Anthony Chappaz

Anthony Chappaz
Central Michigan University | CMU · Department of Earth and Atmospheric Sciences

Ph.D. Water Sciences

About

73
Publications
16,473
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Introduction
Molecular geochemist studying trace elements in geological, environmental and engineered matrixes
Additional affiliations
September 2017 - August 2021
Central Michigan University
Position
  • Professor (Associate)
September 2011 - August 2017
Central Michigan University
Position
  • Professor (Assistant)
October 2008 - August 2011
University of California, Riverside
Position
  • Agouron Institute Fellow

Publications

Publications (73)
Article
Full-text available
The late Cambrian witnessed significant biological and environmental changes. However, the main triggers responsible for that formidable turnover remain largely unknown. This study investigates mercury (Hg) enrichments from the late Miaolingian to Furongian section in a unique Alum Shale drilled core obtained from southeast Sweden. Our results show...
Article
1,4-Dioxane released at the Gelman Site in Washtenaw County, Michigan, produced a series of contaminant plumes migrating up to 3 km through a heterogenous glacial aquifer system. An analysis of 1,4-dioxane concentrations in the Eastern Area of the Gelman Site between 2011 and 2017 documented a mass balance deficit of 2200 kg in excess of 2100 kg of...
Article
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The Marnes Bleues Formation from the Vocontian Basin (Southeastern France) shows many organic rich levels, some concomitant to oceanic anoxic events OAE1a and OAE1b. These organic-rich levels are scattered through a thick homogeneous succession of marls, poor in organic matter (OM). Through a multi-parameter approach, the organic-rich levels from t...
Article
This paper investigates the hyper-enrichments of molybdenum (Mo), uranium (U), and vanadium (V) in the lower Paleozoic, Alum Shale of Denmark, Sweden, Norway, and Estonia. Molybdenum and U are mainly associated with organic matter and the highest contents are found in the Furongian part of the Alum Shale. This Furongian hyper-enrichment of Mo and U...
Article
Molybdenum (Mo) systematics (i.e., total concentration and isotope ratios) are widely used for the reconstruction of paleo-redox conditions in sedimentary records. However, the geochemical processes affecting the distribution of Mo in carbonaceous fine-grained sedimentary rocks remain unclear. This study investigates how the organic matter type may...
Article
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Widespread anoxic events (OAEs) affected the Tethys Ocean during the Mesozoic. The OAE1a (Early Aptian), expressed as the Selli Level or Goguel Level in European basins. The Goguel Level was deposited in the French Vocontian Basin, a semi‐enclosed basin connected to the Tethys. This study presents an integrated approach (Rock Eval, clay minerals, g...
Article
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While marine sediments have been used to constrain a history of redox chemistry throughout the Precambrian, far fewer data have been generated from lakes. With major biological innovations thought to have occurred in Proterozoic lakes, understanding their chemistry is critical for understanding the evolution of eukaryotic life. We use sediment geoc...
Article
https://deepblue.lib.umich.edu/bitstream/2027.42/148595/1/Tessin_et_al_2019_Geology-Mo_speciation_as_an_important_tool_for_understanding_redox.pdf
Article
Molybdenum (Mo) geochemistry is widely used to reconstruct ocean oxygenation throughout Earth's history. However, gaps in our fundamental knowledge of Mo burial within sediments hinder the utility of Mo as a proxy for paleo-redox reconstruction. To improve our understanding of Mo burial pathways and sedimentary Mo speciation, we present combined ge...
Conference Paper
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L’objectif de ce travail est d’étudier la sédimentologie des dépôts organiques dans un bassin hémipélagique (séries mésozoïques du Bassin du S-E de la France) afin de comprendre les processus de transport et de préservation de la matière organique (MO), ainsi que sa distribution dans les différents cortèges sédimentaires. Les résultats démontrent q...
