桑沟湾春、秋季溶存CH4的分布及海-气交换通量

摘要

分析2013-10,2014-05和2015-05对桑沟湾3个航次的调查中采集的表、底层海水样品,研究该海域海水中溶解CH4的分布特征及海-气交换通量.结果表明:春、秋季桑沟湾水体中CH4浓度范围为3.0~356.4 nmol·L-1,底层浓度高于表层.由于水温的季节变化和陆源输入的影响,秋季表、底层平均CH4浓度是春季的3~7倍.受养殖活动的影响,贝藻混养区表、底层CH4均高于其他养殖区和湾外.2013-10,2014-05和2015-05桑沟湾表层海水CH4的平均饱和度分别为(2 704±2 532)%,(330±276)%和(858±417)%,表现为秋季高于春季.根据W2014公式估算出桑沟湾春、秋季表层海水CH4海-气交换通量范围为3.9~19.9 μmol·m-2·d-1,根据N2000公式估算出春、秋季表层海水CH4海-气交换通量范围为5.5~20.6 μmol·m-2·d-1,表明春、秋季桑沟湾是大气CH4的源区.%Three cruises were carried out in Sanggou Bay in October 2013,May 2014,and May 2015 to investigate methane (CH4) distribution,and air-sea fluxes.Results showed that CH4 concentrations in the bay ranged between 3.0~356.4 nmol·L-1,with bottom CH4 usually higher than those in surface waters.CH4 concentrations in autumn were 3~7 times of those in spring due to the influence of water temperature and land source input.Surface and bottom CH4 in kelp and scallop polyculture zone was higher than those in other culture zones and outside the bay,suggesting the influence of aquaculture activities.Average CH4 saturation in surface waters were (2 704±2 532)%,(330±276)% and (858±417)% during October 2013,May 2014 and May 2015,respectively,demonstrating the CH4 saturation was higher in autumn than in spring.Average CH4 fluxes from Sanggou Bay ranged between 3.9~19.9 μmol·m-2· d-1,and 5.5~20.6 μmol·m-2·d-1 by using W2014 and N2000 relations respectively,suggesting the Sanggou Bay is a source for atmospheric CH4 in spring and autumn.