. The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder . 12 16 20 24 28 32 36 TIME (hrs) Figure 27-4. Short-term variability of dissolved methane at stations 46 (a) and Ebb 37 (b) in 1975. tion of methane. In the absence of significant micro- bial oxidative processes, methane dissolved in the shallow brackish waters of the lagoon would be transported through the entrance by tidal pumping (Barsdate et al. 1974). Because the air-sea exchange of methane is relative- ly slow, advection of methane-rich water could be traced east along th
. The Eastern Bering Sea Shelf : oceanography and resources / edited by Donald W. Hood and John A. Calder . 12 16 20 24 28 32 36 TIME (hrs) Figure 27-4. Short-term variability of dissolved methane at stations 46 (a) and Ebb 37 (b) in 1975. tion of methane. In the absence of significant micro- bial oxidative processes, methane dissolved in the shallow brackish waters of the lagoon would be transported through the entrance by tidal pumping (Barsdate et al. 1974). Because the air-sea exchange of methane is relative- ly slow, advection of methane-rich water could be traced east along the Alaska Peninsula for nearly 200 km. Although a cyclonic mean flow in the coastal water does not appear to dominate the shelf salt budget (Coachman and Charnell 1979), a weak coastal current exists along the peninsula (Kinder and Schumacher, Chapter 5, this volume). The surface distribution of methane in July, not unlike temperature, delineates quite sharply the hy- drographic domains over the shelf. Near the shore in water depths less than about 50 m, the concentra- tions of methane were everywhere greater than 100 nl/1 and reflected increased production relative to the previous fall. The source of the methane is not known precisely, but would include coastal sources as well as in-situ production from both bottom sedi- ments and the water column. The Kuskokwim River may also be a significant source of methane as suggested by the high concen- trations (> 400 nl/1) found near Cape Newenham. The Kuskokwim River was not sampled for dissolved hydrocarbons, but the Yukon River plume was sam- pled in July 1979 and found to contain concentra- tions of methane in excess of 2,000 nl/1. We would expect the lower reaches of the two rivers to be similar in dissolved methane content, since their lower drainage basins are similar. As mentioned
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