北海湾近10 年来溶解无机氮含量变化及其与环境因子的关系

根据北海湾1995～2004 年10a 间8 个航次的调查资料, 分析研究了该湾溶解无机氮的含量变化及其与环境因子的关系。结果表明: 该湾溶解无机氮(DIN)含量具有春夏季较高、秋冬季较低的变化特点, 突出了南流江迳流的重大贡献作用; 在DIN 中, 所有航次均具有NO₃^-含量较高、NH₄⁺含量次之、NO₂^- 含量最低的分布特征, 而且除2004 年秋季外, NO₃^- 所占DIN 的比值均在63.38%以上, 已成为该湾DIN 的主要存在形式; 通过不同时期的对比分析, 得出该湾DIN 具有春秋季显著上升、冬夏季显著下降的变化规律, 增养殖排废起主导影响作用; 相关分析显示, DIN 与环境因子之间的相关性, 以与盐度出现的机率最多、显著性也最高, 与COD 的相关性次之, 与其余环境因子的相关性依次排列为pH>DO>Chl.a, 与3 种形态氮之间则以NO₃^- 和NO₂^- 最为密切, 7 个航次达到了显著正相关水平, 而与NH₄⁺的显著正相关只出现在迳流影响较小的秋冬季节。

Variation of dissolve inorganic nitrogen and its relationship with environmental factors in Beihai bay in a 10 year period

Based on the surveying data in eight cruises in Beihai bay from 1995 to 2004, variation of dissolve inorganic nitrogen and its relationship with environmental factors were analysed. It was found that the DIN content was high in spprings and summers, butlow in falls and winters, revealing the important contribution of the runoff of Nanliu river. In all cruises, the content of NO₃ was the highest, the content of NH₄⁺ the second, and NO₂^- the lowest. The percentage of NO₃ in DIN was more than 63.38% except for the Fall of 2004, which was the main existing form of DIN in the bay. By analyzing the data of different terms, we found that the content of DIN significantly ascended in springs and falls but descended in Winter and Summer. More and more culture discharge effluents was the main effect reaction. The correlation analysis indicated that, regarding the dependence between DIN and the environmental factors, salinity was the predominant factor. The dependence between DIN and COD was at the second place. The dependence between DIN and other environment factors were in the order of pH > DO > Chl.a, being most closely related to NO3 and NO₂, as indicated by the strong positive correlations in seven cruises. Strong positive correlation with NH₄⁺ was only present in the fall and winter when runoff had less effects.