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Phosphorus cycling in the Gulf of Maine : a multi-tracer approach

IP.com Disclosure Number: IPCOM000128047D
Original Publication Date: 1998-Dec-31
Included in the Prior Art Database: 2005-Sep-14
Document File: 7 page(s) / 27K

Publishing Venue

Software Patent Institute

Related People

Benitez-Nelson, Claudia R: AUTHOR [+3]

Related Documents

http://theses.mit.edu:80/Dienst/UI/2.0/Describe/0018.mit.theses/1998-272: URL

Abstract

Knowledge of temporal and spatial nutrient turnover and export rates is of great importance for a variety of investigations, ranging from nutrient limitation to contamination uptake and removal. However, there are few methods which allow for the in situ elucidation of these processes. In this thesis research, in situ phosphorus turnover rates and upper ocean export were determined within the southwestern Gulf of Maine using the naturally occurring radionuclides phosphorus-32 (t 1/2 =14.3 d), phosphorus-33 (t 1/2 , = 25.3 d), thorium-234 (t 1/2 = 24.1) and beryllium-7 (t 1/2 = 53.3 d). New techniques were developed for the extraction, purification and measurement of 32 P and 33 P in rainwater and in inorganic, organic and particulate pools in seawater. In order to constrain the input ratio of 33 P/ 32 P, rain samples were collected and measured continuously for 32 P and 33 P, as well as 7 Be and 210 Pb, from March 1996 to March 1998 at woods Hole, MA, and from March 1997 to October 1997 at Portsmouth, NH. The average 33 P/ 32 P ratio was 0.88 0.20. 32 P, 33 P, 7 Be and 2l0 Pb were further used to determine aerosol residence times and as possible tracers of stratospheric/tropospheric exchange, during severe storm events. Four cruises were conducted in Wilkinson Basin, in the Gulf of Maine, during the spring and summer of 1997. 234Th was used to estimate advection and diffusion using 1D steady state and multidimesional non-steady state models. Export ratios (export/primary production) were found to range between 0.11 and 0.37. Vertical eddy diffusivity found using 7 Be varied from 0.5 to 1.5 cm 2 sec -1 Significant changes in phosphorus turnover rates within the reservoirs which contained 32 P and 33 P activity were found between the spring and summer months. In late summer, bacterial activity was substantial, significantly affecting the residence times of dissolved inorganic and organic phosphorus pools. Our results clearly show that 32 P and 33 P can provide much needed information regarding the biogeochemical cycling of P in marine systems and can be of use in the development of ecosystem models which seek to address mechanisms which affect primary production in the ocean. Thesis Supervisor: Kenneth 0. Buesseler Title: Associate Scientist, Department of Maine Chemistry and Geochemistry Woods Hole Oceanographic Institution

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Phosphorus Cycling in the Gulf of Maine: A Multi-Tracer Approach

by

Claudia R. Benitez-Nelson


B. S., University of Washington (1992)

Submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY
WOODS HOLE OCEANOGRAPHIC INSTITUTION

at the Massachusetts Institute of Technology

September 1998
(c) Claudia Benitez-Nelson 1995 All rights reserved.

The author hereby grants to MIT and WHOI permission to reproduce paper and electronic copies of this thesis in whole or in part, and to distribute them publicly.

SIGNATURE OF author: [[signature omitted]]

Joint Program in oceanography Massachusetts Institute of Technology/Woods Hole Oceanographic Institution
CERTIFIED BY: [[SIGNATURE OMITTED]]

Ken O. Buesseler Thesis Supervisor
ACCEPTED BY: [[SIGNATURE OMITTED]]

Edward A. Boyle Chair, Joint Committee for Chemical Oceanography Massachusetts Institute of Technology/Woods Hole Oceanographic Institution ARCHIVES MASSACHUSETTS INSTITUTE OF TECHNOLOGY LIBRARIES OCT 1998

Massachusetts Institute of Technology Page 1 Dec 31, 1998

Page 2 of 7

Phosphorus cycling in the Gulf of Maine : a multi-tracer approach

Phosphorus Cycling in the Gulf of Maine: A Multi-Tracer Approach

by

Claudia R. Benitez-Nelson

Submitted in September 1998 in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Oceanography at the Massachusetts Institute of Technology and the Woods Hole Oceanographic institution

ABSTRACT

Knowledge of temporal and spatial nutrient turnover and export rates is of great importance for a variety of investigations, ranging from nutrient limitation to contamination uptake and removal. However, there are few methods which allow for the in situ elucidation of these processes. In this thesis research, in situ phosphorus turnover rates and upper ocean export were determined within the southwestern Gulf of Maine using the naturally occurring radionuclides phosphorus- 32 (t1/2 =14.3 d), phosphorus-33 (t1/2, = 25.3 d), thorium-234 (t1/2 = 24.1) and beryllium-7 (t1/2 =
53.3 d).

New techniques were developed for the extraction, purification and measurement of 32P and 33P in rainwater and in inorganic, organic and particulate pools in seawater. In order to constrain the input ratio of 33P/32P, rain samples were collected and measured continuously for 32P and 33P, as well as 7 Be and 210Pb, from March 1996 to March 1998 at woods Hole, MA, and from March 1997 to October 1997 at Portsmouth, NH. The average 33P/32P ratio was 0.88 0.20. 32P, 33P, 7 Be and 2l0Pb were further used to determine aerosol residence times and as possible tracers of stratospheric/tropospheric exchange, during severe storm events.

Four cruises were conducted in Wilkinson Basin, in...