中文摘要：

反硝化作用作为水体彻底去除硝态氮的主要途径之一,主要发生在沉积物中。为了调查杭州西湖高硝态氮水体中底泥反硝化作用及其影响因子,2013年12月（冬季）和2014年6月（夏季）在西湖5个子湖区和3个湖湾的13个点位（X1-X13）进行样品采集,以底泥中硝酸盐还原酶活性和反硝化强度代表反硝化作用。结果表明,西湖水体冬夏两季TN浓度分别为1.568-2.613 mg/L和1.117-2.848 mg/L,硝态氮在TN中占比平均值分别为76%和72%。冬夏两季的底泥反硝化强度分别为0.132-1.350 mg/g和0.643-1.286 mg/g,硝酸盐还原酶活性分别为0.015-5.092μg/g和0.665-19.123μg/g;其中,硝酸盐还原酶活性冬季与夏季差异极显著（P〈0.01）,而冬季和夏季的反硝化强度没有显著性差异（P〉0.05）。夏季底泥反硝化强度与水温和泥温极显著正相关（P〈0.01）,与水体氨氮呈显著负相关（P〈0.05）,底泥硝酸盐还原酶活性与底泥总有机碳（TOC）呈显著正相关（P〈0.05）。冬季底泥反硝化强度与硝酸盐还原酶活性呈极显著正相关（P〈0.01）,与表层水体溶解氧（DO）呈显著正相关（P〈0.05）。在沉水植物盖度对反硝化作用影响的调查中发现,一定盖度的沉水植物可以促进反硝化作用,但过多的沉水植物也会抑制反硝化作用。

英文摘要：

Denitrification is one of the effective ways of removing nitrate and it occurs primarily in sediments. Research shows that the intensity of denitrification affects overall nitrogen removal from lakes,and physical and chemical factors in the water body and sediments influence the rate of denitrification. Therefore submerged plants can indirectly influence denitrification by altering physical and chemical parameters. In this study,sediment denitrification and factors influencing denitrification were investigated in West Lake,a lake in Hangzhou with high NO-3-N.The denitrification rate was represented by nitrate reductase activity and denitrification intensity,which were measured and then related to factors that can affect denitrification. In December,2013（ winter） and June,2014（ summer）,the investigation was carried out in five areas of the lake and three lake bays that included 13 sampling sites.Water samples were collected 5-10 cm below the surface for determination of water quality parameters including NH＋4-N,NO-2-N,NO-3-N,TN and TP. Water DO,temperature and p H were determined in situ using an ORION5-Star water quality analyzer. Sediment samples were collected using a sediment corer for determination of total organic carbon（ TOC）,nitrate reductase activity（ Nr） and denitrification intensity（ De）. Concentration ranges of total nitrogen（ TN） in winter and summer were 1. 568-2. 613 mg / L and 1. 117-2. 848 mg / L,respectively,and the average ratios of nitrate（ NO-3-N） to total nitrogen（ TN） were 76% and 72%. The ranges of sediment denitrification intensity in winter and summer were 0. 132-1. 350 mg / g and 0. 643-1. 286 mg / g and for nitrate reductase activity,ranges were 0. 015-5. 092 μg / g and 0. 665-19. 123 μg / g. Nitrate reductase activity displayed a highly significant difference between winter and summer（ P〈0. 01）,while denitrification intensity in winter and summer were not significantly different（ P〉0. 05）. In summer,there was a highly significant positive