Small-scale heterogeneity of dissolved gas concentrations in marine continental shelf waters

[1] Marine continental shelf waters are known to contribute significantly to the global air-sea fluxes of many gases. Biogeochemical cycles in these regions are highly dynamic, and it is thus often difficult to fully resolve the spatial and temporal distribution of gases in the upper water column. High-frequency, realtime gas measurements with a membrane inlet mass spectrometer (MIMS) reveal significant small-scale heterogeneity in the distribution of CO(2), O(2)/Ar ratios, and dimethylsulfide (DMS) in continental shelf waters of the Eastern Subarctic Pacific Ocean and Bering Sea. Decorrelation length scales for the gas distributions ranged from 15 to 25 km, with significant variability observed on subkilometer spatial scales. In the case of DMS, a number of rapid excursions were observed over distances that would be difficult to resolve with conventional methods. Across most of the sampling transects, CO(2) and O(2)/Ar ratios were correlated, suggesting that biological processes dominated the cycling of these gases. In contrast, DMS concentrations were generally uncoupled from CO(2) and O(2)/Ar, although concentrations often did change sharply across hydrographic and productivity fronts. The results presented here suggest that previous field studies may have underestimated the true spatial variability of dissolved gases ( DMS in particular) in surface waters of highly dynamic marine systems. High-frequency gas measurements have significant promise for unraveling complex biogeochemical cycles in these regions.