连云港近海海域水质的季节和年际变化

根据1992～2005年连云港近海海域水质监测资料,对该海域水质的季节变化和年际变化进行研究.结果表明,近海水质有明显的季节变化特征,其中盐度从春、夏季到秋季缓慢降低,冬季升高;溶解无机氮(DIN)与盐度恰恰相反,夏秋季最高且监测的超标率高.溶解氧季节性非常明显,依次为冬季>春季>秋季>夏季.总体上春冬季水质好于夏秋季.年际变化显示,1992～2005年pH和盐度均有降低趋势,尤其是2003年以后降幅更加明显;DO和COD年际变化相对平稳但季节变化幅度较大;2000年12月后油类浓度明显降低且年际变化平稳;近几年DIN有明显增加趋势,无机氮已成为该海域主要污染物.

SEASONAL AND INTER-ANNUAL VARIATIONS OF WATER QUALITY IN LIANYUNGANG INSHORE

Based on the monitoring results of water quality in Lianyungang inshore from 1992 to 2005, the research on seasonal and inter-annual variations of seawater quality in the region is performed. The results show that there are distinct seasonal variations in water quality, with salinity decreasing slowly from spring through summer to autumn while increasing in winter. DIN, in reverse, reaches the peak in summer and autumn with high over-standard rate. The remarkable seasonal variations of DO embody the following tendency: winter>spring>summer>autumn. Generally speaking, the seawater quality in spring and winter is better than in autumn and summer. It can also be seen that the pH and salinity gradually reduce from 1992 to 2005 with sharp drop tendency after 2003; the inter-annual variations of DO and COD are comparatively small, while their seasonal variations great; the oil concentration has a steady inter-annual variation but reduces obviously since December, 2000; DIN shows an upgrade tendency in recent years and has been the major pollutants in the marine area.