Phosphorus Geochemistry of the East China Sea Sediments

• Main Authors: Jui-Lin Chen, 陳瑞霖
• Other Authors: 方天熹
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/13342096824773374734

碩士 === 國立臺灣海洋大學 === 海洋科學系 === 92 === Abstract A four-step sequential extraction method (SEDEX) was applied to chemically separate the sedimentary phosphorus in core sediments from the East China Sea (ECS) into four forms: ferric iron-bound P (CDB-P); authigenic carbonate flourapaite + biogenic apatite + CaCO3-associated P (CFA-P); detrital apatite P (detrital-P); and Organic P (OP). This knowledge allows us to understand the geochemistry of phosphorus and to calculate the buried efficiency and the amount of phosphorus buried in the ECS sediments. The results show that the concentrations of total P (TP) in surface sediments (0-1cm) in the study area ranged form 12-22 mol g-1. Among the four forms of sedimentary phosphorus, the percentages of P concentration ranges were 5.1-13.7% (average 8.4%) for Fe-P, 2.5-10.2% (average 5.8%) for CFA-P, 58.1-83.4% (average 70%) for detrital P, and 7.0-28.4% (average 15.5%) for organic P. The spatial variation of TP concentration in the study area was not marked. However, the higher value of TP contour appeared approximately 200 km horizontal away the mouth of Changjiang estuary. Generally, the concentrations of vertical profiles of CDB-P, CFA-P, detrital P and OP at each station did not show significant variation. This result may suggest that the phosphorus transformation between different forms of P occurred during the diagenetic processes was not obvious in the study area. The concentrations of total P and sedimentation rate, 0.02~1.64 g cm-2 yr-1 obtained from the literature (average sediment rate ca. 0.3 g cm-1 yr-1)(Huh and Su, 1999), were used to calculate the accumulation rate and flux of P in sediments of the study area. The calculated result is 4.1-7.5 mmol P cm-2 yr-1 and the total amount of P buried on the study area (about 5.6×105 km2) is approximately 3.3×109 mol P yr-1. The phosphorus burial efficiency (PBE) in the study area is calculated approximately 75%. Thus, the net total amount of P buried in the study area is 2.6×109 mol P yr-1. And it can be extended to the whole East China Sea and the value is about 8~120×1010 mol P yr-1.