Testing the Validity of Lake Sediment Chronologies Derived  from Distributions of 210Pb and 137Cs
{'Code': '08010208', 'Directorate': {'Abbreviation': 'BIO', 'LongName': 'Direct For Biological Sciences'}, 'Division': {'Abbreviation': 'DEB', 'LongName': 'Division Of Environmental Biology'}}
{'SignBlockName': 'James R. Gosz', 'PO_EMAI': None, 'PO_PHON': None}
Problems have been identified with methods for reconstructing                   histories of lake acidification, water quality, pollution,                      climate, land use, etc., based on lake sediment records.  A study               of 12 Canadian Shield lakes in northwestern Ontario (Experimental               Lakes Area) showed that the flocculent, organic-rich sediments in               each of these lakes had been mixed to depths in some cases &gt;50                  cm.  Organisms capable of mixing sediments to these depths do not               occur in these lakes.  Whether this deep mixing resulted from                   natural physical processes or from a sampling artifact could not                be determined.  However, the important point is that this mixing                was not evident in 210Pb profiles measured in these lakes.                      Without additional information provided by 137Cs and                            radionuclides added experimentally to 4 of these lakes,                         erroneously high sedimentation rates would have been calculated                 from 210Pb profiles.  Consequently, ages assigned to "events"                   recorded in sediments of these lakes would also have been in                    error.                                                                                                                                                          Several of the previously studied lakes have been resampled using               a relatively new in situ freezing technique that precluded                      sediment disturbance during sampling.  These sediments will e                   analyzed for 210Pb, 137Cs, and two radionuclides (60Co and 226Ra)               added experimentally to certain lakes to determine the source of                the mixing noted in out earlier work.  In addition, sediment                    profiles of 210Pb and 137Cs will be measured in annually varved                 lakes to evaluate the extent of downward migration of these                     nuclides by diffusion in pore waters.  The reliability of                       traditional gravity corers for collecting undisturbed sediment                  records will also be assessed.                                                                                                                                  The outcome of this project will be important to all scientist                  working with the records inherent to lake sediments.  The                       institutional setting for the work is excellent as is the record                of accomplishment for the investigator.  A recommendation for                   funding is fully justified.
{'FirstName': 'Robert', 'LastName': 'Anderson', 'PI_MID_INIT': 'F', 'PI_SUFX_NAME': None, 'PI_FULL_NAME': 'Robert F Anderson', 'EmailAddress': 'boba@ldeo.columbia.edu', 'NSF_ID': '000428800', 'StartDate': '02/01/1988', 'EndDate': None, 'RoleCode': 'Principal Investigator'}
{'Name': 'Columbia University', 'CityName': 'NEW YORK', 'ZipCode': '100277922', 'PhoneNumber': '2128546851', 'StreetAddress': '615 W 131ST ST', 'StreetAddress2': 'MC 8741', 'CountryName': 'United States', 'StateName': 'New York', 'StateCode': 'NY', 'CONGRESSDISTRICT': '13', 'CONGRESS_DISTRICT_ORG': 'NY13', 'ORG_UEI_NUM': 'F4N1QNPB95M4', 'ORG_LGL_BUS_NAME': 'THE TRUSTEES OF COLUMBIA UNIVERSITY IN THE CITY OF NEW YORK', 'ORG_PRNT_UEI_NUM': None}
{'Name': None, 'CityName': None, 'StateCode': None, 'ZipCode': None, 'StreetAddress': None, 'CountryCode': None, 'CountryName': None, 'StateName': None, 'CountryFlag': None, 'CONGRESSDISTRICT': None, 'CONGRESS_DISTRICT_PERF': '""'}
{'Code': '1128', 'Text': 'Population & Community Ecology'}
{'url': 'https://www.nsf.gov/awardsearch/download?DownloadFileName=1987&All=true', 'xml': '8717729.xml'}