In:
The Holocene, SAGE Publications, Vol. 22, No. 6 ( 2012-06), p. 697-704
Abstract:
To examine the applicability of C/N and organic carbon stable isotope (δ 13 C) in studies of the Holocene sea level and freshwater discharge in the large river mouth of Yangtze, we observed the distribution of carbon, nitrogen and δ 13 C in a late-Quaternary core (ZK9) collected from the present subaqueous delta. We also collected published data of the two proxies for the suspended particulate matter (SPM) and surficial sediments from the lower Yangtze River to the adjacent East China Sea. The results show that the estuarine front is an important boundary for terrestrial and marine contribution of the organic component in the modern sedimentary environment. In the core ZK9, sediments deposited during c. 13–9 cal. ka BP are characterized by high values of TOC (0.54–1.16%), CaCO 3 (0.35% on average), and C/N ( 〉 12), which reflect an inner tidal estuarine environment dominated by C3 terrestrial organic carbon input. During c. 9–0.7 cal. ka BP, both TOC content (0.57% on average) and C/N ratio ( 〈 10) decrease remarkably while TN increases, indicating a lower estuarine or shallow marine environment. An abrupt sea level rise from c. 9 cal. ka BP resulted in a deeper water environment and reduced terrestrial input at the core location. The low δ 13 C values (−24.23‰ on average) before c. 6 cal. ka BP reflect a dominantly terrestrial source of organic matter associated with increased freshwater discharge into the estuary during that time. The sediments since c. 6 cal. ka BP are characterized by increasing δ 13 C up to −24.1 to −23.39‰, reflecting more contribution from marine algae as freshwater discharge fell. We suggest that in the Yangtze River mouth the C/N ratio indicates an abrupt sea level rise at c. 9 cal. ka BP, while δ 13 C is more useful in reflecting freshwater discharge.
Type of Medium:
Online Resource
ISSN:
0959-6836
,
1477-0911
DOI:
10.1177/0959683611423685
Language:
English
Publisher:
SAGE Publications
Publication Date:
2012
detail.hit.zdb_id:
2027956-5
SSG:
14
SSG:
3,4
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