Abstract

Biotic and abiotic batch experiments were performed in the presence of excess nutrients (N and P) and basaltic rocks in the medium under various conditions (NA, non-agitated; A, agitated). Changes in solution chemistry were monitored to characterize the influence of aerobic heterotrophic bacteria (Virgibacillus marismortui) on the dissolution rates and mechanisms of two basaltic rocks collected from King George (BAn; basaltic andesine) and Deception Island (BD, basalt), Antarctica. The presence of bacteria in the medium accelerated dissolution of basaltic rocks by a factor of 1.5 to 3 depending on both the rock composition and experimental conditions. The calculated linear element release rates in the biotic experiments (B, biotic) are enhanced in comparison with abiotic systems (A, abiotic) in the order: BD-B-NA > BD-B-A > BAn-B-NA. Unlike the abiotic reference experiments (BD-A-NA; BD-A-A, BAn-A-NA) with pH shifts of less than 0.5 units an accelerated release of Si, Ca, Mg, Fe and Al coincided with an increase in protein concentrations and a marked decrease in pH in the biotic experiments. As indicated by solution acidity, element release, trends of the reactive fluids and surface chemistry of the reacted rock samples, the catalytic effect of bacteria on mineral dissolution reactions was predominantly acidification due to bacterial metabolism. The major catalytic effect of acidification on mineral dissolution was likely suppressed by ammonification, resulting in a pH increase in the reactive fluid. The absence of secondary phases (e.g. Fe and Al oxyhydroxides) on the surface of biotically reacted rock particles and the presence of divalent cations (i.e. Ca and Mg) on the cell surfaces further show the role of the bacteria and associated organic ligands for metal-complexation reactions during basalt dissolution. This study shows that aerobic heterotrophic bacteria may play a critical role for acidity driven silicate dissolution in environments rich in nitrogenated organic compounds and may even influence the amount of Ca and Mg being released from Ca and Mg rich silicates to environments.

摘要

在各种条件下（NA，非搅拌； A，搅拌），在培养基中存在过量营养素（N和P）和玄武岩的情况下，进行了生物和非生物批次实验。监测溶液化学变化以表征需氧异养细菌（Virgibacillus marismortui）的影响分别从南极洲的乔治国王（BAn；玄武岩安山岩）和欺骗岛（BD，玄武岩）采集的两个玄武岩的溶出速率和机理。取决于岩石成分和实验条件，培养基中细菌的存在使玄武岩的溶解速度提高了1.5到3倍。与非生物系统（A，非生物）相比，在生物实验（B，生物）中计算的线性元素释放速率按以下顺序增强：BD-B-NA> BD-BA> BAn-B-NA。与非生物参考实验（BD-A-NA; BD-AA，BAn-A-NA）的pH值变化小于0.5个单位不同，Si，Ca，Mg，Fe和Al的加速释放与蛋白质浓度的增加同时发生在生物实验中，pH值明显降低。如溶液酸度，元素释放，反应流体的趋势和反应岩石样品的表面化学趋势，细菌对矿物溶解反应的催化作用主要是由于细菌的新陈代谢引起的酸化。氨化作用可能会抑制酸化作用对矿物溶解的主要催化作用，从而导致反应液的pH值增加。生物反应后的岩石颗粒表面上没有次级相（例如，Fe和氢氧化铝）和细胞表面上存在二价阳离子（即Ca和Mg），进一步表明了细菌和金属相关的有机配体的作用。玄武岩溶解过程中的络合反应。