Interaction of iron species and colloids with dissolved organic matter (DOM), dissolved organic sulfur compounds (DOSC) and low-molecular weight acids (LMWA)

微生物降解的特定生化和共代谢途径往往形成独特的细胞外中间体或代谢物，可用于指示含水层中的原位电子转移过程。芳基琥珀酸酯衍生物已成为甲苯、二甲苯、乙苯和甲基萘在厌氧条件下转化的潜在通用代谢生物标志物。它们在实验室培养物和部分现场样品中被鉴定出来。它们在野外的发生和分布尚未进行系统研究，也未对可能影响代谢物形成和进一步转化的地球化学和水力参数进行研究。因此，我们将在本项目中使用琥珀酸衍生物和其他酸性芳香族或脂肪族代谢物来监测和了解有机化合物通过电子转移过程的转化。代谢物的发生和空间分布数据将进一步用于阐明它们作为电子供体的作用，并估计电子供体功能的相关性。为此，我们将使用纯培养物的柱实验来研究特定代谢物（如芳基琥珀酸、芳基羧酸、低分子量酸）的形成和转化以及影响参数。从这些实验中获得的数据将用于反应输运建模。然后，校准的模型将用于模拟不同情景下代谢物的发生和分布。生物反应器实验将在不同地球化学条件（边界条件）下接种未受污染的泥炭地，解决污染物降解和代谢物形成/周转问题。在这种情况下，代谢物积累将特别有趣。现场测量将在场地的地球化学反应区进行，在那里我们将调查代谢物的模式，它们的空间分布和积累。以液相色谱-串联质谱（LC-MS-MS）为主要分析方法，结合不同的衍生化反应，以确保在小样本量的柱实验和现场地下水样品中成功分析代谢物。

Specific biochemical and co-metabolic pathways of microbial degradation often form unique extracellular intermediates or metabolites, which can be used to indicate in situ electron transfer processes in aquifers. Arylsuccinate derivatives have emerged as potentially universal metabolic biomarkers for the transformation of toluene, xylene, ethylbenzene, and methylnaphthalene under anaerobic conditions. They were identified in laboratory cultures and partly in field samples. Their occurrence and distribution in the field has been neither investigated yet systematically, nor were the geochemical and hydraulic parameters investigated that may influence formation and further turnover of metabolites. Therefore, we will use in this project succinic acid derivatives and other acidic aromatic or aliphatic metabolites to monitor and understand the transformation of organic compounds by electron transfer processes. Data of the occurrence and spatial distribution of metabolites will be further used to elucidate their role as electron donors and to estimate the relevance of the electron donor function. For that purpose we will use column experiments with pure cultures to investigate the formation and turnover of specific metabolites (e.g. arylsuccinates, arylcarboxylic acids, low-molecular weight acids) and influencing parameters. The data obtained from those experiments will be used for reactive transport modeling. The calibrated model will then be used to simulate metabolite occurrence and distribution in different scenarios. Bioreactor experiments will address the question on contaminant degradation and metabolite formation/turnover with an inoculum of non-contaminated peat land under different geochemical conditions (boundary conditions). Metabolite accumulation will be of particular interest in this context. Field measurements will be performed in geochemically reactive zones of the site, where we will investigate metabolite pattern, their spatial distribution and accumulation. Analytical methods mainly with liquid chromatography-tandem mass spectrometry (LC-MS-MS) combined with different derivatization reactions will be developed to guarantee successful metabolite analysis in small sample volumes of column experiments and in groundwater samples of field sites.