三亚湾海水温度季节变化及溶解无机氮的垂直分布特征

VERTICAL DISTRIBUTION CHARACTERISTICS OF SEAWATER TEMPERATURE AND DIN IN SANYA BAY

根据 2 0 0 0年 4月— 2 0 0 1年 3月在三亚湾的定点现场观测资料分析结果表明 :6— 8月份受外来冷水上升流的入侵和影响 ,使该湾水域在该季节形成明显的温跃层 ,底部和中部有明显的低温层。在上升流入侵期间 ,该湾水域平均温跃层强度为 0 .1 3 8— 0 .2 83℃·m- 1 ,最大温跃层强度为 0 .41 9— 0 .440℃·m- 1 ,底部最低水温在 2 2℃左右。 9月—翌年 3月温跃层消失 ,海水混合流动充分 ,温度垂直分布均匀。 3月份水温开始升高 ,至 5月水温总体升至最高 ,并由于高气温及强太阳的辐射作用 ,5月份形成温跃层。溶解无机氮 (DIN)的分布特征表明 ,硝酸盐、亚硝酸盐在冷水上升流入侵季节 ,其含量明显提高 ,比平时分别提高 :1 0 .2 0 %(表层 )、3 7.2 0 %(中层 )、83 .81 %(底层 )和 6 4 .0 4 %(表层 )、82 .96 %(中层 )、1 1 9.41 %(底层 )。氨态氮不直接受上升流影响 ,但季节变化特征明显。

Based on the in-situinvestigation information obtained by The State Key Tropical Marine Biological Research Station during the period from March 2000 to April 2001 in the Sanya Bay, the paper analyzed the vertical and seasonal distribution characteristics of seawater temperature in the Bay and revealed the background and seasonal variations of dissolved inorganic nitrogen ( DIN). The results indicated that there were seasonal cold-water upwellings in the region from June to August, which can cause the formation of thermocline and bring about low temperature in the middle and bottom water layers. The average of thermocline intensity was 0.138-0.283℃·m -1, the max was 0.419-0.440℃·m -1,the lowest temperature in the bottom layer was about 22℃. Meanwhile the upwellings introduced nutrient-rich waters into the corals reef ecosystems in the region, especially nitrite and nitrate. During upwelling season the nitrite concentrations of the surface, middle and bottom water layers increased by 10.20%, 37.20% and 83.81% respectively, and the nitrate concentrations of the surface, middle and bottom water layers increased by 64.04%, 82.96% and 119.41% respectively. It seemed that the ammonium concentration had nothing to do with the upwellings, but its seasonal variation was clear. There were no cold-water upwellings from September to the next March, the vertical distribution of sea temperature was even and the thermocline disappeared. However the thermocline appeared in April again because of high-irradiation.