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Gianniny G, Stark JM, Abbott BW, Lee R, Brahney J. Soil temperature and moisture as key controls of phosphorus export in mountain watersheds. Sci Total Environ 2024; 921:170958. [PMID: 38365042 DOI: 10.1016/j.scitotenv.2024.170958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 02/11/2024] [Accepted: 02/11/2024] [Indexed: 02/18/2024]
Abstract
Oligotrophic mountain lakes act as sensitive indicators of landscape-scale changes in mountain regions due to their low nutrient concentration and remote, relatively undisturbed watersheds. Recent research shows that phosphorus (P) concentrations are increasing in mountain lakes around the world, creating more mesotrophic states and altering lake ecosystem structure and function. The relative importance of atmospheric deposition and climate-driven changes to local biogeochemistry in driving these shifts is not well established. In this study, we test whether increasing temperatures in watershed soils may be contributing to the observed increases in mountain lake P loading. Specifically, we test whether higher soil temperatures increase P mobilization from mountain soils by accelerating the rate of geochemical weathering and soil organic matter decomposition. We used paired soil incubation (lab) and soil transplant (field) experiments with mountain soils from around the western United States to test the effects of warming on rain-leachable P concentration, soil P mobilization, and soil respiration. Our results show that while higher temperature can increase soil P mobilization, low soil moisture can limit the effects of warming in some situations. Soils with lower bulk densities, higher pH, lower aluminum oxide contents, and lower ratios of carbon to nitrogen had much higher rain-leachable P concentration across all sites and experimental treatments. Together, these results suggest that mountain watersheds with high-P soils and relatively high soil moisture could have the largest increases in P mobilization with warming. Consequently, lakes and streams in such watersheds could become especially susceptible to soil-driven eutrophication as temperatures rise.
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Affiliation(s)
- Gordon Gianniny
- Department of Watershed Sciences, Utah State University, Old Main Hill, Logan, UT 84322, United States of America.
| | - John M Stark
- Department of Biology, Utah State University, Old Main Hill, Logan, UT 84322, United States of America
| | - Benjamin W Abbott
- Department of Plant & Wildlife Sciences, Brigham Young University, Provo, UT, United States of America
| | - Raymond Lee
- Department of Plant & Wildlife Sciences, Brigham Young University, Provo, UT, United States of America
| | - Janice Brahney
- Department of Watershed Sciences, Utah State University, Old Main Hill, Logan, UT 84322, United States of America
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2
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Kemeny PC, Torres MA, Fischer WW, Blättler CL. Balance and imbalance in biogeochemical cycles reflect the operation of closed, exchange, and open sets. Proc Natl Acad Sci U S A 2024; 121:e2316535121. [PMID: 38478696 PMCID: PMC10962936 DOI: 10.1073/pnas.2316535121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 02/09/2024] [Indexed: 03/27/2024] Open
Abstract
Biogeochemical reactions modulate the chemical composition of the oceans and atmosphere, providing feedbacks that sustain planetary habitability over geological time. Here, we mathematically evaluate a suite of biogeochemical processes to identify combinations of reactions that stabilize atmospheric carbon dioxide by balancing fluxes of chemical species among the ocean, atmosphere, and geosphere. Unlike prior modeling efforts, this approach does not prescribe functional relationships between the rates of biogeochemical processes and environmental conditions. Our agnostic framework generates three types of stable reaction combinations: closed sets, where sources and sinks mutually cancel for all chemical reservoirs; exchange sets, where constant ocean-atmosphere conditions are maintained through the growth or destruction of crustal reservoirs; and open sets, where balance in alkalinity and carbon fluxes is accommodated by changes in other chemical components of seawater or the atmosphere. These three modes of operation have different characteristic timescales and may leave distinct evidence in the rock record. To provide a practical example of this theoretical framework, we applied the model to recast existing hypotheses for Cenozoic climate change based on feedbacks or shared forcing mechanisms. Overall, this work provides a systematic and simplified conceptual framework for understanding the function and evolution of global biogeochemical cycles.
