Solano-Arguedas Agustín F, Boothman Christopher, Newsome Laura, Pattrick Richard A D, Arguedas-Quesada Daniel, Robinson Clare H, Lloyd Jonathan R
Williamson Research Centre, Department of Earth and Environmental Sciences, School of Natural Sciences, University of Manchester, Manchester, M13 9PL, UK.
Forest Resources Unit (Reforesta), Engineering Research Institute (INII) and School of Chemistry, Universidad de Costa Rica, Montes de Oca, San José, 11501-2260, Costa Rica.
Geochem Trans. 2022 Sep 27;23(1):2. doi: 10.1186/s12932-022-00079-5.
The Santa Elena Ophiolite is a well-studied ultramafic system in Costa Rica mainly comprised of peridotites. Here, tropical climatic conditions promote active laterite formation processes, but the biogeochemistry of the resulting serpentine soils is still poorly understood. The aim of this study was to characterize the soil geochemical composition and microbial community of contrasting landscapes in the area, as the foundation to start exploring the biogeochemistry of metals occurring there. The soils were confirmed as Ni-rich serpentine soils but differed depending on their geographical location within the ophiolite area, showing three serpentine soil types. Weathering processes resulted in mountain soils rich in trace metals such as cobalt, manganese and nickel. The lowlands showed geochemical variations despite sharing similar landscapes: the inner ophiolite lowland soils were more like the surrounding mountain soils rather than the north lowland soils at the border of the ophiolite area, and within the same riparian basin, concentrations of trace metals were higher downstream towards the mangrove area. Microbial community composition reflected the differences in geochemical composition of soils and revealed potential geomicrobiological inputs to local metal biogeochemistry: iron redox cycling bacteria were more abundant in the mountain soils, while more manganese-oxidizing bacteria were found in the lowlands, with the highest relative abundance in the mangrove areas. The fundamental ecological associations recorded in the serpentine soils of the Santa Elena Peninsula, and its potential as a serpentinization endemism hotspot, demonstrate that is a model site to study the biogeochemistry, geomicrobiology and ecology of tropical serpentine areas.
圣埃琳娜蛇绿岩是哥斯达黎加一个经过充分研究的超镁铁质系统，主要由橄榄岩组成。在这里，热带气候条件促进了活跃的红土形成过程，但由此产生的蛇纹岩土壤的生物地球化学仍知之甚少。本研究的目的是对该地区不同地貌的土壤地球化学组成和微生物群落进行表征，作为开始探索该地区金属生物地球化学的基础。这些土壤被确认为富含镍的蛇纹岩土壤，但根据其在蛇绿岩区域内的地理位置而有所不同，呈现出三种蛇纹岩土壤类型。风化过程导致山地土壤富含钴、锰和镍等痕量金属。尽管低地景观相似，但仍表现出地球化学变化：蛇绿岩内部低地土壤更类似于周围的山地土壤，而不是蛇绿岩区域边界的北部低地土壤，并且在同一河岸盆地内，痕量金属浓度在下游朝向红树林区域更高。微生物群落组成反映了土壤地球化学组成的差异，并揭示了对当地金属生物地球化学的潜在地质微生物输入：铁氧化还原循环细菌在山地土壤中更为丰富，而在低地发现了更多的锰氧化细菌，在红树林区域相对丰度最高。在圣埃琳娜半岛的蛇纹岩土壤中记录的基本生态关联及其作为蛇纹石化特有物种热点的潜力表明，它是研究热带蛇纹岩地区生物地球化学、地质微生物学和生态学的一个典型地点。
