Journal of contaminant hydrology最新文献_第2页

Assessing data variability in groundwater quality monitoring of contaminated sites through factor analysis and multiple linear regression models.

IF 3.5 3区环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES

Journal of contaminant hydrology

Pub Date : 2024-11-30 DOI: 10.1016/j.jconhyd.2024.104471

Davide Sartirana, Chiara Zanotti, Alice Palazzi, Ilaria Pietrini, Paola Frattini, Andrea Franzetti, Tullia Bonomi, Marco Rotiroti

Monitoring of long-term contaminant concentrations trends is essential to verify that attenuation processes are effectively occurring at a site. However, monitoring data are often affected by extreme variability which prevents the identification of clear concentration trends. The variability is higher in long-screened monitoring wells, which are currently used at many contaminated sites, although it has been known since the 1980s that monitoring data from long-screened wells can be biased. Understanding the factors that may influence the variability of monitoring data is pivotal. To this end, following hydrochemical conceptual modelling using a multi-method approach, the variability of hydrocarbon concentrations from fully screened monitoring wells was assessed over eleven years at a former oil refinery located in Northern Italy. The proposed methodology combined factor analysis with multiple linear regression models. Results pointed out a higher variability in hydrocarbon concentrations at the plume fringe and a lower variability at the plume source and core. 44-46 % of the total variability in measured hydrocarbon concentrations is due to "intrinsic plume heterogeneity", related to the three-dimensional structure of a contaminant plume, which becomes thinner at the edge, creating a vertical heterogeneity of redox conditions at the plume fringe. This variability, expressed as increasing concentrations of sulfate and decreasing concentrations of methane, represents a background variability that cannot be reduced by improving sampling procedures. The remaining 56-54 % of the total variability may be due to the non-standardization of some purging and sampling operations, such as pump intake position, purging and sampling time/flow rates and variations in the analytical methods. This finding suggests that monitoring improvements in fully screened wells by standardizing all purging/sampling operations or using sampling techniques that can reduce the actual screen length (e.g., packers or separation/dual pumping techniques) would reduce data variability by more than half.

{"title":"Assessing data variability in groundwater quality monitoring of contaminated sites through factor analysis and multiple linear regression models.","authors":"Davide Sartirana, Chiara Zanotti, Alice Palazzi, Ilaria Pietrini, Paola Frattini, Andrea Franzetti, Tullia Bonomi, Marco Rotiroti","doi":"10.1016/j.jconhyd.2024.104471","DOIUrl":"https://doi.org/10.1016/j.jconhyd.2024.104471","url":null,"abstract":"<p><p>Monitoring of long-term contaminant concentrations trends is essential to verify that attenuation processes are effectively occurring at a site. However, monitoring data are often affected by extreme variability which prevents the identification of clear concentration trends. The variability is higher in long-screened monitoring wells, which are currently used at many contaminated sites, although it has been known since the 1980s that monitoring data from long-screened wells can be biased. Understanding the factors that may influence the variability of monitoring data is pivotal. To this end, following hydrochemical conceptual modelling using a multi-method approach, the variability of hydrocarbon concentrations from fully screened monitoring wells was assessed over eleven years at a former oil refinery located in Northern Italy. The proposed methodology combined factor analysis with multiple linear regression models. Results pointed out a higher variability in hydrocarbon concentrations at the plume fringe and a lower variability at the plume source and core. 44-46 % of the total variability in measured hydrocarbon concentrations is due to \"intrinsic plume heterogeneity\", related to the three-dimensional structure of a contaminant plume, which becomes thinner at the edge, creating a vertical heterogeneity of redox conditions at the plume fringe. This variability, expressed as increasing concentrations of sulfate and decreasing concentrations of methane, represents a background variability that cannot be reduced by improving sampling procedures. The remaining 56-54 % of the total variability may be due to the non-standardization of some purging and sampling operations, such as pump intake position, purging and sampling time/flow rates and variations in the analytical methods. This finding suggests that monitoring improvements in fully screened wells by standardizing all purging/sampling operations or using sampling techniques that can reduce the actual screen length (e.g., packers or separation/dual pumping techniques) would reduce data variability by more than half.</p>","PeriodicalId":15530,"journal":{"name":"Journal of contaminant hydrology","volume":"269 ","pages":"104471"},"PeriodicalIF":3.5,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142780260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A modelling framework to analyze climate change effects on radionuclide aquifer contamination.

