黄渤海有机碳的分布特征及收支评估研究

陆架边缘海是陆海相互作用研究中最为关键的区域,也是全球重要的碳储库,在区域物质循环过程中发挥着重要的作用。基于2012年5月和11月对黄渤海海域的综合调查,对该海域水体和沉积物中有机碳的含量与分布进行了分析,并结合相关文献资料对黄渤海有机碳的收支进行了估算。主要结论为:黄渤海溶解有机碳和颗粒有机碳均呈近岸河口区域高、离岸低的分布趋势;有机碳的组成以溶解有机碳为主,颗粒有机碳由海洋自生的有机碳和陆地来源的有机碳组成;黄渤海沉积物有机碳高值区主要分布在河口和泥质区,其组成也是由海洋自生和陆源混合而成,其中渤海以陆源为主,而黄海以海源为主。黄渤海有机碳收支评估表明,有机碳的主要来源为初级生产力产生的有机物,其贡献为(6 760±971)×104t/a,占有机碳输入总量的(74±10)%,沉积物再悬浮的通量为(884±200)×104t/a,东海向黄海输入的通量为(679±107)×104t/a,河流及陆源输入的通量为(643±63)×104t/a,大气干湿沉降的通量为(141±39)×104t/a,其贡献分别占有机碳输入总量的(10±2.2)%,(7.5±1.2)%,(7.0±0.7)%和(1.5±0.4)%;黄渤海有机碳的主要支出为呼吸消耗,其贡献为(5 190±746)×104t/a,占有机碳输出总量的(57±8.2)%,黄海向东海输出的通量为(2 150±370)×104t/a,有机碳沉积通量为(1 030±225)×104t/a,有机碳降解通量为(737±191)×104t/a,其贡献分别占有机碳输出总量的(24±4.1)%,(11±2.5)%和(8.0±2.1)%。有机碳收支评估表明黄渤海有机碳以海洋自生来源为主,且具有潜在碳的"汇"的特性,水体中外源输入和海洋自生有机碳的(1.6±0.3)%埋藏于该海域内。

Distribution and Budget of Organic Carbon in the Bohai and Yellow Seas

Ocean margin is recognized as a most important area for land-sea interaction and also one of the major sinks of organic carbon, which plays a very important role in global biogeochemical cycles of carbon. Based on the comprehensive investigation in the Bohai and Yellow Seas in May and November, 2012 and other available data, distributions of Dissolved Organic Carbon (DOC), Particulate Organic Carbon (POC) and sedimentary Total Organic Carbon (TOC) were discussed, and fluxes and fates of organic carbon in the Bohai and Yellow Seas were estimated. The results show that DOC is the dominate form of organic carbon in the Bohai and Yellow Seas. DOC and POC distributions show a gradient decline trend from nearshore zone to offshore area, and the components of POC is consisted of both terrestrial and marine matters. High content of TOC in sediments distributes in accordance with estuaries and mud areas. Results of budget of organic carbon show that the major sources of organic carbon is phytoplankton related production with a flux of (6 760±971) ×10⁴ t/a, accounting for (74±10)% of total sources, and then the fluxes of sediment resuspension, input from East China Sea, riverine input and atmospheric deposition are (884±200)×10⁴ t/a, (679±107)×10⁴ t/a, (643±63)×10⁴ t/a and (141±39)×10⁴ t/a, with contribution rates of (10±2.2)%, (7.5±1.2)%, (7±0.7)% and (1.5±0.4)%, respectively. Dominate removal of organic carbon in the Bohai and Yellow Seas are bio-respiration with a flux of (5 190±746) ×10⁴ t/a, accounting for (57±8.2)% of organic carbon removal, and then the fluxes of organic carbon output to East China Sea, sedimentation and degradation are (2 150±370)×10⁴ t/a, (1 030±225)×10⁴ t/a and (737±191)×10⁴ t/a, with contribution rates of (24±4.1)%, (11±2.5)% and (8.0±2.1)%, respectively. These indicate that the Bohai and Yellow Seas show a potential sink of organic carbon, and about (1.6±0.3)% of organic carbon from external input and authigenic production is preserved in sediment. Budget indicates that the dominate sources are marine authigenic products, while terrestrial inputs play a minor role in the Bohai and Yellow Seas.