Article
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Relative to continental crust, sediments underlying sulfidic marine waters are molybdenum-rich, a property preserved in the rock record and useful for characterizing paleoenvironments. The enrichment mechanism is not known, but is attributed at least partly to deposition of Fe-Mo-S compounds, which are as yet uncharacterized. Here, we determine the...
Article
Effects of hydrologic variability on reservoir biogeochemistry are relatively unknown, particularly for less studied metals like vanadium (V). Further, few studies have investigated the fate and effects of sediment-associated V to aquatic organisms in hydrologically variable systems. Our primary objective was to assess effects of hydrologic manipul...
Conference Paper
Full-text available
Redox sensitive trace metals (RSTM) are useful paleo-proxies which can unravel chemical histories of the earth's oceans and atmosphere. In aquatic systems RSTM are easily mobilized and partitioned between solid and dissolved reservoirs. For example, within the water column molybdenum (Mo) is depleted below the chemocline when free sulfide is presen...
Conference Paper
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Molybdenum (Mo) is a well-established proxy to detect and estimate the intensity of sulfidic conditions that were prevailing within ancient oceans. Usually, highest Mo enrichments correspond to severe euxinia. The Montney Formation is an Early Triassic tight gas reservoir, located to the northeast of the Cordilleran deformation belt in the Western...
Article
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Paleo-redox proxies are crucial for reconstructing past bottom water oxygen concentration changes brought about by ocean circulation and marine productivity shifts in response to climate forcing. Carbonate I/Ca ratios of multiple benthic foraminifera species from ODP Hole 1017E – a core drilled within the Californian oxygen minimum zone (OMZ), on t...
Article
Sedimentary molybdenum (Mo) accumulation is a robust proxy for sulfidic conditions in both modern and ancient aquatic systems and has been used to infer changing marine redox chemistry throughout Earth’s history. Accurate interpretation of any proxy requires a comprehensive understanding of its biogeochemical cycling, but knowledge gaps remain conc...
Article
The geochemical behavior of molybdenum (Mo) in the oceans is closely linked to the presence of sulfide species in anoxic environments, where Fe availability may play a key role in the Mo scavenging. Here, we show that Mo(VI) is reduced in the presence of particulate organic matter (represented by sulfate-reducing bacteria). Molybdenum was immobiliz...
Article
The sedimentary record of the Coniacian–Santonian Oceanic Anoxic Event 3 (OAE 3) in the North American Western Interior Seaway is characterized by a prolonged period of enhanced organic carbon (OC) burial. This study investigates the role of Fe in enhancing organic matter preservation and maintaining elevated primary productivity to sustain black s...
Conference Paper
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Chromium (Cr), tungsten (W) and vanadium (V) are redox sensitive trace elements. When buried in sediments, they might be remobilized, released into the water column and may induce toxic effects— depending on their speciation. Their unique redox properties make them also promising proxies for studying past anoxic events in aquatic systems. Recent st...
Article
Molybdenum (Mo) concentrations in sedimentary records have been widely used as a method to assess paleo-redox conditions prevailing in the ancient oceans. However, the potential effects of post-depositional processes, such as thermal maturity and burial diagenesis, on Mo concentrations in organic-rich shales have not been addressed, compromising it...
Article
Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analyses of 1,407 sedimentary (diagenetic and syngenetic) pyrites from 45 carbonaceous shale and unconsolidated sulfidic sediment samples, ranging in age from Paleoarchean to present day, show a considerable range of trace element compositions. Arsenic, Ni, Pb, Cu, and Co are a...
Article
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The distinct reactivities of Mo and Re in oxic versus anoxic waters make these elements ideally suited for use as redox proxies. However, their full exploitation as geochemical tracers requires that their chemical transformations in sulfidic water be well understood. While thermodynamic data have been used to predict Mo and Re spe-ciation within su...
Conference Paper
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Newly published models suggest that some orogenic and Carlin-style gold deposits formed by the remobilisation of trace elements during interaction with hydrothermal or metamorphic fluids from early sedimentary pyrite that was enriched in Au, As and Te. The released trace elements are transported by the fluids to favourable trap sites where they are...
