海草床是海洋生态系统中重要的碳库。海草凋落叶分解及其溶解有机碳（DOC）的释放，是海草床碳流动的关键环节。人类活动引起的近岸海域无机氮增加，可能会改变海草凋落叶分解速率及其DOC释放速率，进而对海草床的碳储存能力与微食物环产生影响。因此，探讨无机氮对海草凋落叶分解速率及其DOC释放速率的影响机制极为重要。本项目通过现场调查，研究在不同无机氮梯度下，热带典型海草叶片凋落量及凋落叶分解酶等的基本特征；采用野外原位实验，探讨无机氮对海草凋落叶分解速率的影响；并通过室内模拟实验，研究无机氮对海草凋落叶DOC释放速率及产生量的影响。本项目将有助于认识近岸海域富营养化环境中海草凋落叶有机碳分解机理，揭示富营养化对海草床碳流动关键过程的影响机制，为海草床保护提供科学依据。

Seagrass bed is a significant carbon stock in ocean ecosystem. Decomposition of seagrass leaf litter and its release of dissolved organic carbon (DOC), play an important role in the carbon cycle of seagrass bed. Increased human activities have led to a rise in the availability of inorganic nitrogen in seagrass bed. Excessive inorganic nitrogen may alter decomposition rate of seagrass leaf litter and its release rate of DOC, thereby affecgting the capacity of seagrass communities to store ogranic carbon and microbial food loop. Thus, it is particular important to carry out the project. Through field investigation, leaf litter production of seagrass, decomposition enzyme activity and other features of leaf litter along inorganic nitrogen gradient would be analysed. Based on field experiment, this project intends to study the effect of inorganic nitrogen on decomposition rate of seagrass leaf litter. With laboratory experiment, the effect of inorganic nitrogen on the release rate and production of DOC during decompositon of seagrass leaf litter would be examined. Therefore, this project help to understand the decomposition process of seagrass leaf litter in eutrophic coastal water, to reveal the impact of eutrophication on key process of carbon flow in seagrass bed, and to provide a scientific basis for seagrass bed production.