Department of Earth and Environmental Science

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  • Publication
    The Pulse of Calm Fan Deltas
    (2008-07-01) Kim, Wonsuck; Jerolmack, Douglas J
    At the heart of interpreting the history of Earth surface evolution preserved in the rock record is distinguishing environmental (allogenic) forcing from internally generated (autogenic) “noise.” Allogenic deposits classically have been recognized by their cyclic nature, which apparently results from periodic changes in base level, sediment supply, or tectonics. Autogenic deposits, which are quite variable in their origin and scale, are caused by the nonlinearity of sediment transport and might be expected to have a random or scale-free (fractal) signature. Here we describe a robust mechanism that generates cyclic deposits by an autogenic process in experimental fan deltas. Sheet flow over the fan surface induces deposition and an increase in fluvial slope and curvature to a point where the surface geometry is susceptible to a channelization instability, similar to channel initiation on hillslopes. Channelized flow results in incision and degrading of the fan surface to a lower slope, releasing a pulse of sediment that pushes the shoreline forward. Sheet flow resumes once the surface is regraded, and the cycle repeats in a surprisingly periodic fashion to produce cyclic foreset accretions. We use simple scaling and a one-dimensional fan evolution model to (1) demonstrate how time-varying flow width can cause pulses in sediment discharge at the shoreline in agreement with experiments and (2) reinterpret cyclic deposits reported in the field. Alternating sheet and channelized flows are known to operate on noncohesive fans in nature. Our results suggest that rather than reflecting variation in environmental forcing, many observed cyclic sedimentation packages may be a signature of the autogenic “pulse” of fan deltas under calm environmental conditions.
  • Publication
    Zirconolite: A Review of Localities Worldwide, and a Compilation of its Chemical Compositions
    (1996-06-01) Williams, C T; Gieré, Reto
    A compilation of the chemical data and brief review of the mineral zirconolite, essentially CaZrTi207, is presented. A total of 321 chemical analyses, 169 previously unpublished, from 39 of the 46 known terrestrial localities, and covering IO rock types are tabulated. A brief description of the minerals associated with zirconolite is outlined for each locality. Data from all zirconolite-bearing lunar rocks have also been compiled. The recently published nomenclature scheme for zirconolite is employed throughout.
  • Publication
    Retention of Actinides in Natural Pyrochlores and Zirconolites
    (1994) Lumpkin, Gregory R; Hart, K P; McGlinn, P J; Payne, T E; Gieré, Reto; Williams, C T
    Natural pyrochlore and zirconolite undergo a crystalline-aperiodic transformation caused by alpha-decay of 232Th and 2380 at dose levels between 2 X 1014 and 3 X 1017 a/mg. The principal effects of the transformation are volume expansion and microfracturing, providing potential pathways for fluids. Geochemical alteration of the minerals may occur under hydrothermal conditions or in low temperature, near surface environments, but Th and U usually remain immobile and can be retained for time scales up to 109 years. However, the Th-U isotope systematics of a zirconolite-bearing vein and dolomite host rock may provide evidence for disequilibrium between 230Th, 234U and 238U.
  • Publication
    Recalcitrant Pharmaceuticals in the Aquatic Environment: A Comparative Screening Study of Their Occurrence, Formation of Phototransformation Products and Their in Vitro Toxicity
    (2014-01-01) Bergheim, Marlies; Gminski, Richard; Spangenberg, Bernd; Dębiak, Malgorzata; Bürkle, Alexander; Mersch-Sundermann, Volker; Kümmerer, Klaus; Gieré, Reto
    Data allowing for a complete environmental risk assessment of pharmaceuticals and their photoderatives in the environment are still scarce. In the present study, in vitro toxicity and both bio- and photopersistence of various pharmaceuticals (aciclovir, allopurinol, cetirizine, cimetidine, fluconazole, hydrochlorothiazide, lisinopril, phenytoin, primidone, ranitidine, sotalol, sulpiride, tramadol and valsartane) as well as their phototransformation products were evaluated in order to fill data gaps and to help prioritise them for further testing. Twelve out of the fourteen compounds investigated were found to be neither readily nor inherently biodegradable in the Organisation of Economic Cooperation and Development-biodegradability tests. The study further demonstrates that the photo-induced transformation of the pharmaceuticals was faster upon irradiation with a Hg lamp (UV light) than with a Xe lamp emitting a spectrum that mimics sunlight. Comparing the non-irradiated with the respective irradiated solutions, a higher acute and chronic toxicity against bacteria was found for the irradiated solutions of seven compounds (cetirizine, cimetidine, hydrochlorothiazide, ranitidine, sulpiride, tramadol and valsartane). No cyto- and genotoxic effects were found in human cervical (HeLa) and liver (Hep-G2) cells for any of the investigated compounds or their phototransformation products. This comparative study documents that phototransformation products can arise as a result of UV treatment of wastewater containing these pharmaceuticals. It further demonstrates that some phototransformation products may have a higher environmental risk potential than the respective parent compounds because some phototransformation products exhibited a higher bacterial toxicity.
