钦州湾近岸海域水质状况及富营养化分析

摘要

Water quality was monitored in the coastal area of Qinzhou bay, Qinzhou, Guangxi, southern China in May, 2012. The results showed that all of the basic parameters such as water temperature, salinity, pH and dissolved oxygen in this coast were suitable for the growth and breeding for all kinds of living beings in subtropical oceans during this period. Dissolved inorganic nitrogen and activated SiO2-3 -Si appeared over-abundant in the coastal area, but the dissolved inorganic phosphorus had a feature of low content, the higher N/P ratio means that PO3-4 -P might become a potential factor to limit phytoplankton growth. COD appeared the phenomenon of exceed standard in some stations. The results of pollution index A and single factor pollution index Pi indicated that there was two grade pollution degree in the whole survey region, which belongs to just beginning pollution, and 30% of these stations were polluted by organic aerobic organisms at different degree. The result of eutrophication index suggested that it has not been achieved eutrophication status to the whole study area, but there has been an eutrophication condition for some regions. The mean (range) value of contribution to the eutrophication was 72. 46% (67. 36%-83. 96%). COD has become an important factor for the contribution of eutrophication in the study area.%2012年5月钦州湾近岸海域水质监测结果表明，钦州湾近岸水温、盐度、pH、溶解氧等基本环境参数均有利于亚热带海洋生物的生长繁殖；溶解无机氮( DIN)和活性硅酸盐( SiO2-3-Si)均显示过剩，但溶解无机磷( DIP)具有低磷特征，高的氮磷比值使PO3-4-P可能成为浮游植物生长的潜在限制因子，且COD部分站位出现超标现象。污染指数( A)和单因子污染指数( Pi)结果显示，近期整个钦州湾近岸水域污染程度达到2级，属于开始受到污染，水质受到化学耗氧有机物不同程度的污染，超标率达到30％。富营养状态指数结果表明，钦州湾近岸海域总体尚未达到富营养化，但局部区域已出现富营养化状况。 COD对富营养化的贡献率平均值及范围为72.46％(67.36％~83.96％)，COD已成为影响钦州湾近岸海域富营养化的重要因素。