Journal of Tropical Oceanography ›› 2010, Vol. 29 ›› Issue (5): 56-64.doi: 10.11978/j.issn.1009-5470.2010.05.056cstr: 32234.14.j.issn.1009-5470.2010.05.056

• Marine geology • Previous Articles     Next Articles

Vertical distributions of dissolved oxygen, manganese, and iron in the sediments from Vietnam upwelling zone of South China Sea

XU Kun-ming1, ZOU Wen-bin1, SI Jing-yu1,2   

  1. 1.Environmental Science Research Center, Xiamen University, Xiamen 361005, China; 2. Department of Chemical and Materials Engineering, Hefei University, Hefei 230022, China
  • Received:2009-06-02 Revised:2009-07-30 Online:2010-10-30 Published:2011-10-10
  • About author:许昆明(1965—), 男, 福建省厦门市, 副教授, 博士, 研究方向: 海洋生物地球化学。E-mail: kunmingx@xmu.edu.cn
  • Supported by:

    国家自然科学基金(40476035); 教育部留学回国基金(2004)

Abstract:

Sediments were sampled at three sites in the Vietnam upwelling zone of the South China Sea during a summer cruise in 2007. Microelectrodes were applied to measure the concentrations of dissolved oxygen molecules (DO), Mn2+, Fe2+, and redox potentials in the pore water of the sediments. The fluxes and consumption rates of DO and the consumption rates of total organic carbon (TOC) were estimated. It was found that DO concentration decreased with increasing depth in the sediments and that its penetration depths were between 9 to 48 mm. Mn2+ and Fe2+ were also detected in the sediments. TOC and total nitrogen (TN) were measured by an elemental analyzer. TOC values at the three sites were between 0.7%—1.03%, TN values were between 0.052%—0.10%, and C/N ratios were between 10.5—16.0. From the C/N ratios, it can be seen that the sediments in the region had terrestrial origins. The sampling site located at the freshwater plume of the Mekong River had maximum C/N ratios. The redox potentials indicated that all sediments belonged to reducing environments. This study measured the redox chemical species in sediments from the Vietnam upwelling zone of the South China Sea for the first time and provided vital clues to the biogeochemistry of the sediments in the region.

Key words: sediment, Fe, Mn, organic carbon, dissolved oxygen molecules