文章摘要
徐春英,李玉中,李巧珍,毛丽丽,林伟,强晓晶,郑欠.土壤浸提液中硝酸盐氮氧同位素组成的反硝化细菌法测定[J].农业环境科学学报,2016,35(9):1829-1836.
土壤浸提液中硝酸盐氮氧同位素组成的反硝化细菌法测定
Determination of 15N and 18O isotope abundance in the extractable soil nitrate by the denitrifier method
投稿时间:2016-04-19  
DOI:10.11654/jaes.2016-0551
中文关键词: 反硝化细菌法  土壤浸提液  硝酸盐  氮氧同位素组成
英文关键词: denitrifier method  soil extract  nitrate  15N and 18O isotope abundance
基金项目:国家自然科学基金(41301553,41473004);中央级公益性科研院所基本业务费专项资金;中国农科院科技创新工程资助项目(农业水生产力与水环境创新团队)
作者单位E-mail
徐春英 中国农业科学院农业环境与可持续发展研究所/农业部旱作节水农业重点开放实验室, 北京 100081  
李玉中 中国农业科学院农业环境与可持续发展研究所/农业部旱作节水农业重点开放实验室, 北京 100081 liyuzhong@caas.cn 
李巧珍 中国农业科学院农业环境与可持续发展研究所/农业部旱作节水农业重点开放实验室, 北京 100081  
毛丽丽 中国农业科学院农业环境与可持续发展研究所/农业部旱作节水农业重点开放实验室, 北京 100081  
林伟 中国农业科学院农业环境与可持续发展研究所/农业部旱作节水农业重点开放实验室, 北京 100081  
强晓晶 中国农业科学院农业环境与可持续发展研究所/农业部旱作节水农业重点开放实验室, 北京 100081  
郑欠 中国农业科学院农业环境与可持续发展研究所/农业部旱作节水农业重点开放实验室, 北京 100081  
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中文摘要:
      本研究优化了采用反硝化细菌法同时测定土壤浸提液中硝酸盐氮氧同位素组成的方法。在已有研究结果的基础上,通过采用5000~8000 r·min-1的转速离心、高纯氮气吹扫1 h、减少加样量及改造仪器自动进样器等措施对已发表方法进行了优化。对国际标准样品USGS34的分析表明,0.1~0.8 μg NO3--N样品量即可以得到较稳定、准确的测定值和校正值;同一时间内制备的硝酸盐δ15N的SD介于0.05‰~0.09‰之间,δ18O的SD介于0.28‰~0.48‰之间;在三个月之内δ15N和δ18O的测定值基本一致,表明该方法具有较好的准确度、精密度和稳定性。通过研究浸提剂、保存条件以及加热对测定土壤浸提液中硝酸盐氮氧同位素组成的影响,结果表明:常用的去离子水、KCl、CaCl2可能都含有微量的硝酸盐,随着加样量增大,浸提剂中含有的硝酸盐可能就会影响δ15N和δ18O的测定;对于土壤硝酸盐的浸提液,冷冻保存效果较好,保证了土壤硝酸盐氮氧同位素的准确性和稳定性;尽管加热对硝酸盐标准样品USGS34和IAEA-NO3的δ15N没有显著影响,但δ18O显著升高,说明加热易引起氧同位素分馏;而土壤硝酸盐浸提液样品加热前后的δ15N和δ18O的测定值没有显著变化,因此为避免产生氧同位素分馏和节省测试时间,建议同时测定土壤浸提液硝酸盐δ15N和δ18O时直接和反硝化细菌反应。应用本方法对不同肥料处理田间土壤浸提液硝酸盐的氮氧同位素组成进行了测定。
英文摘要:
      A method has been established for determing simultaneously 15N and 18O isotope abundance in the extractable soil nitrate using denitrifier bacteria. The method was optimized by using 5000~8000 r·min-1 centrifugal rotational speed, purging 1 h with high pure N2, reducing the amounts of samples and improving the autosampler based on the preliminary findings. Analysis of international standard of USGS34 showed that the method presented better accuracy, precision, and stability. The standard deviations(SD) of δ15N and δ18O were 0.05‰~0.09‰ and 0.28‰~0.48‰ respectively in the same sample at the same time within 3 months. Additionally, the effects of some factors such as the extracting agents, storage condition and heating on δ15N and δ18O of soil nitrate were analyzed. The results showed that the extracted solution such as KCl or CaCl2 had no effect on the determination of δ15N and δ18O if sampling amount was small. Nevertheless, the significant difference would be found under bigger sampling amount with impure extracting agents. Moreover, the results also indicated that the cryopreservation method was better than the cold preservation for the δ15N and δ18O in the soil nitrate. Analysis of δ15N and δ18O should be finished as soon as possible; on the other hand, the soil extracted solution should be cryopreserved. No significant effect of the heat treatment was observed for δ15N values of USGS34 and IAEA-NO3. However, the raw δ18O values showed that there were significant differences in heating, and this caused oxygen isotopic fractionation. But no significant differences were observed for δ15N and δ18O in the extracted soil nitrate samples. Therefore, we suggested that the soil nitrate extracts can directly react with denitrifier in order to avoid the oxygen isotopic fractionation and save the test time. Based on these, 15N and 18O isotope abundance in the extractable soil nitrate under the different fertilizer fields were investigated by using this method.
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