Dissolved lithium and silicon through time in microbial dissolution experiments on ODP Leg 209 peridotite

Using peridotite drilled during Ocean Drilling Program Leg 209, a series of enrichment cultures were initiated on board the ship to stimulate microbially enhanced dissolution of olivine. Dissolution was estimated by measured changes in dissolved Li and Si in the media through time (up to 709 days). The results suggest that there was no significant difference between the amounts of dissolved Li and Si in most of the inoculated microbial cultures compared to the control cultures. Alternative explanations for this are that 1. No microbes are living in the culture tubes that can affect the dissolution rates of olivine, 2. The control cultures have microbes effecting the dissolution of olivine as well as the inoculated cultures, 3. Not enough time has passed to build up a large enough microbial population to effect the dissolution of the olivine in the culture tubes, 4. Microbes act to suppress dissolution of olivine instead of enhancing dissolution, and 5. Abiotic dissolution overshadows microbially enhanced dissolution. Further work is required to test these alternatives.本研究借助大洋钻探计划（Ocean Drilling Program, ODP）第209航次钻探获得的橄榄岩（peridotite）样品，在船上开展了一系列富集培养实验，以诱导橄榄石（olivine）发生微生物强化溶解。通过监测培养基中溶解态锂（Li）与硅（Si）的浓度随培养时长的变化（最长培养周期达709天），估算橄榄石的溶解量。实验结果表明，多数接种微生物的培养体系中，溶解态锂与硅的含量与对照培养体系无显著差异。针对该实验结果，提出以下五种潜在解释：1. 培养管内不存在可影响橄榄石溶解速率的活性微生物；2. 对照培养体系与接种组培养体系中均存在可调控橄榄石溶解过程的微生物；3. 培养时长不足，尚未形成足够规模的微生物种群以对橄榄石溶解产生显著影响；4. 微生物对橄榄石溶解起到抑制作用，而非强化作用；5. 非生物溶解过程的贡献远高于微生物强化溶解，掩盖了微生物介导的溶解效应。需开展后续实验以验证上述所有潜在解释。