摘要:
河口滨海湿地是海岸带的重要组成部分,沉积速率高,伴随河流泥沙颗粒物进入海洋的有机质主要埋藏在河口及临近海区。通过对河口滨海湿地碳埋藏能力的研究,能够更全面地认识河口滨海湿地在全球碳循环中的作用,有效评估其对全球气候变化的影响。以青岛胶州湾大沽河口滨海湿地为研究对象,估算研究区自然湿地全新世碳埋藏能力。通过对3根岩心共计117个样品的粒度、有机碳/氮测试分析和统计,结合210Pb、137Cs测年结果计算得出,研究区陆域沼泽湿地环境总碳沉积通量为102 gC/m2/a,其中有机碳沉积通量为84.8 gC/m2/a;滩涂湿地环境总碳沉积通量为93.5 gC/m2/a,其中有机碳沉积通量为69.9 gC/m2/a。估算现代大沽河口31 km2自然湿地范围内,平均年总碳埋藏量为2.96 GgC,有机碳埋藏量为2.27 GgC。根据研究区历史调查资料统计,大沽河口三角洲全新世沉积地层厚度为3~10 m,按平均厚度6 m估算,全新世以来河口湿地总碳埋藏量为66 GgC/km2,有机碳埋藏总量约为51 GgC/km2。
Abstract:
Estuarine wetland with high sedimentation rate is an important component of the coastal zone, where a great amount of organic matters are buried together with river sediments. The research of carbon storage capacity will help understand the role of the estuarine wetland in the global carbon cycle and climate changes. This paper takes the Daguhe estuarine wetland, which is located at Jiaozhou Bay, Qingdao, as an example. Three cores have been collected from the tidal flat and river bank marsh and sampled at a 2 cm interval. 117 samples are analyzed and tested in the laboratory for bold density (BD), grain size, total carbon (TC), total nitrogen (TN) and total organic carbon (TOC), carbon storage capacity are calculated with mass TC/TOC ratio and sedimentation rate which was calculated with 210Pb, 137Cs dating data from one of the three cores. The results show that TC burial flux at the river bank marsh is 102 gC/m2/a, and TOC burial flux is 84.8 gC/m2/a, whereas the TC and TOC burial flux of the tidal flat are 93.5 gC/m2/a and 69.9 gC/m2/a respectively. The area of the present natural wetland in Daguhe estuary is calculated from satellite images. It is estimated that in the 31 km2 well preserved natural wetland,the average annual TC storage is 2.96 GgC, and TOC storage 2.27 GgC. Holocene sedimentary thickness in the Daguhe estuary delta varies from 3 m to 10 m. Take the average thickness of 6m into account, the total amount of carbon sequestration during the Holocene in the Daguhe wetlands was 66 GgC/km2 of TC and 51 gC/m2/a of TOC. These figures are comparable to the carbon storage capacity of the offshore Bohai Sea and Yellow Sea, as well as other estuarine deltas around the world.
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