| 摘要: |
| 浮游植物的初级生产对海洋碳循环起着至关重要的作用，准确测定海洋初级生产力是评估海洋固碳能力的关键。18O法可获得准确的总初级生产力，但其复杂的测定方法限制了现场应用，快速测定18O标记的产物(34O2)是实现18O法广泛应用的关键。研究利用自组装膜进样质谱仪基于18O标记技术测定水体初级生产力，对膜进样质谱仪分析34O2的测量条件以及18O法培养过程进行了优化。结果表明，在进样流速为0.85~1.05 mL min-1，进样时间为3~4 min，恒温槽温度为15~20 ℃的条件下，34O2/32O2的测试精密度为0.1~0.2%，比较适合34O2的测定，在18O-H2O与水样体积比为2.1×10-3~3.4×10-3，培养时间为6 h的培养条件下，可以获得比较满意的总初级生产力的测试结果。利用优化后的方法对春季长江口的初级生产力测试表明：总初级生产力和净群落生产力变化范围分别为0.11~1.2 mmol O2 m-3 h-1、-1.6~0.75 mmol O2 m-3 h-1，水柱总初级生产力为671.5±117.1~2339.8±260.7 mg C m-2 d-1，最大固碳能力为1056.9±662.4 mg C m-2 d-1，与文献报道结果较为一致，高值区位于远离长江口的浅海水和外海水混合区。 |
| 关键词: 18O法 初级生产力 膜进样质谱仪 长江口 |
| DOI：10.11693/hyhz20240300071 |
| 分类号: |
| 基金项目:国家自然科学基金项目（面上项目，重点项目，重大项目） |
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| Optimization of 18O method using membrane inlet mass spectrometry to determine marine primary production and its application in the estuary of the Yangtze River |
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ZHANG Yu-Han1, SONG Guo-Dong2, ZHANG Gui-Ling2, LIU Su-Mei2
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1.College of Chemistry and Chemical Engineering, Ocean University of China;2.Frontiers Science Center for Deep Ocean Multispheres and Earth System/Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China
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| Abstract: |
| The primary production of phytoplankton is crucial to the carbon cycle in ocean. Accurate measurement of primary production is important to assess the marine carbon fixation rate. The Gross primary production can be obtained accurately by the 18O method. However, the technically difficult handling and analysis of 18O-enriched samples result in the 18O method not being widely used. Therefore, rapidly determination of 18O-labeled gas (34O2) is crucial for the widespread use of the 18O method. Accordingly, the operating condition of analyzing the 18O-enriched samples by self-assembled membrane inlet mass spectrometry and incubation procedures for 18O method were optimized. We found that the precision of measured 34O2/32O2 was 0.1%~0.2% when the operating condition with injection flow rate of 0.85~1.05 mL min-1, sampling time of 3~4 min, and thermostat bath temperature of 15~20 ℃, making it more suitable for the determination of 34O2. Additionally, the more satisfactory results for Gross primary production can be obtained when a volume ratio for 18O-H2O to water sample in the incubation bottle of 2.1×10-3~3.4×10-3 and an incubation time of 6 h. Primary production at the estuary of the Yangtze River in spring was measured by the optimized method. The results showed that the Gross primary production and Net community production varied between 0.11~1.2 mmol O2 m-3 h-1 and -1.6~0.75 mmol O2 m-3 h-1, respectively. The range of variation of depth-integrated Gross primary production was 671.5±117.1~2339.8±260.7 mg C m-2 d-1, and the maximum carbon fixation rate was 1056.9±662.4 mg C m-2 d-1, which are consistent with the results from the published literature. The high primary production area is located at the confluence of shallow seawater from the shelf and seawater from the open sea away from the estuary of the Yangtze River. |
| Key words: 18O method Primary production Membrane inlet mass spectrometry the estuary of the Yangtze River |