病原体在土壤中瞬态非饱和迁移的控制机制与模型模拟研究

In recent years, pathogen contamination erupted frequently, making a threat to public drinking water. Protection of water from pathogenic contamination is vital for water designated for use as public drinking water, agricultural irrigation, recreation, and food production. Many studies have been conducted on pathogen transport in saturated, groundwater environments. However, pathogens must pass through a zone of unsaturated soil (the vadose zone) to reach the groundwater environment. Of the few experimental studies for unsaturated flow conditions, most use texturally and geochemically homogeneous soils under steady-state flow conditions. Yet in natural systems, pathogen transport involves soil structural and geochemical heterogeneities and is dominated by unsaturated transient infiltration and drainage events. Thus, this proposed research seeks to determine the unique characteristics and mechanisms of pathogen transport as affected by transient flow and soil heterogeneity. Key scientific issues addressed are soil’s potential for limiting pathogen movement, mechanism clarification, and process modeling. The research objectives will be achieved through transport experiments in 1-, 2- and 3-D soils that contain texturally, structurally, and/or geochemically heterogeneous soils or intact soils using optically labeled pathogens (viruses, bacteria, and protozoa). The dynamic changes in resident pathogen concentration and water content at the same soil location will be concurrently measured in situ in real time manner using a high-resolution fluorescence/bioluminescence imaging system. Microscopic visualization of the pathogen retention at various interfaces within unsaturated pores will be performed using a micromodel integrated with an advanced 3-D laser scanning confocal microscopy for mechanistic elucidation of the Darcy-scale transport processes. A modeling framework will be developed to identify the key processes governed by heterogeneities of soil conditions and flow pathways and dynamics. This research will generate novel scientific information to guide land-application of municipal and animal solid wastes for preveting the burst of water-borne pathogenic deseases and protecting water quality.

预防水体病原微生物污染对公共饮用水、农业灌溉、畜牧业及食品生产至关重要，该研究旨在揭示非稳态不饱和流条件下病原体在物理和化学异质土壤中的不均匀迁移、空间分布、界面保持和间断性迁移的特征及其控制机制。我们将主要使用高精度荧光或生物发光成像系统（IVIS Spectrum）原位实时定量测定三种荧光标记的代表性病原体（病毒、细菌和原生动物）和水分在土壤中的时空分布及其格局变化。病原体在非饱和土壤孔隙中各种相界面上（液-固、液-气和液-固-气）的保持主要使用3-D激光扫描共聚焦显微仪进行微观可视化观测，所得结果将用于解释病原微生物胶体在宏观Darcy尺度上的迁移和分布行为。此外，该研究将建立数值数学模型框架用于分析病原体在不饱和异质土壤中不均匀迁移的关键控制过程和参数。本研究的顺利完成将为再生水安全农灌、市政及畜禽养殖业固废安全土地处理、水源性疾病防控和饮用水源保护等提供重要科学依据和评价工具。

预防水体病原微生物污染对公共饮用水、农业灌溉、畜牧业及食品生产至关重要，该研究旨在揭示非稳态不饱和流条件下病原体在物理和化学异质土壤中的不均匀迁移、空间分布、界面保持和间断性迁移的特征及其控制机制。我们将主要使用高精度荧光或生物发光成像系统（IVIS Spectrum）原位实时定量测定三种荧光标记的代表性病原体（病毒、细菌和原生动物）和水分在土壤中的时空分布及其格局变化。病原体在非饱和土壤孔隙中各种相界面上（液-固、液-气和液-固-气）的保持主要使用3-D激光扫描共聚焦显微仪进行微观可视化观测，所得结果将用于解释病原微生物胶体在宏观Darcy尺度上的迁移和分布行为。此外，该研究将建立数值数学模型框架用于分析病原体在不饱和异质土壤中不均匀迁移的关键控制过程和参数。本研究的顺利完成将为再生水安全农灌、市政及畜禽养殖业固废安全土地处理、水源性疾病防控和饮用水源保护等提供重要科学依据和评价工具。