【作者】 杨朋金；

【导师】 张龙军；

【作者基本信息】 中国海洋大学 ， 环境科学， 2009， 博士

【摘要】 作为一种特殊类型湿地的重要组成部分,裸露潮间带表观CO2通量研究对于开展及完善潮间带碳循环研究意义重大,正确认识裸露潮间带沉积物-大气间表观CO2交换特征及其所受环境因素的影响是潮间带碳循环研究的重要补充之一。本研究使用Li-8100土壤碳通量测量系统(Licor,USA)首次对我国北方裸露潮间带表观二氧化碳(CO2)通量进行了现场观测。根据对石老人风景区裸露砂质潮间带沉积物-大气间表观CO2通量进行的长时间连续观测,总结裸露潮间带沉积物-大气间表观CO2通量变化规律如下:在春、夏、秋三个季节日间,沉积物-大气间表观CO2通量随着落潮慢慢升高,到最低潮时表观CO2释放通量基本达到最大,并延续至涨潮的全过程,表观CO2通量一直稳定在最大测值附近;而在冬季日间,由于表层沉积物温度较低,沉积物-大气间表观CO2通量不论在退潮期间还是在涨潮期间一直维持在较低水平,没有明显的日间变化;由于夜间潮间带表层沉积物温度比日间低且表层沉积物温度自入夜后一直下降,沉积物-大气间表观CO2通量一直维持在较低水平,没有明显的夜间变化。在潮间带不同位置的观测显示,潮间带中部沉积物-大气间CO2通量>潮间带顶部>潮间带底部。对于青岛湾潮间带和胶州湾底潮间带的观测显示,两处潮间带沉积物-大气间表观CO2通量具有与石老人潮间带相同的日间变化规律。潮汐水位、表层沉积物氧化还原电位、温度是影响沉积物-大气间表观CO2通量日变化的重要环境因素。潮汐水位主要影响日间落潮阶段表观CO2通量的变化;表层氧化还原电位会影响日间落潮阶段表观CO2通量对潮高的变化率,同时也影响低氧化还原电位下日间涨潮阶段表观CO2通量平均值的高低;表层沉积物温度会影响高氧化还原电位下日间涨潮阶段表观CO2通量平均值的高低,此外,表层沉积物温度的日夜差别造成了表观CO2通量的日夜差别。由于裸露潮间带沉积物-大气间表观CO2通量日间变化明显,所以测量裸露潮间带沉积物-大气间日间表观CO2通量总量需要长时间的观测。为节省大面积观测所需时间,本研究根据露潮间带沉积物-大气间表观CO2通量日间变化规律及环境因素的影响,归纳出利用较少观测数据计算日间表观CO2通量总量的方法。该方法计算得到的日间表观CO2通量总量对实测结果的线性回归方程为y=0.9353x+0.00872(R2 = 0.75,n=432)。裸露潮间带沉积物-大气间表观CO2通量日间平均值存在明显的月变化,而表层沉积物氧化还原电位和温度的月变化是造成表观CO2通量月变化的主要因素。低氧化还原电位(如Eh<300mv)下,氧化还原电位为影响表观CO2通量月变化最主要的环境因素,高氧化还原电位(300mv<Eh)下,温度为影响表观CO2通量月变化最主要的环境因素。整体上,表层沉积物氧化还原电位越高、温度越高,沉积物-大气间日间平均表观CO2通量越高。以Van’t Hoff方程为基础的包含表层沉积物氧化还原电位和温度日间平均值两个自变量的多元方程F = ( aEh + R0 ’) ekT(式中F为表观CO2释放通量,a为表层氧化还原电位对表观CO2释放通量影响的参数,Eh为1cm深处沉积物氧化还原电位,R0’为归一化至0℃、0mv时CO2释放通量,k为用于计算表观CO2释放通量温度敏感性Q10的参数,T为1cm深处沉积物温度)能够较好的拟合沉积物-大气间表观CO2通量日间平均值的月变化。更多还原

