Browsing by Author "Torres, Mark"

Now showing 1 - 6 of 6
  • Thumbnail Image
    Item
    A Framework for Understanding Whole-Earth Carbon Cycling
    (Cambridge University Press, 2019) Lee, Cin-Ty A.; Jiang, Hehe; Dasgupta, Rajdeep; Torres, Mark; Orcutt, Beth N.; Daniel, Isabelle; Dasgupta, Rajdeep
    Building from the base of knowledge presented in the preceding chapters, this chapter explores how the cycling of carbon in subduction zones and orogenic belts varies with supercontinent cycles and mountain building. It discusses the processes that link short-term and long-term carbon cycling and the timescales of these processes, such as the response times of weathering and atmospheric drawdown at periods of enhanced volcanism. This chapter covers topics of potential fluctuations in the long-term CO2 content of Earth’s atmosphere because of mantle–climate feedback, again taking advantage of the modeling platforms available for further exploration of these topics.
  • Thumbnail Image
    ItemEmbargo
    Differentiation of a CO2-rich, hydrous alkalic basalt and the genesis of carbonatites
    (2024-03-20) Rodriguez, Maria Raquel; Dasgupta, Rajdeep; Lee, Cin-Ty; Torres, Mark
    Intraplate settings almost uniquely host alkaline magmas and carbonatites. Although these magmas are spatially connected, the petrogenetic link between alkali magmas such as ocean island basalts (OIBs) and carbonatites is not well established. While previous studies have sought to identify the source origin of these magmas, the mechanisms behind their differentiation remain poorly understood. To constrain the evolution of alkalic magmas at mid-lithospheric depths, we performed high pressure-temperature, phase equilibria experiments on a hydrous, CO2 rich mantle-derived partial melt composition. The experiments were conducted at 1.5-2.0 GPa and 1200-1500 °C. The experimentally generated samples were studied using electron probe micro-analysis, where phase assemblage consisted of olivine + clinopyroxene + spinel + carbonated-silicate melt ± calcite ± vapor. As the melt composition undergoes evolution, the initial stages of crystallization generate alkalic OIB-like compositions, which subsequently transition towards natural calcio-magnesio carbonatite compositions. Our findings suggest that a single volatile-rich parental melt composition can give rise to OIBs and carbonatites at varying conditions.
  • Thumbnail Image
    Item
    Rainy with a Chance of Sea Salt: Sourcing the Sulfur in Houston's Rainfall
    (Rice University, 2024) Osorio, Valentina; Torres, Mark
    As one of six criteria air pollutants monitored by the US Environmental Protection Agency, sulfur dioxide negatively affects human and environmental health. Upon entering the atmosphere, sulfur dioxide is oxidized and dissolved in water as sulfuric acid; consequently sulfate rains out and can act as a tracer for atmospheric processing of sulfur compounds. Precipitation data were taken in Houston and compared to the Attwater Prairie Chicken National Wildlife Refuge in order to compare sulfur sources in atmospheric deposition between urban and rural regions. Houston rain exhibits chemical sign atures that are suggestive of seawater and dust influences on rain chemistry, but leaves uncertainty in attributions to these sources as well as others expected to be present around Houston. This project evaluates the degree to which solute and water isotope data can be used to source sulfate in rainfall both within the major city of Houston and outside of its large suburban area.
  • Thumbnail Image
    Item
    The hydrochemical signatures of (in) congruent weathering in Iceland
    (2020-04-21) Cole, Trevor L.; Torres, Mark
    Silicate weathering is often invoked as the dominant mechanism for sequestering CO2 over geologic timescales, where extrusive lithologies are assumed to disproportionately contribute to global silicate weathering fluxes due to their higher reactivity relative to intrusive substrate. While Iceland is largely considered monolithologic (i.e. basaltic), compiled bedrock and solute measurements herein suggest that river water is enriched in Ca and Na relative to a bedrock array which ranges from basaltic to rhyolitic. To explore this relationship, we evaluate environmental factors that could explain the solute trends including clay precipitation (type-I incongruent weathering), variable dissolution rates of primary minerals (type-II incongruent weathering), and rhyolite dissolution/ groundwater contributions. Through forward models we conclude that the precipitation of high-Mg smectite exerts the most control on solute movement relative to type-II incongruency or dissolution of rhyolite. However, more direct measurements of clay mineralogy and rhyolitic ash dissolution are necessary to better constrain this dataset.
