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Interest in amino acids in sediments began with the work of Erdman et al. (1956), which showed that these organic compounds are found in recent as well as ancient marine sedimentary deposits. This research, along with Abelson's (1954) investigations on fossils, firmly established the general ubiquity of amino acids in ocean sediments and led to numerous follow-up studies (for reviews, see Abelson (1963), Hare (1969), and Kvenvolden [1975]). Because of the difficulties in sampling marine sediments, the first work was limited to samples taken at depths of less than about 5 meters below the ocean bottom. In this depth range, for example, samples of amino acids were described from reducing sediments from Santa Barbara Basin (Degens et al., 1961) and from oxidizing sediments from the San Diego Trough (Degens et al., 1963). With advancing technology, deeper samples became available, and amino acids were found in sediments from Experimental Mohole (Rittenburg et al., 1963). With the advent of the Deep Sea Drilling Project (DSDP) in 1968, core samples of sediment from all of the world's oceans except the Arctic have become available for organic geochemical studies. Wehmiller and Hare (1972) first discussed the occurrences of amino acids in sediments from Legs 5, 6, 7, and 9, and Aizenshtat et al. (1973) considered the amino acids in a sediment core from Leg 4. This early work on cores recovered by deep ocean drilling stressed not only the content but also the stereochemistry of the amino acids. The importance to geochemistry of the stereochemical properties of amino acids was first recognized by Hare and Mitterer (1967) and Hare and Abelson (1968) through considerations of the diastereomers L-isoleucine and D-alloisoleucine. Lisoleucine from protein undergoes an interconversion (epimerization) to yield D-alloisleucine. The extent of epimerization is used within certain limitations to estimate the age of the sediment (Bada et al., 1970; Wehmiller and Hare, 1971; Bada and Schroeder, 1972). Studies utilizing DSDP samples have considered the epimerization (usually called racemization) of isoleucine in sediment samples from Leg 15 (Hare, 1973; Bada and Man, 1973), Leg 37 (Bada et al., 1977), Leg 42A (Bada et al., 1978a), and Leg 42B (Mopper et al., 1978). In addition to measuring the epimerization of isoleucine, Aizenshtat et al. (1973) determined the extent of racemization of six amino acids in a sediment core from Leg 4,

Amino Acids in Sediments from Leg 68 Site 502