• Lecture

    TBA

    Organizer: Department of Earth and Planetary Sciences
    Speaker: Yakov Weiss
    Date: Sunday, March 1, 2020 Hour: 11:00 Location: Sussman Family Building for Environmental Sciences
  • Lecture

    TBA

    Organizer: Department of Earth and Planetary Sciences
    Speaker: Antonello Provenzale
    Date: Sunday, March 8, 2020 Hour: 11:00 Location: Sussman Family Building for Environmental Sciences
  • Lecture

    Potential role of cloud microorganisms in atmospheric chemistry

    Organizer: Department of Earth and Planetary Sciences
    Speaker: Anne-Marie Delort
    Abstract: We have shown that microorganisms (bacteria, yeast and fungi) were present in clouds and were metabolically active. As a consequence a new scientific question rose: are they able to modify the chemical composition of clouds and be an alternative route to radical chemistry? In the past we have mainly studied the biotransformation of simple carbon compounds (acetate, succinate, formate, methanol, formaldehyde), and oxidants (H2O2). We showed that biodegradation rates were within the same range of order than photo-transformation rates. More recently we investigated their potential biodegradation activity towards atmospheric pollutants. Using GCxGC-HRMS technique we were able to detect and identify over 100 semi-volatile compounds in 3 cloud samples collected at the puy de Dôme station (1465 m, France). Among these compounds, 10 priority pollutants from the US EPA list were identified and quantified. We focused our work on the biodegradation of phenol and catechol in clouds using two strategies. 1) A metatranscriptomic analysis showed in cloud activity of microorganisms. We detected transcripts of genes coding for phenol monooxygenases (and phenol hydroxylases) and catechol 1,2-dioxygenases. These enzymes were likely from Gamma-proteobacteria (Acinetobacter and Pseudomonas genera). 2) 145 bacterial strains isolated from cloud water were screened for their phenol degradation capabilities, 93% of them (mainly Pseudomonas and Rhodococcus strains) were positive. These findings highlighted the possibility of phenol degradation by microorganisms in clouds. To go further we measured the biodegradation rates of Phenol and Catechol by one of the most active strain (Rhodococcus enclensis) and compared them with the transformation rates resulting from the reactivity of °OH and NO3°radicals. In the cloud water phase, both phenol transformation rates were within the same range of order, while biodegradation of catechol was ten times quicker than chemical transformation. The experimentally derived biodegradation rates were included in a multiphase box model to compare the chemical loss rates of phenol and catechol in both the gas and aqueous phases to their biodegradation rate in the aqueous phase under atmospheric conditions. In conclusion our results suggest that cloud microorganisms could play a role in atmospheric chemistry.
    Date: Sunday, March 15, 2020 Hour: 11:00 Location: Sussman Family Building for Environmental Sciences
  • Lecture

    Seismic sensing with optical fibers – principles and applications

    Organizer: Department of Earth and Planetary Sciences
    Speaker: Ariel Lellouch
    Abstract: During the last decade, seismic sensing with optical fibers has become a reality. By analyzing the effect of seismic deformation on the fiber’s optical response, state-of-the-art Distributed Acoustic Sensing (DAS) now offers a 1-meter sensor resolution for tens of kilometers of fiber. In other words, a single DAS system can record up to 40,000 data channels at once – two orders of magnitude more than the entire earthquake-monitoring seismic network in Israel. In this talk, I will first introduce the underlying operating principles of DAS acquisition. These measurements are very different from conventional seismic sensors and need to be analyzed accordingly. Subsequently, most of the talk will revolve around DAS applications in various scenarios. We use the ambient seismic field, recorded on a standard telecommunication fiber deployed around the Stanford campus, to analyze subsurface properties. We also acquired DAS data from a downhole fiber deployed in the SAFOD well and utilized it to reconstruct the earth’s structure and detect earthquakes. Finally, we study DAS data from an unconventional gas field and show how to conduct a simple analysis that unveils reservoir properties.
    Date: Tuesday, March 17, 2020 Hour: 10:30 Location: Sussman Family Building for Environmental Sciences
  • Lecture

    TBA

    Organizer: Department of Earth and Planetary Sciences
    Speaker: Bar Oryan
    Date: Sunday, March 29, 2020 Hour: 11:00 Location: Sussman Family Building for Environmental Sciences
  • Lecture

    TBA

    Organizer: Department of Earth and Planetary Sciences
    Speaker: Colin Price
    Date: Sunday, April 5, 2020 Hour: 11:00 Location: Sussman Family Building for Environmental Sciences