乳山湾邻近海域低氧现象及成因浅析

根据2009-06-2009-09及2010-05-2010-06在乳山湾及其毗邻海域的综合调查,分析了该海域溶解氧的变化,初步探讨了影响溶解氧变化及底层低氧形成的原因。结果表明,夏季乳山湾邻近海域存在季节性低溶解氧区,溶解氧在6,7月份相对较高,而在8,9月份相对较低,最低值出现在8月份,为3.21mg/L(饱和度为35.5%),表观耗氧量为5.82mg/L。乳山湾外邻近水域溶解氧略高于湾口和湾内。底层溶解氧水平受到潮汐的影响,具有较大的周日波动性,变化范围介于3.74～8.26mg/L;在落潮时质量浓度降低而在涨潮时质量浓度升高。在这一区域存在较为强烈的温、盐跃层,从而限制了表、底层溶解氧的交换,而COD质量浓度的升高为这一区域的耗氧过程提供了一定的物质基础。潮汐、黄海冷水团的顶托作用、有机物质在底层水域的氧化作用以及底泥耗氧过程导致底层溶解氧的亏损。

Hyposia and Its Cause of Formation in the Adjacent Waters of Rushan Bay

The cruises on hypoxia investigation were carried out in the mouth of Rushan Bay and its adjacent area in both June to September,2009and May to June,2010.Dissolved oxygen and cause of hyposia formation were analyzed.The result indicated that there was a low-oxygen area in Rushan Bay mouth and its adjacent waters.The DO was higher in surface water but lower in bottom.The minimum value of DO(3.21mg/L)was found at the bottom in August,oxygen saturation was 35.5%and apparent oxygen utilization(AOU)was 5.82mg/L.The DO was lower in high tide level and higher in low tide,with distinct diurnal variations(3.74～8.26mg/L).Yellow Sea Cold Water Mass,tide,water stratification,high concentration of organic substance,and sediment oxygen demand were the major factors causing the formation of the hypoxia.