IF 3.5 3区环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES

Journal of contaminant hydrology

Pub Date : 2024-11-29 DOI: 10.1016/j.jconhyd.2024.104470

Thomas Matteo Coscia, Francesco Di Maio, Enrico Zio

Non-stationarity of climatic variables (e.g., temperature and precipitation) due to Climate Change (CC) can affect the migration processes of radionuclides released from nuclear activities. In this paper, a framework of analysis is developed to predict the evolution in time of contaminant concentration and fluence under different Climatic Boundary Conditions (CBCs) of precipitation scenarios provided by a climate model integrated with an accurate physical coupled hydraulic-transport model. A case study is worked out with respect to the migration of a radioactive contaminant (²³²Th) at Kirtland Air Force Base (Albuquerque, New Mexico, USA), for which the different CBCs considered are: i) stationary and ii) non-stationary precipitation. The effects of such alternative hypotheses on the physical modelling results are analysed, using a cross-wavelet analysis. It is shown that fluence is strongly affected by precipitation extremes, more than concentration, and it is claimed that a daily scale on the information and data of CBCs is necessary to model, with sufficient accuracy, the migration process and properly assess the impact of future CC on groundwater contamination.

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引用次数: 0

Use of process-based coupled ecological-hydrodynamic models to support lake water ecosystem service protection planning at the regional scale

IF 3.5 3区环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES

Journal of contaminant hydrology

Pub Date : 2024-11-26 DOI: 10.1016/j.jconhyd.2024.104469

Andrea Fenocchi , Nicolò Pella , Diego Copetti , Fabio Buzzi , Daniele Magni , Nico Salmaso , Claudia Dresti

Protection plans of lake waters are based on ecological and/or chemical targets, often simplified in terms of total phosphorus (TP) concentrations, customarily the depth-averaged ones at spring mixing for temperate environments. These target lake TP concentrations are then commonly employed to determine target external loading through reverse use of Vollenweider-OECD-type steady-state empirical models. Such models are also adopted in their direct form to estimate lake TP concentrations following hypothetical external load reductions. However, such approaches suffer from extreme parameterisation and often give inaccurate results. Process-based coupled ecological-hydrodynamic models offer a much wider flexibility and produce an extensive set of information, solving many of the issues of Vollenweider-OECD-type models. However, their application has been up to now restricted to single lakes due to calibration effort and data availability burdens. To overcome these obstacles, in this study we developed a simplified application of the process-based coupled model QWET over 9 lakes in Northern Italy, making use of the ParSAC automatic calibration tool and feeding the models only with general data available from public monitoring. QWET models were calibrated over past observations, simulating nutrient reduction scenarios for the near-future decades. The advantages over traditionally employed models for lake water protection planning at the regional scale were hence identified through a practical application, determining the strengths and limits of the herein-adopted simplified process-based approach over lakes with different features. Obtained results were also analysed considering the specific case study.

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引用次数: 0

Potential health, environmental implication of microplastics: A review on its detection

IF 3.5 3区环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES

Journal of contaminant hydrology

Pub Date : 2024-11-22 DOI: 10.1016/j.jconhyd.2024.104467

Bhawana Yadav , Payal Gupta , Vinay Kumar , Mridul Umesh , Deepak Sharma , Jithin Thomas , Suraj Kumar Bhagat

Microplastic contamination of terrestrial and aquatic environment has gained immense research attention due to their potential ecotoxicity and biomagnification property when enterer into food chain. Heterogenous nature of microplastics coupled with their ability to combine with other emerging pollutants have increased the severity of this crisis. Existing detection methods often fails to accurately quantify the amount of microplastic components present in environmental and biological samples. Thus, a great deal of research gap always exists in our current understanding about microplastics including the limitations in screening, detection and mitigation. This review work presents a comprehensive out look on the impact of microplastics on both terrestrial and aquatic environment. Furthermore, an in-depth discussion on various microplastic detection techniques recently used for microplastic quantification along with their significance and limitations is summarised in this review. The review also elaborates various physical, chemical and biological methods used for the mitigation of microplastics from environmental samples.

