SAMPLING AND DETERMINATION OF MARINE DISSOLVED ORGANIC CARBON

详细探讨了溶解有机碳(DOC)样品的采集与分析过程中的条件,以期发展DOC从采样到分析较为标准化(Robust)的方法步骤。影响DOC分析结果的关键有:采样过程中的样品瓶、垫片、滤膜、滤芯的选择及预处理,重力过滤,洁净台操作以及样品分析过程中仪器空白的确定。2001年5月和2002年11月两个航次在南海北部陆架上同一站位得到的DOC数据结果显示,夏季表层DOC浓度比冬季高10μmol/L,随深度增加DOC快速下降,50m以下DOC下降较为缓慢,冬、夏两季DOC分布特征基本相同。同一水样用不同方法(GF/F过滤采样方法与走航式滤芯过滤采样方法)所得到的DOC浓度的几次比对结果如下:盐度1.14,走航采样方法为(493±14)μmol/L(n=3),GF/F方法为(478±7)μmol/L(n=3);盐度20,走航采样方法为(112±2)μmol/L(n=3),GF/F方法为(123±2.6)μmol/L(n=3);盐度33.9,走航采样方法为(102±0.7)μmol/L(n=3),GF/F方法为(93±1.5)μmol/L(n=3)。结果表明,不论是在高盐度还是低盐度区域,两种方法结果基本相符,走航式采样过滤、方法可以应用于河口DOC的研究。Study on the dynamic behavior of DOC in seawater is important to understanding the global oceanic carbon cycle, in which the procedures of DOC sampling and determination remain to be improved for higher efficiency and accuracy. The authors developed a robust system to integrate all involving procedures from sampling, pretreatment, assaying (high temperature combustion oxidation, HTCO) and so on. The system was applied and has been proved valid on Chinese cases based on high quality data from the northern South China Sea sampled at a station in May 2001 and November 2002. Similar DOC concentration profiles between samples taken in the two periods were presented. Besides, a simplified sampling method-underway pumping and cartridge filtration—was applied; and the results are largely the same to that using traditional GF/F filtration method.国家自然科学基金项目“缺氧区形成机制——碳、氮生物地球化学过程的耦合分析”,40576036