摘要
溶解氧是水生态系统中最基础的元素，与其他参数相比，溶解氧更能反映水生态系统中新陈代谢的情况。沉积物是水体中物质与能量代谢的重要场所，它包含众多的微生物种群以及各种化合物，氧环境决定了物质在沉积物中的赋存形态与最终归趋。沉积物中的溶解氧主要来源于上覆水体的传递，而沉积物-水界面（diment-water interface，SWI）是氧传递发生的重要区域。论文采用涡度相关法，测试了不同水体水动力条件下SWI氧通量，探索了水动力条件对SWI氧通量的影响。基于测得的通量结果，结合沉积物氧剖面分析和沉积物氧利用速率以及实验前后Fe2+、Mn2+、有机质质量分数的变化，计算了沉积物生物耗氧量与化学耗氧量，探究了沉积物耗氧机制，建立了水体水动力条件对SWI氧通量与沉积物耗氧量之间的响应关系，获得了SWI氧通量产生机制。同时利用高通量测序技术对装置内沉积物进行测试，从微生物分子生物学的角度分析了沉积物中可能消耗溶解氧的相关功能菌的信息。
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论文的研究结论如下：
①不同水动力条件对SWI溶解氧浓度有影响。当水体平均流速较低（对应平均流速为0.00m/s、0.03m/s）时，SWI溶解氧浓度既可围绕平均值上下波动，也可缓慢上升，或者两者兼有。当水体平均流速较高（对应平均流速为0.07m/s、0.12 m/s、0.20 m/s）时，SWI溶解氧浓度随水体平均流速的加快不断上升。
②SWI氧通量与垂直涡动扩散系数受水体水动力条件的影响明显，随水体平均流速的上升而上升。实验在平均流速为0.00m/s时获得SWI氧通量与垂直涡动扩散系数的最小值，平均值分别为1.197±0.121mmol·m-2·h-1、1.859×10-9±8.716 ×10-11m2·s-1；在平均流速为0.20m/s获得SWI氧通量与垂直涡动扩散系数的最大值，平均值分别为43.981±1.326mmol·m-2·h-1、1.137×10-6±7.299×10-8m2·s-1。
③SWI氧通量与垂直涡动扩散系数随水体水动力条件改变的变化趋势一致，可划分为三阶段。第一阶段，SWI中的氧传质主要由分子扩散决定，水体由静止开始缓慢流动，氧通量较小。第二阶段，SWI中的氧传质主要由涡动扩散决定，水体流速加快，清晰稳定的泥水界面消失，沉积物开始悬浮，氧通量增长较快。第三阶段，SWI中的氧传质主要由涡动扩散决定，水体流速进一步加快，SWI表层沉积物完全悬浮，上覆水变得浑浊，氧通量达到最高值。
请别离开我④沉积物中的溶解氧主要来自大气复氧，运用质量守恒定律，可以建立起单位面积沉积物在计算时段内SWI氧通量与沉积物耗氧量之间的等式关系。实验通过氧通量传输进入沉积物的溶解氧总量平均为0.662mmol，沉积物生物耗氧量平均为
0.175mmol，占26.4%；化学耗氧量平均为0.045mmol，占6.8%；氧残存量增加值平均为0.082mmol，占12.4%；其他耗氧量平均为0.360mmol，占54.4%。娇欲青春
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⑤水体水动力条件通过决定水体大气复氧及复氧向水下扩散的速率，深刻地影响着沉积物所处的氧环境。当水体平均流速较低，沉积物处于缺氧状态时，沉积物耗氧量以生物耗氧量为主。当水体平均流速较高，沉积物由缺氧状态转变为好氧状态时，生物耗氧量减小，化学耗氧量与其他耗氧量中的化学过程耗氧量占沉积物耗氧量的比重逐步提高，且此时发生的沉积物再悬浮对沉积物耗氧量组成影响很大。
⑥通过与Greengene数据库进行对比，在L、R两个样品中物种丰度均大于
0.5%的物种共有18个。在两个样品中的平均丰度大于3%的有7门，其中变形菌门占比最大，为52.54%；其余依次为拟杆菌门（8.60%）、广古菌门（7.56%）、疣微菌门（5.39%）、绿弯菌门（4.94%）、硝化螺旋菌门（4.32%）、酸杆菌门（3.66%）。
⑦变形菌门是实验沉积物中丰度最大的细菌，其功能复杂，营养条件多样，是控制实验沉积物环境、造成沉积物生物过程与化学过程耗氧量的关键菌种。实验在L、R两个样品中检测到变形菌门下的硫酸盐还原菌主要有脱硫盒菌目、脱硫杆菌目、脱硫弧菌目、除硫单胞菌目、互营杆菌目；检测到的具有氨氧化能力的细菌主要有产碱杆菌科、亚硝化单胞菌科；除产碱杆菌科与亚硝化单胞菌科以外，未检测到属于变形菌门且具有亚硝态氮氧化能力的细菌，硝化螺旋菌门下的硝化螺旋菌纲在硝化反应中占主导地位。
关键词：沉积物-水界面，氧通量，涡度相关法，沉积物耗氧量，耗氧机制
ABSTRACT
Dissolved oxygen is the most basic element in aquatic ecosystems. Compared with other parameters, dissolved oxygen can better reflect the metabolism of aquatic ecosystems. Sediment is an important site for the metabolism of matter and energy in water bodies. It contains numerous microbial populations and various compounds. The oxygen environment determines the occurrence and final fate of substances in diment. Dissolved oxygen in diment mainly comes from the transmission of overlying water bodies, and diment-water interface (SWI) is an important area where oxygen transmission occurs. In this disrtation, eddy covariance method is ud to test the SWI oxygen flux under different hydrodynamic conditions, and the influence of hydrodynamic conditions on SWI oxygen flux is explored. Bad on the measured flux results, combined with oxygen profile analysis and oxygen uptake rate (OUR) of diment, as well as changes in Fe2+, Mn2+, and organic matter mass fractions before and after the experiment, the biological oxygen consumption and chemical oxygen consumption of diment are calculated, the mechanism of oxygen consumption in diment is investigated, the respon relationship between hydrodynamic conditions and SWI oxygen flux as well as diment oxygen consumption is established, and the me
chanism of SWI oxygen flux is obtained. At the same time, the high-throughput quencing technology is ud to test the diment inside the device. From the perspective of microbial molecular biology, the information on the functional bacteria that may consume dissolved oxygen in diment is analyzed.
