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Xu, Hairong,

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Combining Models and GEOTRACES Observations to Quantify Lithogenic Inputs of Aluminum and Thorium to the Global Ocean /

Record Type:	Electronic resources : Monograph/item
Title/Author:	Combining Models and GEOTRACES Observations to Quantify Lithogenic Inputs of Aluminum and Thorium to the Global Ocean // Hairong Xu.
Author:	Xu, Hairong,
Description:	1 electronic resource (244 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 86-06, Section: B.
Contained By:	Dissertations Abstracts International86-06B.
Subject:	Chemical oceanography. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=31636855
ISBN:	9798346858485

Combining Models and GEOTRACES Observations to Quantify Lithogenic Inputs of Aluminum and Thorium to the Global Ocean /
Xu, Hairong,

Combining Models and GEOTRACES Observations to Quantify Lithogenic Inputs of Aluminum and Thorium to the Global Ocean /Hairong Xu. - 1 electronic resource (244 pages)

Source: Dissertations Abstracts International, Volume: 86-06, Section: B.

Marine phytoplankton, pivotal in carbon sequestration, rely on micronutrients like iron (Fe) which enters the ocean mainly through dust deposition and sediment discharge from continental margins. Existing models, however, struggle to accurately quantify lithogenic iron inputs, impacting our understanding of the biological pump and its response to environmental changes. This research employs aluminum (Al) and Thorium-232 (232Th) as tracers to illuminate the complex iron cycling processes, thus enhancing our grasp of marine biogeochemical cycles and their global climate impacts.Chapter 2 introduces a novel approach to modeling the oceanic Al cycle through the development of a three-dimensional data-assimilation model. This model is specially designed to tackle the complexity of accurately estimating atmospheric Al inputs, a task complicated by various interacting processes. These include reversible particle scavenging, diatom biological uptake, hydrothermal vent contributions, and sediment resuspension, all of which significantly influence Al distribution within the ocean. By incorporating these processes, the model offers a nuanced understanding of the oceanic Al cycle, enabling the extraction of the atmospheric Al signal from GEOTRACES observations.In Chapter 3, 232Th serves as a tracer to investigate lithogenic Fe inputs to the global ocean. The chapter employs a data-assimilation model encompassing both Thorium-230 (230Th ) and 232Th cycles. It thoroughly evaluates the 232Th fluxes concerning dust deposition and compare these against established benchmarks for Al. The study understands the magnitude and controlling factors of sedimentary supply, seeking to enhance its representation within Fe cycle models. Beyond estimating boundary fluxes, the analysis probes marine thorium isotope cycling, concentrating on scavenging rates and the contributions of various particulate types.Chapter 4 delves into thorium isotopes application in dust flux reconstruction, focusing on the "dissolved 232Th mass balance method" with unidentified systematic limitations and biases. To address this, a one-dimensional model simulating the biogeochemical cycles of dissolved 232Th and 230Th is introduced, integrating ocean mixing, advection, and particle scavenging to assess the method's biases. The study identifies and clarifies biases in the "dissolved 232Th mass balance method". It also proposes an alternative approach to address these limitations, offering the potential for more accurate estimations.

English

ISBN: 9798346858485Subjects--Topical Terms:

516760
Chemical oceanography.
Subjects--Index Terms:

Marine phytoplankton

Combining Models and GEOTRACES Observations to Quantify Lithogenic Inputs of Aluminum and Thorium to the Global Ocean /
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520 $a Marine phytoplankton, pivotal in carbon sequestration, rely on micronutrients like iron (Fe) which enters the ocean mainly through dust deposition and sediment discharge from continental margins. Existing models, however, struggle to accurately quantify lithogenic iron inputs, impacting our understanding of the biological pump and its response to environmental changes. This research employs aluminum (Al) and Thorium-232 (232Th) as tracers to illuminate the complex iron cycling processes, thus enhancing our grasp of marine biogeochemical cycles and their global climate impacts.Chapter 2 introduces a novel approach to modeling the oceanic Al cycle through the development of a three-dimensional data-assimilation model. This model is specially designed to tackle the complexity of accurately estimating atmospheric Al inputs, a task complicated by various interacting processes. These include reversible particle scavenging, diatom biological uptake, hydrothermal vent contributions, and sediment resuspension, all of which significantly influence Al distribution within the ocean. By incorporating these processes, the model offers a nuanced understanding of the oceanic Al cycle, enabling the extraction of the atmospheric Al signal from GEOTRACES observations.In Chapter 3, 232Th serves as a tracer to investigate lithogenic Fe inputs to the global ocean. The chapter employs a data-assimilation model encompassing both Thorium-230 (230Th ) and 232Th cycles. It thoroughly evaluates the 232Th fluxes concerning dust deposition and compare these against established benchmarks for Al. The study understands the magnitude and controlling factors of sedimentary supply, seeking to enhance its representation within Fe cycle models. Beyond estimating boundary fluxes, the analysis probes marine thorium isotope cycling, concentrating on scavenging rates and the contributions of various particulate types.Chapter 4 delves into thorium isotopes application in dust flux reconstruction, focusing on the "dissolved 232Th mass balance method" with unidentified systematic limitations and biases. To address this, a one-dimensional model simulating the biogeochemical cycles of dissolved 232Th and 230Th is introduced, integrating ocean mixing, advection, and particle scavenging to assess the method's biases. The study identifies and clarifies biases in the "dissolved 232Th mass balance method". It also proposes an alternative approach to address these limitations, offering the potential for more accurate estimations.
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650 4 $a Chemical oceanography. $3 516760
650 4 $a Environmental science. $3 677245
650 4 $a Geochemistry. $3 539092
653 $a Marine phytoplankton
653 $a Environmental changes
653 $a Aluminum
653 $a Thorium
653 $a Global ocean
690 $a 0403
690 $a 0768
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710 2 $a University of Rochester. $b School of Arts and Sciences. $e degree granting institution. $3 3816231
720 1 $a Weber, Thomas $e degree supervisor.
773 0 $t Dissertations Abstracts International $g 86-06B.
790 $a 0188
791 $a Ph.D.
792 $a 2024
856 4 0 $u https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=31636855