Dissolved fatty acids in seawater from a fringing reef and a barrier reef at Grand Cayman

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109809/1/lno19762120315.pd

Impacts of late Quaternary fluctuations in water level on the accumulation of sedimentary organic matter in Walker Lake, Nevada

Walker Lake, a terminal saline lake in western Nevada, has experienced major fluctuations in its water level due to changes in regional climate and river diversions during the late Quaternary. Change in the degree of preservation of sediment organic matter has accompanied the lake level fluctuations, and changes in the biotic sources of organic matter to the lake sediments have occurred in response to the climate changes and water diversions. The record of these events has been studied using organic matter C/N ratios and carbon isotope contents and employing molecular compositions of geolipids extracted from the sediment. Modern sediments contain mostly lake-derived organic matter which has been altered by microbial reworking. Decreases in the degree of preservation of organic matter indicate lake lowstands. Increases in the proportion of land-plant components in sediment organic matter also indicate lowstand conditions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28535/1/0000333.pd

Scientific ocean drilling: Opportunities for organic geochemistry

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27578/1/0000622.pd

Monitoring of hydrocarbons in benthic crustaceans during offshore drilling and petroleum exploration

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22740/1/0000295.pd

Changes in organic carbon stable isotope ratios across the K/T boundary: global or local control?

A global shift in carbonate carbon [delta]13C-values from heavier values in the Maastrichtian to lighter values in the early Danian indicates recycling of isotopically light organic carbon to inorganic carbon reservoirs during a period of depressed marine productivity. Comparison of organic carbon [delta]13-values from globally dispersed K/T sections does not show a similar, globally well-developed pattern. Several factors evidently overwhelm the potential impact of an isotopically lighter inorganic carbon source on organic matter isotopic signatures: (1) species changes in biological assemblages may modify the averaged isotopic fractionation of organic matter; and (2) shifts in the proportion of land/marine organic matter contributions to coastal marine locations may overprint the isotopic record. Local phenomena evidently outweigh global change in determining the isotope signature of organic carbon deposited in K/T boundary sections.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29837/1/0000184.pd

Evidence of mid-Holocene climate instability from variations in carbon burial in Seneca Lake, New York

The amounts and types of carbon delivered to the sediments Seneca Lake, New York, have varied since the middle Holocene. Concentrations of CaCO 3 first fluctuate between 14 and 6% around 7 ka before decreasing erratically until about 5 ka and then remain 2% in younger sediments. Because the amount of calcite that precipitates in hard-water lakes is related to summertime thermal stratification, the carbonate fluctuations suggest that cyclic strengthening and weakening of seasonality at intervals of about three centuries accompanied the end of the Holocene Hypsithermal in northeast North America. Organic C/total N values record short, decade-long intervals of enhanced delivery of land-plant material during episodes of wetter climate that are independent of the temperature variations. Higher organic δ 13 C values indicate that recent fertilization of lake waters from soil disturbance and land-derived runoff has increased aquatic productivity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43086/1/10933_2004_Article_399636.pd

A method for analysis of fatty acids in coral

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109910/1/lno19741950846.pd

Lacustrine organic geochemistry--an overview of indicators of organic matter sources and diagenesis in lake sediments

The factors affecting the amounts and types of organic matter in lacustrine sediments are summarized in this review, and synthesis, of published studies. Biota living in the lake and in its watershed are the sources of the organic compounds initially contributed to the lake system. Microbial reworking of these materials during sinking and early sedimentation markedly diminishes the total amount of organic matter while replacing many of the primary compounds with secondary ones. Much of the organic matter content of sediments is the product of this microbial reprocessing. Various organic matter components of lake sediments nonetheless retain source information and thereby contribute to the paleolimnological record. Carbon/nitrogen ratios of total organic matter reflect original proportions of algal and land-derived material. Carbon isotopic compositions indicate the history of lake productivity and carbon recycling. Biomarker compounds provide important information about contributions from different biota. Sterol compositions and chainlength distributions of n-alkanes, n-alkanoic acids, and n-alkanols help distinguish different algal and watershed sources and also record diagenetic alterations.Stabilization of functional-group-containing biomarkers by conversion into saturated or aromatic hydrocarbons or by incorporation into bound forms improves their preservation and hence record of source information. Lignin components provide important evidence of watershed plant cover, and pigments reflect algal assemblages. The interplay of the factors influencing the organic matter content of lake sediments is illustrated by overviews of sedimentary records of four lake systems--Lake Biwa (Japan), Lake Greifen (Switzerland), Lake Washington (Pacific Northwest), and the Great Lakes (American Midwest).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30617/1/0000257.pd