Methane in the Columbia River Plume

近岸和大陆架地区的甲烷饱和程度明显高于公海，但由于缺乏数据，全球甲烷预算忽略了这一事实。对华盛顿州和俄勒冈州近岸地区的调查，特别是受哥伦比亚河羽流影响的地区的调查，以及对该羽流对CH4逃逸到大气速率的影响的评估，将有助于建立准确的CH4预算。平均而言，哥伦比亚河下游的甲烷含量是其过饱和的120倍。河中也有活跃的甲烷氧化菌群，平均每天消耗20纳米甲烷。初步证据表明，在河口内，当盐度增加到千分之五以上时，这种微生物活动就停止了。这项研究将确定，当哥伦比亚河的羽流向下游移动并消耗剩余的甲烷时，海洋中的甲烷氧化生物种群是否已经形成，或者河流中的甲烷供应是否完全被逃逸到大气中。这项研究与所有河流系统相关，对目前开发海洋甲烷预算的尝试具有重要意义。

Near shore and continental shelf areas are significantly more supersaturated with CH4 than are the open oceans, yet global CH4 budgets ignore this fact because of the paucity of data. Investigations of the near shore regions of Washington and Oregon, particularly those areas influenced by the Columbia River plume and evaluations of the impact of this plume on the rate of CH4 evasion to the atmosphere will help to construct accurate CH4 budgets. The lower Columbia River is, on average, supersaturaterd with methane by a factor of 120. There is also an active population of methane oxidizing bacteria within the river with an average consumption rate of 20 nM methane per day. Preliminary evidence indicates that within the estuary, as the salinity increases above about 5 parts per thousand, this microbial activity ceases. This study will determine whether a marine population of methane oxidizing organisms becomes established as the Columbia River plume moves downstream and consumes the residual methane or if the riverine supply of methane is completely evaded to the atmosphere. Ths study is relevant to all river systems and is of significance to current attempts to develop a methane budget for the oceans.