Linking rock age and soil cover across four islands on the Galápagos archipelago

Zehetner, Franz; Gerzabek, Martin H.; Shellnutt, J. Gregory; Ottner, Franz; Lüthgens, Christopher; Miggins, Daniel P.; Chen, Pei Hao; Candra, I Nyoman; Schmidt, Greta; Rechberger, Maria V.; Sprafke, Tobias

doi:10.1016/j.jsames.2020.102500

Cited by 16 publications

(25 citation statements)

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“…At each site, three replicate soil profiles at an approximate distance of 5–10 m were sampled down to the parent material, and their detailed characterization is addressed in other publications ( e.g ., Candra et al., 2021; Zehetner et al., 2020). The solum thickness at the study sites ranged from few centimeters to over 2 m. To ensure comparability with the less developed, shallow soils, we focused in this study on the topsoils (0–10 cm depth), which were air‐dried and sieved to 2 mm after sampling.…”

Section: Methodsmentioning

confidence: 99%

“…The topsoil samples used in this study are described in detail in previous studies (Rechberger et al., 2020; Zehetner et al., 2020). Briefly, the topsoil samples were taken in 2016 and 2017 on four of the Galápagos Islands (Isabela, Floreana, Santa Cruz, and San Cristóbal), Ecuador.…”

Section: Methodsmentioning

confidence: 99%

“…Details on the dating of the parent materials and their further characterization can be found in Zehetner et al. (2020). Soil types ranged from Histosols and Andosols on the youngest studied island, Isabela, to highly weathered Nitisols (IUSS Working Group WRB, 2015) on the oldest island of the chronosequence, San Cristóbal.…”

Section: Methodsmentioning

confidence: 99%

“…Additionally, two comparison sites located in dry/very dry climate zones (C3a, C5a) were selected. P contents in the parent materials (basaltic scoria) ranged from 0.86 to 2.26 g kg –1 (Zehetner et al., 2020).…”

Section: Methodsmentioning

confidence: 99%

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Phosphate sorption‐desorption properties in volcanic topsoils along a chronosequence and a climatic gradient on the Galápagos Islands

Rechberger

Zehetner

Gerzabek

2021

J. Plant Nutr. Soil Sci.

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Background Phosphorus (P) retention behavior in the soil is one of the main factors driving ecosystem productivity and changes strongly during soil weathering. Volcanic soils are known for their high phosphate (PO4) sorption capacity (PSC). However, the changes of PO4 buffering properties and fixation processes in the course of their pedogenic development are not fully understood. Aim We investigated the short‐term and longer‐term PO4 sorption‐desorption behavior in volcanic topsoils from the Galápagos Islands along a precipitation gradient (elevation sequence, 47–866 m asl) and a soil age gradient (chronosequence, 1.45–1070 ka) under humid climate. Methods Labile P (Mehlich‐3, resin‐P), P desorption (resin‐desorbable P after 1 and 6 months incubation), PSC (sorption isotherms, equilibration time = 72 h) and sorption kinetics (4 h–62 days) were analyzed and compared against a broad range of topsoil parameters. Results Soils developed very high PSC within 4.3 ka of soil weathering (Langmuir Qmax = 18.2 g P kg–1) due to the development of amorphous soil constituents. As the colloidal fraction changed to 2:1‐type crystalline clays after 26 ka of soil weathering under humid climate, PSC declined rapidly, while labile P and resin‐desorbable P reached a maximum. In older topsoils (≥ 165 ka), acidification and prevalence of aluminium (Al) and iron (Fe) (hydr)oxides led to increased P sorption again. Along the elevation sequence, increased precipitation favored the formation of amorphous constituents, resulting in a steep increase of P sorption capacity (from 0.9 to 19.9 g P kg–1) from the arid lowlands to the very humid highlands. Conclusion Amorphous Fe and Al phases as well as Fe and Al bound to organic matter seemed to be the main driving factors for P sorption along the studied pedogenic gradients.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Phosphate sorption‐desorption properties in volcanic topsoils along a chronosequence and a climatic gradient on the Galápagos Islands

Rechberger

Zehetner

Gerzabek

2021

J. Plant Nutr. Soil Sci.

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“…In a recent study on soil samples from the Galápagos Islands it was shown that glyphosate was massively applied in the past and volcanic soils from these islands still contain a high amount of this herbicide (Gerzabek et al, 2019). Further, it was evidenced that some of these soils were heavily weathered (Zehetner et al, 2020), being rich in kaolinite.…”

