黄渤海氮磷营养盐的分布、收支与生态环境效应

摘要

基于在黄渤海的综合调查结果，分析了水体和沉积物间隙水中溶解无机氮(DIN)和溶解无机磷(DIP)的分布；结合历史数据构建了黄渤海 DIN和 DIP 的收支模型，并分析了陆源输入变化对研究区域生态环境的影响.结果表明，黄渤海 DIN 和 DIP 的含量受季节、河流输入和沉积物界面扩散作用的影响，具有秋季高于春季和近岸高于离岸的时空分布特征.收支模型计算结果表明，底界面扩散是黄渤海水体 DIN 的主要来源，其次是大气、周边河流、地下水和东海的输入；黄渤海水体 DIN 的支出主要是通过沉积埋藏和反硝化.黄渤海水体 DIP 的来源主要是磷酸盐吸附解吸，占91%，底界面扩散和大气输入为其次，河流和地下水的输入贡献较小.DIP 的支出主要是通过沉积埋藏和向东海的输出.黄渤海每年有11Gmol 的氮在水体积累，并导致其浓度提高约0.6µmol/(L·a).近些年来陆地向黄渤海输入氮的持续增加，加剧了氮营养盐的积累，导致非硅藻类浮游植物比例以及赤潮发生频率和面积显著增加，同时还提高了水体初级生产力和海洋磷的埋藏量以及加剧了磷限制的趋势，并可能威胁生态系统的稳定.%Based on results obtained from the comprehensive investigation in the Bohai Sea and the Yellow Sea (BYS), distributions and sources of dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) in the sea water and sediment pore water in the study area were discussed; and a budget model of nitrogen (N) and phosphorus (P) in the BYS was established. Concentrations of DIN and DIP in the study area are affected by riverine input and benthic flux. The major sources of the DIN in the water column of the BYS are benthic diffusion, followed by the atmospheric deposition and inputs from adjacent rivers the groundwater and the East China Sea; while the dominant removals of DIN from water column in the BYS are phytoplankton utilization and sedimentation. The key sources of the DIP are phosphorus minerals desorption and weathering, accounting for 91%, followed by benthic flux and atmospheric deposition, then riverine flux and groundwater input; while the dominant outputs of DIP are sedimentation and the outflow to the East China Sea. There was a 11Gmol/a of nitrogen accumulated in the BYS, which would result in an increasing of DIN concentration by 0.6 µmol/(L·a). DIN concentrations and N/P ratio in the Bohai Sea and the Yellow Sea BYS kept increasing in recent decades due to the increasing of nitrogen N accumulation and phosphorus P sedimentation. Terrestrial nitrogen loadings might enhance the primary production and alter the structure and function of ecosystem, which had would have significant effects on the ecosystem of Bohai Sea and Yellow Sea the BYS in the long-time scale. We, therefore, should reduce the riverine nitrogen N loads to maintain the ecosystem stability in the BYS Bohai Sea and Yellow Sea.