胶州湾东北部营养盐的季节和多年变化

Seasonal and long-term variations in nutrients in north-eastern of Jiaozhou bay,China

根据1991-2004年的调查资料,探讨了胶州湾东北部水域营养盐及其摩尔比的月、旬的变化和多年变化以及与年、Chla的关系。月和旬的变化表明春、夏季,各种营养盐浓度以锯齿状的形式呈缓慢上升趋势,与外源性营养盐增加密切相关,只有SiO3-Si在8月份出现明显峰值,SiO3-Si/DIN和SiO3-Si/PO4-P比也有相似的变化;秋季以后营养盐浓度急剧增加,特别是SiO3-Si和DIN,导致了冬季赤潮的爆发。在赤潮高峰时,营养盐大量消耗,特别是SiO3-Si几乎耗尽(0.49μmol/L),SiO3-Si/DIN和SiO3-Si/PO4-P比迅速下降(分别为0.01和1.04),SiO3-Si成为浮游植物生长的限制因子,控制了赤潮的进一发展,并初步讨论了赤潮发生的化学海洋学机制。营养盐的季节变化与Chla含量呈明显的消长关系。营养盐及其结构的多年变化表明,1999年以后比1991-1998年DIN和SiO3-Si的平均浓度分别增加了1.0和2.2倍,DIN/PO4-P比和SiO3-Si/PO4-P比分别增加了0.4和0.9倍,PO4-P、SiO3-Si/DIN比略有增加,营养盐之间的摩尔比都偏离了Redfield比,这与青岛市社会经济发展密切相关。

Based on the observed data from 1991 to 2004, in north-eastern of Jiaozhou Bay, the variations of months, ten-day period and long-term in nutrient concentration and their molar ratios, and the relations between them and the chlorophyll a content are discussed in this paper. The various nutrient concentrations slowly increase in a wave in spring and summer which are closel related with the input of the outer-source nutrients. Big variations in a ten-day period in nutrient concentrations and their molar ratios mainly reflect instability of the input of the outer-source nutrients. Among various nutrients, the obvious peak value is found in August only for SiO3-Si and there are similar variations to SiO3-Si/DIN and SiO3-Si/PO4-P ratios related to rainy season which brings a lot of SiO3-Si. After autumn, the nutrient concentrations rapidly increase, particularly SiO3-Si and DIN, as high as 97.7 and 173.4μmol/L respectively, and lead to the bloom of Lauderia annulata Cleve in winter which is found first time in winter in Jiaozhou Bay. During the peak of bloom, nutrients are heavily consumed, and SiO3-Si is almost exhausted （0.49μmol/L） and SiO3-Si/DIN and SiO3-Si/PO4-P ratios rapidly drop down to 0.01and 1.04 respectively. SiO3- Si becomes the limiting factor of phytoplankton growth and the bloom is finally controlled. The study shows that there are close relations of growth and decay between the season variations of nutrients concentrations and phytoplankton. The long-term variations of nutrients and their structure show that, compared the 1999 - 2004 period with the 1991 - 1998, the average DIN and SiO3-Si concentrations increase by 1.0 and 2.2 times, respectively, and the average DIN/PO4-P and SiO3-Si/PO4-P ratios increase by 0.4 and 0.9 times, respectively, and the PO4-P concentration and the SiO3-Si/DIN ratio increase a little. All the molar ratios of nutrients are much different from the Redfield ratios （N/P= 16, Si/P= 16, Si/N = 1）. It is close related to the developments of a society and its economy of Qingdao city.