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引用次数: 0

Experimental investigation on heat and moisture transfer of propylene glycol-mixed steam in porous media 多孔介质中丙二醇混合蒸汽的传热和传湿实验研究

IF 3.5 3区环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES

Journal of contaminant hydrology

Pub Date : 2024-11-19 DOI: 10.1016/j.jconhyd.2024.104468

Zhixin Chen, Yan Tian, Liming Hu

Propylene glycol (PG)-mixed steam enhanced extraction is a promising remediation technique for removing semi-volatile organic compounds (SVOCs) from the unsaturated zone. However, the mechanisms of heat and moisture transfer during PG-mixed steam injection remain unclear. In this study, a 2D experimental system was developed to enable non-invasive monitoring of the spatio-temporal distribution of temperature and degree of saturation during steam injection into porous media. Experiments were conducted to observe the migration of PG-mixed steam in horizontal and vertical planes across three varying particle sizes, while pure superheated steam injection experiments serving as a comparison. Temperature field results show that the addition of PG decreases the zone of influence during steam migration, while significantly enhancing the emergence of the superheated steam zone. The influence of particle size on the area variance of the saturated steam zone is greater than that of the superheated steam zone. The downward migration of the superheated steam front due to density different between PG vapor and air is impeded with decreasing permeability. Furthermore, saturation field results reveal that the condensed liquid within the superheated zone is a PG solution. The downward migration of condensates with high PG concentration might increase the potential risk of beneath groundwater pollution, highlighting the significance of understanding PG migration during PG-mixed steam injection.

丙二醇（PG）混合蒸汽强化萃取是一种很有前景的修复技术，可用于去除非饱和带中的半挥发性有机化合物（SVOC）。然而，PG-混合蒸汽注入过程中的热量和水分传递机制仍不清楚。本研究开发了一个二维实验系统，用于无创监测蒸汽注入多孔介质过程中温度和饱和度的时空分布。实验观察了混合 PG 蒸汽在水平和垂直平面上穿过三种不同粒径的迁移情况，同时将纯过热蒸汽注入实验作为对比。温度场结果表明，在蒸汽迁移过程中，添加 PG 会减小影响区，同时显著增强过热蒸汽区的出现。颗粒大小对饱和蒸汽区面积变化的影响大于过热蒸汽区。由于 PG 蒸汽和空气的密度不同，过热蒸汽前沿的下移会随着渗透率的降低而受到阻碍。此外，饱和场结果显示，过热区内的冷凝液体是 PG 溶液。高浓度 PG 的冷凝液向下迁移可能会增加地下水污染的潜在风险，因此了解 PG 混合蒸汽注入过程中的 PG 迁移具有重要意义。

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引用次数: 0

Experimental application of micro/nano bubbles to control P release and separate P particles from benthic lake sediment 实验应用微/纳米气泡控制 P 释放并分离湖底沉积物中的 P 颗粒。

IF 3.5 3区环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES

Journal of contaminant hydrology

Pub Date : 2024-11-17 DOI: 10.1016/j.jconhyd.2024.104466

Yong-Ho Choi , Yong-Hoon Jeong , Hong-Hue Thi Nguyen , Dong-Heui Kwak

Under persistent hypoxic conditions in the bottom layer of a lake, phosphorus (P) can be released from benthic sediments, significantly impacting the lake ecosystem. Hypoxia reduces iron ions, leading to P release through biogeochemical reactions associated with organic matter degradation, which in turn depletes dissolved oxygen (DO) in the sediment. The application of bubble technology is beneficial, as microbubbles (MBs) effectively remove P and enhance DO levels in both the overlying water and sediment surface. To identify the optimal bubble size for application, we conducted a series of flotation experiments and P fractionation studies using MBs and nanobubbles (NBs). Results indicate that NBs achieved a flotation efficiency of 12 %, MBs reached 44 %, and the combined use of NBs and MBs attained the highest flotation efficiency at 62 %, confirming that a combination of bubble sizes can enhance flotation efficiency. Furthermore, the introduction of air bubbles to mitigate hypoxia in the overlying water increased DO concentrations from 1 to 5 mg/L, followed by a gradual decline. P release in the bubble-injected groups was up to three times lower than in the control group. Water quality profiling of P distribution in sediments revealed a significant increase of approximately 10 % in iron-bound P under aerobic conditions, highlighting its critical role in regulating P release. Our findings suggest that utilizing a combination of bubble sizes, including NBs, enhances P removal efficiency and improves the anaerobic conditions of the lake's bottom layer, thereby further reducing P release from sediments.