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confidence: 99%

On glyphosate–kaolinite surface interactions. A molecular dynamic study

Galicia‐Andrés

Tunega

Gerzabek

et al. 2020

European J Soil Science

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Glyphosate is an important and widely used herbicide, its environmental behaviour being of scientific and public interest. Computational models of clay minerals and their interactions with small organic molecules are valuable in studying adsorption processes at an atomistic resolution. We analysed the adsorption process of glyphosate on kaolinite, a clay mineral with a high abundance in several types of soils (e.g., of subtropical or tropical origin), in terms of the adsorption strength. The molecular interactions are characterized by monitoring the occurrence of hydrogen bonds, the orientation of the molecular dipole relative to the interface and the interaction energy. Two different ionic forms of glyphosate were considered: neutral and anionic (−1). It was shown that the main mechanism of the binding of both glyphosate forms to the aluminol surface of kaolinite is through multiple hydrogen bonds. The standard free energy of adsorption of neutral glyphosate from water solution to the basal octahedral surface of kaolinite was computed at −5 kJ mol −1 , whereas for the anionic form this quantity amounted to −14 kJ mol −1 . Our finding showed that kaolinite has an important contribution to overall adsorption capacity of soils for glyphosate, specifically in its anionic form. Highlights• The adsorption free energy of glyphosate on a kaolinite surface is quantified • Interactions are computed by quantum mechanics and by classical force field • Molecular interactions are characterized in terms of hydrogen bonds and orientations • The effect of polarization of the medium on the calculations is analysed K E Y W O R D S adsorption free energy, clay mineral interface, herbicide, molecular modeling, polarization | INTRODUCTIONGlyphosate (N-(phosphonomethyl)-glycine) is a nonselective herbicide for weed elimination, which has been widely used in recent history (Duke, 2018;Duke & Powles, 2008). Specifically, no-till agricultural management systems often rely on glyphosate for weed control. In some countries, it contributes more than 50% of all herbicide applications (Okada, Costa, & Bedmar, 2019). It seems that glyphosate remains in soil for longer time

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Cadmium retention and microbial response in volcanic soils along gradients of soil age and climate on the Galápagos Islands

et al. 2021

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The behavior of trace metals may vary strongly in the course of volcanic soil development. Cadmium retention in soils is specifically important for some Galápagos islands where agriculture is leading to anthropogenic Cd contamination. To assess the influence of soil development factors on soil Cd retention and toxicity, we performed Cd sorption-desorption experiments with volcanic topsoils from the Galápagos Islands sampled along gradients of (a) substrate age (chronosequence, 1.5-1,070 ka) and (b) climate (elevation sequence, 47-866 m asl) ranging from arid lowland areas to humid highland areas. Additionally, the effects of Cd toxicity on the soil microbial community composition were evaluated for two soils of the chronosequence. In young volcanic soils, the sorption capacity was very high but decreased rapidly with soil age and increasing elevation. These trends were coupled with decreases in soil weathering indicators (e.g., electrical conductivity, pH, and effective cation exchange capacity) as well as changes in soil mineralogy. Cadmium addition did not influence total phospholipid fatty acids and basal respiration in most soils. However, with increasing Cd concentration, a pronounced reduction in the Gram-negative/Gram-positive bacteria ratio (from 0.32 to 0.12) occurred in an old, highly weathered soil with low Cd retention capacity. Our results show that up to 60% of added Cd was only weakly sorbed in old volcanic soils. As a consequence, the old volcanic soils of Galápagos bear the potential risk that the mobile Cd fraction is taken up by soil microorganisms, transferring this element into the food chain.

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Linking rock age and soil cover across four islands on the Galápagos archipelago

Cited by 16 publications

References 48 publications

Phosphate sorption‐desorption properties in volcanic topsoils along a chronosequence and a climatic gradient on the Galápagos Islands

Phosphate sorption‐desorption properties in volcanic topsoils along a chronosequence and a climatic gradient on the Galápagos Islands

On glyphosate–kaolinite surface interactions. A molecular dynamic study

Cadmium retention and microbial response in volcanic soils along gradients of soil age and climate on the Galápagos Islands

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