中国近海生物固碳强度与潜力

通过现场调查和数据分析,首次探讨了中国近海浮游植物的固碳强度与潜力以及近海人工养殖大型藻类的固碳能力.结果表明,渤、黄、东海的浮游植物固碳强度约为2.22亿t a-1,固碳量的季节变化从大到小的顺序依次为春季、夏季、秋季、冬季,其中春夏季的固碳量占全年的65.3%.南黄海1999～2005年10～11月间浮游植物固碳强度有较大的年际变化,10～11月份7a间其浮游植物最低固碳量为3.54万t d-1,最高为16.58万t d-1,平均为10.50万t d-1,没有明显的年际变化趋势,磷对浮游植物固碳强度的影响最为明显,次之的影响因素是Chl a和亚硝氮 (NO2-N)的含量.南海的固碳能力约为渤黄东海的2倍,为4.16亿t a-1,其季节变化和渤黄东海不同,南海浮游植物在冬季的固碳能力最强,在夏季最弱.整个中国近海浮游植物年固碳量达6.38亿t,可占全球近海区域浮游植物年固碳量的5.77%.实际外海龙须菜的养殖发现,龙须菜每年固定的碳为8.18 t,养殖密度与方式对其产量和固碳量影响巨大.近几年,我国大型经济藻类养殖产量每年在120～150万t左右,换算为固碳量为36～45万t,平均每年40万t,如果海藻养殖产量每年增加5%,到2010年,我国大型经济藻类养殖的固碳量可达57万t a-1,海藻养殖是海洋增加碳汇有多重价值的重要措施.

Carbon fixed by phytoplankton and cultured algae in China coastal seas

Carbon fixed by phytoplankton and cultured algae is discussed by in situ investigation and data analysis in China coastal seas. The results show that the carbon fixed by phytoplankton is about 2.22×108t a^-1 with a clear seasonal variation in the Bohai Sea, the Yellow Sea and the East China Sea, which decreases from spring, summer, autumn to winter in turns and the carbon fixed by phytoplankton in spring and summer occupies 65.3% of that in a year. The carbon fixed by phytoplankton has clear variation in October and November from 1999 to 2005 in the southern Yellow Sea., and the minimum is 3.54×104 t d^-1 and the maximum is 1.66×105 t d^-1, with an average of 1.05×105 t a^-1, but the fixed carbon has no regular variation tendency in every year. Among the influence factors for carbon fixed by phytoplankton, the phosphate concentration in seawater is the most important, and then the Chl-a and NO2-N in seawater. The carbon fixed by phytoplankton is about 4.16×108t a^-1 in the South China Sea, which is twice of that in the Bohai Sea, the Yellow Sea and the East China Sea. The seasonal variation of fixed carbon which the highest value appeared in winter and the lowest in summer is clearly different from the east China seas (including the Bohai Sea, the Yellow Sea and the East China Sea). The carbon fixed by phytoplankton in total China coastal seas is about 6.38×108t a^-1 and accounts for 5.77% of that in global margin seas. According to marine aquaculture rusults, Gracilaria lemaneiformis can fix 8.18 t carbon in a year, and the rearing density and models play an important role in its yield and carbon fixation. In recent years, the yield of the large-sized economic seaweeds in China marginal seas is about from 1.20×106 to 1.50×106 t a^-1, and it is estimated that carbon fixed is about from 3.6×105 to 4.5×105 t a^-1 with an average of 4.0×105 t a^-1. If the seaweed cultured yield increases 5% every year in China marginal seas, carbon fixed by the large-sized economic seaweeds will reach to 5.7×105 t a^-1 in 2010. Therefore, algae breeding, which has much benefit, is a very important way for increasing marine carbon sink.