南印度洋海区营养盐的分布特征

Nutrients Distribution in the South Indian Ocean

探讨了南印度洋海区总有机磷(TOP)、总有机氮(TON)以及溶解无机营养盐的分布规律。分析结果表明:研究海区内溶解无机营养盐受水体中生物活动和物理过程的综合影响,表层水体由于生物活动的消耗,其磷酸盐等无机营养元素的含量一般是采样水深范围内最低的;中深层水体由于生物活动的降低以及有机质矿化作用的影响,无机营养元素的变化范围较小。表层水体中TOP和TON含量占TP和TN的主要部分,说明表层水体中的氮和磷主要以有机态形式存在,且沿着37.8°S从西向东,TOP和TON的含量以及TOP/TP和TON/TN的比值呈降低的趋势。研究海区叶绿素a的分析结果表明,初级生产力的变化可能是控制研究海区TON和TOP空间分布的主要因素。不同形态氮、磷营养元素的相关分析表明,有机营养盐和无机营养盐之间互为补充,且表层水体中有机氮和磷是水体初级生产所需营养盐的重要来源,总氮、总磷的关系表明研究区初级生产力并不受氮、磷的限制。

The distributions of total organic phosphorus（TOP）,total organic nitrogen（TON）,and dissolved inorganic nutrients in the south Indian Ocean were studied.The results suggest that the dissolved inorganic nutrients concentrations in the surface water are the minimum values in the sampled water depth because of the influences of physical and biological processes.Their concentrations in the deep water show little variations because of organic material remineralization and the decrease of phytoplankton consumption.In the surface water,TON and TOP are the major components of TN and TP,which suggests that the organic forms are the main forms for nitrogen and phosphorus.In the surface water,there is a distinctive eastern gradient of TON and TOP concentrations,TOP/TP and TON/TN ratios along 37.8° S.The simultaneous measurements of chlorophyll a in photic zone reveal that the primary production variation may be the major controlling factor for spatial distributions of TON and TOP.The correlation between various forms of nitrogen and phosphorus shows that organic and inorganic nutrients are inter complementary,and TON and TOP are the important sources for phytoplankton production in the surface water.The TN/TP ratios indicate that the nitrogen and phosphorus are not the limiting factors for the primary production in the research region.