Laperriere Sarah

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Laperriere
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Sarah
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  • Article
    Microbial functional diversity across biogeochemical provinces in the central Pacific Ocean
    (National Academy of Sciences, 2022-09-13) Saunders, Jaclyn K. ; McIlvin, Matthew R. ; Dupont, Christopher L. ; Kaul, Drishti ; Moran, Dawn M. ; Horner, Tristan J. ; Laperriere, Sarah ; Webb, Eric A. ; Bosak, Tanja ; Santoro, Alyson E. ; Saito, Mak A.
    Enzymes catalyze key reactions within Earth’s life-sustaining biogeochemical cycles. Here, we use metaproteomics to examine the enzymatic capabilities of the microbial community (0.2 to 3 µm) along a 5,000-km-long, 1-km-deep transect in the central Pacific Ocean. Eighty-five percent of total protein abundance was of bacterial origin, with Archaea contributing 1.6%. Over 2,000 functional KEGG Ontology (KO) groups were identified, yet only 25 KO groups contributed over half of the protein abundance, simultaneously indicating abundant key functions and a long tail of diverse functions. Vertical attenuation of individual proteins displayed stratification of nutrient transport, carbon utilization, and environmental stress. The microbial community also varied along horizontal scales, shaped by environmental features specific to the oligotrophic North Pacific Subtropical Gyre, the oxygen-depleted Eastern Tropical North Pacific, and nutrient-rich equatorial upwelling. Some of the most abundant proteins were associated with nitrification and C1 metabolisms, with observed interactions between these pathways. The oxidoreductases nitrite oxidoreductase (NxrAB), nitrite reductase (NirK), ammonia monooxygenase (AmoABC), manganese oxidase (MnxG), formate dehydrogenase (FdoGH and FDH), and carbon monoxide dehydrogenase (CoxLM) displayed distributions indicative of biogeochemical status such as oxidative or nutritional stress, with the potential to be more sensitive than chemical sensors. Enzymes that mediate transformations of atmospheric gases like CO, CO2, NO, methanethiol, and methylamines were most abundant in the upwelling region. We identified hot spots of biochemical transformation in the central Pacific Ocean, highlighted previously understudied metabolic pathways in the environment, and provided rich empirical data for biogeochemical models critical for forecasting ecosystem response to climate change.
  • Article
    An intercomparison of oceanic methane and nitrous oxide measurements
    (Copernicus Publications on behalf of the European Geosciences Union, 2018-10-05) Wilson, Samuel T. ; Bange, Hermann W. ; Arévalo-Martínez, Damian L. ; Barnes, Jonathan ; Borges, Alberto V. ; Brown, Ian ; Bullister, John L. ; Burgos, Macarena ; Capelle, David W. ; Casso, Michael A. ; de la Paz, Mercedes ; Farías, Laura ; Fenwick, Lindsay ; Ferrón, Sara ; Garcia, Gerardo ; Glockzin, Michael ; Karl, David M. ; Kock, Annette ; Laperriere, Sarah ; Law, Cliff S. ; Manning, Cara C. ; Marriner, Andrew ; Myllykangas, Jukka-Pekka ; Pohlman, John W. ; Rees, Andrew P. ; Santoro, Alyson E. ; Tortell, Philippe D. ; Upstill-Goddard, Robert C. ; Wisegarver, David P. ; Zhang, Gui-Ling ; Rehder, Gregor
    Large-scale climatic forcing is impacting oceanic biogeochemical cycles and is expected to influence the water-column distribution of trace gases, including methane and nitrous oxide. Our ability as a scientific community to evaluate changes in the water-column inventories of methane and nitrous oxide depends largely on our capacity to obtain robust and accurate concentration measurements that can be validated across different laboratory groups. This study represents the first formal international intercomparison of oceanic methane and nitrous oxide measurements whereby participating laboratories received batches of seawater samples from the subtropical Pacific Ocean and the Baltic Sea. Additionally, compressed gas standards from the same calibration scale were distributed to the majority of participating laboratories to improve the analytical accuracy of the gas measurements. The computations used by each laboratory to derive the dissolved gas concentrations were also evaluated for inconsistencies (e.g., pressure and temperature corrections, solubility constants). The results from the intercomparison and intercalibration provided invaluable insights into methane and nitrous oxide measurements. It was observed that analyses of seawater samples with the lowest concentrations of methane and nitrous oxide had the lowest precisions. In comparison, while the analytical precision for samples with the highest concentrations of trace gases was better, the variability between the different laboratories was higher: 36% for methane and 27% for nitrous oxide. In addition, the comparison of different batches of seawater samples with methane and nitrous oxide concentrations that ranged over an order of magnitude revealed the ramifications of different calibration procedures for each trace gas. Finally, this study builds upon the intercomparison results to develop recommendations for improving oceanic methane and nitrous oxide measurements, with the aim of precluding future analytical discrepancies between laboratories.