在湖泊底层持续缺氧的条件下，磷（P）会从底栖沉积物中释放出来，对湖泊生态系统产生重大影响。缺氧会减少铁离子，导致磷通过与有机物降解相关的生物地球化学反应释放出来，进而消耗沉积物中的溶解氧（DO）。气泡技术的应用是有益的，因为微气泡（MBs）能有效去除 P 并提高上覆水体和沉积物表面的溶解氧水平。为了确定应用的最佳气泡尺寸，我们使用微气泡和纳米气泡（NBs）进行了一系列浮选实验和 P 分馏研究。结果表明，NBs 的浮选效率为 12%，MBs 为 44%，而结合使用 NBs 和 MBs 的浮选效率最高，达到 62%，这证实了气泡大小的组合可提高浮选效率。此外，通过引入气泡来缓解上层水的缺氧状况，溶解氧浓度从 1 毫克/升上升到 5 毫克/升，随后逐渐下降。气泡注入组的 P 释放量是对照组的三倍。沉积物中 P 分布的水质剖面图显示，在有氧条件下，铁结合的 P 显著增加了约 10%，突出了其在调节 P 释放中的关键作用。我们的研究结果表明，利用包括 NBs 在内的多种气泡尺寸组合可提高对 P 的去除效率，改善湖泊底层的厌氧条件，从而进一步减少沉积物中 P 的释放。

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引用次数: 0

Rainfall-induced microplastic fate and transport in unsaturated Dutch soils 降雨引起的微塑料在荷兰非饱和土壤中的归宿和迁移。

IF 3.5 3区环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES

Journal of contaminant hydrology

Pub Date : 2024-11-12 DOI: 10.1016/j.jconhyd.2024.104456

Rozita Soltani Tehrani, Xiaomei Yang, Jos van Dam

Microplastic pollution has become a growing concern in terrestrial ecosystems, with significant implications for environmental and human health. Understanding the fate and transport of microplastics in soil environment is crucial for effective mitigation strategies. This study investigates the dynamics of microplastic (Low-density polyethylene (LDPE), polybutylene adipate terephthalate (PBAT), and starch-based biodegradable plastic) transport in unsaturated soils under varying rainfall intensities and soil types, aiming to elucidate the factors influencing their behavior. Effluent samples were analyzed to measure microplastic transport, with microplastic balance analysis ensuring experimental accuracy. The setup replicated real-world flow conditions, providing insights into microplastic transport in unsaturated porous media. Microplastic balance analysis revealed high recovery factors (between 64 % and 104 %), indicating the reliability of the experimental approach. Microplastic transport varied significantly between sandy loam and loamy sand soils, with loamy sand soils exhibiting higher wash-off rates due to their unique properties. LDPE microplastics showed a higher tendency to detach from soil columns compared to PBAT and starch-based particles. Higher rainfall intensity in loamy sand soil columns resulted in an increased washout of LDPE, PBAT, and starch-based particles by 92 %, 144 %, and 85 %, respectively, compared to low rainfall intensity. In sandy loam soil, increased rainfall intensity resulted in a significantly higher washout of LDPE, PBAT, and starch-based particles with percentages of 93 %, 69 %, and 45 %, respectively. This underscores the important role of water flow in mobilizing microplastics within the soil matrix.

