Collaboratvie Research: Biogeochemical Influences on Geophysical Signatures at Light Non-Aqueous Phase Liquids (LNAPL) Impacted Sites

0003692 Atekwana介绍土壤环境中的污染物，如轻非水相液体（LNAPLs）后，土壤介质的物理，化学和生物特性。 最初，土壤性质的改变主要是物理的，因为LNAPL占据了常驻土壤的孔隙。 随着时间的推移，LNAPL经历了由微生物介导的改变土壤性质的过程所驱动的变化。 地球物理方法能够检测土壤中新释放的LNAPLs，因为它们具有较高的电阻率，很容易与背景孔隙和地下水区分开来。 然而，许多老化的LNAPL泄漏的电阻率测量显示下降，而不是预期的增加。 因此，在这项研究中要解决的关键假设是，在地电签名从电阻的“新鲜的溢出”导电的“老”或生物降解溢出伴随着在受影响的介质中的LNAPL的地球化学修饰的转变。 这项工作是由需要获得一个基本的了解，相互关联的生物，化学，地质和水文过程中LNAPL影响的土壤，以及如何将这些相互关系转化为可测量的变化在地电响应的动态驱动。 我们的目标是实验记录重要的土壤物理和化学参数，从微生物降解的LNAPL和他们的作用，控制土壤的geoelectrical properties. We的实验使用灭菌的实验室柱填充砂从现场与LNAPL的影响。 一些柱用LNAPL分层并接种来自现场的微生物。 保留阳性和阴性对照柱。 地电测量是用植入柱中的电极获得的。 实验的目的是：通过监测微生物类型、种群和群落结构的变化以及潜在电子供体的变化来验证微生物LNAPL降解;记录土壤物理（颗粒）性质和孔隙流体地球化学的变化。（i）记录LNAPLs的微生物降解和随后影响介质的地球化学变化如何影响土壤地电响应;（ii）支持开发量化这些地球化学过程所需的地电模型;（iii）为将实验室地球物理退化模型扩展到受有机化学污染的实地提供基础

0003692Atekwana Introduction of pollutants in the soil environment such as Light Non-Aqueous Phase Liquids (LNAPLs) after the physical, chemical, and biological properties of the soil media. Initially, the alteration of the soil properties is primarily physical as the LNAPL occupies pores of the resident soils. With time, the LNAPL undergoes changes driven by microbial-mediated processes that alter soil properties. Geophysical methods are able to detect freshly released LNAPLs in soils because their higher electrical resistivity readily distinguishes from background pore and groundwater. Nevertheless, many resistivity measurements of aged LNAPL spills reveal a decrease and not the expected increase. Hence, the key hypothesis to be addressed in this study is that shifts in geoelectrical signatures from resistive in "fresh spills" to conductive in "aged" or biodegrading spills accompany biogeochemical modifications of LNAPL in the impacted media. The work is driven by the need to gain a basic understanding of the dynamics that interrelate biological, chemical, geological, and hydrological processes in LNAPL-impacted soils and how these interrelations translate into measurable changes in the geoelectrical response. The objective is to experimentally document important soil physical and chemical parameters that result from microbial degradation of LNAPL and their role in controlling the soil's geoelectrical properties.Our experiments use sterilized laboratory columns filled with sands from a field site impacted with LNAPL. Some of the columns are layered with LNAPL and inoculated with microbes from the field site. Positive and negative control columns are maintained. Geoelectrical measuremens are obtained using electrodes implanted in the columns. The experiments are designed to: Verify microbial LNAPL degradation by monitoring changes in microbial types, population and community structure, and changes in the presence of potential electron donors; andDocument changes in soil physical (grain) properties and in pore fluid geochemistry.Integrating geophysics, geochemistry, and microbiology will: (i) document how microbial degradation of LNAPLs and subsequent biogeochemical modifications of the impact media influence soil geoelectrical responses; (ii) support development of geoelectrical models necessary to quantify these biogeochemical processes; and (iii) provide a basis for extending laboratory geophysical degradation models to field sites contaminated with organic chemical