National Institute of Oceanography,(1) Dona-Paula, Goa 403004, India.
Mar Environ Res. 2010 Sep-Oct;70(3-4):272-82. doi: 10.1016/j.marenvres.2010.05.009. Epub 2010 May 27.
Nutrient characteristics of four water masses in the light of their thermohaline properties are examined in the eastern Equatorial Indian Ocean during winter, spring and summer monsoon. The presence of low salinity water mass with "Surface enrichments" of inorganic nutrients was observed relative to 20 m in the mixed layer. Lowest oxygen levels of 19 microM at 3 degrees N in the euphotic zone indicate mixing of low oxygen high salinity Arabian Sea waters with the equatorial Indian Ocean. The seasonal variability of nutrients was regulated by seasonally varying physical processes like thermocline elevation, meridional and zonal transport, the equatorial undercurrent and biological processes of uptake and remineralization. Circulation of Arabian Sea high salinity waters with nitrate deficit could also be seen from low N/P ratio with a minimum of 8.9 in spring and a maximum of 13.6 in winter. This large deviation from Redfield N/P ratio indicates the presence of denitrified high salinity waters with a seasonal nitrate deficit ranging from -4.85 to 1.52 in the Eastern Equatorial Indian Ocean.
对冬季、春季和夏季季风期间东赤道印度洋中根据其热盐特性的四股水体的营养特征进行了研究。在混合层中，20 米深处存在着低盐度水体和“表层富营养化”无机营养物。在 3 度北纬的光区中，氧气最低水平为 19 microM，表明低氧高盐度阿拉伯海海水与赤道印度洋混合。营养物的季节性变化受季节变化的物理过程如温跃层抬升、经向和纬向输送、赤道逆流和吸收和再矿化的生物过程调节。从低 N/P 比（春季最小值为 8.9，冬季最大值为 13.6）也可以看出，具有硝酸盐亏损的阿拉伯海高盐度水的循环。与 Redfield N/P 比值相比，这种大的偏差表明存在经过脱氮的高盐度水，在东赤道印度洋中，季节性硝酸盐亏损范围为-4.85 至 1.52。
