浒苔绿潮消亡腐败过程中的营养盐释放及其对近海环境的影响

为探讨浒苔绿潮消亡腐败过程中的营养盐释放规律以及浒苔绿潮聚积腐烂对海水水质的影响，在室外模拟近岸浒苔绿潮聚积腐烂过程，并于2018年6月在浒苔绿潮靠岸前开始对主要浒苔绿潮聚积地(鳌山湾、鳌山湾口的海参池、石老人海域)进行观测，实时记录浒苔腐烂状况及对周边环境的影响。模拟实验结果表明:各形态氮、磷营养盐在浒苔腐烂分解过程中升高明显，且以溶解有机态、颗粒态为主。其中生物量为5 g/L实验组溶解有机氮(Dissolved Organic Nitrogen，DON)、颗粒态氮(Particulate Nitrogen，PN)、溶解有机磷(Dissolved Organic Phosphorus，DOP)、颗粒态磷(Particulate Phosphorus，PP)的浓度在浒苔腐烂分解过程中达本底浓度的5～10倍以上。现场调查结果显示，随着浒苔绿潮在青岛近岸聚积，各调查站点的溶解无机氮(Dissolved Inorganic Nitrogen，DIN)、DON、DOP受浒苔绿潮吸收影响均降至最低值，后随着浒苔绿潮腐烂逐渐上升，水质恶化。其中鳌山湾受浒苔绿潮腐烂影响最为严重，在调查期间水体甚至劣于二类水质。PN、PP为调查区内营养盐的主要赋存形式，其中鳌山湾海域PP变化最为明显，随着浒苔绿潮聚积腐烂达到最高值(2.02 μmol/L)。相比于鳌山湾，石老人海域海水交换能力强且在浒苔绿潮靠岸后进行了及时拦截打捞，受浒苔绿潮消亡腐烂影响较小。浒苔绿潮靠岸聚积腐烂，使海域内营养盐含量与结构明显变化，影响海域浮游植物群落结构的稳定,可能引发赤潮等次生生态灾害。因此需要及时清理聚积在青岛近岸的浒苔，避免其腐烂对周边环境造成影响。

On nutrient releases from the decomposition of Ulva prolifera green tide and their impacts on nearshore seawaters in the southern Yellow Sea

The decomposing process of Ulva prolifera green tide was simulated in the outdoor pond to study laws of the nutrient release. Simultaneously, we carried out field investigation in the coast of Qingdao in June 2018, such as the Aoshan Bay, the outside of Aoshan Bay and the Shilaoren Beach, to monitor regularly the seawater quality. Simulation experiment results showed that the concentrations of nitrogen and phosphorus nutrients were increasing significantly during the decomposition of Ulva proliferas and dissolved organic and particulate states are the main forms of nitrogen and phosphorus nutrients. The concentrations of dissolved organic nitrogen (DON), particulate nitrogen (PN), dissolved organic phosphorus (DOP) and particulate phosphorus (PP) nutrients in the water of 5 g/L biomass experiment were much higher than original water. Field investigation results showed that the nitrogen and phosphorus nutrients contents in the seawater reduced to the minimum gradually due to the absorption of the green tide. And then, as the decomposing of the Ulva prolifera green tide, the contents of nitrogen and phosphorus nutrients in the sea water were gradually increasing. Aoshan Bay was most affected by the Ulva prolifera green tide, it was even inferior to the second-class water quality standard. PN and PP were the main forms of nutrients in the investigation area, this situation was most obvious in the Aoshan Bay (PP, 2.02 μmol/L). Compared with Aoshan Bay, the seawater exchange capacity of the Shilaoren Beach was strong, and it was intercepted and salvaged in time after that the Ulva prolifera green tide was docked, which was less affected by the decomposing of Ulva prolifera green tide. With the accumulation and decay of the Ulva prolifera, the nutrients content and structure of the sea area changed significantly, which had severe impact on the stability of the phytoplankton community, which may cause secondary disasters of red tide. Therefore, we must promptly clean up the Ulva prolifera gathered near the coast of Qingdao to reduce the impact on nearshore seawaters in the southern Yellow Sea.