【作者】 陈勇；

【导师】 袁东星；

【作者基本信息】 厦门大学 ， 环境科学， 2007， 硕士

【摘要】 氧化亚氮（N₂O）是一种氮氧化物,在全球氮循环中扮演着重要角色;N₂O是温室气体之一,也是臭氧层的耗竭物之一。随着工农业生产和社会经济的发展,大气中N₂O的含量以每年约0.2%的速率增加。海洋是N₂O的重要源,研究海洋中N₂O的时空分布,有利于估算海洋释放的N₂O量。因此,发展可靠灵敏的海水和沉积物中N₂O的分析方法成为关键所在。本论文针对现有方法的不足,研发灵敏度高、实验成本低、操作简便的海水和沉积物中N₂O的分析方法。主要内容和结果如下:（1）建立了海水中N₂O的常温吹扫捕集-气相色谱分析法考察了不同吸附材料对N₂O的捕集能力,选择常温下捕集效率最佳的80～100目5A|°分子筛为吸附材料。对柱温、吸附温度、脱附温度、吹扫时间、吹扫气流速等实验条件进行了优化。检测限达2.8×10^-10 mol/L,标准工作曲线的线性相关系数达0.9995（n=5）,线性范围为3.4～39.2×10^-9 mol/L,5条曲线斜率的相对标准偏差为2.84%,回收率为93.93±3.1%（n=5）。本方法避免了冷阱的使用,在常温下完成对N₂O的捕集,降低了实验成本,样品用量少（5 mL）,灵敏度高,重现性好,操作简单。（2）建立了沉积物中N₂O的常温吹扫捕集-气相色谱分析法在海水中N₂O分析方法的基础上,利用吹扫捕集自动进样系统建立了沉积物中N₂O的常温吹扫捕集-气相色谱分析法。对吹扫气流速、吹扫时间和吹扫时的温度等实验参数进行了优化选择。方法检测限为4.5×10^-9 mol/L,标准工作曲线的线性相关系数为0.9985（n=3～6）,线性范围为0.42～21.06×10^-7 mol/L,方法的重复性较好,平行样的相对标准偏差为3.5%（n=5）,回收率为75.1±3.3%（n=3）。采用了吹扫捕集法直接测定沉积物中的N₂O,实验灵敏度高;采用了吹扫捕集自动进样系统（Archon）自动分析,大大减少了实验操作时间和可能误差;样品用量少,所需样品量不多于2 mL。（3）常温吹扫捕集-气相色谱法在微环境反硝化速率研究中的应用应用本论文建立的海水和沉积物中N₂O的常温吹扫捕集-气相色谱分析法分别测定微环境水体和沉积物中N₂O的含量,进而测定微环境的反硝化速率。将自然环境中的水和沉积物样品在实验室的微环境中进行培养,利用乙炔抑制N₂O还原酶的活性（乙炔抑制法）,分别测定培养初期和培养结束时模拟微环境中水体和沉积物中N₂O的含量,根据产生的N₂O量计算出微环境的反硝化速率。结果证明,采用本法测定微环境的反硝化速率,操作简单、成本低、耗时少。更多还原

【Abstract】 Nitrous oxide （N₂O） plays an important role in the nitrogen cycle. Atmospheric N₂O directly contributes to the greenhouse effect, and affects the ozone layer through various photochemical reactions. Since the industrial revolution, the increase in N₂O abundance is reported as 0.2%/yr. Ocean is the important source of N₂O. Through the study of temporal and spatial distribution of N₂O in ocean, the flux of N₂O between sea and atmosphere is evaluated. Therefore, analytical methods for N₂O in the seawater and sediment are significant. In this dissertation, the analytical methods for N₂O in seawater and sediment had been developed and applied to measure denitrifaction rate of microenvironment. The detail information is as follows:（1） Establishment of analytical method for N₂O in seawater with room temperature purge and trap-gas chromatography （PT-GC）Experimental parameters, including different sorbent, GC column temperature, trap temperature, desorbing temperature, purge time and purge flow rate, were optimized. 80¹00 mesh 5? molecular sieve was chosen as the optimal sorbent. The method detection limit, linearity of N₂O calibration curve, RSD of 5 calibration curve slopes and average recovery were 2.8×10-10 mol/L, 3.4～39.2×10（-9） mol/L, 2.84% and 93.93±3.1% （n=5）, respectively.N₂O was trapped at room temperature by 80¹00 mesh 5A|°molecular sieve. The method was found to be economical, sensitive, simple and repeatable.（2） Establishment of analytical method for N₂O in sediment with room temperature purge-trap and gas chromatography （PT-GC）Based on the established method for N₂O in seawater samples, a novel room temperature PT-GC method with purge-trap autosampler system had been developed for the determination of N₂O in sediment. Experimental parameters, including purge flow rate, purge time and purge temperature, were optimized. The method detection limit, linearity of N₂O calibration curve, RSD of 5 parallel samples and average recovery were 4.5×10（-9） mol/L, 0.42～21.06×10^-7 mol/L, 3.5% and 75.1±3.3% （n=3）, respectively.The method, which simplifies experimental procedures through using purge-trap autosampler system, showed advantages of high sensitivity and reproducibility.（3） Application of room temperature purge-trap and gas chromatography on the study of denitrification rate of microenvironmentMicroenvironments were established in the laboratory. The analytical methods of N₂O in seawater and sediment were applied on the study of denitrification rate of microenvironment. Acetylene （C₂H₂） was used to inhibit key enzymes involved in nitrification and denitrification （N₂O reductases）. Then denitrification rate was evaluated from the data of N₂O accumulation rate.更多还原