^(15)N示踪-离子质谱法测定新生产力的研究

MEASUREMENT OF NEW PRODUCTION BY ^(15)N TRACEION MASS SPECTROMETRY METHOD

本文提出了^(15)N示踪-离子质谱法实测新生产力的方法,并于1991年11月—1992年5月结合胶州湾现场调查的实际样品,对示踪剂量、培养时间、样品贮存、消解剂量和时间、铵离子的扩散吸收,以及方法的空白值、检出限、精密度和准确度等进行了实验研究。结果表明,该法具有较高的精密度和良好的准确度,与经典的气体质谱法相比,还具有进样量少以及可同时分析^(15)N丰度、总氮浓度和水中铵离子浓度等特点,对于含氮量极低、铵氮再生迅速的海洋环境中新生产力的研究,具有特殊的意义。

A new approach of 15N isotope measurement with ion-mass spectrometer was introduced for new production study by 15N techniques, which take NH4+, other than N2 as usual, as an analytical state. Experimental conditions including the variatio of nitrogen uptake rate with different addition of labeled compound and linea uptake duration lasted in incubation, and analytical procedures (particularly pre-treatment of incubated samples, such as digestion condition, the effects of NH4+ transference from digested samples to analytical samples) were examined with field samples from the Jiaozhou Bay collected from Nov., 1991 to May, 1992. The results showed a good achievment in accuracy and precision of the method (CV≤2%, RE≤1%). Furthermore, comparison to the classical mass-spectrometry method, the new approach is characterized by its lesser demand for nitrogen amount in samples (10μg), and by its simultaneous measurement of 15N abundance, particulate nitrogen and ambient NH4+ concentration. These are advantageous for new production studies in marine environment where nitrogen content is often extremely low, and isotope dilution is sometimes severe due to rapid ammonium regeneration