Abstract:

Rapid industrialization in China has imposed significant risks to regional ecosystems and public health owing to the persistent release of diverse hazardous pollutants from industries. The intricate interactions between soil and groundwater systems exacerbate cross-media contamination. Existing environmental criteria systems are often inadequate for systematically evaluating pollutant migration process across different media and their associated health risks because they fail to account for the intricate interactions among various environmental factors. To address these shortcomings, this study introduces the Soil and Groundwater Multi-Element Synergistic Environmental Criteria for Human Health (S&G MESEC_-HH), a comprehensive theoretical framework designed to assess the synergistic effects of multiple environmental factors on pollutant behavior and human health. The S&G MESEC_-HH framework integrates four core elements: (1) Pollutant Characteristics, including contaminant types, chemical forms, and physicochemical properties, which critically determine mobility and bioavailability. (2) Hydrogeological Conditions, including soil stratification, groundwater level fluctuations, and flow direction. (3) Soil Physicochemical Properties, such as pH, organic matter content, and particle size distribution. (4) Meteorological Factors, which primarily include temperature and precipitation patterns. This study emphasizes that the characteristics of pollutants play a crucial role in determining their mobility and bioavailability. For instance, heavy metals and organic pollutants exhibit different behaviors in soil and groundwater systems because of their chemical forms and interactions with soil particles. Understanding these characteristics is essential for predicting the behavior of pollutants in the environment and assessing their potential risks to human health. Additionally, the study delineates three principal synergistic mechanisms that dictate pollutant transport and transformation within the soil-groundwater continuum: (1) Chemical Synergy, which involves multiphase partitioning and valence state transformations of contaminants. (2) Physical Synergy, characterized by processes such as advection-diffusion and adsorption-desorption. (3) Biological Synergy, pertains to microbial metabolic activities that can alter the fate of pollutants. These mechanisms underscore the intricacy of pollutant interactions and the necessity of a multifaceted approach to environmental risk assessment. By systematically analyzing these multi-factor coupled mechanisms, the S&G MESEC_-HH framework offers an approach to understand how pollutants migrate and transform in complex environmental settings. This paradigm not only augments the prognostic capabilities regarding contaminant behavior but also affords a comprehensive appraisal of the public health risks associated with exposure to such pollutants and their environmental persistence. The S&G MESEC_-HH framework comprises several critical elements that collectively influence the behavior of pollutants in soil and groundwater systems. These factors are essential for understanding the complex dynamics of contaminant transport and transformations. The key elements identified include: (1) Stratigraphic Heterogeneity, wherein variability in geological strata notably affects pollutant migration; disparities in permeability, adsorption capacity, and ion exchange potential across diverse lithologies govern contaminant mobilization within subsurface matrices. (2) Hydrogeological Parameters, such as hydraulic conductivity, porosity, and dispersivity, are indispensable for characterizing groundwater flow regimes and contaminant transport kinetics. These parameters directly dictate the pollutant migration pathways, residence times, and transformation rates. (3) Groundwater Depth and Fluctuations, since groundwater table depth and temporal variations can modulate soil moisture conditions, redox states, and microbial activity, thereby influencing the mobilization and retention of contaminants, particularly heavy metals. (4) Soil Gas, where VOCs present in soil gas can significantly affect the extent of pollution. The distribution and concentration of VOCs in the gas phase can lead to underestimations of environmental risks if not considered adequately. (5) Non-Aqueous Phase Liquids (NAPLs), whose presence in free, dissolved, or adsorbed phases poses persistent contamination challenges. The density-dependent behavior of both light and dense NAPLs in heterogeneous geological media complicates the prediction of contaminant plumes. (6) Microbial Activity, wherein indigenous microbial communities facilitate the biodegradation of organic pollutants. Their metabolic processes can transform contaminants, thereby affecting their toxicity and mobility. Environmental factors, such as oxygen levels, nutrient availability, temperature, and pH critically influence microbial pathways, thereby affecting contaminant toxicity, persistence, and degradation kinetics. (7) Climatic and Meteorological Factors, including temperature fluctuations and precipitation patterns, govern the physical, chemical, and biological processes that regulate the fate of contaminants. Variations in seasonal temperature may alter the solubility and sorption characteristics of organic pollutants, whereas rainfall can affect soil moisture and leaching. By integrating these elements into the S&G MESEC_-HH framework, this study aims to provide a comprehensive understanding of the multifactorial interactions that govern pollutant behavior, thereby enhancing risk assessment fidelity and informing the development of robust environmental management strategies and resilience metrics. Moreover, this study delves into the ramifications of the S&G MESEC_-HH framework for regulatory and environmental management practices. By providing a theoretical basis for the systematic assessment of health risks in complex polluted environments, this framework can guide policymakers in establishing more effective environmental regulations and remediation strategies in the future. The integration of multi-element interactions into environmental criteria can lead to more accurate risk assessments, ultimately protecting public health and the environment. The S&G MESEC_-HH framework also opens avenues for future research, particularly in terms of risk communication. Furthermore, the framework’s adaptability to incorporate emerging technologies, such as remote sensing and machine learning, facilitates the enhancement of data collection and analysis. These advancements have the potential to improve the precision of predictions regarding pollutant behavior, thereby facilitating the timely identification of contamination events. Consequently, these advancements can help protect public health. Additionally, the implementation of the S&G MESEC_-HH framework is versatile, allowing adaptation to different geographical contexts, thereby ensuring its suitability for diverse environmental conditions and pollutant profiles. This adaptability is imperative for addressing the unique challenges faced by different regions, particularly in areas with varying industrial activities and ecological sensitivities. By adapting the framework to local conditions, it can provide more relevant and actionable insights into the environmental management. In conclusion, this study establishes a foundation for subsequent research endeavors aimed at refining the S&G MESEC_-HH framework and its application in real-world applications. This underscores the necessity for continuous research on the interactions among diverse environmental factors and their collective impact on pollutant behavior and human health. These findings emphasize the significance of interdisciplinary collaboration in addressing the multifaceted challenges posed by soil and groundwater pollution, ultimately contributing to the establishment of effective pollution prevention and remediation strategies.

