当前位置: X-MOL 学术Mar. Chem. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Method for determining stable isotope ratios of dissolved organic carbon in interstitial and other natural marine waters.
Marine Chemistry ( IF 3 ) Pub Date : 1991-01-01 , DOI: 10.1016/0304-4203(91)90076-9
J E Bauer 1 , R I Haddad , D J Des Marais
Affiliation  

A procedure is described for the analysis of the stable carbon isotopic composition of dissolved organic carbon (DOC) in natural waters from marine and higher-salinity environments. Rapid (less than 5 min) and complete oxidation of DOC is achieved using a modification of previous photochemical oxidation techniques. The CO2 evolved from DOC oxidation can be collected in less than 10 min for isotopic analysis. The procedure is at present suitable for oxidation and collection of 1-5 micromoles of carbon and has an associated blank of 0.1-0.2 micromole of carbon. Complete photochemical oxidation of DOC standards was demonstrated by quantitative recovery of CO2 as measured manometrically. Isotopic analyses of standards by photochemical and high-temperature sealed-tube combustion methods agreed to within 0.3%. Photochemical oxidation of DOC in a representative sediment pore-water sample was also quantitative, as shown by the excellent agreement between the photochemical and sealed-tube methods. The delta 13C values obtained for pore-water DOC using the two methods of oxidation were identical, suggesting that the modified photochemical method is adequate for the isotopically non-fractionated oxidation of pore-water DOC. The procedure was evaluated through an analysis of DOC in pond and pore waters from a hypersaline microbial mat environment. Concentrations of DOC in the water column over the mat displayed a diel pattern, but the isotopic composition of this DOC remained relatively constant (average delta 13C = -12.4%). Pore-water DOC exhibited a distinct concentration maximum in the mat surface layer, and delta 13C of pore-water DOC was nearly 8% lighter at 1.5-2.0-cm depth than in the mat surface layer (0-0.5-cm depth). These results demonstrate the effectiveness of the method in elucidating differences in DOC concentration and delta 13C over biogeochemically relevant spatial and temporal scales. Carbon isotopic analysis of DOC in natural waters, especially pore waters, should be a useful probe of biogeochemical processes in recent environments.

中文翻译:

确定间隙和其他天然海水中溶解有机碳的稳定同位素比的方法。

描述了一种用于分析来自海洋和高盐度环境的天然水中溶解的有机碳(DOC)的稳定碳同位素组成的程序。使用以前的光化学氧化技术的改进,可以快速(不到5分钟)完全氧化DOC。可以在不到10分钟的时间内收集由DOC氧化产生的CO2进行同位素分析。该方法目前适用于氧化和收集1-5微摩尔碳,并且具有0.1-0.2微摩尔碳的相关空白。通过测压法定量回收二氧化碳,证明了DOC标准品的完全光化学氧化。通过光化学和高温密封管燃烧方法对标样进行同位素分析,结果在0.3%以内。代表性沉积物孔隙水样品中DOC的光化学氧化也是定量的,如光化学法和密封管法之间的极好的一致性所表明的。使用两种氧化方法获得的孔隙水DOC的δ13C值相同,这表明改良的光化学方法足以用于孔隙水DOC的同位素非分级氧化。通过分析高盐度微生物垫环境中池塘和孔隙水中的DOC,评估了该程序。垫子上方水柱中DOC的浓度呈diel模式,但该DOC的同位素组成保持相对恒定(平均δ13C = -12.4%)。孔隙水DOC在垫层表面层中表现出明显的最大浓度,孔隙水DOC的δ13C在1.5-2.0-cm深度处比垫子表层(0-0.5-cm深度)轻了近8%。这些结果证明了该方法在阐明生物地球化学相关的时空尺度上DOC浓度和δ13C差异方面的有效性。天然水,尤其是孔隙水中DOC的碳同位素分析,应该是近来环境中生物地球化学过程的有用探针。
更新日期:2019-11-01
down
wechat
bug