  • Publication
    Surface Crystal Chemistry of Phyllosilicates Using X-Ray Photoelectron Spectroscopy: A Review
    (2016-10-01) Elmi, Chiara; Guggenheim, Stephen; Gieré, Reto
    The characterization of freshly cleaved mica surfaces for surface structure and chemical composition was briefly reviewed and focused on surface crystal chemistry using X-ray photoelectron spectroscopy (XPS) and other surface-sensitive techniques. This paper considers micas, which are useful as a first approximation for the behavior of many clay surfaces. Emphasis was given to phyllosilicate XPS binding energies (''chemical shift''), which were described and used to obtain oxidation state, layer charge, and chemical bonding information from the chemical shifts of different peaks. The chemical shift of the Si2p binding-energy to lower values can result from a negative charge increase because of Si4+ replacement by Al3+ and/or Fe3+. The apparent interlayer coordination number reduction from twelve to eight at muscovite and tetraferri-phlogopite (001) surfaces was indicated by the XPS measured K2p binding-energy and is consistent with bond relaxation. Although chemical shifts are valuable to distinguish chemical bonding and oxidation state, chemical shifts usually cannot distinguish between different Al coordination environments where Al is in both tetrahedral and octahedral sites.
  • Publication
    Magnetite in the Human Body: Biogenic vs. Anthropogenic
    (2016-10-01) Gieré, Reto
    Magnetite is an iron-oxide mineral that occurs naturally on Earth. Because it is also an important component of many anthropogenic materials (e.g., coal fly ash) and synthetic products (e.g., black toner powders), magnetite can be released to the environment through human activities (1). In PNAS,Maher et al. (2) describe the abundant presence in the human brain of magnetite nanoparticles, some of which they attribute to air pollution. This finding could have major implications.
  • Publication
    Dynamics of River Mouth Deposits
    (2015-09-01) Fagherazzi, Sergio; Edmonds, Douglas A; Nardin, William; Leonardi, Nicoletta; Canestrelli, Alberto; Falcini, Federico; Jerolmack, Douglas J; Mariotti, Giulio; Rowland, Joel C; Slingerland, Rudy L
    Bars and subaqueous levees often form at river mouths due to high sediment availability. Once these deposits emerge and develop into islands, they become important elements of the coastal landscape, hosting rich ecosystems. Sea level rise and sediment starvation are jeopardizing these landforms, motivating a thorough analysis of the mechanisms responsible for their formation and evolution. Here we present recent studies on the dynamics of mouth bars and subaqueous levees. The review encompasses both hydrodynamic and morphological results. We first analyze the hydrodynamics of the water jet exiting a river mouth. We then show how this dynamics coupled to sediment transport leads to the formation of mouth bars and levees. Specifically, we discuss the role of sediment eddy diffusivity and potential vorticity on sediment redistribution and related deposits. The effect of waves, tides, sediment characteristics, and vegetation on river mouth deposits is included in our analysis, thus accounting for the inherent complexity of the coastal environment where these landforms are common. Based on the results presented herein, we discuss in detail how river mouth deposits can be used to build new land or restore deltaic shorelines threatened by erosion.
