| 摘要: |
| 为了验证细菌反硝化法对水体中硝酸盐氮、氧同位素组成测定的适用性、重现性及准确性, 在不同时间(2019年7月28日、8月19日、8月26日)利用反硝化细菌分别将海水、湖水和自来水样品中的硝酸盐转化为氧化亚氮（N2O）, 并进行氮、氧同位素测定。结果表明, 不同时间段3个批次实验的硝酸盐氮同位素校准曲线斜率都接近理论值1, 相关性系数均高于0.999, 说明反硝化细菌在将样品中的硝酸盐全部还原为N2O的过程中氮同位素分馏效应很小; 同一样品3个批次测定的硝酸盐的氮同位素值基本相同, 表明细菌反硝化法对硝酸盐氮同位素的测定在长时间周期内具有很好的重现性和准确性。3个批次氧同位素校准曲线斜率稳定在0.61～0.63之间, 相关性系数均高于0.99, 单批次内海水、湖水和自来水3类样品中硝酸盐氧同位素比值的标准偏差范围在0.18‰～0.69‰之间, 表明经过氧同位素校准曲线的校正, 可以准确反映样品中硝酸盐氧同位素组成; 同一样品3个批次测定的氧同位素值差异较大, 其变化范围为1.33‰～16.38‰, 可能是由于样品储存过程中硝酸盐与水之间发生的氧同位素交换作用所致。 |
| 关键词: 海洋化学 反硝化细菌 氧化亚氮 硝酸盐 氮同位素 氧同位素 |
| DOI：10.3969/J.ISSN.2095-4972.2021.04.009 |
|
| 基金项目:自然资源部第三海洋研究所科研业务费资助项目(海三科2016046) |
|
| Study and application of the isotopes N and O in nitrate determination by bacterial denitrification |
| CUI Kunlei,YIN Xijie,LI Yanli,YANG Haili,PEI Shengxiang,SU Jing |
| (Henan Polytechnic University, Jiaozuo 454000, China;Third Institute of Oceanography, MNR, Xiamen 361005, China) |
| Abstract: |
| In order to verify the applicability, reproducibility and accuracy of bacterial denitrification method for the determination of N and O isotope composition of nitrate in water, denitrifying bacteria were used to convert nitrate to N2O in sea water, lake water and tap water samples on 28 July, 19 and 26 August of 2019 . The results show that the slope of the nitrogen isotope calibration curve of nitrate obtained from the 3 batches of experiments in different time periods was close to its theoretical value of 1, and the correlation coefficient was higher than 0.999. It indicates that the nitrogen isotope fractionation effect caused by denitrifying bacteria was relatively low when transfering from nitrate to N2O in the samples. The nitrogen isotope values of nitrate obtained from the same samples in the 3 batches were basically the same, indicating that the determination of nitrogen isotopes of nitrate by bacterial denitrification method had good reproducibility and accuracy in a long time period. The slopes of the oxygen isotope calibration curves of the 3 batches were stable between 0.61 and 0.63. The correlation coefficients were higher than 0.99. And the standard deviation of oxygen isotope ratio of nitrate in 3 types of water samples in each batch ranged from 0.18‰ to 0.69‰. The correction results demonstrate that the oxygen isotope composition of nitrate in the samples can be accurately reflected by the respective oxygen isotope calibration curves. The range of oxygen isotope values of the same sample was 1.33‰ to 16.38‰. It was very different from each other among the 3 batches due to the reason probably caused by the oxygen isotope exchange between nitrate and water during the storage. |
| Key words: marine chemistry denitrifying bacteria N2O nitrate nitrogen isotope oxygen isotope |