  • Thumbnail Image
    Item
    The Impacts of Concrete on pH and Calcium Concentration in Houston’s Bayous
    (Rice University, 2021-05) Hale, Meagan; Torres, Mark
    As the human population grows, so does the percentage of people living in urban areas. This means that an increasing amount of landmass must be used for urban infrastructure and housing to accommodate a greater number of people. The environmental impacts of urbanization are not completely understood. However, one important aspect that may be impacted is water quality. For instance, the concrete used to construct water transport and drainage systems can leach Ca2+ions into urban rivers and increase water pH. These changes are of concern because pH range is a major factor in determining the toxicity and bioavailability of chemical compounds. Additionally, many aquatic microorganisms can only thrive within certain ranges of pH and Ca concentrations. To investigate how the concrete used in urban infrastructure impacts water quality, I studied two major rivers in Houston, TX, USA. The first, White Oak Bayou, is lined with concrete; the second, Buffalo Bayou, has a natural river bottom. These two rivers were compared with the non-urban but still geographically similar Trinity River, since river chemistry may be affected by the presence of concrete anywhere within a river’s watershed. I collected water samples from Buffalo and White Oak bayous and analyzed their major anions and cations using ion chromatography (IC) and inductively-coupled plasma mass spectrometry (ICP-MS) methods, respectively. In addition, I analyzed roughly 50 years’ worth of public water quality data for each bayou and the Trinity River. The data suggest that the concrete-lined White Oak Bayou has a higher Ca concentration and pH value than Buffalo Bayou. The results of this research expand our knowledge of the environmental impacts of water transport and drainage systems.
  • Thumbnail Image
    Item
    Using forty years of research to view Bahía Almirante on the caribbean coast of Panama as an integrated social-ecological system
    (Elsevier, 2024) Collin, Rachel; Adelson, Anne E.; Altieri, Andrew H.; Clark, Kasey E.; Davis, Kristen; Giddings, Sarah N.; Kastner, Samuel; Mach, Leon; Pawlak, Geno; Sjögersten, Sofie; Torres, Mark; Scott, Cinda P.
    Tropical coastal systems play a vital role in sustaining biodiversity, performing ecological functions, and providing ecosystem services. They are also home to 75% of people in the tropics. Given that coasts face intense anthropogenic pressures including climate change, human population growth, and land-use change, it is critical to develop an understanding of the linkages between physical processes, biological interactions, and social dynamics in the complex environment where land and sea meet. Here, we review and synthesize 40 years of research from the Bahía Almirante region on the Caribbean coast of Panama, summarizing the large knowledge base of marine ecology, paleontology, ecosystem science and social science and adding newer information on physical processes. We describe how the system experiences both global and local drivers that are common to many tropical coastal systems and examine the crosscutting linkages that shape the system's response to change. To accomplish this, we utilized the Press-Pulse Dynamics framework as a lens to organize the many strands of research and to allow the interdisciplinary research team to generate explicit illustrative hypotheses about important socioecological linkages related to stressors such as the variability in precipitation and increased migration and tourism. The goal for this review and synthesis is to encourage researchers in Bahía Almirante and other estuarine systems to consider the landscape and seascape more broadly, to reach beyond their immediate field of expertise, and to consider both social and environmental aspects as they seek to increase system understanding in ways that can enable more productive public discourse surrounding policy, infrastructural change, and conservation. Resumen: Los sistemas costeros tropical juegan un rol vital en el mantenimiento de la biodiversidad, cumpliendo funciones ecológicas y previendo servicios ecosistémicos. Estos también representan el hogar para el 75% de las personas en los Trópicos. Dado que las costas enfrentan intensas presiones antropogénicas, incluido el cambio climático, el crecimiento de la población humana y el cambio en el uso de la tierra, es fundamental desarrollar una comprensión de los vínculos entre los procesos físicos, las interacciones biológicas y la dinámica social en el complejo entorno donde se encuentran la tierra y el mar. Aquí, revisamos y sintetizamos 40 años de investigación en la región de la Bahía de Almirante en la costa Caribeña de Panamá. Resumimos la gran base de conocimientos principalmente de ecología marina, paleontología y ciencias sociales y reunimos información más reciente sobre procesos físicos. Describimos cómo el sistema experimenta impulsores tanto globales como locales que son comunes a muchos sistemas costeros tropicales y examinamos los vínculos transversales que dan forma a la respuesta del sistema al cambio. Para lograr esto, se utilizó el marco Press-Pulse Dynamics como lente para organizar las muchas líneas de investigación y permitir que el equipo de investigación interdisciplinario genere hipótesis ilustrativas explícitas sobre importantes vínculos socioecológicos relacionados con factores estresantes como la variabilidad en las precipitaciones y el aumento de la migración. Y turismo. El objetivo de esta revisión y síntesis es alentar a los investigadores de Bahía Almirante y otros sistemas estuarinos a considerar el paisaje y el paisaje marino de manera más amplia, ir más allá de su campo inmediato de especialización y considerar aspectos sociales y ambientales mientras buscan aumentar el sistema. Comprensión de manera que pueda permitir un discurso público más productivo en torno a las políticas, el cambio infraestructural y la conservación.