【作者】 李锋；

【导师】 董树刚；

【作者基本信息】 中国海洋大学 ， 生态学， 2007， 硕士

【摘要】 本文探讨了使用GC-ECD测定水中和空气中N₂O的方法,并引入扩散薄层模型用以计算水—大气界面的N₂O通量;然后以青岛市南九水河和李村河为研究对象,研究了这两条河流河口区域的环境概况、大气中N₂O含量、水—大气界面的N₂O通量的周年变化及其影响因子,并估算出了南九水河和李村河全年N₂O的释放量,主要得出以下结论:2005年～2006年南九水河河口区域N₂O的水—气通量范围是-193.27 nmol N₂O-N/m2/h～93093.02 nmol N₂O-N/m2/h, N₂O的释放量的范围是-30.37 mol N₂O-N～333421.90 mol N₂O-N,全年总计361453.30 mol N₂O-N。李村河河口区域N₂O的水—气通量范围是-151.31 nmol N₂O-N/m2/h～105350.72 nmol N₂O-N/m2/h, N₂O的释放量的变化范围是-25.52 mol N₂O-N～21533.69mol N₂O-N,全年总计97990.81 mol N₂O-N。这一数据与英国的Colne河口的N₂O水—气通量相比较大了约大了70～100倍。李村河与南九水河河口区域N₂O水—气通量的季节变化规律是:春夏季的N₂O水—气通量较大,秋冬季的N₂O水—气通量较小,6月至10月N₂O水—气通量占了全年通量的60%～96%。2005年～2006年李村河与南九水河河口区域的大气中N₂O平均值为1392 ppb（V/V）,远远高于314 ppb（V/V）的全球平均水平,最大值为6834 ppb（V/V）更是全球平均水平的21.76倍;最小值也为330 ppb（V/V）,略高于全球平均水平。通过作N₂O水—气通量与大气中N₂O浓度的相关性分析发现:两者之间相关系数为0.932,P<0.01,说明N₂O水—气通量与大气中N₂O浓度之间极具相关性,且有非常显著的统计学意义,也说明河口地区是大气中N₂O潜在的补给源。通过从2005年12月份到2006年10月份对李村河与南九水河的上各站点的水质和N₂O的水—气通量的同步监测结果的分析,发现与N₂O的水—气通量相关且具有显著的统计学意义（P<0.05）的环境因子有:水中亚硝酸盐的浓度、水温、溶解氧和硝酸盐的浓度。通过控制水温、水中亚硝酸盐的浓度、溶解氧和水中硝酸盐的浓度又做了偏相关分析,结果发现水中硝酸盐的浓度和溶解氧是通过水中亚硝酸盐的浓度这一因子来影响N₂O水—气通量的,控制N₂O的水—气通量的关键环境因子是水中亚硝酸盐的浓度和水温。在随后的以溶解氧、水中硝酸盐的浓度和亚硝酸盐的浓度为控制因子的室内短期动力学实验也证明了:N₂O的水—气通量随水中亚硝酸盐的浓度增加而增加;N₂O的水—气通量随溶解氧的降低而增加,但完全厌氧又会阻碍N₂O的产生;水中硝酸盐的浓度对N₂O的水—气通量的影响是相对复杂的;溶解氧和水中亚硝酸盐能直接影响河口区域N₂O水—气通量,水中亚硝酸盐的浓度是控制河口区域N₂O水—气通量的关键因子。通过以上研究得出了结论:控制李村河与南九水河释放N₂O的关键因子是控制向河水中排放硝酸盐和亚硝酸盐,降低河水中硝酸盐和亚硝酸盐的浓度成为控制河口排放N₂O的关键。最后,给出了一些可行的降低河口区域N₂O释放量的建议,以达到降低河口区域产生N₂O温室气体量的目的。更多还原

【Abstract】 Firstly, this article discussed the method of testing N₂O in water and atmosphere. After we took into account all the operating parameters which affecting separation effect of chromatography, we chose four variables to research: the flow rate of carrier gas, make-up flow rate, the temperatures of the detector and the column detector temperature.The atmospheric N₂O concentration of Nanjiushui and Licun estuary （qingdao） are investigated from December 2005 to October 2006. The annual change of water- atmosphere N₂O emissions and the characters of seasonal changes of water- atmosphere N₂O emissions were also analyzed. The flowing is the main conclusions. In situ of Nanjiushui estuary gaseous flux measurements revealed water- atmosphere N₂O emissions in the range -193.27 nmol N₂O-N/m2/h to 93093.02 nmol N₂O-N/m2/h.The total estuarine emissions of N₂O for 2005²006 was estimate at 361453.30 mol N₂O-N. In situ of Licun estuary gaseous flux measurements revealed water- atmosphere N₂O emissions in the range -151.31 nmol N₂O-N/m2/h to 105350.72 nmol N₂O-N/m2/h.The total estuarine emissions of N₂O for 2005²006 was estimate at 97990.81 mol N₂O-N. The water- atmosphere N₂O emissions on Nanjiushui and Licun estuary show obviously seasonal change. The maximum of water- atmosphere N₂O emissions appears August in 2006.So the global N₂O emission from estuaries is a large source of N₂O and should therefore be included in global balance estimates for N₂O in atmosphere.The atmospheric N₂O concentrations at different were discrepant. Longitudinal atmosphere surveys conducted on Nanjiushui and Licun estuary （qingdao） showed very high in situ N₂O concentration maxima particularly during summer （up to 1392 ppb ） .There was a strong significant correlation （ P<0.01 , r2=0.932） overall between the nitrous oxide fluxes across the water- atmosphere interface.Surveys showed estuary may be a sedimentary source of N₂O.The characters of seasonal changes of water- atmosphere N₂O emissions were also analyzed. Surveys showed there is a very significant positive relationship between the nitrous oxide fluxes across the water-atmosphere interface and the nitrite concentration in overlying water（P﹤0.01）. There is also a very significant positive relationship between the nitrous oxide fluxes across the water-atmosphere interface and water temperature （P﹤0.01）. There is a significant negative relationship between the nitrous oxide fluxes across the water-atmosphere interface and the O2 concentration in overlying water（P﹤0.05）. The nitrate and the nitrite in overlying water can promote the production of nitrous oxide in sediment. The O2 in overlying water can repress the production of nitrous oxide in sediment, and this indicated the denitrification is an anaerobic reaction.The results of factor control experiment also indicate that the nitrate and the nitrite in overlying water can promote the production of nitrous oxide in sediment. The O2 in overlying water can repress the production of nitrous oxide in sediment, and this indicated the denitrification is an anaerobic reaction. Surveys showed controlling for the nitrate and nitrite in the overlying water is the key to reduce the N₂O emission from estuaries. At last, some advice had been given to reduce the N₂O emission from estuaries.更多还原