| 题名 | 基于溶解氧剖面分布的沉积物硝化耗氧研究--以滏阳河为例 |
| 作者 | 王超 |
| 学位类别 | 博士 |
| 答辩日期 | 2014-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 单保庆 |
| 关键词 | 溶氧剖面 硝化作用 溶氧消耗 沉积物 滏阳河 微电极 oxygen profile nitrification oxygen depletion sediment Fuyang River microelectrode |
| 其他题名 | Study of sediment nitrification and oxygen depletion based on oxygen profile in the Fuyang River |
| 学位专业 | 环境工程 |
| 中文摘要 | 氨氮硝化过程造成的耗氧效应是影响水系统中溶解氧水平的重要因素之一。随着我国COD污染的逐步控制，氨氮污染日益凸显，氨氮硝化耗氧可能成为河流及湖泊低氧现象产生的重要驱动因素。明确硝化耗氧过程及其对水体溶氧消耗的贡献程度，对于我国氨氮污染控制对策的制定和控制标准的设置均具有重要意义。沉积物是硝化过程发生的主要区域，沉积物中硝化过程主要受到溶解氧的限制，溶解氧的剖面分布对硝化耗氧速率具有决定作用。测定和分析沉积物溶解氧剖面，明确沉积物溶解氧分布与硝化速率的对应关系，形成基于溶解氧剖面的硝化耗氧计算通用模式，是沉积物硝化耗氧研究的关键。 本论文首先构建沉积物溶氧分析方法体系，建立溶解氧剖面分析基础。然后以滏阳河水系为研究对象，对滏阳河水系沉积物样品进行溶解氧剖面测定和分析，并通过潜在硝化速率和表面硝化速率测定，明确滏阳河水系沉积物硝化速率空间分布特征。随后在模拟实验和理论推导的基础上，分析氨氮与溶解氧的相互作用关系，并形成沉积物硝化耗氧计算模型。基于沉积物硝化耗氧计算模型，给出滏阳河水系氨氮硝化耗氧的基本特征。主要研究结论如下： （1）构建了沉积物溶氧分析方法体系，实现沉积物溶解氧剖面测定和分析。基于溶氧微电极和测控装置构建了一套沉积物溶解氧分析系统，制作的金-汞齐溶氧微电极成功地测定了制备沉积物中溶氧的垂向分布，最小分辨距离0.03mm。以零级和一级反应动力学为基础，构建了溶氧剖面方程，并推导了溶氧反应速率，溶氧穿透深度和水-沉积物界面溶氧通量的计算方法。剖面模型能够成功拟合观测数据，拟合过程中零级反应动力学模型复相关系数较高。根据推导模型，溶氧穿透深度取决于厌氧临界条件ch的取值，水-沉积物界面的溶氧通量取决于沉积物孔隙度和界面溶氧浓度梯度。 （2）明确了滏阳河水系沉积物耗氧速率（SOD）和硝化速率分布特征，其中SOD处于较高水平，硝化过程受溶解氧限制无法充分进行。对滏阳河24个样点的制备沉积物进行了溶氧剖面测定和分析。拟合得到溶氧穿透深度在6.20-0.01mm之间，通过水-沉积物界面的溶氧梯度，计算得到滏阳河SOD在0.02-0.20mg/cm2/d之间，与其它地区相比处于较高水平。SOD的高值样点与主要城市耦合，对应高密度的非农业人口和工业产值分布。分别测定了滏阳河水系沉积物潜在硝化速率（PNR）和表面硝化速率（ANR）。PNR在0.00-0.22μmol∙h-1之间，ANR在0.002-0.045μmol∙h-1之间，二者空间分布特征类似，高值样点出现在汪洋沟及洨河下游区域和滏阳河邯郸段下游。PNR明显高于其它地区，但ANR由于溶解氧的限制与其它地区无显著差异。 （3）理清了沉积物硝化速率对溶解氧的响应关系，构建了沉积物氨氮耗氧计算模型。在硅胶稀释实验中，推导出沉积物溶解氧分布可以通过穿透深度表征。通过硝化速率实测结果和计算结果比对，证明了沉积物溶解氧穿透深度对硝化速率具有决定作用。构建了潜在硝化速率模型和表面硝化速率模型，并基于表面硝化速率模型给出了沉积物硝化耗氧计算公式。潜在硝化速率重点考虑生物量、温度和氨氮浓度三项因素的影响，表面硝化速率模型在潜在硝化速率模型的基础上增加了溶解氧穿透深度的影响。 （4）模型计算结果表明，滏阳河水系硝化耗氧对沉积物耗氧总量有显著贡献，且夏季是硝化耗氧的主要时段。通过表面硝化速率换算，计算得到的硝化耗氧量占沉积物耗氧总量的比例为25%，高于其它地区水体氨氮耗氧比例。氨氮硝化耗氧具有明显的季节性，夏季平均硝化速率为40nmol/m2/h，是冬季的4倍，春秋季的2倍。硝化耗氧具有明显的平台效应，只有在氨氮浓度降低至4mg/L以下时，硝化耗氧速率才会出现显著下降。 |
| 英文摘要 | Oxygen depletion caused by nitrification is one of the most significant factors determining the oxygen content in the aquatic system. With the controlling of COD pollution, the problem of ammonia pollution becomes prominent, which may be the driving factor of hypoxia in many rivers and lakes. Therefore, identifying the contribution of nitrification to the oxygen depletion in aquatic system is important to the control standard setting in ammonia pollution control. Nitrification primarily occurres in sediment and is mainly limited by the sediment oxygen distribution. It is necessary to measure and analyze the sediment oxygen profile and specify the relationship between sediment oxygen distribution and nitrification rate, which is the key when studying the sediment nitrification. In this thesis, the method of analyzing sediment oxygen was proposed. Based on this method, oxygen profiles of sediments in Fuyang River were measured. Sediment nitrification was investigated through potential nitrification rate and surface nitrification rate. Experiments in lab were carried out to identify the relationship between nitrification and oxygen depletion, and to provide basic parameters for the construction of nitrification model. With the nitrification model, oxygen depletion caused by nitrification in the Fuyang River was calculated. The primary conclusions were as follows (1) Method to analyze sediment oxygen was formed and oxygen profile measuring and modeling was