February 14, 2019 | Atlanta, GA

Relationships based on “you scratch my back and I’ll scratch yours” are everywhere in the biological world. The recently established Center for the Origin of Life (COOL) will harness these mutualisms to unravel the distant past.

“Mutualisms are persistent and reciprocal exchange of benefit. A species proficient in obtaining certain benefits confers those on a reciprocating partner,” Loren Williams says. Williams is a professor in the School of Chemistry and Biochemistry at Georgia Tech. He will lead COOL. The NASA-funded interdisciplinary team based in Georgia Tech is one of several groups cooperating to identify planetary conditions that might give rise to life.

The COOL team itself is enabled by mutualistic scientific collaborations. Joining Williams as co-investigators are Georgia Tech’s Jennifer Glass and Anton Petrov, Kate Adamala and Aaron Engelhart of the University of Minnesota, George Fox from University of Houston, and Nita Sahai from University of Akron.

Glass is an assistant professor in the School of Earth and Atmospheric Sciences. Petrov is a research scientist in the Schools of Chemistry and Biochemistry and of Biological Sciences. Williams and Glass are members of the Parker H. Petit Institute for Bioengineering and Bioscience.

“We represent a rare symbiosis of biochemists and geochemists,” Glass says. “This gives us a unique vantage point from which to tackle this big question that no single discipline can solve alone.”

Williams and his team have discovered that inanimate species – such as molecules, metals, and minerals – engage in mutualism relationships. Those interactions can explain much about modern biology and the origin of life, Williams says. “Mutualisms are fundamental drivers in evolution, ecology, and economics. They sponsor coevolution, foster innovation, increase fitness, inspire robustness, and foster resilience.”

The COOL team aims to use mutualism phenomena to develop tools to study the origins and evolution of life on Earth. One area of study is the mutualism between metals and biomolecules under ancient-Earth conditions, such as between ferrous iron and proteins to form metalloproteins.

Another is the mutualism between minerals and biomolecules, such as between metal sulfide nanoclusters and RNA, peptides, and lipids to form functional biopolymers.

“Understanding how minerals interact with small organic molecules or biopolymers could help predict whether similar processes could occur on other worlds,” Sahai says.

The team will also study mutualisms in the most ancient universal life processes: translation and replication. “We are studying how nucleic acids and proteins joined forces as the biochemical foundation of life,” Petrov says.

The ribosome, the universal cellular machine where proteins are made, is a molecular relict where nucleic and acids and proteins work side by side to translate genotype to phenotype.

“The ribosome is a molecular fossil. It’s a window to the emergence of life,” Engelhart says.

 “We are exploring alternative pathways for the evolution of the translation system,” Adamala says.

“A key to understanding the translation system is by integrating a vast array of information,” Fox says.

COOL is one of four Teams in NASA’s recently launched Prebiotic Chemistry and Early Earth Environments (PCE3) Consortium. One of PCE3’s goals is to guide future NASA missions to discover habitable worlds by understanding how conditions on Earth gave rise to life.

Williams is a member of the steering committee of PCE3. “I am particularly excited to frame the beginnings of life within the context of our planet’s early, dynamic habitability and to use those lessons to imagine how planets around distant stars similarly could have favored the origins and evolution of life,” Williams said about PCE3.

Figure Caption
COOL principal investigators are (clockwise from top left) Kate Adamala, Aaron Engelhart, George Fox, Loren Williams, Nita Sahai, Anton Petrov, and Jennifer Glass. 

The School of Earth and Atmospheric Sciences Presents Dr. Elizabeth "Beth Ann" Bell, University of California Los Angeles

Hellish or Habitable? Constraints on the Environment of Early Earth

Several lines of evidence suggest that life on Earth may be as or more ancient than 3.8 Ga.  As such, there is a real possibility that Earth became habitable within its first few hundred million years.  The chief difficulty in assessing various hypothesized scenarios for the early Earth’s environment is the lack of a known rock record prior to 4.02 Ga.  

This earliest eon of Earth history (the Hadean) can be studied directly only by detrital minerals in later sediments.  The most well-studied suite of Hadean minerals is the Jack Hills detrital zircons (Western Australia), ranging to nearly 4.4 Ga in age and containing a variety of geochemical and petrological information about the Hadean magmas in which they crystallized.  

While pointing to the composition of at least part of the Hadean crust, these zircons and their cargo of mineral inclusions also provide indirect evidence for conditions in the surface and near-surface environment of Hadean Earth through a variety of isotopic systems and trace elements.  

