九龙江河口区夏季反硝化作用初探  

Preliminary Results Concerning Summer-time Denitrification in the Jiulong River Estuary

作　　者：陈能汪[1,2] 吴杰忠[2] 洪华生[1,2] 

机构地区：[1]厦门大学海洋与海岸带发展研究院,福建省海陆界面生态环境联合重点实验室,厦门361005 [2]厦门大学环境科学与工程系,厦门361005

出　　处：《环境科学》2011年第11期3229-3234,共6页Environmental Science

基　　金：国家自然科学基金项目(41076042);国家自然科学基金国际(地区)合作交流项目(40810069004)

摘　　要：河口反硝化是削减入海河流氮污染的重要途径,为探明地处亚热带的九龙江河口混合区的反硝化作用,于2010年7月开展13个站位的面上调查,利用N2:Ar法和膜进样质谱分析仪(MIMS)直接测定反硝化产物溶解N2浓度,用吹扫捕集-气相色谱法测定溶解N2O浓度,并估算二者净增量和水气交换通量.结果表明,溶解N2和N2O净增量有明显的区域变化,从淡水端向海域减少,N2净增量为-9.9～66.8μmol.L-1,N2O净增量为4.3～31.5 nmol.L-1;N2O饱和度为170%～562%,平均352%;N2水气通量为-2.9～53.2 mmol.(m2.d)-1,N2 O水气通量为5.2～23.9μmol.(m2.d)-1,N2 O通量占总通量的0.03%～1.2%(平均0.25%).温度和营养盐(氮、磷)是影响九龙江河口区反硝化作用的重要因子;淡水端(盐度<0.5)反硝化作用及其空间分布主要受硝酸盐含量控制,海水端溶解N2与N2O的增加主要来自淡水端的输送,并受盐度梯度(混合作用)影响.Denitrification is an important process mitigating nitrogen（N） pollution in aquatic systems.Water samples in 13 sites throughout the Jiulong River Estuary were collected in July,2010 in a preliminary investigation of the denitrification rate in this area.As end-products of denitrification,dissolved N2 was measured by determining N2：Ar ratios using MIMS（HPR-40）,while the concentration of nitrous oxide（N2O） dissolved in water was determined by Purge and Trap-Gas Chromatography.The results showed significant spatial variance of net increase of dissolved N2（ranging between-9.9 and 66.8 μmol·L-1） and N2O（ranging between 4.3 and 31.5 nmol·L-1） in the Jiulong River Estuary.The net increase of dissolved N2 and N2O declined gradually from river sites to sea sites.Dissolved N2O was supersaturated by 170%-562%.The air-water fluxes of N2 ranged between-2.9 and 53.2 mmol·（m2·d）-1,and N2O between 5.2 and 23.9 μmol·（m2·d）-1.The N2O yield shared only 0.03%-1.2%（average 0.25%） of total N air-water flux.The results suggested that water temperature and nutrient（N and P） were the key factors influencing denitrification.The denitrification rate is controlled by nitrate level at fresh-water sites with salinity 0.5‰.However,in salty waters,net increase in N2 and N2O mainly originated from denitrification occurring upstream of the estuary,and was dominated by the salinity gradient due to tidal mixing.

关 键 词：反硝化 N2:Ar法 氮 水气通量 九龙江河口 

分 类 号：X171.1[环境科学与工程—环境科学]