微塑料污染已成为陆地生态系统中日益严重的问题，对环境和人类健康产生了重大影响。了解微塑料在土壤环境中的归宿和迁移对于制定有效的缓解策略至关重要。本研究调查了在不同降雨强度和土壤类型下，微塑料（低密度聚乙烯（LDPE）、聚己二酸丁二醇酯（PBAT）和淀粉基生物降解塑料）在非饱和土壤中的迁移动态，旨在阐明影响其行为的因素。通过分析污水样本来测量微塑料迁移，微塑料平衡分析确保了实验的准确性。该装置复制了真实世界的流动条件，为了解微塑料在非饱和多孔介质中的迁移提供了依据。微塑料平衡分析显示了较高的回收率（介于 64 % 和 104 % 之间），表明了实验方法的可靠性。砂质壤土和壤土的微塑料迁移差异很大，壤土因其独特的性质而表现出更高的冲刷率。与 PBAT 和淀粉基颗粒相比，低密度聚乙烯微塑料更容易从土柱中脱离。与低降雨强度相比，壤质砂土土柱中较高的降雨强度导致低密度聚乙烯、PBAT 和淀粉基颗粒的冲刷率分别增加了 92%、144% 和 85%。在砂质壤土中，降雨强度增加导致低密度聚乙烯、PBAT 和淀粉基颗粒的冲刷率明显增加，分别为 93%、69% 和 45%。这突出表明了水流在土壤基质中移动微塑料的重要作用。

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引用次数: 0

Micro-nano bubbles enhanced immobilized Chlorella vulgaris to remove ofloxacin from groundwater 微纳米气泡增强固定化小球藻去除地下水中的氧氟沙星

IF 3.5 3区环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES

Journal of contaminant hydrology

Pub Date : 2024-11-10 DOI: 10.1016/j.jconhyd.2024.104458

Mengyao Jing , Jianping Zhang , Guijuan Li , Dan Zhang , Fengjia Liu , Shengke Yang

The phenomenon of antibiotic pollution has emerged as a significant global environmental concern. However, there is a lack of technical research on the effective removal of antibiotics based on the characteristics of the groundwater environment. This paper used micro-nano bubbles (MNBs) enhanced immobilized Chlorella technology to remove ofloxacin (OFLX) from groundwater. The study discussed the impact of initial antibiotic concentration (5–30 mg/mL), algae concentration (0.25–4 bead/mL), aeration time (5–30 min), and coexisting ions on the antibiotic removal rate and analyzed the removal mechanism by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The results showed that MNBs increased Chlorella vulgaris biomass by 2.48 times and significantly improved OFLX removal efficiency. The removal rate of OFLX exhibited a significant positive correlation with the algal concentration and coexisting ions and a significant negative correlation with the aeration time and the initial concentration of antibiotics. Enhanced immobilization of Chlorella vulgaris by MNBs for OFLX removal may involve -NH, -OH, -C=O, -CH₂, and -C-O-C groups. Degradation (including biodegradation and non-biodegradation) is the primary mechanism of antibiotic removal. Overall, intensive immobilization of Chlorella by MNBs promises to be a technically feasible method for removing antibiotics from groundwater.

抗生素污染现象已成为全球关注的重要环境问题。然而，根据地下水环境的特点有效去除抗生素的技术研究还很缺乏。本文利用微纳米气泡（MNBs）增强固定化小球藻技术去除地下水中的氧氟沙星（OFLX）。研究探讨了初始抗生素浓度（5-30 mg/mL）、藻类浓度（0.25-4 珠/mL）、曝气时间（5-30 分钟）和共存离子对抗生素去除率的影响，并通过扫描电子显微镜（SEM）和傅立叶变换红外光谱（FT-IR）分析了去除机理。结果表明，MNBs 使小球藻的生物量增加了 2.48 倍，并显著提高了 OFLX 的去除率。OFLX 的去除率与藻类浓度和共存离子呈显著正相关，与曝气时间和抗生素的初始浓度呈显著负相关。MNBs 在去除 OFLX 方面对小球藻的强化固定作用可能涉及 -NH、-OH、-C=O、-CH2 和 -C-O-C 基团。降解（包括生物降解和非生物降解）是去除抗生素的主要机制。总之，用 MNBs 强化固定小球藻有望成为去除地下水中抗生素的一种技术上可行的方法。

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引用次数: 0

Quantifying aquifer heterogeneity using superparamagnetic DNA particles 利用超顺磁性 DNA 粒子量化含水层的异质性。