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Affiliation(s)
| | - Mark A. Torres
- Department of Earth, Environmental, and Planetary Sciences, Rice University, Houston, TX
| | - Woodward W. Fischer
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA
| | - Clara L. Blättler
- Department of the Geophysical Sciences, The University of Chicago, Chicago, IL
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3
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Bufe A, Rugenstein JKC, Hovius N. CO 2 drawdown from weathering is maximized at moderate erosion rates. Science 2024; 383:1075-1080. [PMID: 38452079 DOI: 10.1126/science.adk0957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 02/02/2024] [Indexed: 03/09/2024]
Abstract
Uplift and erosion modulate the carbon cycle over geologic timescales by exposing minerals to chemical weathering. However, the erosion sensitivity of mineral weathering remains difficult to quantify. Solute-chemistry datasets from mountain streams in different orogens isolate the impact of erosion on silicate weathering-a carbon dioxide (CO2) sink-and coupled sulfide and carbonate weathering-a CO2 source. Contrasting erosion sensitivities of these reactions produce a CO2-drawdown maximum at erosion rates of ~0.07 millimeters per year. Thus, landscapes with moderate uplift rates bolster Earth's inorganic CO2 sink, whereas more rapid uplift decreases or even reverses CO2 sequestration. This concept of an "erosion optimum" for CO2 drawdown reconciles conflicting views on the impact of mountain building on the carbon cycle and permits estimates of geologic CO2 fluxes dependent upon tectonic changes.
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Affiliation(s)
- Aaron Bufe
- Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Munich, 80333, Germany
| | | | - Niels Hovius
- GFZ German Research Center for Geosciences, Potsdam, 14473, Germany
- Department of Earth Sciences, University of Potsdam, Potsdam, 14476, Germany
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Reershemius T, Kelland ME, Jordan JS, Davis IR, D'Ascanio R, Kalderon-Asael B, Asael D, Suhrhoff TJ, Epihov DZ, Beerling DJ, Reinhard CT, Planavsky NJ. Initial Validation of a Soil-Based Mass-Balance Approach for Empirical Monitoring of Enhanced Rock Weathering Rates. Environ Sci Technol 2023; 57:19497-19507. [PMID: 37961896 DOI: 10.1021/acs.est.3c03609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Enhanced rock weathering (ERW) is a promising scalable and cost-effective carbon dioxide removal (CDR) strategy with significant environmental and agronomic co-benefits. A major barrier to large-scale implementation of ERW is a robust monitoring, reporting, and verification (MRV) framework. To successfully quantify the amount of carbon dioxide removed by ERW, MRV must be accurate, precise, and cost-effective. Here, we outline a mass-balance-based method in which analysis of the chemical composition of soil samples is used to track in situ silicate rock weathering. We show that signal-to-noise issues of in situ soil analysis can be mitigated by using isotope-dilution mass spectrometry to reduce analytical error. We implement a proof-of-concept experiment demonstrating the method in controlled mesocosms. In our experiment, a basalt rock feedstock is added to soil columns containing the cereal crop Sorghum bicolor at a rate equivalent to 50 t ha-1. Using our approach, we calculate rock weathering corresponding to an average initial CDR value of 1.44 ± 0.27 tCO2eq ha-1 from our experiments after 235 days, within error of an independent estimate calculated using conventional elemental budgeting of reaction products. Our method provides a robust time-integrated estimate of initial CDR, to feed into models that track and validate large-scale carbon removal through ERW.
