form- Approved REPORT DOCUMENTATION PAGE OMB NO. 07044188 Public reoortinq bunten for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing daca «Hire« aattwrinaand maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other asoect of tint cotttaion of information, including suggestions for reducing this burden, to Washington Headquarters Services. Directorate for information Operations and Reports. «IS Jeffenon Oavi» Highway Suite 1204. Arlington. VA 22202-4302. and to the Office of Management and Sudget; Paperwork Reduction Project (07044188). Washington. OC 20503. 1. AGENCY USE ONLY (Leave blank) 2. REPORT OATE 3. REPORT TYPE ANO OATES COVERED 4. TITLE ANO SUBTITLE S. FUNDING NUMBERS "Strontium I*otopic Composition, in Arctic Pleis- N00014-93-1141 tocene and Pliocene Marine Sediments" 6. AUTHOR(S) Scott Lehman/William Curry 7. PERFORMING ORGANIZATION NAME(S) ANO AOORESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER Woods Hole Oceanographic institution Woods Hole, MA 02543 13114100 9. SPONSORING /MONITORING AGENCY NAME(S) ANO AOORESS(ES) — eariNSORING/ MONITORING 0NR , Mom w Ballston Tower One 800 North Quincy St. Arlington, VA 22217-5660 11. SUPPLEMENTARY NOTES Approved for public release; distribution is limited 12a. DISTRIBUTION /AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE Approved for public release; distribution is unlimited 13. ABSTRACT (Maximum 200 words) The primary goal of the research was to use 87Sr/86Sr as a geochronometer in Arctic Ocean sediments. This attempt was unsuccessful because the analytical precision of the analysis (+/-0.000010) was insufficient to differentiate the expected change in oceanic 87Sr/86Sr. New data published after the submission of this proposal indicated that the change was on 0.000025, half that of previously published data. However, a study of the strontium isotopic composition of foraminifera from the Arctic implied that there is enrichment of radiogenic strontium in the Arctic halocline. Although the mean values are statistically different in the Arctic Ocean and the South Atlantic, contamination by clay minerals in the Arctic cannot be ruled out. A simple box model indicates that some enrichment of strontium in surface waters must occur, but the amount is very sensitive to the strontium isotopic composition of Arctic rivers. Models using the most recent riverine data do not produce the observed enrichment. 15. NUMBER OF PAGES U. SUBJECT TERMS 16. PRICE COOE 17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT OF REPORT OF THIS PAGE OF ABSTRACT UL unclassified unclassified unclassified Standard Form 298 (Rev. 2-89) NSN 7540-01-280-5500 Prescribed by ANSI Std. Z39-I8 DTK) QUALITY INSPECTED 1 298-102 WOODS HOLE OCEANOGRAPHIC INSTITUTION 360 Woods Hole RdVClark Labs Woods Hole, Massachusetts 02543-1542 mo Department of Geology & Geophysics Phone: (508)289-2591 Fax: 508-457-2187 email:[email protected] June 23, 1998 Defense Technical Information Center 8725 John J. Kingman Road STE 0944 Ft. Belvoir, VA 22060-6218 In compliance with the reporting requirements on ONR Grant No. N00014-93-1-1141 entitled "Strontium Isotopic Composition in Arctic Pleistocene and Pliocene Marine Sediments' Pi's Scott Lehman/W. B. Curry, enclosed are two copies of the report for your files. Sincerely yours, WBC/amp Enclosure Grant Number: NO0014-93-1-1141 FORM A2-2 AUGMENTATION AWARDS FOR SCIENCE S ENGINEERING RESEARCH TRAINING (AASERT 1 REPORTING FORM The Department of Defense (DOD) requires certain information to evaluate the effectiveness of the?AASERT program. By accepting this Grant Modification which bestows the AASERT funds, the Grantee agrees to provide the information requested below to the Government's technical point of contact by each annual anniversary of the AASERT award date. 1. Grantee identification data: (R & T and Grant numbers found on Page 1 of Grant) a. Woods Hole Oceanographic Institution University Name b. N00014-93-1-1141 4255155-01 Cm Grant Number R & T Number "~ d. S. Lehman/W.B. Curry From; 9/1/95 Tor 2/28/97 e# P.I. Name AASERT Reporting Period NOTE: