남해 표층 퇴적물에서의 인의 존재상 = Phosphorus Pahses in the Surface Sediment of the South Sea

다국어 초록 (Multilingual Abstract)

To understand the role of shelf sediment in phosphorus biogeochemical cycle, we carried out sequential sediment extraction (SEDEX) of P and porewater analysis on 14 core samples collected in the South Sea of Korea. SEDEX classified P-pools into 5 phases and results are grouped into two cateories: reactive P (loosely sorbed-P and Fe bound-P) and refractory P (detrital inorganic-P, authigenic mineral-P and organic-P). Total P concentrations are decreased with sediment depth in all samples as a result of dissolution to porewater. Reactive P comprises about 20∼50% of total P, and iron bound-P is the major form consisting 70∼80% of reactive P-pool. Iron bound-P decreases sharply with depth. Depth profiles of dissolved P concentration in porewater show mirror image of iron bound-P, revealing the role of FeOOH as a regulator of reactive P supply to overlying water culumn. Authigenic mineral-P consists less than 5% of total P, thus removal of reactive P by converting into refractory P seems inefficient in shelf sediment. This implies that continental shelf sediment sequesters P temporarily rather than permanently. Results show local variation. Nakdong estuary receiving large amount of terrigenous input shows the highest concentration of total P and reactive P. Here iron oxyhydroxides at the surface sediment control the water column flux of P from sediment. Although total P content at the surface is comparable (500∼600 ㎍ g^(-1)) between the South Sea and East China Sea, the former contains more iron bound-P and less derital inorganic-P than the latter. Reasons for the difference seem due in part to particle texture, and to biological productivity which depends roughly on the distance from land.