Miller Ana Z, Jiménez-Morillo Nicasio T, Coutinho Mathilda L, Gazquez Fernando, Palma Vera, Sauro Francesco, Pereira Manuel F C, Rull Fernando, Toulkeridis Theofilos, Caldeira Ana T, Forti Paolo, Calaforra José M
Instituto de Recursos Naturales y Agrobiologia de Sevilla (IRNAS-CSIC), Seville, Spain.
HERCULES Laboratory, University of Évora, Évora, Portugal.
iScience. 2022 Jun 9;25(7):104556. doi: 10.1016/j.isci.2022.104556. eCollection 2022 Jul 15.
The network of lava tubes is one of the most unexploited natural wonders of the Galapagos Islands. Here, we provide the first morphological, mineralogical, and biogeochemical assessment of speleothems from volcanic caves of the Galapagos to understand their structure, composition, and origin, as well as to identify organic molecules preserved in speleothems. Mineralogical analyses revealed that moonmilk and coralloid speleothems from Bellavista and Royal Palm Caves were composed of calcite, opal-A, and minor amounts of clay minerals. Extracellular polymeric substances, fossilized bacteria, silica microspheres, and cell imprints on siliceous minerals evidenced microbe-mineral interactions and biologically-mediated silica precipitation. Alternating depositional layers between siliceous and carbonate minerals and the detection of biomarkers of surface vegetation and anthropogenic stressors indicated environmental and anthropogenic changes (agriculture, human waste, and cave visits) on these unique underground resources. Stable isotope analysis and Py-GC/MS were key to robustly identify biomarkers, allowing for implementation of future protection policies.
熔岩管网络是加拉帕戈斯群岛最未被开发的自然奇观之一。在这里，我们首次对加拉帕戈斯火山洞穴中的石笋进行了形态学、矿物学和生物地球化学评估，以了解它们的结构、组成和成因，并识别保存在石笋中的有机分子。矿物学分析表明，贝拉维斯塔洞穴和皇家棕榈洞穴中的月奶石和珊瑚状石笋由方解石、蛋白石-A和少量粘土矿物组成。细胞外聚合物、化石细菌、二氧化硅微球以及硅质矿物上的细胞印记证明了微生物与矿物的相互作用以及生物介导的二氧化硅沉淀。硅质和碳酸盐矿物之间交替的沉积层以及对地表植被和人为压力源生物标志物的检测表明了这些独特地下资源的环境和人为变化（农业、人类废弃物和洞穴参观）。稳定同位素分析和热解气相色谱/质谱联用技术是可靠识别生物标志物的关键，有助于实施未来的保护政策。
