In the bioremediation field, geophysical techniques are commonly applied, at lab scale and field scale, to perform the characterization and the monitoring of contaminated soils. We propose a method for detecting the dielectric properties of contaminated soil during a process of bioremediation. An open-ended coaxial probe measured the complex dielectric permittivity (between 0.2 and 20 GHz) on a series of six soil microcosms contaminated by diesel oil (13.5% V_oil/V_tot). The microcosms had different moisture content (13%, 19%, and 24% V_w/V_tot) and different salinity due to the addition of nutrients (22 and 15 g/L). The real and the imaginary component of the complex dielectric permittivity were evaluated at the initial stage of contamination and after 130 days. In almost all microcosms, the real component showed a significant decrease (up to 2 units) at all frequencies. The results revealed that the changes in the real part of the dielectric permittivity are related to the amount of degradation and loss in moisture content. The imaginary component, mainly linked to the electrical conductivity of the soil, shows a significant drop to almost 0 at low frequencies. This could be explained by a salt depletion during bioremediation. Despite a moderate accuracy reduction compared to measurements performed on liquid media, this technology can be successfully applied to granular materials such as soil. The open-ended coaxial probe is a promising instrument to check the dielectric properties of soil to characterize or monitor a bioremediation process.

中文翻译：

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笔端同轴探针在生物修复过程中对柴油污染土壤中复介电常数的测量

在生物修复领域，通常在实验室规模和现场规模应用地球物理技术来进行污染土壤的表征和监测。我们提出了一种在生物修复过程中检测污染土壤介电特性的方法。一个开放式同轴探针在一系列六个被柴油污染的土壤微观环境中（13.5％V_油/ V _tot）测量了复介电常数（0.2至20 GHz之间）。微观世界的水分含量不同（V _w / V _tot为13％，19％和24％）和由于添加营养素（22和15 g / L）而产生的不同盐度。在污染的初始阶段和130天后评估复介电常数的实部和虚部。在几乎所有的微观世界中，真实成分在所有频率下均显着下降（最多2个单位）。结果表明，介电常数的实部的变化与降解量和水分含量的损失有关。虚部主要与土壤的电导率有关，在低频时显着下降至几乎为零。这可以用生物修复过程中盐分的消耗来解释。尽管与在液体介质上进行的测量相比，精度有所降低，该技术可以成功地应用于土壤等粒状材料。开放式同轴探针是一种有前途的仪器，可以检查土壤的介电特性以表征或监测生物修复过程。