A group of zircons with anomalous chemistry ca. 3.9 Ga may have formed through recrystallization – potentially representing some of the first terrestrial evidence for the Late Heavy Bombardment.  Carbonaceous mineral inclusions may provide evidence for Hadean carbon cycling: an isotopically light graphite inclusion in a 4.1 Ga zircon may provide evidence for life on Earth by 4.1 Ga.  By more fully exploiting mineral inclusions and trace element chemistry, especially in Hadean-Archean zircons from sites other than Jack Hills, we can develop a better grasp on the diversity of materials making up the Hadean crust and the diversity of their thermal histories during hypothesized bombardment episodes.  

These nontraditional mineral records may help to more clearly constrain not only the igneous crustal composition but potentially also the surficial environment and geodynamic settings at the dawn of life.

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The School of Earth and Atmospheric Sciences Presents Dr. Shaunna Morrison, Carnegie Science Geophysical Laboratory

In Situ X-ray Diffraction and Crystal Chemistry of Martian Minerals with Implications for the Habitability and Geologic History of Mars

The Mars Science Laboratory rover, Curiosity, is providing observations of rocks and soils in Gale crater. Since landing in 2012, Curiosity has analyzed the mineralogy of sediments with the CheMin instrument, the first X-ray diffractometer on another planet (Blake et al. 2013). 

CheMin performs quantitative mineralogical analyses of drilled powders and scooped sediment to determine mineral abundances, unit-cell parameters of major crystalline phases, and to estimate the chemical composition of major phases (Morrison et al. 2018a-b). 

The mineralogy of analyzed samples plays a key role in characterizing various 3.5 billion-year-old fluvio-lacustrine paleoenvironments in Gale crater, including provenance as well as degree and nature of alteration (e.g., Achilles et al. 2017; Yen 2017; Rampe et al. 2018).

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A School of Earth and Atmospheric Sciences Presents Dr. Laura Fierce, Brookhaven National Laboratory

Particle-Based Methods for Improving the Representation of Aerosol Effects on Climate

Aerosol effects on clouds and radiation have remained a large source of uncertainty in quantifying anthropogenic changes to Earth’s energy balance, despite increases in model complexity. 

Climate‐relevant aerosol properties depend on characteristics of individual particles, but particle‐level characteristics are not easily represented in atmospheric models. Instead, global and regional aerosol schemes approximate the representation of particle size and composition, leading to errors in predictions of climate-relevant aerosol properties that have not been well quantified. 

In my talk, I will describe two different particle-based methods for advancing aerosol representations in large-scale models. 

In the first part of my talk, I will discuss a multi-scale framework for combining particle-resolved model simulations with detailed laboratory measurements to quantify error in, and improve, reduced representations of aerosol absorption in large-scale models. I will show that neglecting diversity in composition and morphology yields large errors in modeled light absorption and introduce a method for improving the representation of aerosol absorption in large-scale models. 

In the second part of my talk, I will introduce a new sparse-particle model based on the quadrature method of moments, which is designed for use in large-scale atmospheric models. I will demonstrate that cloud condensation nuclei activity of particle-resolved populations, which are comprised of 10,000 to 1,000,000 Monte Carlo particles, are accurately represented by an optimized set of only ten sparse particles. 

This study is a first step toward a new aerosol simulation scheme that will track multivariate aerosol distributions with sufficient computational efficiency for inclusion in large-scale atmospheric models.

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The School of Earth and Atmospheric Sciences Presents Dr. Wendell Walters, Brown University

Investigating Atmospheric Reactive Nitrogen Utilizing Novel Isotopic Constraints

Anthropogenic activities have significantly perturbed the global nitrogen (N) budget through emissions of reactive nitrogen (Nr) primarily in the form of nitrogen oxides (NOx = NO + NO2) and ammonia (NH3) from accelerated fossil fuel combustion and agricultural activities since the second half of the 20th century. 

These compounds have important human health, climate, and environmental consequences including the formation of fine particulate matter, influence on the atmospheric oxidation budget, and deposition of excess Nr in sensitive ecosystems. Therefore, constraining Nr emission sources and their chemical, human health, and climate feedbacks is critical for future policy regulations to mitigate these affects. 

Here, I will present recent results of tracking the contribution of traffic-derived NH3 emissions and its role in fine particulate matter formation in a coastal urban environment utilizing novel N stable isotope analysis (δ15N) of NH3 and its secondary product, ammonium (NH4 + ). New methodologies and theoretical frameworks have been developed to accurately and precisely characterize and interpret δ 15N of NH3 and pNH4 + in ambient environments. The δ15N composition (or “fingerprint”) of NH3 has been characterized in vehicle-derived plumes in both stationary and mobile measurement campaigns in Northeastern United States as well as in Shenyang, China. 

