渤海近20年来营养盐变化趋势研究

通过对1982、1992、1998年渤海近20年来营养盐类的变化趋势分析得出，近20年来渤海的营养盐类均发生了不同程度的变化，20世纪90年代活性磷酸盐含量与80年代相比处于较低水平。硅酸盐含量处于波动状态，80年代硅酸盐含量处于较高水平，90年代初处于较低水平，到90年代末又有所回升。无机氮含量基本呈逐渐升高趋势。渤海的营养结构均发生了显著变化，表现为N／P比值升高，SUN比值下降。渤海水域氮限制的状况正在逐步向磷限制方向演化，若按此趋势演化，必将造成磷和硅限制。近年来黄河断流减少了主要由风化过程产生的硅的入海量，以及农用化肥的流失总量并未改变，是造成上述变化趋势的主导因子。但对于一些近岸水域，因大量生活污水和工业废水的排放，有时会造成局部水域的富营养化，使近年来渤海近岸水域时有赤潮发生。

The variation trend of nutrient salts in the Bohai Sea

The variation trend of nutrient salts was analyzed in the Bohai Sea according to the investigation results for the last twenty years. The results showed that the content of nutrient salts had shown some change to a certain degree, the content of phosphates was lower in the 1990s than that of the 1980s, the content of silicate was in fluctuant state, and the content of organic nitrogen was in rising trend basically. The distinct variation of nutrient structure had happened in the Bohai Sea. The level of nutrition was changing from nitrogen limit to phosphate limit gradually. The ruling factors which caused the variation above named was reducing amount of silicon flowing into the sea when the Yellow River dries rot, and the loss amount of chemical fertilizer was not changed. But the abundant industrial wastewater and domestic sewerage were led into some offshore waters, the eutrophication can be brought sometimes forpartial waters, and the red tide occurred in offshore waters of the Bohai Sea in recent years.