Effect of tectonic processes on biosphere-geosphere feedbacks across a convergent margin
Effect of tectonic processes on biosphere-geosphere feedbacks across a convergent margin
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DOI：
10.1038/s41561-021-00725-0
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发表时间：
2021-04-22
影响因子：
18.3
通讯作者：
Lloyd, Karen G.
中科院分区：
文献类型：
--
作者：
Fullerton, Katherine M.;Schrenk, Matthew O.;Lloyd, Karen G.
地下是地球上最大的生物群落之一，但微生物群落在构造板块边界上的变化程度或与俯冲尺度地质过程的相互作用仍然未知。在这里，我们比较了哥斯达黎加汇聚边缘的21个温泉的细菌群落组成和深层地下地球化学。泉水的正离子和阴离子组成反映了下伏构造的倾角和位置，也与细菌群落有关。与使用反三羧酸循环（rTCA）的培养化能岩石自养生物相关的共生微生物团以及宏基因组rTCA基因的丰度与板状挥发碳的浓度相关。结合碳同位素的证据，这表明板状植物产生的二氧化碳被固定到生物量中可能支持一个以化学岩石自养为基础的地下生态系统。我们计算出，这个弧前地下生物圈每年可以吸收1.4 × 10(9)至1.4 × 10(10) mol的碳，这将使向地幔输送的总碳估计减少2%至22%。根据观察到的相关性，我们认为地下细菌群落的分布和组成可能受到哥斯达黎加辐合边缘深部构造过程的影响，并且通过吸收俯冲过程中挥发的碳，这些趋化岩石自养群落反过来影响地圈。根据哥斯达黎加边缘温泉的细菌和地球化学相关性，跨越辐合边缘的地下生物圈可能反映了构造过程，减少了向地幔的碳转移。
The subsurface is among Earth's largest biomes, but the extent to which microbial communities vary across tectonic plate boundaries or interact with subduction-scale geological processes remains unknown. Here we compare bacterial community composition with deep-subsurface geochemistry from 21 hot springs across the Costa Rican convergent margin. We find that cation and anion compositions of the springs reflect the dip angle and position of the underlying tectonic structure and also correlate with the bacterial community. Co-occurring microbial cliques related to cultured chemolithoautotrophs that use the reverse tricarboxylic acid cycle (rTCA) as well as abundances of metagenomic rTCA genes correlate with concentrations of slab-volatilized carbon. This, combined with carbon isotope evidence, suggests that fixation of slab-derived CO2 into biomass may support a chemolithoautotrophy-based subsurface ecosystem. We calculate that this forearc subsurface biosphere could sequester 1.4 x 10(9) to 1.4 x 10(10) mol of carbon per year, which would decrease estimates of the total carbon delivered to the mantle by 2 to 22%. Based on the observed correlations, we suggest that distribution and composition of the subsurface bacterial community are probably affected by deep tectonic processes across the Costa Rican convergent margin and that, by sequestering carbon volatilized during subduction, these chemolithoautotrophic communities could in turn impact the geosphere.The subsurface biosphere across a convergent margin may reflect tectonic processes and reduce carbon transfer to the mantle, according to bacterial and geochemical correlations from hot springs across the Costa Rican margin.