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.

中文翻译：

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圣埃伦娜蛇绿岩中热带蛇纹石土壤的地球化学和微生物学，一种景观生物地理学方法

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，但由此产生的蛇纹石土壤的生物地球化学仍然知之甚少。本研究的目的是描述该地区对比景观的土壤地球化学成分和微生物群落，作为开始探索那里发生的金属生物地球化学的基础。土壤被确认为富含镍的蛇纹石土壤，但根据其在蛇绿岩区域内的地理位置而有所不同，显示出三种蛇纹石土壤类型。风化过程导致山区土壤富含钴、锰和镍等微量金属。尽管具有相似的景观，但低地显示出地球化学变化：内部蛇绿岩低地土壤更像是周围的山地土壤，而不是蛇绿岩区边界的北部低地土壤，并且在同一河岸盆地内，向红树林区域下游的痕量金属浓度较高。微生物群落组成反映了土壤地球化学成分的差异，揭示了对当地金属生物地球化学的潜在地球微生物输入：山地土壤中铁氧化还原循环细菌更丰富，而低地土壤中锰氧化细菌更多，相对丰度最高在红树林地区。圣埃伦娜半岛蛇纹石土壤中记录的基本生态关联及其作为蛇纹石化特有热点的潜力，