春夏季长江口及其邻近海域表层和底层环境因素、氮分布分析

Analysis on the Environmental Factors and Dissolved Inorganic Nitrogen in the Changjiang(Yangtze River) Estuary and in the Adjacent East China Sea in Spring and Summer

以2007─2013年连续7年长江口及邻近海域(包括长江口、杭州湾和舟山渔场)春、夏两季的调查资料为依据,研究了长江口及其邻近海域表层和底层温度和盐度的空间分布特征、无机氮(DIN)含量的分布趋势及DIN含量的结构特征。研究结果表明:长江口、杭州湾和舟山渔场3个区域春、夏两季表层和底层温度分布均呈现西高东低。表层东西向相差3℃左右,底层东西向相差2.2℃左右,表层和底层温度无显著性差异。3个区域盐度分布不同,长江口盐度分布呈现西低东高,梯度明显,杭州湾盐度变化不明显,舟山渔场东部和南部盐度较高;3个区域表层和底层盐度无明显差别。长江口表层和底层DIN含量有差别,表层含量大于底层;在杭州湾和舟山渔场表层和底层DIN含量变化不明显。长江口、杭州湾和舟山渔场表层和底层的DIN结构均以NO_3^--N(硝酸盐)为主,其次是NH_4^+-N(氨氮),含量最低的为NO_2^--N(亚硝酸盐)。表层和底层的温度和盐度无显著性差异,可能是表层和底层DIN含量结构一致的主要因素。2007─2013年春、夏季表层和底层DIN结构比例变化一致,DIN的结构分布受水深的影响不大。表层和底层的NO_3^--N所占DIN百分比基本在60%以上,NH_4^+-N所占DIN百分比在3%~41%,NO_2^--N所占DIN的百分比均低于5%。因此,DIN含量的变化主要受NO_3^--N和NH_4^+-N的变化影响。

According to monitoring data in spring and summer from 2007 to 2013, the spatial trend of temperature and salinity wereanalyzed at the surface and bottom water in the Changjiang （Yangtze River） Estuary and in the adjacent East China Sea （includingChangjiang Estuary, Hangzhou Bay and Zhoushan fishing ground）. And the spatial trend and structure of dissolved inorganicnitrogen （DIN） were also analyzed. The results indicated that the temperature was higher in the west than that in the east. Thedifference value between the west and the east was 3 ℃ at the surface and 2.2 ℃ at the bottom. The temperature at the surface andthe bottom water was not obvious. The trend of salinity was different in Changjiang Estuary, Hangzhou Bay and Zhoushan fishingground. The salinity was lower at the east than at the west in Changjiang Estuary. The salinity variation was not obvious in HangzhouBay. The salinity was higher in the east and south in Zhoushan fishing ground. The salinity was not obvious at the surface and bottomwater in Changjiang Estuary, Hangzhou Bay and Zhoushan fishing ground. The DIN content at the surface water was higher than thebottom water in Changjiang Estuary, and was not obvious in Hangzhou Bay and Zhoushan fishing ground. Among the DIN forms,nitrate was main content, then was ammonium, the lowest was nitrite in Changjiang Estuary, Hangzhou Bay and Zhoushan fishingground. The temperature and salinity was not obvious difference, which was possible factor for accordant structure of DIN at surfaceand bottom water. From 2007 to 2013 the percentage of nitrogen forms in DIN at surface water was coincident with bottom water,which was indistinctively affected by water depth. The percentage of nitrate nitrogen in DIN was over 60% at surface and bottomwater. The percentage of ammonium nitrogen in DIN was 3%~41% at surface and bottom water. The percentage of nitrite nitrogen inDIN was lower than 5% at surface and bottom water.