Key words: soil-groundwater system, multi-element synergistic effects, cross-medium migration, human health environmental criteria, compound pollution risk

摘要：

随着中国工业化进程的快速推进，土壤-地下水跨介质污染问题日益突出。然而，现有环境基准体系因未能充分考虑介质间的交互作用，难以系统地评估污染物跨介质迁移过程及其人体健康风险。为此，该文在系统梳理土壤与地下水污染防治领域研究进展的基础上，初步探索并提出了一个面向人体健康的土壤-地下水多要素协同作用环境基准（S&G MESEC_-HH）的理论框架。首先，该框架系统整合并强调了四大关键要素体系：1）污染物特征（种类、形态等）；2）水文地质条件（土层结构、地下水位波动等）；3）土壤理化性质（pH、有机质含量等）；4）气候气象因子（温度、降水等）。其次，该框架深入分析并归纳了三大协同作用机制：1）化学协同（多相分配、价态转换等）；2）物理协同（对流-扩散、吸附-解吸等）；3）生物协同（微生物代谢等）。在此基础上，尝试突破传统单一介质评价的局限，探讨了污染物跨介质通量模型、动态水文地质参数与区域气候特征的多尺度耦合，初步构建了包含工业活动类型、土地利用方式、敏感受体特征、暴露途径及健康风险评估在内的完整技术框架。该文旨在为复合污染环境下健康风险的系统评估提供一种新的理论视角和方法学思路，对完善中国环境基准体系具有重要的科学意义。

关键词: 土壤-地下水系统, 多要素协同作用, 跨介质归趋, 人体健康环境基准, 跨介质污染风险