형광 용존유기물을 이용한 서인도양 심층수 수괴 추적

Abstract

Meridional distributions of fluorescent dissolved organic matter (FDOM) and various chemical and physical water properties were investigated along 67˚E of the Western Indian Ocean in July 2017. Three FDOM components were identified by theparallel factor analysis model: two humic-like (FDOMH) and one protein-like components (FDOMP ). Our result showed that the highest fluorescence of FDOMH was found in the North Indian Deep Water (NIDW), but relatively lower value in the intruding water masses from the upper layer. The deep FDOMH was significantly correlated with Apparent Oxygen Utilization (AOU) as previously studies. In particular, the slopes of the regression lines varied with the different water masses and two humic components. Here, to identify the factor inducing the variations, we estimated the relative water fraction of each water mass using a salinity-FDOMH diagram. The FDOMH components were positively correlated to the relatively agedwater fraction (i.e., NIDW), but negatively correlated with fresher ones. The relationship patterns with water fractions corresponded to those with the ratio of two humic components. The results indicated that the distribution and variation of FDOMH with AOU is affected by the mixing of various deep-water masses with different production and removal rate of FDOMH during the global ocean circulation.