Applying a new method for direct collection, volume quantification and determination of N_2 emission from water  

作　　者：Xinhong Liu Yan Gao Honglian Wang Junyao Guo Shaohua Yan 

机构地区：[1]Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences [2]College of Resources and Environmental Science, Nanjing Agricultural University

出　　处：《Journal of Environmental Sciences》2015年第1期217-224,共8页环境科学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China (No.41301575);Special Preliminary Study Program of the National Basic Research Program (973) of China (No. 2012CB426503)

摘　　要：The emission of N2 is important to remove excess N from lakes, ponds, and wetlands. To investigate the gas emission from water, Gao et al.（2013） developed a new method using a bubble trap device to collect gas samples from waters. However, the determination accuracy of sampling volume and gas component concentration was still debatable. In this study, the method was optimized for in situ sampling, accurate volume measurement and direct injection to a gas chromatograph for the analysis of N2 and other gases. By the optimized new method, the recovery rate for N2 was 100.28% on average; the mean coefficient of determination（R2） was 0.9997; the limit of detection was 0.02%. We further assessed the effects of the new method, bottle full of water, vs. vacuum bag and vacuum vial methods, on variations of N2 concentration as influenced by sample storage times of 1,2, 3, 5, and 7 days at constant temperature of 15°C, using indices of averaged relative peak area（%） in comparison with the averaged relative peak area of each method at 0 day.The indices of the bottle full of water method were the lowest（99.5%–108.5%） compared to the indices of vacuum bag and vacuum vial methods（119%–217%）. Meanwhile, the gas chromatograph determination of other gas components（O2, CH4, and N2O） was also accurate. The new method was an alternative way to investigate N2 released from various kinds of aquatic ecosystems.The emission of N2 is important to remove excess N from lakes, ponds, and wetlands. To investigate the gas emission from water, Gao et al.（2013） developed a new method using a bubble trap device to collect gas samples from waters. However, the determination accuracy of sampling volume and gas component concentration was still debatable. In this study, the method was optimized for in situ sampling, accurate volume measurement and direct injection to a gas chromatograph for the analysis of N2 and other gases. By the optimized new method, the recovery rate for N2 was 100.28% on average; the mean coefficient of determination（R2） was 0.9997; the limit of detection was 0.02%. We further assessed the effects of the new method, bottle full of water, vs. vacuum bag and vacuum vial methods, on variations of N2 concentration as influenced by sample storage times of 1,2, 3, 5, and 7 days at constant temperature of 15°C, using indices of averaged relative peak area（%） in comparison with the averaged relative peak area of each method at 0 day.The indices of the bottle full of water method were the lowest（99.5%–108.5%） compared to the indices of vacuum bag and vacuum vial methods（119%–217%）. Meanwhile, the gas chromatograph determination of other gas components（O2, CH4, and N2O） was also accurate. The new method was an alternative way to investigate N2 released from various kinds of aquatic ecosystems.

关 键 词：New method N2 Ebullition collection Direct injection Gas chromatograph 

分 类 号：X832[环境科学与工程—环境工程]