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| Optimization of Pretreatment Methods for Nitrogen Isotopic Analysis of Nitrate in Water |
| Received:October 31, 2023 Revised:May 30, 2024 |
| View Full Text View/Add Comment Download reader |
| DOI：10.3969/j.issn.2095-1035.2024.07.005 |
| KeyWord:Aquifer; Nitrate; Stable nitrogen isotopic analysis; Pretreatment method;Ultrasonic assisted |
| Author | Institution |
| yuanhongzhao |
中国科学院亚热带农业生态研究所 |
| hezhen |
中国科学院亚热带农业生态研究所 |
| zhangliping |
中国科学院亚热带农业生态研究所 |
| GENG Meimei |
中国科学院,亚热带农业生态研究所 |
| XU Liwei |
中国科学院,亚热带农业生态研究所 |
| CHEN Wen |
中国科学院,亚热带农业生态研究所 |
| PENG Can |
中国科学院,亚热带农业生态研究所 |
| TANG Siyu |
中国科学院,亚热带农业生态研究所 |
| wangjiurong |
中国科学院亚热带农业生态研究所 |
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| Abstract: |
| Elevated nutrient inputs doubled the amount of bioavailable N (particularly in the form of nitrate - NO3-) in aquifer system have led to increased eutrophication worldwide. Consequently, cascading environmental impacts are now the largest threat to aquatic ecosystems known as Algal blooms, fish and shrimp anoxic death, drinking water quality deterioration problems, etc. The isotope ratio of nitrogen has a specific composition in a particular source of nitrogen. Therefore, the accurate determination of the stable isotopic composition of dissolved nitrate in water has been widely used to explore nitrogen biogeochemical processing and trace the origin of nitrogen, especially could provide valuable information for the identification of nitrate population resource. In this study, a pre-treatment method of Cd-Cu2+ catalytic compound combined with ultrasonic assisted was developed for nitrogen isotopic analysis of nitrate in water. The optimized method significantly improved the pretreatment efficiency, and shortened the pretreatment time from 16 hours to 3 hours with high conversion efficiency of nitrate to N2O. The 15N analysis of reference NO3-_N solutions with different concentrations and 15N abundance was carried out by using the newly developed method combined with the PreCon-IRMS system. The results showed that, in the new reaction system, the detection limit was as low as 1.0 μg N and the accuracy of δ15N were within 1‰. The 15N values of all tested samples were consistent with the reference values (deviation< 0.5‰). The method had been applied to analyze various water samples as compared with the previous method. The comparison of the analytical data from the two analytical systems indicates that the new method provides better nitrogen stable isotope data in reproducibility and accuracy(CV<1%)than the data from the previous method. Overall, our method has the advantages of being rapid, convenient, and applicable to N stable isotope ratio analysis of nitrate in water. |
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