北部湾北部海域潜在低氧分布及影响研究

通过对2011年北部湾北部海域春季和夏季溶解氧（DO）及其他环境要素进行分析讨论，发现DO的季节性差异较大，春季DO含量（平均8.11 mg/L）明显高于夏季（平均6.05 mg/L）。夏季北部湾底层部分区域存在DO低值，该低值区常年存在，并且DO最低值逐渐降低、低值区范围逐渐扩大。利用相关性分析和灰色关联度分析的方法，对夏季底层DO低值的成因进行分析发现：夏季底层水体浮游植物产氧作用较弱，海水层化作用强，阻碍了表底层DO的交换；另外底层有机质分解的耗氧作用明显，出现了氧气的净消耗，由此导致夏季底层水体出现DO的低值。同时，由于2011年之后北部湾北部海域陆源污染排放和赤潮的频发使得该海域低氧状况加剧，潜在低氧区逐渐发展为低氧区。

Characteristics of potential hypoxic zone and its influencing factors in the northern Beibu Gulf

In this study, the dissolved oxygen (DO) content and other environmental factors in the northern Beibu Gulf in the spring and summer of 2011 were analyzed. The results showed that the seasonal differences in DO are large, and the DO in spring (ave=8.11 mg/L) was significantly higher than that in summer (ave=6.05 mg/L). In summer, there was a low-DO area in the northern Beibu Gulf; the low DO remained all year round and became lower year by year. Correlation analysis and gray correlation analysis were performed to analyze the cause of the low DO in summer. It was found that oxygen production was weak in the bottom water during summer and that the stratification was strong, which prevented the exchange of DO between the surface and bottom. In addition, the oxygen consumption by organic matter was greater than the oxygen amount produced by phytoplankton, which led to a low DO in the bottom water in summer. Moreover, owing to the occurrence of terrestrial pollution and red tide in the Beibu Gulf since 2011, the hypoxic conditions have intensified, and the potential hypoxic zone has become hypoxic.