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以黄海绿潮暴发的主要漂浮种类浒苔(Ulva prolifera)为材料,在实验室条件下研究了浒苔光合参数、固碳速率及提升海水pH的作用,结果表明:浒苔光合作用半饱和常数Km为0.25mmol/dm3,光合作用饱和时海水溶解无机碳(DIC)浓度也只需1.2mmol/dm3,为正常海水DIC浓度(2.4mmol/dm3)一半,故黄海绿潮暴发时藻体可以一直保持光合作用饱和与旺盛生长状态。水生条件下浒苔藻体主要吸收海水中的DIC,0.5g/dm3培养密度下,1个光周期内净光合固碳速率为10.92mg/(g.d)(鲜重)。连续培养5d,0.5,1.0和2.5g/dm3培养密度组的DIC浓度从22mg/dm3分别降为4.85,2.62和0.66mg/dm3,表明DIC去除率随藻体培养密度提高而增强,分别可达77.78%,88.00%,96.98%;藻体吸收海水中无机碳的同时可使海水pH升高,0.5g/dm3培养密度下,1个光周期内净提升pH速率高达0.96/(dm3.g.d)。连续培养5d,0.5,1.0和2.5g/dm3培养密度组第1天其pH分别可达到9.1,9.2和9.7,表明藻体密度越高pH提升越快,而且第5天pH均可稳定在9.9左右。浒苔暴露在空气中可直接吸收空气中CO2,1个光周期内其光合固碳速率约为46.14mg/(g·d),而在海水中的光合固碳速率为10.92mg/(g·d),可见浒苔在空气中的光合固碳速率是水中的4.23倍。水生和气生时单位质量藻体的固碳效率因藻体间相互遮蔽而下降。结果可为今后黄海绿潮暴发机制及CO2减排和防止海洋酸化作用的评估提供技术支撑。
Ulva prolifera, a major floating species in the Yellow Sea green tide, was used to study photosynthetic parameters, carbon sequestration rate and pH of seawater under laboratory conditions. The results showed that the photosynthetic half-saturation constant Km is 0.25mmol / dm3, the concentration of seawater dissolved inorganic carbon (DIC) at the time of photosynthesis saturation is only 1.2mmol / dm3, which is half of normal seawater DIC concentration (2.4mmol / dm3) Maintain photosynthesis saturation and strong growth status. In the aquatic environment, Enteromorpha species mainly absorbed DIC in seawater, and the net photosynthetic carbon fixation rate in one photoperiod was 10.92mg / (g.d) (fresh weight) under the culture density of 0.5g / dm3. The concentration of DIC in 5, 5, 1.0 and 2.5g / dm3 culture density groups decreased from 22mg / dm3 to 4.85, 2.62 and 0.66mg / dm3 respectively, indicating that the DIC removal rate increased with the increase of culture density 77.98%, 88.00% and 96.98% respectively. When the algae absorbed inorganic carbon in seawater, the pH value of seawater was increased. Under the culture density of 0.5g / dm3, the net increase of pH in one photoperiod was as high as 0.96 / dm3.gd, . After cultured for 5 days, the pH of the culture medium reached to 9.1, 9.2 and 9.7 respectively on the first day after 0.5, 1.0 and 2.5g / dm3 cultivation density, indicating that the higher the density of the algae, the faster the pH increase, and the 5th day the pH could be stabilized at 9.9 about. Enterobacteriaceae exposed to air can directly absorb CO2 in the air, the photosynthetic carbon fixation rate is 46.14mg / (g · d) in one photoperiod, and the photosynthetic carbon sequestration rate in seawater is 10.92mg / (g · d), visible Enteromorpha photosynthetic rate of carbon in the air is 4.23 times the water. The rate of carbon fixation per unit mass of algae decreased during aquatic and aeration because of the mutual occlusion between the algae. The results will provide technical support for the assessment of the outbreak mechanism of the Yellow Sea green tide and the reduction of CO2 emissions and the prevention of ocean acidification in the future.