Soil water percolation and nutrient fluxes as a function of topographical, seasonal and soil texture variation in Central Amazonia, Brazil

Journal Article · 10 April 2024 · Hydrological Processes

DOI: https://doi.org/10.1002/hyp.15148 · OSTI ID:2336604

Rodrigues, Jardel Ramos ^[1]; Solander, Kurt C.  ^[2]; Cropper, Stephen ^[3]; Newman, Brent D. ^[2]; Collins, Adam D. ^[2]; Warren, Jeffrey M. ^[4]; Negron‐Juarez, Robinson ^[5]; Gimenez, Bruno O. ^[6]; Spanner, Gustavo Carvalho ^[1]; Menezes, Valdiek da Silva ^[1]; Ríos‐Villamizar, Eduardo Antonio ^[7]; de Oliveira, Regison Costa ^[1]; Ferreira, Sávio José Filgueiras ^[8]; Higuchi, Niro ^[1]

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1. Forest Management Laboratory–LMF National Institute for Amazonian Research (INPA) Manaus Brazil
2. Earth and Environmental Sciences Division Los Alamos National Laboratory Los Alamos New Mexico USA
3. Department of Atmospheric and Oceanic Sciences University of California Los Angeles USA
4. Environmental Science Division Climate Change Science Institute‐Oak Ridge National Laboratory Oak Ridge Tennessee USA
5. Climate and Ecosystem Science Division Lawrence Berkeley National Laboratory Berkeley California USA
6. Forest Management Laboratory–LMF National Institute for Amazonian Research (INPA) Manaus Brazil, Department of Geography University of California Berkeley Berkeley California USA
7. Hydrological Research Coordination–CPH, Programa de Grande Escala Biosfera‐Atmosfera na Amazônia–LBA National Institute for Amazonian Research (INPA) Manaus Brazil, Centro de Estudos Superiores de Tabatinga–CESTB Universidade do Estado do Amazonas–UEA Tabatinga Amazonas Brazil
8. Hydrological Research Coordination–CPH, Programa de Grande Escala Biosfera‐Atmosfera na Amazônia–LBA National Institute for Amazonian Research (INPA) Manaus Brazil

Abstract Understanding soil water dynamics and transport of nutrients is challenging in tropical rainforests due to the uniqueness of several properties related to soils, vegetation and seasonality that make relating patterns found in temperate environments to tropical sites difficult. We address the need for better edaphic characterization in tropical environments by investigating soil water percolation rates and chemistry across topographic, soil texture and seasonal gradients in a mature tropical rainforest in Central Amazonia, Brazil. We utilized a passive wick flux meter (e.g., drainage lysimeter) to directly measure real‐time percolation fluxes at 60‐cm depth, and to sample a suite of chemical species across plateau, slope and valley topographic positions. We found percolation flux volume and chemical exports generally increase with decreasing elevation and clay content, which was lowest in the valley. Daily percolation flux was observed to be 2.39 ± 0.44 in plateau, 3.01 ± 0.50 in slope and 6.16 ± 0.83 mm in valley. Most solutes were present in small amounts of <1 mg L ⁻¹ , such as PO₄ ³⁻ , Fe ²⁺ /Fe ³⁺ and Mn ²⁺ ; however, NO ₃ ⁻ concentrations were >20 mg L ⁻¹ , even exceeding 100 mg L ⁻¹ in the valley. Based on additional isotopic analysis, we speculate high NO ₃ ⁻ concentrations are partially an artefact of root decomposition following installation of the flux meters. The empirical relationships we show among percolation volume and nutrient exports under varying topographies and soil textures can improve Earth System Model performance by better constraining ecohydrological relationships to nutrient fluxes, which can in‐turn better illuminate the important factors that govern their behaviour.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE; USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Biological and Environmental Research (BER)
• Grant/Contract Number: 89233218CNA000001; AC02-05CH11231; AC05-00OR22725
• OSTI ID: 2336604
• Report Number(s): LA-UR-23-22162; e15148
• Journal Information: Hydrological Processes, Journal Name: Hydrological Processes Journal Issue: 4 Vol. 38; ISSN 0885-6087
• Publisher: Wiley Blackwell (John Wiley & Sons)Copyright Statement
• Country of Publication: United Kingdom
• Language: English