한반도 주변 퇴적물중 유기물에 대한 탄소, 질도 동위원소 변화: 기원과 지역 고해양학

Abstract

Because carbon and nitrogen isotope values have been used to determine the source of organic matter, including that in the deep-water mass (Ganeshram et al., 2000; Minoura et al. 1997), we determined the carbon and nitrogen isotope values of organic matter from sediment samples taken from the East China Sea (ECS) and East Sea of Korea, and compiled unpublished data from nearby sites.The isotopic composition of δ13C and δ15N in organic matter showed extreme spatiotemporal variation. Significant differences in the δ13C values were seen between Holocene and glacial sediments in ECS core sediments. The δ13C values were around -24.5 to -25.5‰ during the transgressive and glacial periods, whereas they ranged from -20.5 to -22.5‰ in the Holocene. The values of Holocene were about 2‰ heavier than those of the transgressive and glacial periods. This distinct difference between the Holocene and glacial periods allows discrimination of the sedimentary characteristics and related paleoceanography. Based on the results of Lamb et al. (2006), the organic matter was thought to have formed in marine and freshwater dissolved organic carbon (DOC) environments in the ECS during the Holocene and glacial periods, respectively.In East Sea core sediments, strongly enriched total organic carbon (TOC) contents between 12 and 8 ka and enriched δ15N values between 15 and 9 ka were found in the southern East Sea core, and this result was strongly coupled with the δ18O(diatom) excursions, suggesting increased productivity. The δ13C of this core did not show distinct features that identified the source of the organic matter, although it showed a gradual upward decrease and values similar to those of the East China Sea in core top sediments. The average values of 21.5‰ for δ13C and 5.67‰ for δ15N (n = 21) from the East Sea surface sediments suggest a supply of nutrients from neighboring land areas. Strong coupled variation between δ15N and δ18O(d) supports the hypothesis that