柘林湾网箱养殖海域溶解氧分布及其影响因素

Preliminary studies on the relationships between dissolved oxygen and environmental factors in the cage culture area of Zhelin Bay

根据 1998年 7月在南海东北部柘林湾的调查数据 ,探讨网箱养殖海域溶解氧的分布及其与其他环境因子间的关系。结果显示夏季海水溶解氧浓度为 3.0 8～ 7.86mg/L(平均 5.30 ) ,其分布为网箱区 (平均 4 .4 4 )低于对照区 (平均 6.12 ) ,表层 (平均 5.69)高于底层 (平均 4 .67) ,退潮时 (平均 5.71)高于涨潮时 (平均 4 .65) ,涨潮时网箱区内贫氧 ( <4 mg/L)。多元逐步回归分析表明 ,对溶解氧浓度有重要影响的水质因子为 p H和水温 ,其次为盐度、COD和营养盐 ,它们的变化与 DO的变化有较好的相关性。区域比较表明 ,海水溶解氧浓度与观测位置到网箱区的距离呈正相关 ( P<0 .0 2 ) ,与底质硫化物、PO4 - P含量呈负相关 ( P<0 .0 5)。溶解氧浓度偏低与养殖环境的污染有直接关系。

Based on investigation data in July, 1998,this paper deals with variations of dissolved oxygen (DO) in the waters of cage culture area of Zhelin Bay,and the relationships between DO and other environmental factors. It was observed that DO concentrations were 3 08~7 86mg/L (average of 5 30), DO concentrations(average of 4 44) in culture area,(average of 4 65) in high tide and (average of 4 67)at bottom,were lower than those(average of 6 12) in control area,(average of 5 71)in low tide and when tide set at the surface (average of 5 69). Multiple regression shows that pH and temperature are the important factors affecting the variations of DO (followed by salinity, COD, and nutrient salts) and that they have significant correlation with DO. Preliminary results indicate that DO concentration is positively related to distance from culture area ( P <0 02), but negatively correlated to sulfide content and PO 4 P content ( P <0 05) of surface sediments.