夏季黄海不同水团溶解有机物分布特征

Distribution of dissolved organic matter in different water masses in the Yellow Sea in summer

依据2017年8—9月对黄海海域溶解有机物(DOM)的调查,探讨了夏季黄海海水中溶解有机碳(DOC)和有色溶解有机物(CDOM)的空间分布特征。在表层海水中,受陆源影响较大的近岸海域CDOM含量相对较高,北黄海冷水团区域由于水产养殖的饵料引起DOC浓度升高,且该部分DOC以无色为主。DOC浓度随深度逐渐降低,而CDOM逐渐升高,该特征在冷水团区域更为显著,因此DOC和CDOM在冷水团区域的表底差异远大于浅水区的非冷水团区域。陆源输入和初级生产是引起表层DOC升高的主要原因,而光漂白则引起CDOM降低,同时光漂白还导致表层水体中CDOM分子量和芳香性低于底层。底层溶解氧饱和度在冷水团为80%~93%,均表现为弱不饱和状态。层化不仅阻碍了O2向底层水体输送,还抑制了DOC和CDOM的垂向混合,这是引起冷水团区域表底层DOC和CDOM差异较大的主要原因。

Based on the investigation of dissolved organic matter(DOM)in the Yellow Sea from August to September 2017,the spatial distributions of dissolved organic carbon(DOC)and chromophoric dissolved organic matter(CDOM)were studied in the Yellow Sea.In surface seawater,CDOM was higher in the nearshore water,which might be caused by the relatively significant influence by the river input,while colorless DOC concentration in the north Yellow Sea Cold Water(YSCW)area was enhanced by aquaculture.The DOC concentration decreased along depth in the water column,but an inverse trend for CDOM,especially in the YSCW area.Terrestrial DOC input and primary production were mainly responsible for the surface DOC enhancement,while photobleaching induced the decrease of CDOM.Additionally,photobleaching also decreased the molecular weight and aromaticity of CDOM in surface water.In the YSCW,O2 was slightly unsaturated,with the saturation degree of 80%–93%.In this area,strong stratification prevented the vertical diffusion of O2 to bottom water.Additionally,stratification could also restrain the vertical mixing of DOC and CDOM,which was mainly responsible for the large difference of DOC and CDOM between surface and bottom waters.