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,进样时间为3～4min,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H218O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0.11～1.20 mmol O2/(m3·h)、-1.60～0.75 mmol O2/(m3·h),水柱总初级生产力为(671.5±117.1)～(2 339.8±260.7)mg C/(m2·d),最大固碳能力为1 056.9±662.4 mg C/(m2·d),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.
Abstract
The primary production of phytoplankton is crucial to the carbon cycle in ocean.Accurate measurement of primary production is important to assess marine carbon fixation rate.The gross primary production can be obtained accurately by the 18O method.However,the technical difficulties in handling and analysis of 18O-enriched samples limited in-situ application of the 18O method.Therefore,rapid determination of 18O-labeled gas(34O2)is crucial for the promotion of the 18O method.Therefore,the operating condition of analyzing the 18O-enriched samples by self-assembled membrane inlet mass spectrometry and incubation procedures for 18O method were optimized.Results show that the precision of measured 34O2/32O2 was 0.1％～0.2％under optimal operating conditions of inlet flow rate at 0.85～1.05 mL/min,sampling time at 3～4 min,and thermostat bath temperature at 15～20 ℃,which is suitable for the determination of 34O2.In addition,satisfactory results for gross primary production were obtained when the volume ratio of H218O to water sample in the incubation bottle was 2.1×10 3～3.4×10 3 and the incubation time was 6 h.Primary production in the estuary in spring was measured using the optimized method.Results show that the gross primary production and net community production ranged 0.11～1.20 mmol O2/(m3·h)and-1.60～0.75 mmol O2/(m3·h),respectively.The range of variation in depth-integrated gross primary production was(671.5±117.1)～(2 339.8±260.7)mg C/(m2·d),and the maximum carbon fixation rate was 1 056.9±662.4 mg C/(m2·d),which are consistent with the results from available published data.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 Changjiang River estuary.
基金项目
国家自然科学基金(42076035号)
国家自然科学基金(42376044号)
国家自然科学基金(U1806211号)
泰山学者项目()
国家自然科学基金委员会共享航次计划项目(42149903)
"蓝海201"号科考船实施(NORC2022-03)
万方数据