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胞外中间产物或代谢产物，可用于指示含水层中的原位电子传递过程。芳基琥珀酸酯衍生物已成为潜在的通用代谢生物标志物的转化甲苯，二甲苯，乙苯，和甲基萘在厌氧条件下。它们是在实验室培养物中鉴定出来的，部分是在现场样本中鉴定出来的。它们在野外的发生和分布尚未得到系统的调查，也没有调查可能影响代谢物形成和进一步周转的地球化学和水力参数。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的数据将进一步用于阐明其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（例如芳基琥珀酸盐、芳基羧酸、低分子量酸）的形成和周转以及影响参数。从这些实验中获得的数据将用于反应性运输建模。然后将使用校准模型模拟不同情景下的代谢物发生和分布。生物反应器实验将解决污染物降解和代谢物的形成/营业额与接种物的非污染泥炭地在不同的地球化学条件（边界条件）的问题。在这种情况下，代谢物积累将特别令人感兴趣。现场测量将在现场的地球化学反应区进行，我们将调查代谢物的模式，它们的空间分布和积累。将开发主要采用液相色谱-串联质谱法（LC-MS-MS）结合不同衍生反应的分析方法，以确保在柱实验的小样品体积和现场地下水样品中成功进行代谢物分析。

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.