黄渤海海域秋季营养盐及有色溶解有机物分布特征

本文利用2013年11月黄渤海海域航次采集的海水样品,对该海域有色溶解有机物(CDOM)、营养盐等的组成、来源、分布特征和主要环境影响因子进行了分析研究.通过三维荧光光谱-平行因子分析法(EEMs-PARAFAC)对CDOM进行分析,共鉴别出2类4种荧光组分:类腐殖质组分C1(325/410 nm)、C2(275,370/435 nm)、C3(270,395/495 nm)和类蛋白质组分C4(290/340 nm).3种类腐殖质组分在黄渤海海域各层的平面分布均为由近岸向远岸逐渐递减.黄海表层和渤海中层类蛋白质组分荧光强度在近岸和远岸海域均出现极大值,而其在渤海表底层及黄海中底层的分布呈现由近岸到远岸逐渐降低的趋势.各层CDOM高值区主要分布在近岸海域.渤海表层溶解无机氮(DIN)和溶解有机氮(DON)浓度高于底层浓度,底层溶解无机磷(DIP)浓度高于表层浓度.渤海DIN呈现由近岸到远岸逐渐降低的趋势,DIP由曹妃甸近岸海域及中部海域的高值区向北部、东部和南部海域逐渐降低的趋势,DON则呈现由渤海中部偏南海域的高值区向四周逐渐递减的趋势.黄海底层DIN和DIP浓度高于表层,而表层DON浓度最高.黄海表中层DIN和DIP呈现由近岸到远岸逐渐降低的趋势,底层DIN和DIP则呈现由近岸到远岸逐渐增加的趋势,DON呈现由近岸到远岸逐渐降低的趋势.渤海DIN、DON和DIP的总体浓度均高于黄海.将4种荧光组分(C1~C4)、吸收系数(a_(355))、溶解有机碳(DOC)与叶绿素a(Chl-a)、盐度(S)、溶解氧(DO)、DIN、DON、DIP进行冗余分析,结果表明黄渤海各荧光组分(C1~C4)主要受陆源输入的影响,DOC受陆源与海源的共同影响,但陆源影响较大.渤海DIN受陆源输入的影响较大,而DON受海源影响较大;黄海DIN受陆源和海源共同影响,而DON主要受陆源输入影响.黄渤海DIP均受陆源和海源共同影响.

Distribution Characteristics of Chromophoric Dissolved Organic Matter and Nutrients from the Yellow Sea and Bohai Sea in Autumn

Water samples were collected from the Yellow and Bohai seas during November 2013 and the chromophoric dissolved organic matter (CDOM) and nutrients concentrations were investigated, including their composition, source and distribution characteristics. CDOM was analyzed by excitation-emission matrix spectroscopy (EEMS) in combination with a parallel factor analysis (PARAFAC). Three terrestrial humic-like substances (C1, C2, and C3) and one protein-like (C4) substances were identified. The three terrestrial humic-like components had a similar horizontal distribution, decreasing from inshore to offshore. The protein-like component, showed higher values for both inshore and offshore areas in the Yellow Sea at the surface layer and the middle layer of the Bohai Sea, while in other layers it had a similar distribution pattern as the terrestrial humic-like components. In the Bohai Sea, the dissolved inorganic nitrogen (DIN) concentration showed a decreasing trend from inshore to offshore areas and the concentration of dissolved inorganic phosphorus (DIP) gradually decreased from the Caofeidian coastal and central areas to other adjacent areas. The dissolved organic nitrogen (DON) showed an increasing from inshore to the central area of the Bohai Sea. DIN and DON were higher in surface layer than in the bottom layer and for DIP this was the opposite in the Bohai Sea. In the Yellow Sea, DON concentrations showed a decreasing trend from inshore to offshore areas. DIN and DIP had higher concentrations at inshore areas in the surface and middle layers, while in the bottom layer they had higher concentrations in offshore areas. The vertical distribution of the DIN and DIP showed higher values in the bottom layer than surface layers and for DON this was the opposite. These results also showed that the concentrations of DIN, DON, and DIP in the Bohai sea were overall higher than the Yellow Sea. A discriminant analysis was performed through redundancy analysis (RAD) of these water quality parameters, including the four fluorescent components, an absorption coefficient (a₃₅₅), chlorophyll a concentration, conductivity, dissolved oxygen (DO), dissolved organic carbon (DOC), DIN, DON, and DIP. The RDA indicated that the four fluorescent components are mainly affected by terrestrial inputs. DOC was affected by both terrestrial and marine sources but terrestrial inputs were the major contributor. It was also indicated that the DIN concentration was affected by terrestrial inputs in the Bohai Sea area and by both terrestrial and marine sources in the Yellow Sea. DON concentrations were mainly affected by marine sources in the Bohai Sea and terrestrial inputs in the Yellow Sea. DIP concentrations were affected by both terrestrial and marine sources in the studied areas.