Integrative application of geoelectrical methods for the characterization of preferential flow and reactive transport in the vadose soil zone

地电方法综合应用表征包气土区优先流和反应输运

• 批准号: 201146931
• 负责人: Dr. Markus Wehrer
• 金额: --
• 依托单位: Lehrstuhl für Hydrogeologie
• 依托单位国家: 德国
• 项目类别: Research Fellowships
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2012-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/201146931?language=en
• 关键词: Integrative; application; geoelectrical; methods; characterization

Preferential flow phenomena are ubiquitous in unsaturated subsurface environments and have multiple influences on water balance, transport of mobile substances and microbial activity. Quantification and modelling of such phenomena is still difficult and could be greatly improved by geophysical methods. The aim of this proposal is the characterization of preferential flow and its impact on reactive transport in a soil core by means of tomographic geoelectrical methods. In a time variable and unsaturated medium geophysical data interpretation is usually not unique. For instance, infiltrating water, release of ions from the soil and production of carbonates due to microbial activity result in a larger electrical conductivity of the soil core. This non-uniqueness will be reduced by a combination of electrical resistivity, induced polarization and self potential measurements. These methods will be applied in a controlled laboratory environment, because it is assumed that the non-uniqueness can furthermore be reduced by an appropriate selection of boundary conditions and tracers. To be able to characterize one process of influence on a geophysical variable like electrical conductivity, it is necessary to achieve steady state conditions for the remaining processes of influence. This can be done, for example, by varying the flow between steady state and transient regime or with the application of input solutions with different chemical properties, for example solutions, which either inhibit or provoke microbial activity. In this project, the geophysical methods will be supported by lysimeter techniques like frequency domain reflectometry (FDR) probes, tensiometers and a multi-compartment suction plate. The proposed project is innovative as it applies several geoelectrical methods simultaneously in an unsaturated, heterogeneous soil core in combination with time variable but controlled flow boundary conditions.

优先流现象在不饱和的地下环境中普遍存在，对水平衡、移动物质的运输和微生物活动有多重影响。对此类现象的量化和建模仍然很困难，可以通过地球物理方法大大改善。该提案的目的是通过层析地电方法表征优先流及其对土芯反应输运的影响。在时间变量和不饱和介质中，地球物理数据解释通常不是唯一的。例如，渗透水、土壤中离子的释放以及微生物活动导致碳酸盐的产生，导致土壤核心的电导率更大。这种非唯一性将通过电阻率、诱发极化和自电位测量的组合来减少。这些方法将应用于受控实验室环境，因为假设可以通过适当选择边界条件和示踪剂来进一步减少非唯一性。为了能够表征对地球物理变量（如电导率）的影响过程，有必要为其余影响过程实现稳态条件。例如，这可以通过改变稳态和瞬态状态之间的流动或通过应用具有不同化学性质的输入溶液（例如抑制或激发微生物活性的溶液）来完成。在该项目中，地球物理方法将得到频域反射计 (FDR) 探头、张力计和多室吸盘等蒸渗仪技术的支持。该项目具有创新性，因为它在不饱和的异质土芯中同时应用了多种地电方法，并结合了时间可变但受控的流动边界条件。