期刊
ENVIRONMENTAL SCIENCE & TECHNOLOGY
卷 48, 期 24, 页码 14490-14498出版社
AMER CHEMICAL SOC
DOI: 10.1021/es5033713
关键词
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资金
- National Natural Science Foundation of China [41475141, 41275024]
- Natural Science Foundation of Jiangsu Province, China [BK2011830]
- Ministry of Education of China [PCSIRT]
- Priority Academic Program Development of Jiangsu Higher Education Institutions [PAPD]
Inland lakes play important roles in water and greenhouse gas cycling in the environment. This study aims to test the performance of a flux-gradient system for simultaneous measurement of the fluxes of water vapor, CO2, and CH4 at a lakeair interface. The concentration gradients over the water surface were measured with an analyzer based on the wavelength-scanned cavity ring-down spectroscopy technology, and the eddy diffusivity was measured with a sonic anemometer. Results of a zero-gradient test indicate a flux measurement precision of 4.8 W m(2) for water vapor, 0.010 mg m(-2) s(-1) for CO2, and 0.029 mu g m(-2) s(-1) for CH4. During the 620 day measurement period, 97%, 69%, and 67% of H2O, CO2, and CH4 hourly fluxes were higher in magnitude than the measurement precision, which confirms that the flux-gradient system had adequate precision for the measurement of the lakeair exchanges. This study illustrates four strengths of the flux-gradient method: (1) the ability to simultaneously measure the flux of H2O, CO2, and CH4; (2) negligibly small density corrections; (3) the ability to resolve small CH4 gradient and flux; and (4) continuous and noninvasive operation. The annual mean CH4 flux (1.8 g CH4 m(-2) year(-1)) at this hypereutrophic lake was close to the median value for inland lakes in the world (1.6 g CH4 m(-2) year(-1)). The system has adequate precision for CH4 flux for broad applications but requires further improvement to resolve small CO2 flux in many lakes.
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