IF 3.5 3区环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES

Journal of contaminant hydrology

Pub Date : 2024-11-04 DOI: 10.1016/j.jconhyd.2024.104454

Swagatam Chakraborty , Fuad Alqrinawi , Jan Willem Foppen , Jack Schijven

Identifying and determining hydraulic parameters of physically heterogeneous aquifers is pivotal for flow field analysis, contaminant migration and risk assessment. In this research, we applied a novel uniquely sequenced DNA tagged superparamagnetic silica microparticles (SiDNAmag) to quantify hydraulic parameters and associated uncertainties of a heterogeneous sand tank. In the sand tank with lens shaped heterogeneity, we conducted three sets of multi – point injection experiments in unconsolidated (1) homogeneous (zone 0), (2) heterogeneous with a no-conductivity-zone (zone 1), and (3) heterogeneous with a high-conductive-zone (zone 2). From the breakthrough curves (BTC), we estimated the parameters distributions of hydraulic conductivity (k), effective porosity (n_e), longitudinal dispersivity (α_L), transverse vertical (α_TV), and transverse horizontal dispersivities (α_TH) applying Monte Carlo simulation approach for BTC fitting. The estimated parameters and associated uncertainties for each of the heterogeneous sections were further statistically compared (distribution non-specific Mann Whitney U test) these parameter distributions with parameter distributions estimated from the conservative salt tracer. While the time of arrival and time to peak concentration of SiDNAmag and salt in effluent were comparable, peak concentration of SiDNAmag was 1–3 log reduced as compared to the salt tracer due to first order kinetic attachment. Nonetheless, the parameters and associated uncertainty distributions (5 %–95 %) of K, n_e, α_L, α_TV, and α_TH, determined from SiDNAmag BTCs were statistically equivalent to the salt tracer in all three experiment systems. Through our experimental and modelling approach, our work demonstrated that in a coarse to very coarse grain sand medium, with lens shaped heterogeneity, the uniquely sequenced SiDNAmag were a promising tool to identify heterogeneity and determine hydraulic parameters and associated uncertainty distributions.

识别和确定物理异质含水层的水力参数对于流场分析、污染物迁移和风险评估至关重要。在这项研究中，我们采用了一种新颖的独特测序 DNA 标记超顺磁性硅微颗粒（SiDNAmag）来量化异质砂槽的水力参数和相关的不确定性。在具有透镜状异质性的砂槽中，我们在未固结（1）均质区（0 区）、（2）无导电区异质性区（1 区）和（3）高导电区异质性区（2 区）中进行了三组多点注入实验。根据突破曲线（BTC），我们采用蒙特卡洛模拟法对导水率（k）、有效孔隙度（ne）、纵向分散度（αL）、横向垂直分散度（αTV）和横向水平分散度（αTH）的参数分布进行了估算。将每个异质截面的估计参数和相关不确定性与根据保守盐示踪剂估计的参数分布进行了进一步的统计比较（分布非特异性曼-惠特尼 U 检验）。虽然 SiDNAmag 和盐在污水中的到达时间和达到峰值浓度的时间相当，但由于一阶动力学附着，SiDNAmag 的峰值浓度比盐示踪剂低 1-3 个对数。尽管如此，在所有三个实验系统中，根据 SiDNAmag BTC 确定的 K、ne、αL、αTV 和 αTH 参数及相关不确定性分布（5 %-95 %）在统计学上与盐示踪剂相当。通过我们的实验和建模方法，我们的工作表明，在具有透镜状异质性的粗粒至极粗粒砂介质中，唯一测序的 SiDNAmag 是识别异质性和确定水力参数及相关不确定性分布的有效工具。

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引用次数: 0

Quantification of contaminant mass discharge and uncertainties: Method and challenges in application at contaminated sites 污染物质量排放和不确定性的量化：污染场地的应用方法与挑战。

IF 3.5 3区环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES

Journal of contaminant hydrology

Pub Date : 2024-11-03 DOI: 10.1016/j.jconhyd.2024.104453

A. Bøllingtoft , P.L. Bjerg , V. Rønde , N. Tuxen , W. Nowak , M. Troldborg

Contaminant mass discharge (CMD) estimation involves combining multilevel concentration and flow measurements to quantify the contaminant mass passing through a control plane downgradient of a point source. However, geological heterogeneities and limited data introduce uncertainties that complicate CMD estimation and risk assessment. Although CMD is increasingly used in groundwater management, methods for quantifying and handling these uncertainties are still needed. This study develops and tests a CMD estimation method based on Bayesian geostatistics to quantify CMD uncertainties using data from a control plane perpendicular to the contaminant plume.