Utilizing this newly established δ15N “fingerprint” the sources of NH3 in an urban environment have been determined in a year-long field study. Other on-going and future applications will (1) characterize the chemical coupling between NOx and biological volatile organic compounds utilizing oxygen stable isotopes (Δ17O & δ18O) in controlled laboratory chamber studies, (2) determine seasonal sea-atmosphere NH3 bi-directional flux in a large estuary, and (3) track modern Martian atmospheric nitrate formation in controlled experimental studies.

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The School of Earth and Atmospheric Sciences Presents Dr. Michelle Kim, California Institute of Technology

Marine Controls Over Atmospheric Chemistry

Spanning over 70% of Earth’s surface, the vast majority of the atmospheric boundary layer is a marine environment. The atmospheric chemistry in these relatively pristine regions are highly sensitive to perturbations. Production rates of oxidants (which dictate greenhouse gas lifetimes) and particulate matter (which influence radiative balance) are both strongly influenced by local sources and sinks. Despite this sensitivity, marine controls over reactive trace gases are poorly constrained, with some global source estimates spanning several orders of magnitude.

This talk presents recent advances in our mechanistic understanding of the controls over oxidants and particulate matter in the marine atmosphere, including biogenic production of gaseous precursors of climate-forcing agents, depositional controls over coastal air quality, and the development of novel techniques to provide direct constraints on air-sea exchange rates.

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The School of Earth and Atmospheric Sciences Presents Dr. Pengfei Liu, Harvard University

Climate-Relevant Properties of Atmospheric Organic Aerosols

Atmospheric aerosol particles are ubiquitous in the atmosphere and exert a significant influence on regional and global climate. The aerosol particles affect climate by scattering and absorbing solar radiation, as well as by serving as nuclei for cloud formation. A large fraction of the sub-micrometer particle mass consists of secondary organic material, produced by atmospheric oxidation of volatile organic compounds. The properties of secondary organic material remain uncertain given the diversity of precursor types and oxidation conditions.

Further, there is limited understanding about how organic aerosol particles interact with surrounding gas molecules. These interactions can affect the production and chemical aging of organic particles in the atmosphere. Here, I developed novel thin-film-based experimental approaches to characterize the climate-relevant properties of secondary organic material.

These properties include the optical constants, phase states, volatility, and hygroscopicity. These new measurements can be used to answer the following scientific questions: 1) How organic particles interact with solar radiation? 2) How do organic particles interact with water vapor and serve as cloud condensation nuclei? 3) How does the phase state of organic particles influence the gas-particle partitioning of semi-volatile species and multiphase reactions rates?

The results highlight different properties observed between secondary organic materials derived from anthropogenic and biogenic sources. These differences should be considered in the modeling of atmospheric organic aerosols.  

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The School of Earth and Atmospheric Sciences Presents Dr. Joseph Wilkins, Environmenal Protection Agency 

Modeling Fire and Ecosystems: Improving the Vertical Allocation of Smoke in a Chemical Transport Model

The area burned by wildland fires (prescribed and wild) across the contiguous United States has expanded by nearly 50% over the past 20 years, now averaging 5 million ha per year. 

Chemical transport models are used by environmental decision makers to both examine the impact of air pollution on human health and to devise strategies for reducing or mitigating exposure of humans to harmful levels of air pollution. Since wildfires are increasing in size and burning more intensely, the exposure of humans to fine particulate matter (PM2.5) and ozone (O3) is projected to grow. 

Currently, there is little consensus on fire pollution vertical transport methods. The height to which a biomass burning plume is injected into the atmosphere, or plume rise, is not only difficult to qualitatively determine but also comes with quantitative difficulties due to poor understanding of physical constraints within models. 

Many air quality models rely on plume rise algorithms to determine vertical allocation of emissions using various input models or in-line plume height calculations to determine plume height vertical structures and invoke transport of emissions. In this work, we test basic plume rise methods currently being used in chemical transport modeling in order to determine where the Community Multiscale Air Quality (CMAQ) modeling system’s current capabilities can be improved. 

We investigate proposed improvements for allocating the vertical distribution of smoke by separately characterizing the impacts of model grid resolution, emissions temporal profile, and plume rise algorithm.

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Kevin Pitts is Professor of Physics and Vice Provost for Undergraduate Education, University of Illinois. He is one of three finalists for the College of Sciences Dean search. He will present his vision of the college in this public seminar.

More information about Pitts is here.

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Rodolfo Torres is University Distinguished Professor of Mathematics, University of Kansas. He is one of three finalists for the College of Sciences Dean search. He will present his vision of the college in this public seminar.

More information about Torres is here.

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