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Item type:Publication, Development of global temperature and pH calibrations based on bacterial 3-hydroxy fatty acids in soils(Copernicus Publications, 2020-11-24)Abstract. 3-hydroxy fatty acids (3-OH FAs) with 10 to 18 C atoms are membrane lipids mainly produced by Gram-negative bacteria. They have been recently proposed as temperature and pH proxies in terrestrial settings. Nevertheless, the existing correlations between pH/temperature and indices derived from 3-OH FA distribution (RIAN, RAN15 and RAN17) are based on a small soil dataset (ca. 70 samples) and only applicable regionally. The aim of this study was to investigate the applicability of 3-OH FAs as mean annual air temperature (MAAT) and pH proxies at the global level. This was achieved using an extended soil dataset of 168 topsoils distributed worldwide, covering a wide range of temperatures (5 °C to 30 °C) and pH (3 to 8). The response of 3-OH FAs to temperature and pH was compared to that of established branched GDGT-based proxies (MBT'5Me/CBT). Strong linear relationships between 3-OH FA-derived indices (RAN15, RAN17 and RIAN) and MAAT/pH could only be obtained locally, for some of the individual transects. This suggests that these indices cannot be used as paleoproxies at the global scale using simple linear regression models, in contrast with the MBT'5Me and CBT. However, strong global correlations between 3-OH FA relative abundances and MAAT/pH were shown by using other algorithms (multiple linear regression, k-NN and random forest models). The applicability of the k-NN and random forest models for paleotemperature reconstruction was tested and compared with the MAAT record from a Chinese speleothem. The calibration based on the random forest model appeared to be the most robust. It showed similar trends with previously available records and highlighted known climatic events poorly visible when using local 3-OH FA calibrations. Altogether, these results demonstrate the potential of 3-OH FAs as paleoproxies in terrestrial settings. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Development of global temperature and pH calibrations based on bacterial 3-hydroxy fatty acids in soils(Copernicus GmbH, 2021-07-01)Gram-negative bacteria produce specific membrane lipids, i.e. 3-hydroxy fatty acids with 10 to 18 C atoms. They have been recently proposed as temperature and pH proxies in terrestrial settings. Nevertheless, the existing correlations between pH or temperature and indices derived from 3-OH FA distribution are based on a small soil dataset (ca. 70 samples) and only applicable regionally. The aim of this study was to investigate the applicability of 3-OH FAs as mean annual air temperature (MAAT) and pH proxies at the global level. This was achieved using an extended soil dataset of 168 topsoils distributed worldwide, covering a wide range of temperatures (5 to 30 ∘C) and pH (3 to 8). The response of 3-OH FAs to temperature and pH was compared to that of established branched glycerol dialkyl glycerol tetraether (GDGT)-based proxies (MBT'5Me/CBT). Strong linear relationships between 3-OH-FA-derived indices (RAN15, RAN17 and RIAN) and MAAT or pH could only be obtained locally for some of the individual transects. This suggests that these indices cannot be used as palaeoproxies at the global scale using simple linear regression models, in contrast with the MBT'5Me and CBT. However, strong global correlations between 3-OH FA relative abundances and MAAT or pH were shown by using other algorithms (multiple linear regression, k-NN and random forest models). The applicability of the three aforementioned models for palaeotemperature reconstruction was tested and compared with the MAAT record from a Chinese speleothem. The calibration based on the random forest model appeared to be the most robust. It generally showed similar trends with previously available records and highlighted known climatic events poorly visible when using local 3-OH FA calibrations. Altogether, these results demonstrate the potential of 3-OH FAs as palaeoproxies in terrestrial settings. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Edaphic and meteorological parameters as determinants of radon exhalation and its environmental implication in Peruvian agroecosystems(Nature Research, 2025)Radon exhalation is a natural process by which atoms of the radioactive gas radon diffuse in the soil and then exhale to an indoor and/or outdoor environment. High radon concentration levels, possibly from high radon exhalation rate levels, can generate an impact on public health and environmental safety, particularly in agricultural areas where prolonged exposure may affect nearby populations. While studies have examined radon exhalation, few have focused on modeling its behavior in agricultural settings or identifying key environmental and soil parameters that influence its variation. This study addresses this gap by applying Artificial Neural Network (ANN) models and Monte Carlo methods. Three distinct approaches were developed based on radon exhalation measurements from four Peruvian agricultural regions, incorporating meteorological and soil physicochemical data. First, the ANN model determined environmental factors affecting radon exhalation, achieving R² values of 0.7949 (training) and 0.7656 (validation). Second, simulations analyzed radon diffusion under varying wind conditions, assessing dispersion risks. Third, gamma radiation measurements quantified radon progeny contributions (2.82 × 10⁻⁴ ± 1.15 × 10⁻⁵ efficiency) for soil moisture detection. This integrated methodology advances understanding of agricultural radon dynamics, supporting improved radiological safety protocols and soil monitoring techniques.1 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Microbial death in the Andes: necromass declines despite growth and carbon-use-efficiency increases with decadal soil warming(Elsevier, 2026)The growth and death of soil microbes are important drivers of soil carbon formation. A warming climate is predicted to affect both the production of microbial biomass and the stability of microbial residues (necromass) held in soils. However, we have very little information on how warming in tropical soils will affect these processes, and on the effect of temperature on microbial production and turnover over different time-scales. To address this, we studied temperature effects on microbial-mediated C cycling across two different time-scales, using a 20 ⁰C mean annual temperature gradient in the Peruvian Andes (long-term effects) and decadal experimental-warming via soil translocation (11-years of temperature effects). At long-term timescales, a legacy of warmer temperatures decreased microbial carbon use efficiency (CUE), microbial biomass C, and decreased fungal and bacterial necromass concentration in soils. At decadal timescales, experimental warming increased CUE, microbial production and microbial biomass concentration (likely the result of concomitant changes in substrate availability). However, this did not translate into increased microbial necromass concentration, which generally declined with warming across all temporal scales. Together, we show that warmer temperatures over decadal (11-year) timescales affect soil microbial processes to potentially increase their C input to soil (increased CUE, microbial production, and biomass) but we find no evidence that this C became stabilized as the necromass C pool decreased. Our results indicate that warming can alter microbial community metabolism to potentially increase necromass C inputs to soil, although we find no evidence to show that this offset overall soil C loss with warming.2