By combining geostatistical conditional simulations of the spatial concentration distribution with the flow, an ensemble of CMD realizations is generated, from which a cumulative distribution function is derived. A key element of this approach is the use of a macrodispersive transport model to simulate the spatial concentration trend. This ensures that the estimated concentration reflects the expected physical behavior of the contaminant plume while also allowing the integration of site-specific conceptual information.

The method is applicable to plumes with dissolved contaminants, such as chlorinated solvents, petroleum hydrocarbons, Per- and polyfluoroalkyl substances (PFAS) and pesticides. Site-specific conceptual understanding is used to inform the prior probability density functions of the structural model parameters and to define acceptable simulated concentration limits. We applied the method at three sites contaminated with chlorinated ethenes, demonstrating its robustness across varying information levels and data availability.

Our results shows that strong site-specific conceptual knowledge and high sampling density constrain the CMD uncertainty (CV = 21 %) and results in estimated model parameters and a spatial concentration distribution that agrees well with the conceptual model. For a site with less data and limited conceptual knowledge, CMD and concentration distribution estimates are still feasible, though with higher uncertainty (CV = 41 %). Extending the method to account for multiple source zones and complex plume migration improved parameter identification and reduced the 95 % CMD confidence interval by 11 % ([4950–8750] to [5090–8480] g yr⁻¹), while also providing a spatial concentration distribution in better agreement with the plume conceptualization.

This study highlights the importance of integrating site-specific conceptual knowledge in CMD estimation, particularly for less-sampled sites. The method can furthermore assist in identifying remediation targets, evaluating remedial effectiveness, and optimizing sampling strategies.

污染物质量排放（CMD）估算包括结合多级浓度和流量测量，对通过点源下游控制平面的污染物质量进行量化。然而，地质异质性和有限的数据带来了不确定性，使 CMD 估算和风险评估变得更加复杂。虽然 CMD 在地下水管理中的应用越来越广泛，但仍需要量化和处理这些不确定性的方法。本研究开发并测试了一种基于贝叶斯地质统计学的 CMD 估算方法，利用与污染物羽流垂直的控制面数据量化 CMD 的不确定性。通过将空间浓度分布的地质统计条件模拟与流量相结合，可生成 CMD 真实值集合，并从中得出累积分布函数。这种方法的一个关键要素是使用宏观分散传输模型模拟空间浓度趋势。这可以确保估算的浓度反映污染物羽流的预期物理行为，同时还可以整合特定地点的概念信息。该方法适用于含有溶解污染物的羽流，如氯化溶剂、石油碳氢化合物、全氟和多氟烷基物质 (PFAS) 以及杀虫剂。对特定场地的概念理解可用于为结构模型参数的先验概率密度函数提供信息，并确定可接受的模拟浓度限值。我们在三个受氯化醚污染的地点应用了该方法，证明了该方法在不同信息水平和数据可用性下的稳健性。我们的结果表明，强大的特定场地概念知识和较高的采样密度限制了 CMD 的不确定性（CV = 21%），并得出了与概念模型十分吻合的估计模型参数和空间浓度分布。对于数据较少且概念知识有限的地点，CMD 和浓度分布估计值仍然可行，但不确定性较高（CV = 41%）。扩展该方法以考虑多个源区和复杂的羽流迁移，可改进参数识别，并将 95 % CMD 置信区间缩小 11 %（[4950-8750] 至 [5090-8480] g yr-1），同时还可提供与羽流概念更一致的空间浓度分布。这项研究强调了在 CMD 估算中整合特定地点概念知识的重要性，尤其是对于采样较少的地点。该方法还有助于确定补救目标、评估补救效果和优化采样策略。

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引用次数: 0