沙海蜇(Nemopilema nomurai)模拟消亡过程中氮与磷的释放

NITROGEN AND PHOSPHORUS RELEASE FROM NEMOPILEMA NOMURAI IN SIMULATED DECOMPOSITION

在实验室内模拟研究了沙海蜇消亡过程中氮与磷的释放特征。模拟结果表明:沙海蜇消亡过程中向水体释放氮、磷可分为两个阶段,且氮的释放速率比磷高一个数量级。在沙海蜇消亡的初期阶段,水体中溶解态氮、磷和总氮、总磷的浓度迅速增高,氮可以达到其消亡过程中的最高浓度;在后期阶段,水体中溶解态氮和总氮的浓度不断下降,但水体中的磷在这一阶段达到消亡过程中的最高浓度碱性条件有利于氮的释放,酸性条件有利于磷的释放;盐度越高氮与磷的释放速率越小;温度对氮、磷的释放影响不大;水体中氮与磷含量越高,沙海蜇消亡的速度越慢,而且氮的浓度越高,氮与磷释放到水体中的速率就越慢。

Jellyfish populations grew rapidly to attain large biomasses and therefore represent significant stocks of carbon and nitrogen in the ecosystem. Blooms were also generally short-lived, lasting for just weeks or months, after which time the population decline rapidly, sink and decompose. The releases of nitrogen and phosphorus from decomposing Nemopilema nomurai were examined in a series of experiments at different pH values, salinities, temperatures and nitrogen and phosphorus concentrations as incubate conditions. The release of nitrogen and phosphorus from decomposing N. no- murai could be divided into two stages, but the releases of nitrogen and phosphorus were quite different, and the nitrogen effiuxed at rates more than one order greater than phosphorus. In the early stages of N. nomurai decomposition, the con- centrations of dissolved nitrogen, dissolved phosphorus, total nitrogen and total phosphorus in sea water increased rapidly. The concentration of nitrogen was highest in the whole degradation process, which dissolved nitrogen reached 1042μmol/L, total nitrogen reached 1650μmol/L, dissolved nitrogen release rates reached 44.8mg/（kg-d）, total nitrogen release rates reached 56mg/（kg-d）, DN/DP ratio increased rapidly and reached maximum 229 ： 1. In the later stages of N. nomurai decomposition, the concentration of dissolved nitrogen and total nitrogen continues to decline, while the phosphorus concentration in water can reach the maximum concentration during the degradation process, which dissolved phosphorus reached 28.2μmol/L, total phosphorus reached 37.9μmol/L, dissolved phosphorus release rates reached 3.14mg/（kg.d）, total phos- phorus release rates reached 4.4mg/（kg.d）, the DN/DP ratio decreased rapidly to 24 ： 1 and gradually stabilized. Sea water pH had different influence on the release of nitrogen and phosphorus. Alkaline conditions favor the release of nitrogen, and acidic conditions favor the release of phosphorus. The nitrogen and phosphorus release rates increased with the salinity of sea water, and the amount of nitrogen and phosphorus released increased with their rates. Temperature had little impact on the release of nitrogen and phosphorus during the process of N. nomurai decomposition. The content of nitrogen and phosphorus in sea water had significant impact on the release of nitrogen and phosphorus. The rate of N. nomurai decom- position decreased with the increase of nitrogen and phosphorus content in sea water. The nitrogen and phosphorus release rates decreased with the increase of the concentration of nitrogen. So the rate of nitrogen and phosphorus release would be slowed during the process ofN. nomurai decomposition in the eutrophication sea water.