realized. Based on the gold amalgam microelectrode, the sediment oxygen analyzing system was constructed. The vertical distribution of dissolved oxygen can be measured with minimum resolution of 0.03mm. The oxygen profile model was proposed in the case of zero-order and first-order kinetics respectively. Based on the profile model, formulas calculating oxygen reaction rate, penetration depth and flux across the sediment-water interface were deducted. The profile model performed well in the fitting with observed data, and zero-order kinetics model produce high fitting R2. According to the deducted formulas, the oxygen penetration depth depends on the critical value of anoxic condition and the oxygen flux depends on the interface concentration gradient and sediment porosity. (2) The spatial distribution of SOD (Sediment Oxygen Demand) and nitrification rate in the Fuyang River was identified. The oxygen profiles of 24 sediments in the Fuyang River were measured and analyzed. The simulated oxygen penetration depth ranged from 0.01mm to 6.20mm, and calculated SOD ranged from 0.02mg/cm2/d to 0.20mg/cm2/d. the sampling sites with high SOD were close to urban, which corresponded with high density of population and industrial production. The potential nitrification rate (PNR) and areal nitrification rate (ANR) were mearsured. PNR ranged from 0.00μmol∙h-1 to 0.22μmol∙h-1 while ANR ranged from 0.002μmol∙h-1 to 0.045μmol∙h-1, and they displayed the similar distribution pattern. High rate of nitrification mainly occrued in the lower parts of Wangyang Ditch, Xiao River Handan Reach; low nitrification rate primary appeared in upper part of Wangyang Ditch, Niuwei River, upper part of Handan Reach and Hengshui Reach. (3) The interaction between nitrification of oxygen content was clarified and the nitrification-caused oxygen consumption model was constructed. Through silicon dilution experiment, the penetration depth was proved an effective indicator of oxygen vertical distribution. The comparison between modeled and observed results indicated that nitrification rate depends on oxygen penetration of the sediment. The potential nitrification model was constructed based on biomass, temperature and ammonia substrate and the effect of oxygen penetration was added in the areal nitrification model. The nitrification-caused oxygen consumption was proposed through areal nitrification model. (4) The characteristics of nitrification-caused oxygen consumption were identified based on the constructed models. The areal nitrification rate was converted to oxygen consumption rate by stoichiometric ratio. The calculated results indicated that nitrification-caused oxygen depletion took up 25% of the total sediment oxygen demand, which was higher than the proportion of most places. The seasonal change of nitrification rate was obvious. The nitrification rate in summer was 40nmol/m2/h, which was 4 times higher than winner and 2 times higher than spring and autumn. Oxygen consumption rate by nitrification reached platform when ammonia was higher than 4mg/L and declined distinctly only when oxygen was lower than 4mg/L |
| 公开日期 | 2015-06-16 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.rcees.ac.cn/handle/311016/13475]  |
| 专题 | 生态环境研究中心_环境水质学国家重点实验室 |
| 推荐引用方式 GB/T 7714 | 王超. 基于溶解氧剖面分布的沉积物硝化耗氧研究--以滏阳河为例[D]. 北京. 中国科学院研究生院. 2014. |
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