【Abstract】 The research on the apparent CO2 flux in the bare intertidal zone which is an important compose of an especial kind of wetland is of consequence. Understanding the variety of the apparent CO2 flux in the bare intertidal zone and the influence from the environmental factors correctly is one of the important complementarities for the research on intertidal carbon cycle. Using a Li-8100 automated soil CO2 flux system (Licor, Lincoln, Nebraska, USA), this work observed the apparent CO2 flux from the sedinment to the atmosphere in situ in the bare intertidal zone in northern China for the first time. According to the long-term observation on the apparent CO2 flux from the sedinment to the atmosphere in the bare sandy intertidal zone in the Laoshan Mountain Scenic Area, Qingdao, sum up the variety of the apparent CO2 flux as follows: during the daytime in the spring, summer and the autumn, the apparent CO2 flux between the sediment and the atmosphere gradually increased as tide ebbed, reached the maximum when the tide reached its lowest ebb and remained at the maximum during the flood tide; however, during the daytime in the winter, the apparent CO2 flux between the sediment and the atmosphere was low in both the ebb tide and the flood tide without obvious variety because the sediment temperature was lower; the apparent CO2 flux between the sediment and the atmosphere was low without obvious variety in the evening because the he sediment temperature was lower in the evening than in the daytime and decreased at all times in the evening. In addition, according to the observation at different position in the same intertidal zone(in the Laoshan Mountain Scenic Area, Qingdao), the apparent CO2 flux in the middle of the intertidal zone>the apparent CO2 flux at the top of the intertidal zone>the apparent CO2 flux at the bottom of the intertidal zone. It was shown that the daytime variety of the apparent CO2 flux between the sediment and the atmosphere in the Qingdao bay and Jiaozhou bay was the same as that in the Laoshan Mountain Scenic Area, Qingdao.Tide, sediment redox potential and temperature were the main environmental factors impacting the apparent CO2 flux from intertidal sediments to the atmosphere. The tide mainly impacted the apparent CO2 flux in the daytime ebb tide; the sediment redox potential didn’t only impact the rate in which the apparent CO2 flux changed with the height to tide in the daytime ebb tide but also impacted the average apparent CO2 flux in the daytime flood tide when the sediment redox potential was low; the sediment temperature impacted the average apparent CO2 flux in the daytime flood tide when the sediment redox potential was high, in addition, the low sediment temperaure induced to the low apparent CO2 flux in the evening.Observing the total apparent CO2 flux from the sediment to the atmosphere in the daytime needs lots of time because of the obvious daytime vaiety of the apparent CO2 flux. This work summed up the method which can be used to estimate the total daytime apparent CO2 flux with a few of data based on the variety of the apparent CO2 and the influnce from environment factors. The linear regression between the estimated and measured apparent CO2 fluxes was y= 0.9353x+0.0872(R2 = 0.75).The monthly variety of the daytime average apparent CO2 flux was obvious, and redox potential and temperature were two main factors impacting the diurnal apparent CO2 flux from intertidal sediments to the atmosphere. When the redox potential was below 300 mv, the redox potential was the key factor controlling apparent CO2 flux while the impact of temperature was limited; when redox potential ranged from 300 to 500 mv, both redox potential and temperature were main factors regulating the variation in apparent CO2 flux, with more important role of temperature than redox potential; when the redox potential was above 500 mv, the apparent CO2 flux was high because both the redox potential and temperature were high, while the impact of the variation in redox potential at this high value on apparent CO2 flux was limited, thus leaving temperature variation the sole important influencing factor. Thus, the higher the redox potential and temperature are, the higher the apparent CO2 flux from sandy intertidal sediment to the atmosphere. The equation F = ( aEh + R0 ’) ekT including both the redox potential and temperature based on Van’t Hoff equation could estimate the the daytime average apparent CO2 flux better. In this equation, F is the daytime average apparent CO2 flux, a is the rate in which the apparent CO2 flux changes with redox potential, Eh is the redox potential at the depht of 1cm, R0’is the apparent CO2 flux at 0℃and 0mv, k is a canstant and can be used to calculate Q10, T is the temperature at the depth of 1cm.更多还原