Bacterial Associations with Weathering Minerals at the Regolith-Bedrock Interface, Luquillo Experimental Forest, Puerto Rico

Minyard, Morgan L.; Bruns, Mary Ann; Liermann, Laura J.; Buss, Heather L.; Brantley, Susan L.

doi:10.1080/01490451.2011.619640

Cited by 26 publications

(16 citation statements)

References 37 publications

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“…Additionally, the difference in the environments inside versus the outside of the mineral bags may have been greater for kaolinite than for the other minerals, due to its very small particle size, further differentiating the kaolinite environment. This highlights the importance of considering these minerals and our findings not only in the context of their mineralogy, but also the effect of their particle size and surface areas, which affects factors such as weathering rates (Turpault et al ., ; White, ) and microbially habitable surface (Minyard et al ., ).…”

Section: Discussionmentioning

confidence: 97%

Microbial community assembly differs across minerals in a rhizosphere microcosm

Whitman

Neurath

Perera

et al. 2018

Environmental Microbiology

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Mineral-associated microbes drive many critical soil processes, including mineral weathering, soil aggregation and cycling of mineral-sorbed organic matter. To investigate the interactions between soil minerals and microbes in the rhizosphere, we incubated three types of minerals (ferrihydrite, kaolinite and quartz) and a native soil mineral fraction near roots of a common Californian annual grass, Avena barbata, growing in its resident soil. We followed microbial colonization of these minerals for up to 2.5 months - the plant's lifespan. Bacteria and fungi that colonized mineral surfaces during this experiment differed across mineral types and differed from those in the background soil, implying that microbial colonization was the result of processes in addition to passive movement with water to mineral surfaces. Null model analysis revealed that dispersal limitation was a dominant factor structuring mineral-associated microbial communities for all mineral types. Once bacteria arrived at a mineral surface, capacity for rapid growth appeared important, as ribosomal copy number was significantly correlated with relative enrichment on minerals. Glomeromycota (a phylum associated with arbuscular mycorrhizal fungi) appeared to preferentially associate with ferrihydrite surfaces. The mechanisms enabling the colonization of soil minerals may be foundational in shaping the overall soil microbiome composition and development of persistent organic matter in soils.

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Section: Discussionmentioning

confidence: 97%

Microbial community assembly differs across minerals in a rhizosphere microcosm

Whitman

Neurath

Perera

et al. 2018

Environmental Microbiology

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“…Within these two monolithologic catchments ( Fig. 1), we focus on two ridgetop regolith profiles that have been previously studied (Buss et al, 2005(Buss et al, , 2010Chapela Lara et al, 2017;Liermann et al 2015;Lugolobi et al, 2010;Minyard et al, 2011Minyard et al, , 2012Murphy et al, 1998;Pett-Ridge, 2009;Pett-Ridge et al, 2009a,b;Schulz and White, 1999;Siebert et al, 2015;Yi-Balan et al, 2014). Key observations from soil pits at both of our field sites include a thin These redoximorphic features are more marked and more frequent in the volcaniclastic regolith profile, where the mottling between ~1.3 and 1.5 m depth (Yi-Balan et al, 2014) indicates that Mnoxides closely co-exist with lighter-colored, reduced Fe, while the bright red layer at the same depth indicates the presence of Fe(III) phases, especially hematite (-Fe2O3; Schaetzl and Anderson, 2005).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

The effects of lithology on trace element and REE behavior during tropical weathering