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Affiliation(s)
- Tom Reershemius
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut 06511, United States
| | - Mike E Kelland
- Leverhulme Centre for Climate Change Mitigation, School of Biosciences, University of Sheffield, Sheffield S10 2TN, U.K
| | - Jacob S Jordan
- Porecast Research, Lawrence, Kansas 66049, United States
| | - Isabelle R Davis
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut 06511, United States
- School of Ocean and Earth Science, University of Southampton Waterfront Campus, Southampton SO14 3ZH, U.K
| | - Rocco D'Ascanio
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut 06511, United States
| | - Boriana Kalderon-Asael
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut 06511, United States
| | - Dan Asael
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut 06511, United States
| | - T Jesper Suhrhoff
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut 06511, United States
- Yale Center for Natural Carbon Capture, Yale University, New Haven, Connecticut 06511, United States
| | - Dimitar Z Epihov
- Leverhulme Centre for Climate Change Mitigation, School of Biosciences, University of Sheffield, Sheffield S10 2TN, U.K
| | - David J Beerling
- Leverhulme Centre for Climate Change Mitigation, School of Biosciences, University of Sheffield, Sheffield S10 2TN, U.K
| | - Christopher T Reinhard
- School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Noah J Planavsky
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut 06511, United States
- Yale Center for Natural Carbon Capture, Yale University, New Haven, Connecticut 06511, United States
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Krause AJ, Sluijs A, van der Ploeg R, Lenton TM, Pogge von Strandmann PAE. Enhanced clay formation key in sustaining the Middle Eocene Climatic Optimum. Nat Geosci 2023; 16:730-738. [PMID: 37564379 PMCID: PMC10409649 DOI: 10.1038/s41561-023-01234-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 06/26/2023] [Indexed: 08/12/2023]
Abstract
The Middle Eocene Climatic Optimum (around 40 million years ago) was a roughly 400,000-year-long global warming phase associated with an increase in atmospheric CO2 concentrations and deep-ocean acidification that interrupted the Eocene's long-term cooling trend. The unusually long duration, compared with early Eocene global warming phases, is puzzling as temperature-dependent silicate weathering should have provided a negative feedback, drawing down CO2 over this timescale. Here we investigate silicate weathering during this climate warming event by measuring lithium isotope ratios (reported as δ7Li), which are a tracer for silicate weathering processes, from a suite of open-ocean carbonate-rich sediments. We find a positive δ7Li excursion-the only one identified for a warming event so far -of ~3‰. Box model simulations support this signal to reflect a global shift from congruent weathering, with secondary mineral dissolution, to incongruent weathering, with secondary mineral formation. We surmise that, before the climatic optimum, there was considerable soil shielding of the continents. An increase in continental volcanism initiated the warming event, but it was sustained by an increase in clay formation, which sequestered carbonate-forming cations, short-circuiting the carbonate-silicate cycle. Clay mineral dynamics may play an important role in the carbon cycle for climatic events occurring over intermediate (i.e., 100,000 year) timeframes.
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Affiliation(s)
| | - Appy Sluijs
- Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands
| | - Robin van der Ploeg
- Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands
- Shell Global Solutions International B.V., Amsterdam, The Netherlands
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Wilf P, Kooyman RM. Do Southeast Asia's paleo-Antarctic trees cool the planet? New Phytol 2023. [PMID: 37369251 DOI: 10.1111/nph.19067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 05/23/2023] [Indexed: 06/29/2023]
Abstract
Many tree genera in the Malesian uplands have Southern Hemisphere origins, often supported by austral fossil records. Weathering the vast bedrock exposures in the everwet Malesian tropics may have consumed sufficient atmospheric CO2 to contribute significantly to global cooling over the past 15 Myr. However, there has been no discussion of how the distinctive regional tree assemblages may have enhanced weathering and contributed to this process. We postulate that Gondwanan-sourced tree lineages that can dominate higher-elevation forests played an overlooked role in the Neogene CO2 drawdown that led to the Ice Ages and the current, now-precarious climate state. Moreover, several historically abundant conifers in Araucariaceae and Podocarpaceae are likely to have made an outsized contribution through soil acidification that increases weathering. If the widespread destruction of Malesian lowland forests continues to spread into the uplands, the losses will threaten unique austral plant assemblages and, if our hypothesis is correct, a carbon sequestration engine that could contribute to cooler planetary conditions far into the future. Immediate effects include the spread of heat islands, significant losses of biomass carbon and forest-dependent biodiversity, erosion of watershed values, and the destruction of tens of millions of years of evolutionary history.
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Affiliation(s)
- Peter Wilf
- Department of Geosciences and Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA, 16802, USA
| | - Robert M Kooyman
- Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia
- Research Centre for Ecosystem Resilience, Royal Botanic Gardens and Domain Trust, Sydney, NSW, 2000, Australia
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Abstract
The dependence of rock weathering on temperature helps to steer Earth's climate.
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Affiliation(s)
- Robert G Hilton
- Department of Earth Sciences, University of Oxford, Oxford, UK
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