The conclusions of this disrtation are summarized as follows:
①The different hydrodynamic conditions have influence on SWI dissolved oxygen concentration. When the average flow velocity is low (the corresponding average flow velocity is 0.00m/s, 0.03m/s), the SWI dissolved oxygen concentration can not only fluctuate around the average, but also increa slowly, or both. When the average flow velocity is high (the corresponding average flow velocity is 0.07m/s, 0.12 m/s, 0.20 m/s), the SWI dissolved oxygen concentration increas with the increa of the average flow velocity.
②The SWI oxygen flux and coefficient of vertical eddy diffusion (K V) are significantly affected by the hydrodynamic conditions and increa with the increa of the average flow velocity. The minimum SWI oxygen flux and K V are obtained at an
clotoaverage flow velocity of 0.00 m/s, and the average values are 1.197±0.121 mmol·m-2·h-1 and 1.859
×10-9±8.716×10-11 m2·s-1 respectively. The maximum of SWI oxygen flux and K V are obtained at an average flow velocity of 0.20 m/s, and the average values are
的和得的用法区别43.981±1.326 mmol·m-2·h-1 and 1.137×10-6±7.299×10-8 m2·s-1 respectively.
城南旧事读书笔记③The SWI oxygen flux and K V are consistent with the changing trend of hydrodynamic conditions, and can be divided into three stages. In the first stage, the oxygen transfer in SWI is mainly determined by molecular diffusion. The water body starts to flow slowly from a stationary state, and the oxygen flux is small. In the cond stage, the oxygen transfer in SWI is mainly determined by the eddy diffusion. The flow velocity is accelerated, and the clear and stable SWI disappears. The diments begin to suspend, and the oxygen flux grows faster. In the third stage, the oxygen transfer in SWI is mainly determined by the eddy diffusion. The flow velocity is further faster. The surface diments of SWI are completely suspended, and the overlying water becomes turbid, as well as the oxygen flux reaches the highest value.
④The dissolved oxygen in diment mainly comes from atmospheric reoxygenation. Using the law of conrvation of mass, the equations between the SWI oxygen flux and diment oxygen consumption during the calculation period of per unit diment area can be established. The total am
ount of dissolved oxygen transport into the diment through the oxygen flux is 0.662 mmol on average. The average biological oxygen consumption of diments is 0.175 mmol, accounting for 26.4%. The average chemical oxygen consumption is 0.045 mmol, accounting for 6.8%. The average increa in oxygen residue is 0.082 mmol, accounting for 12.4%. And the other oxygen consumption is 0.360 mmol, accounting for 54.4%.
春节趣事作文⑤The hydrodynamic conditions affect the oxygen environment of the diment profoundly by determining the rates of atmospheric reoxygenation and oxygen diffusion to the bottom. When the average flow velocity is low and the diment is in an anoxic state, the oxygen consumption of the diment is mainly bad on the biological oxygen consumption. When the average flow velocity is high and the diment changes from an anoxic state to an aerobic state, the biological oxygen consumption decreas, and the proportion of chemical oxygen consumption as well as other oxygen consumption caud by chemical process increa gradually, and the diment resuspension occurred at this time has a great influence on the composition of the diment oxygen consumption.
⑥Compared with the Greengene databa, there are 18 species with species abundance greater than 0.5% in both L and R samples. Between the two samples, there
are 7 phylums with average abundance greater than 3%, of which Proteobacteria accounted for the largest proportion, 52.54%, followed by Bacteroidetes(8.60%), Euryarchaeota(7.56%), Verrucomicrobia(5.39%), Chloroflexi(4.94%), Nitrospirae
(4.32%), Acidobacteria (3.66%).
⑦The Proteobacteria is the most abundant bacteria in the diment. It has complex functions and diver nutrient conditions. It is the key strain that controls the diment environment and caus the oxygen consumption of the biological process and chemical process in the diment. In the experiments, the sulfate-reducing bacteria (SRB) attribute to the Proteobacteria are detected in the L and R samples. They are mainly Desulfarculales, Desulfobacterales, Desulfovibrionales, Desulfuromonadales, and Syntrophobacterale. The detected ammonia-oxidizing bacteria (AOB) mainly include Alcaligenaceae and Nitrosomonadaceae. No Proteobacteria with nitrite-oxidizing ability are detected except Alcaligenaceae and Nitrosomonadaceae, and Nitrospira dominate the nitrification.
Keywords: Sediment-water interface, Oxygen flux, Eddy covariance method,
Sediment oxygen consumption, Oxygen consumption mechanism