  • Publication
    The development of a diatom-based transfer function along the Pacific coast of eastern Hokkaido, northern Japan—an aid in paleoseismic studies of the Kuril subduction zone
    (2004-12-01) Sawai, Yuki; Horton, Benjamin P; Nagumo, Tamotsu
    This paper provides a dataset to develop a diatom-based transfer function, which is applicable to paleoseismic studies at southwestern Kuril subduction zone, northern Japan. Modern diatom samples were collected from five transects from saltmarshes of Lakes Akkeshi and Onnetoh along the Pacific coast of eastern Hokkaido. The relationships between diatom species and environmental variables were elucidated by canonical correspondence analysis (CCA) and partial CCAs. Partial CCAs associated with Monte Carlo permutation tests show that elevation accounts for a significant portion of the total variance in the diatom data. Therefore, statistically significant transfer functions quantifying the relationship between modern diatom assemblages and elevation were developed using weighted averaging partial least squares and applied to fossil diatom assemblages from Lake Onnetoh. The reconstructed curve of elevations contains five emergence and four submergence events and the transfer functions calculated the amplitude of four of the emergence events to be at least 1 m. The results are consistent with paleoecological data produced by previous studies. If these events represent uplift associated with interplate earthquake and subsidence during an interseismic period along the Kuril subduction zone, transfer functions of eastern Hokkaido can contribute to reconstruction of the recurrence intervals and the amplitude of earthquakes.
  • Publication
    Foraminiferal biostratigraphy of Late Oligocene-Miocene reefal carbonates in southwestern Puerto Rico
    (2000-12-01) Banerjee, Amit; Yemane, Keddy; Johnson, Arthur H
    Recently exposed Oligocene-Miocene (O-M) strata in Santa Elena, Guyanilla and the section at Playa de Jaboncilla, southwestern Puerto Rico show variations in lithology and in the occurence and relative abundance of planktonic and benthic foraminifers. The planktonic foraminifers are interspersed in the relatively deeper, open marine shelf segments, wheras the intervening shallower segments are characterized by an abundance of benthic foraminifers. Although shallow marine, smaller benthic foraminifers are generally of limited use for biostratigraphy, they are used in conjunction with planktonic taxa to develop a high-resolution biostratigraphy for the Oligocene-Miocene reefel carbonates of southwestern Puerto Rico. Upper Oligocene mudstone and packstone and overlying Miocene argillaceous limestone and chalk yielded a diverse foraminiferal fauna comprising both planktonic (Catapsydrax, Chiloguembelina, Dentoglobigerina, Globigerina, Globigerinoides) and benthic (Anomalinoides, Arcaias, Cancris, Elphidum, Eorupertia, Hanzawaia, Heterostegina, Lepidocyclina, Miogypsina, Miosorites, Neorotalia, Rosalina, Siphonina, Stilostomella and Yaucorotalia) taxa. This assemblage indicates a late Oligocene-Miocene (P21 - M14 Zone)age for the Santa Elena and Playa de Jaboncilla sections, with a break in sedimentation at the top of the upper Oligocene. Significant shallowing occurred between the upper Oligocene and Miocene resulting in a hiatus, comparing well with the global seal-level regression at that time. This hiatus lasted for 3.3 million years as shown by the absence of planktonic foram Zone P22 (27.1 Ma - 23.8 Ma).
  • Publication
    A Dendroctonus Bark Engraving (Coleoptera: Scolytidae) From A Middle Eocene Larix (Coniferales: Pinaceae): Early Or Delayed Colonization?
    (2001-11-01) Labandeira, Conrad C; LePage, Ben A; Johnson, Arthur H
    An engraving made by a scolytid bark beetle, assigned to the genus Dendroctonus of the tribe Tomicini, has been identified on a mummified, middle Eocene (45 Ma) specimen of Larix altoborealis wood from the Canadian High Arctic. Larix altoborealis is the earliest known species of Larix, a distinctive lineage of pinaceous conifers that is taxonomically identifiable by the middle Eocene and achieved a broad continental distribution in northern North America and Eurasia during the late Cenozoic. Dendroctonus currently consists of three highly host-specific lineages that have pinaceous hosts: a basal monospecific clade on Pinoideae (Pinus) and two sister clades that consist of a speciose clade associated exclusively with Pinoideae and six species that breed overwhelmingly in Piceoideae (Picea) and Laricoideae (Pseudotsuga and Larix). The middle Eocene engraving in L. altoborealis represents an early member of Dendroctonus that is ancestral to other congeneric species that colonized a short-bracted species of Larix. This fossil occurrence, buttressed by recent data on the phylogeny of Pinaceae subfamilies and Dendroctonus species, indicates that there was phylogenetically congruent colonization by these bark-beetle lineages of a Pinoideae + (Piceoideae + Laricoideae) host-plant sequence. Based on all available evidence, an hypothesis of a geochronologically early invasion during the Early Cretaceous is supported over an alternative view of late Cenozoic cladogenesis by bark beetles onto the Pinaceae. These data also suggest that host-plant chemistry may be an effective species barrier to colonization by some bark-beetle taxa over geologically long time scales.