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曾强,董海良,汪丹. 2019. 高温微生物铁还原条件下绿脱石对有机质的保存作用研究. 岩石学报, 35(1): 193-203
高温微生物铁还原条件下绿脱石对有机质的保存作用研究
作者单位E-mail
曾强 中国地质大学地球科学与资源学院, 北京 100083  
董海良 中国地质大学地球科学与资源学院, 北京 100083
中国地质大学生物地质与环境地质国家重点实验室, 北京 100083 
dongh@cugb.edu.cn 
汪丹 中国地质大学地球科学与资源学院, 北京 100083  
基金项目:本文受国家自然科学基金项目(41572328)资助.
摘要:
      粘土矿物在地表环境中广泛存在,并且与环境中的有机质紧密结合在一起。前人的研究发现,粘土矿物的可膨胀层间域可以有效地保存有机质,防止其在微生物诱导的氧化还原环境的波动的环境中被矿化。然而这一过程在高温条件下是否同样成立尚属未知。本文选取一种代表性有机质12-氨基十二酸(ALA)与典型含铁粘土矿物绿脱石(NAu-2)合成有机质-粘土矿物复合体,在两株高温-超高温铁还原细菌的作用后,通过多种水化学和矿物学的表征手段,研究其矿物结构的变化、有机质的结合稳定性和脱附情况。结果发现细菌对绿脱石结构铁的还原过程中造成的矿物结构的破坏(还原性溶解)是控制ALA从NAu-2中脱附的主要原因。高温条件也会略微促进ALA从NAu-2的层间域中脱附出来。总体来说,受限于微生物对结构铁的还原程度(<30%),最终在结构铁还原反应结束后还是有相当大量的ALA在层间保存了下来。这一结果证明了粘土矿物的层间域在高温条件下同样也能够作为有机质保存的有效场所。
英文摘要:
      Clay minerals are ubiquitous in surface environments and are closely associated with organic matters therein. Previous studies found that the expandable interlayers could effectively protect organic matters from mineralization in microbial-induced redox environments. But the specific mechanism is still unknown under high temperature. In this study, a model organic compound, 12-Aminolauric acid (ALA) and nontronite were used to synthesize organo-clay mineral composites. Various wet chemical and mineralogical methods were used to characterize the structural changes and ALA desorption from the composites after the bioreduction by two high temperature iron-reducing bacteria, Thermus scotoductus SA-01 and Geoglobus ahangari. Results showed that both bacteria could effectively reduce the structural Fe(Ⅲ) in nontronite. The presence of ALA in the interlayers of nontronite and its sorption on the mineral surfaces would interfere with the electron transfer between the structural Fe(Ⅲ) and bacteria, thus slowing the reduction rate. Reductive mineral dissolution resulted from microbial reduction of nontronite controlled the desortion of ALA from NAu-2. High temperature slightly promoted the mineral dissolution and desorption of ALA from the interlayers of NAu-2. Nano-sized silica was observed in bioreduced reaction groups. The presence of ALA did not seem to affect the secondary mineral formation. In summary, due to the limited microbial reduction extent of structural Fe (<30%) and the progressive microbial reduction pattern of structural Fe(Ⅲ) (from edge to the interior), there were still considerable amount of ALA preserving within the interlayers after the bioreduction ceased. These results demonstrate that the interlayer regions of clay minerals can serve as effective places for preserving the organic matters even under high temperature. These results also have important implication for petroleum generation as the interlay regions of clay mineral are considered to be important sites for this reaction.
关键词:绿脱石  微生物铁还原  高温  有机质保存
投稿时间:2018-07-01  修订日期:2018-10-15
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