2018

Self Cite

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The thick regolith developed in the humid tropics represents an endmember of critical zone evolution, where shallow and deep biogeochemical cycles can be decoupled in terms of the predominant source of trace elements (atmospheric input at the surface, weathering at depth) and of the processes that control their cycling. To investigate the influence of lithology on trace element behavior and in this potential decoupling, we studied two deep (9.3 and 7.5 m), highly-leached, ridgetop regolith profiles at the Luquillo Critical Zone Observatory, Puerto Rico. These profiles have comparable internal (degree of weathering, topography) and external (vegetation, climate) characteristics, but differ in their underlying bedrock (andesitic volcaniclastic and granitic). At these two sites, we analyzed a large suite of trace elements and used the rare earth elements and yttrium (REY) as tracers of critical zone processes because they are fractionated by the chemical reactions involved in weathering and pedogenesis (e.g., sorption, dissolution, colloidal transport) and by redox fluctuations. ACCEPTED MANUSCRIPT A C C E P T E D M A N U S C R I P TWe found that both regolith profiles show atmospheric inputs of trace elements at the surface and evidence of bedrock dissolution at depth, as expected. We also found noticeable differences in the re-distribution of trace elements and REY within the profiles, indicative of different geochemical environments with depth and lithology. In the volcaniclastic profile, trace element and REY behavior is controlled mainly by redox-mediated, sorption/desorption reactions, whereas pHcontrolled dissolution/precipitation and sorption reactions predominate in the granitic profile. The most noticeable difference between the two regolith profiles is in the long-term redox conditions, inferred from redox-sensitive elements and Ce anomaly variations, which are more variable and stratified in the volcaniclastic profile and change gradually with depth in the granitic profile. The contrasting redox conditions and the different sources of elements (dust vs. bedrock) produce a decoupling between the surface and deep geochemical environments of the volcaniclastic regolith.The difference in redox conditions between the two lithologies likely stems from the finer grain size and higher clay content of the volcaniclastic regolith.

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“…This impact results from mechanical weakening of rock through roots and microbial symbionts (e.g. mycorrhizal fungi; Blum et al, 25 2002;Brantley et al, 2017;Hasenmueller et al, 2017;Minyard et al, 2012;Quirk et al, 2014;van Schöll et al, 2007), and from a variety of biogeochemical processes that alter the weatherability of minerals. These mechanisms include root respiration releasing protons and CO2 which lowers the soil pH, exudation of organic ligands through roots hence increasing the solubility of nutrients by complexation, and the uptake, uplift, and recycling of pore fluids and nutrients from solution (e.g.…”

Section: Introductionmentioning

confidence: 99%

Decoupling silicate weathering from primary productivity – how ecosystems regulate nutrient uptake along a climate and vegetation gradient

Oeser

Blanckenburg

2020

Preprint

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In addition to the supply of primary minerals and water flow the presence and growth rate of land plants are thought to drive rock weathering. While doubtlessly plants and their associated below-ground microbiota possess the tools for considerable weathering work, the quantitative evaluation of their impact relative to the common abiogenic weathering 10 processes remains poorly known. Here we report on a strategy to decipher the relative impact of these two drivers. We did so by quantifying weathering rates and nutrient uptake along the "EarthShape" transect in the Chilean Coastal Cordillera where landscapes are subjected to a substantial north to south gradient in precipitation and vegetation growth, whereas rock type is granitoid throughout and tectonic process rates do not differ much along the gradient. We quantified the bio-available fraction of nutritive elements in regolith and we measured 87 Sr/ 86 Sr isotope ratios in the different compartments of the Earth's Critical 15 Zone (bedrock, regolith, bio-available fraction in saprolite and soil, and vegetation) to identify the sources of mineral nutrients to plants. We thereby budgeted inventories, gains, and losses of nutritive elements in and out of these ecosystems, and quantified mineral nutrient recycling. We found that the weathering rates do not increase with precipitation from north to south along the climate gradient. Instead, the simultaneous increase in biomass growth rate is accommodated by faster nutrient recycling. The absence of an increase in weathering rate in spite of a five-fold increase in precipitation leads us to hypothesize 20 that the presence of plants can negatively impact weathering through inducing secondary-mineral formation and by fostering a microbial community that is adapted for nutrient-recycling rather than nutrient-acquisition through weathering.

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Bacterial Associations with Weathering Minerals at the Regolith-Bedrock Interface, Luquillo Experimental Forest, Puerto Rico

Cited by 26 publications

References 37 publications

Microbial community assembly differs across minerals in a rhizosphere microcosm

Microbial community assembly differs across minerals in a rhizosphere microcosm

The effects of lithology on trace element and REE behavior during tropical weathering

Decoupling silicate weathering from primary productivity – how ecosystems regulate nutrient uptake along a climate and vegetation gradient

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