大亚湾湿地沉积物氮矿化特征及影响因素探究

为探讨大亚湾滨海湿地沉积物中有机氮矿化作用的时空分布规律及其影响因素，于2017年3月（枯水期）和8月（丰水期）分别采集了大亚湾典型湿地3个断面的表层沉积物，利用连续淹水培养法对沉积物有机氮矿化过程进行了测定.结果发现，不同站位沉积物氮的矿化速率差异较大，其矿化速率范围为1.88~15.12mg/（kg·d），平均速率为（6.45±3.47）mg/（kg·d），整体呈现S3（红树林断面）> S1（光滩断面）> S2（河口断面）的分布规律.矿化速率的最高值出现在S3红树林断面，表明红树植物的生长能够促进微生物的矿化作用.蛋白酶和脲酶的活性平均值分别为（8.52±4.21）mg/（kg·d）和（25.34±11.11）μg/（g·d），蛋白酶活性空间分布上与矿化速率的分布特征一致，表现为S3 > S1 > S2.蛋白酶和脲酶活性最高的区域均出现在S3断面的高潮带，这主要由于红树林影响地区具有较高的生产力和微生物丰度，促进了微生物代谢酶的产生.蛋白酶的活性远高于脲酶活性，表明人类活动对近岸湿地生态系统的物质输入可能主要以大分子类有机氮为主.在河口断面，矿化速率和酶活活性均较低，与该地区较高的NH₄⁺-N含量有关.整体上，湿地沉积物矿化速率与蛋白酶和脲酶之间呈现出显著的正相关性（P<0.01），说明蛋白酶和脲酶在有机氮的矿化过程中发挥了关键作用.

Sediment nitrogen mineralization characteristics and its influencing factors in coastal wetlands of Daya Bay

To explore the spatial and temporal distribution of the organic nitrogen mineralization process in sediment and the corresponding influencing factors, the sediment organic nitrogen mineralization rates were determined with continuous waterlogging culture of coastal wetland in Daya bay which has been collected during March (dry season) and August (wet season) in 2017. The results showed that the mineralization rates of these stations varied significantly, ranging from 1.88 to 15.12mg/(kg·d), with an average rate of (6.45±3.47)mg/(kg·d), and showed a tendency of the distribution of S3 (mangrove section) > S1 (light beach section) > S2 (estuarine section). The highest mineralization rate in the section of S3, indicated that the growth of mangrove plants could promote the mineralization of microorganisms. The mean values of the activity of protease and urease were (8.52±4.21)mg/(g·d) and (25.34±11.11)g/(g·d), respectively. The spatial distribution of protease activial was consistent with the tendency of the mineralization rate. The highest activity of protease and urease in the high tidal of S3 were mainly because of the boosting production of metabolism enzymes induced by the high productivity and abundance of microorganisms in mangrove forest zone. The higher activity of protease than that of urease suggested that the input of human activities to the coastal wetland mainly by macromolecular organic nitrogen. The lower mineralization rate and enzyme activity in estuarine section was related to the higher NH₄⁺-N content in this area. Generally, significant positive correlation between the mineralization rate and protease and urease (P<0.01) were detected, inferring that protease and urease played a key role in the mineralization of organic nitrogen.