徐闻珊瑚礁保护区营养盐时空分布特征

2006年8月(夏季)、2006年11月(秋季)、2007年2月(冬季)和2007年4月(春季)在徐闻珊瑚礁自然保护区灯楼角至流沙湾近岸海域调查徐闻珊瑚礁保护区的营养盐变化及空间分布特征。结果表明:徐闻珊瑚礁保护区水域溶解态无机氮以NO3--N为主,其含量超过总溶解无机氮的50%;各站点NO2--N含量相对较低,冬季NO3--N和NH4+-N含量均高于其它季节;无机磷含量在0mg/L～0.030mg/L之间变化;活性硅含量表现为夏秋季节高、冬春季节低;表层水体硝酸盐氮/无机磷原子比值(N/P)夏季较低,不存在无机磷受限情况,而冬季N/P整体较高,此时水体主要受无机磷限制。

Spatio-temporal Distribution of Nutrients in the Xuwen Coral Reef

The variations in the concentration and distribution of nutrients in the Xuwen Coral Reef were investigated based on the data obtained during field observations in August 2006 (summer), November 2006 (autumn), February 2007 (winter) and April 2007 (spring). The results showed that the concentrations of nitrate in surface seawater were much higher than those of nitrite and ammonia, which accounted for over 50% of the dissolved inorganic nitrogen in all the year around. For the concentration of nitrate and ammonia, it was much higher in autumn than in other seasons. Nitrite displayed the similar low-concentration level for all stations in all seasons. The corresponding concentrations of phosphate of all stations were kept low levels and changed mostly between 0 mg/L and 0.030 mg/L in different seasons. The concentrations of silicate for all stations, however, showed much higher in summer and autumn than in winter and spring. Based on the results of the atomic ratio of nitrate vs phosphate, it was suggested that the phosphate supply was sufficient in summer and thus phosphate was not a limiting factor for the growth of phytoplankton. However in winter, the primary production in the Xuwen Coral Reef might be limited by phosphate because of the high atomic ratio of nitrate vs phosphate in this season.