Conference Paper
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Molybdenum (Mo) has long been used as a proxy for diagnosing anoxic, sulfidic conditions in both modern and ancient sediments. Additionally, Mo isotopes have emerged as a novel tool for revealing the history of deep ocean oxygenation. However, accurate proxy interpretation requires a thorough understanding of their biogeochemical cycling, including...
Conference Paper
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Coastal anoxia is a proliferating environmental problem. Knowledge of the controls on anoxic incidents may assist in creating strategies for mitigating dead zone development. While the geochemistry of Mo may provide the means to acquiring this knowledge, interpreting Mo records is stymied by an incomplete understanding of Mo depositional processes....
Conference Paper
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Molybdenum (Mo) has emerged as a powerful paleo-indicator of sulfidic conditions in studies of the evolution of Earth's early oxygenation, either by examining patterns of Mo enrichment and/or the δ 98 Mo isotopic signature in sedimentary records. In oxygenated water, inorganic Mo speciation occurs dominantly as unreactive molybdate (Mo VI O 4 2-)....
Article
Molybdenum (Mo) is a popular paleoproxy for tracking the spatiotemporal pattern of euxinic (anoxic and sulfidic) conditions in the ancient ocean, yet surprisingly little is known about the processes leading to its fixation under sulfidic conditions. Pyrite has been proposed to be the main host phase for Mo sequestration. To clarify the role played...
Conference Paper
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BODY: Lake Ontario has undergone a steady increase in nitrate since the early 1970s, a phenomenon also occurring in other large lakes. Possible causes of this increase include rising urban and agricultural runoff, atmospheric deposition, less demand for N due to effective point source P control, and trace metal-N co-limitation as observed in Lake E...
Conference Paper
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Over the last decade, molybdenum (Mo) and rhenium (Re) have emerged as promising redox proxies in studies of oxygen levels in the ocean through geologic time and assessments of the development of modern dead zones in costal areas. Nevertheless, many unknowns remain about their geochemistry under sulfidic conditions, especially their speciation. Thi...
Conference Paper
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Molybdenum is a redox sensitive metal used to investigate oxygen content in ancient oceans from sedimentary records. Specifically, Mo enrichment, Mo/TOC ratio and 98 Mo-isotopic signature in black shales are determined to characterize euxinic deposition, seawater Mo concentration, and global ocean oxygenation, respectively. However, these approache...
Article
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Lakes are important for storage of the essential micronutrient molybdenum (Mo) during its transfer from the continents to the oceans, but little is known about the major sources and sinks for Mo in lacustrine ecosystems. We studied Mo cycling in Castle Lake, a small subalpine lake in the Klamath-Siskiyou Mountains of Northern California underlain p...
Article
Metal speciation is important for understanding the toxicity of metals in aquatic systems, and can be predicted for mixtures of metals in presence of dissolved organic matter (DOM) with thermodynamic models like WHAM VI. The influence of the DOM source (quality) has been demonstrated, but is presently neglected in predicting Cu activity (WHAM VI)....
Article
Marine euxinic sediments, particularly organic-rich black shales, are important sinks for oceanic molybdenum (Mo), and the determination of Mo concentration and isotopic composition are used to constrain oxygenation state and specifically expansion of marine anoxic and sulfidic (euxinic) waters in ancient oceans. The use of Mo as a paleo-redox trac...
Article
Full-text available
We measured the molybdenum isotope compositions (δ(98)Mo) of well-dated sediment cores from two lakes in eastern Canada in an effort to distinguish between natural and anthropogenic contributions to these freshwater aquatic systems. Previously, Chappaz et al. (1) ascribed pronounced 20th-century Mo concentration enrichments in these lakes to anthro...
Conference Paper
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Molybdenum (Mo) has attracted attention as a paleoredox proxy particular because of its isotopic behavior and concentration relationships in sediments [1,2]. Much of this strength lies with the specifics of Mo redox behavior. In oxygenated water, Mo occurs dominantly as unreactive molybdate (Mo VI O4 2-). When sulfide appears under in the sediments...
