摘要
分别于2012年3和7月对长江口及其邻近海域进行了大面调查,测定了表、底层海水中溶解甲烷浓度,并对其海-气交换通量进行了估算。结果表明,春、夏季表层甲烷的平均浓度分别为(28.33±38.33)和(19.92±19.18)nmol·L-1,甲烷浓度从内河口向外海逐渐降低。长江口溶解甲烷浓度和饱和度有明显季节变化,其中春季内河口甲烷浓度和饱和度高于夏季,但外河口及邻近海域则相反,这主要是温度和长江冲淡水中甲烷浓度的季节差异造成的。该海域溶解甲烷的分布受陆源输入影响显著,夏季长江冲淡水影响范围较春季更广,但由于稀释效应夏季甲烷浓度低于春季。夏季沉积物的释放对河口区甲烷的贡献较春季更为明显。调查期间该海域溶解甲烷都处于过饱和状态,是大气甲烷的净源;根据W92公式初步估算出长江口及其邻近海区年释放CH4量约为8.81×108 mol·a-1,占全球海洋年释放量的0.08%,远高于其面积比0.01%,因此该海区是甲烷产生和释放的活跃海域。
Distribution and air-sea fluxes of methane in the Changjiang Estuary and its adjacent area were investigated during two cruises in March and July 2012, respectively. Average surface CH4 concen- tration in Spring and Summer are （28. 33±38. 33） and （19.92±19.18） nmol · L-1, respectively, and decreased from the inner estuary to the open sea. CH4 concentration and saturation in surface and bot- tom watersshowed obvious seasonal variation. In the inner estuary, higher CH4 concentration and satu- ration occurred in spring, however, outside the estuary higher concentration and saturation occurred in summer, which was mainly due to the temperature and seasonal variation of CH4 concentration in the Changjiang diluted water. Distribution of dissolved CH4 was obviously influenced by terrestrial input. In Summer, the impact area of Changjiang diluted water was much wider and CH4 release from the sedi- ments was more obvious than in Spring in the outer Estuary and its adjacent area. Surface CH4 were all oversaturated during our surveys, hence the Changjiang estuary and its adjacent area were net sources of atmospheric methane. Annual CH4 emission from the Changjiang estuary and its adjacent area was pre- liminarily estimated to be 8. 81 × 108 mol · a-1, which accounted for about 0. 08G of the global annual o- ceanic CH4 fluxes, and the value was 8-fold of its corresponding area proportion（about 0. 01%）, indica ting that the Changjiang estuary and its adjacent area were active sites for CH4production and emission.
出处
《中国海洋大学学报（自然科学版）》
CAS
CSCD
北大核心
2014年第12期61-68,共8页
Periodical of Ocean University of China
基金
国家重点基础研究发展规划项目(2011CB409802)
国家自然科学创新研究群体基金项目(41221004)
国家自然科学基金国际合作项目(41020164005)
国家自然科学基金项目(41076067)
自然科学基金项目"长江口科学考察实验研究"项目(41149902)资助
关键词
长江口
甲烷
分布
海-气交换通量
Changjiang Estuary
methane
distribution
sea-to-air fluxes
