Type
Text
Type
Thesis
Advisor
Henry Bokuniewicz | Kirk Cochran. | Robert C. Aller.
Date
2011-05-01
Keywords
diffusive flux, hypoxia, Mn, Ra, radioisotope | Geochemistry -- Chemical Oceanography
Department
Department of Marine and Atmospheric Science
Language
en_US
Source
This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree.
Identifier
http://hdl.handle.net/11401/71580
Publisher
The Graduate School, Stony Brook University: Stony Brook, NY.
Format
application/pdf
Abstract
The four naturally occurring Ra isotopes serve as tools to quantify submarine groundwater discharge (SGD) in coastal areas. In constructing the Ra mass balance for a given system, Ra sources and sinks must be accurately determined, then measured or eliminated as negligible. SGD &mdash a Ra source &mdash is commonly determined by difference. In Long Island Sound (LIS), a significant Ra source is diffusive flux from muddy sediments. This study investigates the seasonality of 223,224Ra diffusive fluxes linked to seasonal Mn redox cycling correlated with hypoxia (dissolved oxygen &le 3.0 mg l-1) in LIS. The three components of this study &mdash water column and nearshore concentrations and laboratory flux core incubations &mdash demonstrate a coupling of Ra and Mn cycling in LIS, both temporally and spatially. The overall relationship between Mn and Ra in LIS suggests that seasonal redox cycling of Mn is an important factor controlling Ra distributions in the Sound. Solid phase Mn4+ (under oxic conditions) appears to restrict the diffusion of Ra from muddy sediment, whereas dissolved phase Mn2+ (under hypoxic conditions) is associated with higher Ra concentrations in LIS and `pulses' of Ra in laboratory flux core incubations. Therefore, the diffusive flux of Ra to a given coastal sea should be evaluated seasonally to more accurately quantify SGD.
Recommended Citation
Daniel, John Wallace Roland, "Coupled Ra and Mn cycling in Long Island Sound" (2011). Stony Brook Theses and Dissertations Collection, 2006-2020 (closed to submissions). 785.
https://commons.library.stonybrook.edu/stony-brook-theses-and-dissertations-collection/785