Acta Geographica Sinica ›› 2004, Vol. 59 ›› Issue (6): 918-926.doi: 10.11821/xb200406015

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Carbon and Nitrogen Stable Isotopes as Tracers to Source Organic Matter in the Yangtze Estuary

LIU Min1, HOU Lijun2, XU Shiyuan1, OU Dongni1, JIANG Haiyan1, YU Jie1, GARDNER Wayne S3   

  1. 1. Department of Geography, Key Laboratory of Geo-information Science of the Ministry of Education, East China Normal University, Shanghai 200062, China;
    2. State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China;
    3. Marine Science Institute, The University of Texas at Austin, Texas 78373-5015, USA
  • Received:2004-04-15 Revised:2004-09-26 Online:2004-11-25 Published:2004-11-25
  • Supported by:

    National Natural Science Foundation of China, No.40131020, No.49801018; Foundation for University Key Teacher by the Ministry of Education; Shanghai Key Disciplinary Project

Abstract:

In this article, we mainly focus on the geochemical characteristics of stable carbon and nitrogen isotopes in order to trace the source and fate of organic matter in the Yangtze estuary and its tidal flat sediments. According to the features of physical geographical environment and the discrepancy in the effects of human activities in the study area, 12 typical sampling stations were selected along the Yangtze estuarine and coastal line. Based on the analysis of stable carbon and nitrogen isotopes in the tidal flat superfacial sediments from the Yangtze estuary, it was found that the ratios of stable carbon and nitrogen isotopes were respectively -29.80‰~-23.7‰ and 1.0‰~5.5‰ in the flood seasons, while they were -27.3‰~-25.6‰ and 1.6‰~7.7‰ in the dry seasons respectively, indicating that the seasonal distribution of discharges from the Yangtze River has significantly affected the seasonal variation of stable carbon and nitrogen isotopes in sedimentary organic matter. In general, the distribution of stable carbon and nitrogen isotopes revealed the mixing inputs of terrigenous and marine organic matter controlled the stable carbon and nitrogen isotope compositions in sedimentary organic matter. However, a series of physical, chemical and biogeochemical processes occurring in the local environments, to some extent, have the significant influence on the stable carbon and nitrogen isotope compositions in organic matter.

Key words: stable carbon isotope, stable nitrogen isotope, sediment, the Yangtze estuary