Crane co which AASEBT award La acrached La referred co hereafter a» "Parent Agreement;-" 2. Total funding of the Parent Agreement and the number of full-time equivalent graduate students (FTEGS) supported by the Parent Agreement during the 12-month period prior to the AASERT award date. a. Funding: . $ 144,000 N00014-92-J-1301 b. Number FTEGS: 0 3. Total funding of the Parent Agreement and the number of FTEGS supported by the Parent Agreement during the current 12-month reporting period. a. Funding: $ 0 ; b. Number FTEGS: 0 4. Total AASERT funding and the number of FTEGS and undergraduate students (UGS) supported by AASERT funds during the current 12-month reporting period. a. Funding: $ 59,484 b. Number FTEGS: 1 c. Number UGS: VERIFICATION STATEMENT: I hereby verify that all students supported by the AASERT/award are U.S. citizens. / Principal Inves"tiga£br \ Date Final Report ONR ASSERT Award N00014-93-1-1141 Title: Strontium Isotope Composition of Arctic Ocean Carbonates PI: Scott Lehman and William Curry Students Robert Ackert Susan Aldermann Michael Horowitz Graduate education and laboratory support were supplied to three students with this ASSERT award: 1) For Robert Ackert, the primary goal of the research was to use 87Sr/86Sr as a geochronometer in Arctic Ocean sediments. This attempt was unsuccessful because the analytical precision of the analy- sis (+/-0.000010) was insufficient to differentiate the expected change in oceanic 87Sr/86Sr. New data published after the submission of of this proposal indicated that the change was on 0.000025, half that of previously published data. However, a study of the strontium isotopic composition of foraminifera from the Arctic implied that there is enrichment of radiogenic strontium in the Arctic halocline. Although the mean values are statistically different in the Arctic Ocean and the South Atlantic, contamination by clay minerals in the Arctic cannot be ruled out. A simple box model indicates that some enrichment of strontium in surface waters must occur, but the amount is very sensitive to the strontium isotopic composition of Arctic rivers. Models using the most recent riverine data do not produce the observed enrichment. 2) For Susan Aldermann, the award provided support for stipend and laboratory analyses for her Masters Thesis in the MIT/WHOI Joint Program in Oceanography. Her thesis was on the observed changes in foraminiferal flux and isotopic composition observed in a sediment trap from the ea of Okhotsk. Her principal results show that the population of foraminiferal are calcifying in the upper 30 meters of the water column, constrained to shallow depths by the presence of the very cold dichother- mal layer at about 100 meters. The coiling ratio of N. pachyderma, which in other locations around the world shows a change in direction at about 7 to 8 °C, is less sensitive to temperature here. In this location, left coiling N. pachyderma are found in waters where surface temperatures are as warm as 14 °C because they are able to find much colder water only several tens of meters below the sea surface. Inasmuch as the Sea of Okhotsk is an analogue for the glacial North Atlantic, reconstruction of past SSTs which rely on N. pachyderma (1) may be biased. 3) Support for Michael Horowitz was provided for a short interval during his first year in the Joint Program at a time when he was taking classes in preparation for his general examination. Publications Ackert, R. P., Lehman, S, and Kurz, M., (1995). Evidence for heterogeneous strontium isotopic ratios in Arctic Ocean water. Fifth International Conference on Paleoceanography, Halifax, Nova Scotia. Aldermann, S. Honjo, S. and Curry, W., (1996). Seasonal transition of species composition and isotopic variability of planktonic foraminifera in the Sea of Okhotsk. EOS, Transactions of the American Geophysical Union, v. 76, p. OS76. Aldermann, Susan, (1996). Planktonic foraminifera in the Sea of Okhotsk: population and stable isotopic analysis from a sediment trap. MIT/WHOI Joint Program in oceanography, Masters Thesis, 99 pp.