Conference Paper
Full-text available
Over the last decade, molybdenum (Mo) has emerged as one of the most promising paleoredox proxies in studies of oxygen levels in the ancient ocean and specifically for anoxia and euxinia through geologic time. Nevertheless, many of the details about its sequestration in sediments under sulfidic conditions remain poorly known, including the mechanis...
Conference Paper
We used X-Ray Absorption Spectroscopy (XAS) and isotopic techniques to study molybdenum geochemistry in euxinic settings. Over the last decade, Mo has emerged as one of the most promising paleoredox proxies in studies of oxygen levels in the ancient ocean and specifically for anoxia and euxinia through geologic time. Nevertheless, many of the detai...
Conference Paper
The late Paleozoic glaciation (~300 million years ago) marks the last major, pre-Cenozoic icehouse climate. Delivery of reactive Fe-rich eolian particles to the nutrient-depleted open ocean potentially stimulates primary production during glacial intervals, yet the details remain unclear for recent glaciations and completely unknown for the ancient...
Conference Paper
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Concentrations and isotope trends of molybdenum in organic-rich shales are among the favored tracers for euxinia in the ancient ocean on local and global scales. With the successes, however, has also come increasing awareness of the complexity. The purpose of this talk is to synthesize the broad range of refining and defining proxy developments and...
Conference Paper
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Introduction Recently it has been proposed by Large et al. that diagenetic pyrite may be the source of gold and arsenic in shale hosted orogenic gold deposits in areas such as Sukhoi Log, Russia (Large et al., 2007) and Bendigo, Australia (Large et al., 2009). The research presented in this poster has been conducted to determine whether diagenetic...
Article
Uranium geochemistry has been investigated in three acid lakes located on the Canadian Shield and one circumneutral lake in the Appalachian Region of Eastern Canada. In all Shield lakes, dissolved U concentrations were higher in the porewater than in the overlying water. In one of them, whose hypolimnion is perennially oxic, U released to porewater...
Article
The concentrations of Re, as well as those of several other geochemical variables, were measured in dated sediment cores and in porewater samples from four lacustrine basins in Eastern Canada: one, perennially oxic, located 40 km from Québec City and three, seasonally anoxic, located within 25 km of non-ferrous metal smelters. The drainage basins o...
Conference Paper
Full-text available
The concentrations of Re, as well as those of several other geochemical variables, were measured in dated sediment cores and in porewater samples from four lacustrine basins in Eastern Canada: one, perennially oxic, located 40 km from Québec City and three, seasonally anoxic, located within 25 km of non-ferrous metal smelters. The drainage basins o...
Conference Paper
The concentrations of Re, as well as those of several other geochemical variables, were measured in dated sediment cores and in porewater samples from four lacustrine basins in Eastern Canada: one, perennially oxic, located 40 km from Québec City and three, seasonally anoxic, located within 25 km of non-ferrous metal smelters. The drainage basins o...
Article
We measured the vertical distributions of Mo, Fe, Mn, sulfide, sulfate, organic carbon, major ions, and pH in sediment porewater from one perennially oxic and three seasonally anoxic lacustrine basins in Eastern Canada, as well as those of Mo, acid volatile sulfide, Fe, Mn, Al, organic C, 210Pb and 137Cs in sediment cores from the same sites. The o...
Conference Paper
Molybdenum enrichments in sediments are used as an indicator of past reducing conditions of the aquatic environment. To assess the anthropogenic influence on sedimentary Mo enrichments, we have determined the vertical distribution of Mo in sediments and sediment porewater from one perennially oxic and three seasonally anoxic lakes located in Easter...
Article
The aim of this work is to study the As retention capacity of two natural sand, a quartz sand and a volcanic red sand. Sorption experiments were performed in batch reactors at a constant ionic strength (0.010 M Na0$_3$). pH was controlled by acid or base microadditions. As, Fe, Al and Si were analysed in the aqueous phase to control their fate. Kin...