Gas and solute reactive transport in variably saturated porous media

渗透带，即从地表延伸到地下水位的部分水饱和土壤和沉积物，构成了一个动态环境，通过降水入渗吸收水分，与大气交换气体，并受到一系列地球化学和微生物介导的过程以及植物-土壤相互作用的影响。例如，通过意外泄漏、地下储罐泄漏或管道破裂接触土壤的有机污染物，可以在污染完全饱和的地表水区之前通过增强生物降解活性来减弱。同样，气包带在大气或地下厌氧含水层对温室气体的吸收和破坏中也起着重要作用。另一方面，土壤和湿地可以显著促进温室气体的产生和排放。为了理解这些复杂的相互作用，并预测污染物衰减和与大气的气体交换，有必要将根际（即受植物根系影响的土壤区）、渗透区和饱和地下水区作为一个综合系统来考虑。这种方法可以评估渗漏带过程如何影响地下水质量，以及土壤和湿地中的运输和反应过程如何影响温室气体与大气的交换。

The vadose zone, i.e. partially water saturated soils and sediments that extend from ground surface to the water table, constitutes a dynamic environment which receives water through infiltration of precipitation, exchanges gases with the atmosphere, and is affected by a range of geochemical and microbially mediated processes and plant-soil interactions. For example, organic contaminants, which have contacted soils through accidental spills, leaky underground storage tanks, or pipelines breaks, may be attenuated by enhanced biodegradation activity prior to contaminating the fully saturated groundwater zone. Similarly, the vadose zone can play an important role in the uptake and destruction of greenhouse gases from the atmosphere or from underlying anaerobic aquifers. On the other hand, soils and wetlands can significantly contribute to the production and emission of greenhouse gases. To understand these complex interactions and to predict contaminant attenuation and gas exchange with the atmosphere, it is necessary to consider the rhizosphere (i.e. the soil zone affected by plant roots), the vadose zone, and the saturated groundwater zone as an integrated system. Such an approach allows an evaluation of how vadose zone processes affect groundwater quality, and how transport and reaction processes in soils and wetlands affect the exchange of greenhouse gases with the atmosphere.