于q和C0/Ceq; 在合理设计污染源区修复方案时, 应重点调查GF0; 在预测污染源区寿命时, fg为重要调查对象; 对于所有结构的污染源区, q和C0/Ceq均为重要调查对象, 对于GTP较大的污染源区, 应将调查成本重点应用于GF0, 对于GTP较小的污染源区, 应重点调查fg。
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| 关 键 词： | 重非水相液体 溶解通量 升尺度模型 全局敏感性分析 局部敏感性分析 |
| 收稿时间： | 2022-06-07 |
Sensitivity analysis of upscaling prediction of the mass flux at DNAPL contaminated sites |
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| Affiliation: | a.School of Earth Science and Engineering, Nanjing University, Nanjing 210023, Chinab.Key Laboratory of Surficial Geochemistry of Ministry of Education, Nanjing University, Nanjing 210023, China |
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| Abstract: | Dense nonaqueous phase liquid (DNAPL) contamination is a growing problem. To assess the environmental risk of DNAPL-contaminated sites, the mass flux of the dissolved phase (mass flux) in the source zone of DNAPL contamination is often extrapolated using upscaling models. Due to the large number of parameters in the upscaling model and the high cost of investigation, the key parameters in the model need to be screened to guide the design of a reasonable observation data collection scheme for actual contaminated sites. In this paper, a global sensitivity analysis was first conducted on six parameters (mean groundwater velocity q, standardized concentration C0/Ceq, the mass ratio of ganglia GF0, the fraction of the mass flux attributable to the ganglia dissolution fg, and fitting parameters β1 and β2) in the upscaling model to identify the key parameters, and then a local sensitivity analysis was used to quantify the impact of changes in the key parameters on mass flux prediction. The results showed that the parameters q, C0/Ceq, GF0 and fg had a large impact on the mass flux prediction. The sensitivities of q and C0/Ceq were relatively high throughout the depletion process, while those of GF0 and fg increased continuously with the depletion process, reaching peaks in the middle and late stages of depletion, respectively. For source zones with different structures, the increase in mass flux was essentially constant when q or C0/Ceq increased. As the ganglia-to-pool (GTP) mass ratio increased in source zones, its effect on the mass flux prediction continued to increase or decrease when GF0 or fg increased. Therefore, the investigation needs to focus on q and C0/Ceq when predicting the mass flux, on GF0 when reasonably designing the remediation plan of the source zone, and on fg when predicting the lifetime of the source zone. For all structural source zones, q and C0/Ceq are the most important to investigate, and the investigation cost should be focused on GF0 for source zones with large GTP and fg for source zones with small GTP. |
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