A method for measuring methane oxidation rates using low-levels of C-14-labeled methane and accelerator mass spectrometry

作者：Pack Mary A^*; Heintz Monica B; Reeburgh William S; Trumbore Susan E; Valentine David L; Xu Xiaomei; Druffel Ellen R M

来源：Limnology and Oceanography-Methods, 2011, 9: 245-260.

DOI：10.4319/lom.2011.9.245

We report a new method for methane oxidation rate measurements that uses 10(3)-10(5) times less C-14-CH4 than existing measurements by taking advantage of the high sensitivity of accelerator mass spectrometry. Methane oxidation in the marine environment is a microbial process of global importance because it prevents methane released from underlying reservoirs from reaching the ocean and atmosphere. Rate measurements provide a crucial tool for assessing the efficacy of this process across a range of environments, but the current methods use high amounts of radioactive elements (H-3- or C-14-CH4), tend to increase methane concentrations in a sample markedly over in situ levels, and are limited by strict health and safety regulations. The low-level method presented here uses levels of C-14-CH4 that are below transportation regulations, produce samples that do not require treatment as radioactive waste, and allow for tracer level rate measurements in low methane environments. Moreover, the low-level method lays the analytical foundation for a below-regulation rate measurement that could be used broadly and in-situ. Parallel rate measurements with the low-level C-14-CH4 and existing H-3-CH4 methods are generally consistent with a correlation coefficient of 0.77. However, the low-level method in most cases yields slower rates than the H-3 method possibly due to temperature, priming, and detection limit effects.

• 出版日期2011-6