模拟研究沙海蜇消亡过程中海水pH变化及对海水酸化的影响

The variations of pH and seawater acidification during simulated Nemopilema nomurai decomposing process

通过室内模拟实验,研究了不同pH、盐度、温度和氮磷比控制条件下沙海蜇(Nemopilema nomurai)消亡过程中水体pH的变化特征及对海水酸化的影响。结果表明,沙海蜇块体分解会造成pH的显著降低,水体出现明显酸化。随着沙海蜇的分解,本底海水组(本底海水+实验用沙海蜇)水体pH呈现先下降,后缓慢回升直至稳定的趋势,并在第2天形成最小值,且水体pH下降0.5～1.3。沙海蜇块体在不同pH、盐度、氮磷比、温度控制条件下分解时,水体pH变化趋势相似,均表现为先下降,达到最小值后再缓慢回升,但不同控制条件下水体pH出现最小值的时间并不一致,从先到后的顺序是温度组(第3天)、pH和盐度组(第4天)及氮磷比组(第5天),这与沙海蜇块体分解速率顺序一致。沙海蜇分解过程中,这4个实验组水体pH下降0.5～1.8,水体发生明显的酸化,这其中海水盐度、pH的变化及温度的降低所导致的沙海蜇消亡过程中海水酸化程度比较严重;因此,在当今海水富营养化及海水温度升高的情况下,沙海蜇的暴发及其消亡会造成海洋生态系统遭受更严重的破坏。

We studied variations of pH and seawater acidification under the influence of pH, salinity, temperature and N/P in Nemopilema nomurai decomposing process in a stimulation test. It was found that the pH of seawater droped and seawater acidification occurred during degradation of N. nomurai. The pH of seawater firstly droped, then increased and finally gradually stabilized with the decompostion of N. nomurai in the seawater, pH, salinity, temperature and N/P groups, where the pH declined by 0.5-1.8 units. In addition, the time that the pH reached the lowest level was the second day （the seawater group）, the third day （the temperature group）, the fourth day （the salinity and pH groups）, and the fifth day （the N/P group）, respectively. Under changes of pH and salinity and the decrease of temperature, the seawater developed more serious acidification during decomposition of N. nomurai Moreover, when the N. nomurai forms large blooms in the sea area of increasing temperature and eutrophication, decaying jellyfish may cause severe impact on the marine ecosystem.