摘要:
为研究水生植物光合作用对岩溶碳汇的贡献,选取板寨河水域为研究区,分冬季和夏季测定典型水生植物的生物量以及各采样点水生植物碳同位素组成(δ13 C 值),并利用水生植物稳定碳同位素与碳酸酐酶间的关系建立的二端元模型,估算板寨河水生植物光合作用的固碳量。结果发现夏季生物量小于冬季生物量,水生植物的δ13 C 值变化在-35.45‰~-24.62‰之间,其中挺水植物的δ13 C 值最大,平均为-27.89‰,其次为沉水植物,平均为-29.96‰。浮水植物的δ13 C 值最低,平均为-32‰,受流速、CO 2浓度、光合途径等影响引起同种水生植物间同位素差异。水域水生植物固定下的 HCO -3碳量为19.52tc/(a.km2),其利用 HCO -3作为无机碳源进行光合作用的比例平均为47.84%,显示出巨大的固碳潜力,是全球岩溶碳汇的一个重要组成部分。
Abstract:
Aquatic plants play a key role in study of the carbon cycle by using inorganic carbon as a source for photosynthesis.The object of this work is to figure out the contribution of aquatic vegetations to carbon se-questration with the Banzhai catchment in Guizhou as study area.The biomass of typical aquatic plants both in summer and winter was measured.Meanwhile,theδ1 3 C of 4 kinds of aquatic plants,which grew at sam-pling sites,were tested.The results show that the biomass in summer is less than that in winter.Besides, the obtained values ofδ1 3 C for emergent aquatic plants range from -33.59 ‰ to -27.05 ‰,with an aver-age of -30.32 ‰,for floating plants from -35.45 ‰ to -24.62 ‰,with an average of -29.96 ‰,re-spectively,and for submerged plants it was measured a value of -27.89 ‰.The meanδ1 3 C values of various plants in descending order are emergent plants,floating plants,and submerged plants.Additional to this re-sults the double-meta model was used,by this model the percentage of HCO -3 uptake from water by aquat-ic photosynthesis can be estimated.The calculated HCO -3 carbon consumption by photosynthesis was 1 9.52 tC/(a·km2 ),HCO -3 used by aquatic plants for photosythesis accounted for almost 47.84 % of the total uesd inorganic carbon in Banzhai river,and this part of HCO -3 was converted into organic carbon and fixed in aquatic plants.The results indicate that the contribution of aquatic plants to carbon sequestration,especially to the net carbon sink estimation in karst regions cannot be neglected.
下载: