南宁市朝阳溪甲烷排放通量及其影响因素研究
发布时间：2019-05-28 14:37
【摘要】：甲烷(CH4)是一种影响全球气候变化和大气化学的重要温室气体,近年来由于甲烷源汇的失衡,大气中CH4含量逐渐升高。河流是大气CH4的自然源,随着工业化的进程,城市黑臭河道更为突出,城市黑臭河道由于受到人为活动的影响,生活污水和工业污水的排入,CH4释放异常活跃,对大气CH4贡献显著。因此,研究城市黑臭河道甲烷排放规律及其环境影响因子之间的关系,有助于深入认识各种水体甲烷排放通量,从而为全球甲烷估算提供一定的参考和数据支持,通过现场调查及实验室实验探究环境因子对产甲烷速率的影响,获得主要成果如下：(1)本文通过对城市黑臭河道—南宁市朝阳溪现场进行调查,利用静态箱法测定南宁市上、中、下游产甲烷通量,并测定水体中CODCr、TN. TP、NH4+-N、温度、pH及底泥有机碳的含量,结果表明：朝阳溪是重要的甲烷排放源,夏季甲烷排放通量平均值为12.2mg/(m2·h),上游、中游、下游排放通量变化不显著。利用偏最小二乘法进行相关性分析可得,甲烷通量与温度、化学需氧量、底泥有机碳呈显著正相关,与溶解氧呈显著负相关,与总氮、氨氮、总磷、pH相关性较小。(2)利用顶空瓶测定底泥及水体甲烷生成量可得,水体产甲烷很微小,几乎为零,底泥产甲烷速率呈现先增加后减少的趋势,且底泥在第5天产甲烷速率最大,为0.0056mg·g-1。底泥在第15天后产甲烷的速率很小。根据本实验数据可得南宁市朝阳溪底泥在厌氧和25℃的条件下底泥甲烷初始释放量与培养时间的数学关系y=0.4558×d0.7280。(3)在不同温度条件下对底泥产甲烷的影响实验中,设置3组不同的温度分别为15℃、25℃、35℃。温度对底泥产甲烷具有显著的影响,且随着温高的升高产甲烷速率增大,在35℃时产甲烷速率比15℃产甲烷速率大1.9倍。温度对底泥污染物的释放具有显著的影响,温度越高底泥污染物释放的速率越快,温度在35℃时底泥CODCr、TN、TP释放速率为15℃的2、4.5和3.8倍,底泥有机碳的降解速率在35℃为15℃的1.7倍,温度对水体溶解氧降低的速率具有重要的影响,当水体有机物含量较高时,水体中溶解氧的含量对底泥产甲烷的影响较少。在隔绝空气条件下底泥甲烷生成量与培养时间及温度的数学关系为CMethane=0.4182·T0.9509·log10(0.091t+1)。隔绝空气条件下底泥的甲烷生成量与底泥所释放出的CODCr、TP呈正相关关系,与底泥所释放出TN和水体溶解所消耗速率的相关性较少,隔绝空气条件下底泥所降解的有机碳与底泥甲烷生成量呈显著的正相关关系。(4)在不同的水体初始pH条件下对底泥产甲烷的影响实验中,设置3组不同的水体初始pH分别为6、7.5、9。pH对底泥产甲烷具有重要的影响,不同pH甲烷生成量不同,其中在pH为9最大,pH为7.5时次之,pH为6时最小。当水体初始pH为9有利于底泥向底泥——水界面中水体体释放TP、CODCr。当水体初始pH为7.5时有利于底泥向底泥—水界面中水体释放TN。甲烷生成量与上覆水CODCr含量呈正相关,与泥水界面TN、TP浓度不具相关性。不同pH条件下底泥甲烷生成量与培养时间的数学关系可表示为：CMethane=0.8472·pH1.577·log10(0.036d+1)。
[Abstract]:Methane (CH4) is an important greenhouse gas that affects global climate change and atmospheric chemistry. In recent years, the content of CH4 in the atmosphere is increasing due to the imbalance of the source of methane. The river is the natural source of the atmospheric CH4. With the process of industrialization, the city's black-smelling channel is more prominent. The city's black-smelling channel is affected by man-made activities, and the discharge of domestic sewage and industrial sewage, CH4 release is abnormal, and the contribution of CH4 to the atmosphere is significant. Therefore, the study of the relationship between the methane emission law and the environmental impact factors in the urban black-smelling channel can help to understand the methane emission flux in various water bodies, thus providing some reference and data support for the global methane estimation. The effect of environmental factors on the rate of methane production was investigated by on-site investigation and laboratory experiments. The main results are as follows: (1) The main results are as follows: (1) In this paper, the methane flux in the upper, middle and lower reaches of Nanning city is determined by the static tank method. And the CODCr and TN in the water body are measured. The organic carbon content of TP, NH 4 +-N, temperature, pH and bottom mud shows that the average of methane emission is 12.2 mg/ (m2 路 h), and the change of emission flux in the upstream, middle reaches and downstream is not significant. The correlation between the methane flux and the temperature, the chemical oxygen demand and the organic carbon of the sediment is positively correlated with the dissolved oxygen, and the correlation with the total nitrogen, the ammonia nitrogen, the total phosphorus and the pH is small. (2) The methane production rate of the bottom mud and the water body is obtained by using the top empty bottle, the methane production rate of the water body is very small, almost zero, the methane production rate of the bottom mud is increased, and the methane production rate of the bottom mud is at the maximum of 0.0056 mg 路 g-1 at the fifth day. The rate of methane production after the 15th day was very small. Under the condition of anaerobic and 25 鈩，
本文编号：2487139
[Abstract]:Methane (CH4) is an important greenhouse gas that affects global climate change and atmospheric chemistry. In recent years, the content of CH4 in the atmosphere is increasing due to the imbalance of the source of methane. The river is the natural source of the atmospheric CH4. With the process of industrialization, the city's black-smelling channel is more prominent. The city's black-smelling channel is affected by man-made activities, and the discharge of domestic sewage and industrial sewage, CH4 release is abnormal, and the contribution of CH4 to the atmosphere is significant. Therefore, the study of the relationship between the methane emission law and the environmental impact factors in the urban black-smelling channel can help to understand the methane emission flux in various water bodies, thus providing some reference and data support for the global methane estimation. The effect of environmental factors on the rate of methane production was investigated by on-site investigation and laboratory experiments. The main results are as follows: (1) The main results are as follows: (1) In this paper, the methane flux in the upper, middle and lower reaches of Nanning city is determined by the static tank method. And the CODCr and TN in the water body are measured. The organic carbon content of TP, NH 4 +-N, temperature, pH and bottom mud shows that the average of methane emission is 12.2 mg/ (m2 路 h), and the change of emission flux in the upstream, middle reaches and downstream is not significant. The correlation between the methane flux and the temperature, the chemical oxygen demand and the organic carbon of the sediment is positively correlated with the dissolved oxygen, and the correlation with the total nitrogen, the ammonia nitrogen, the total phosphorus and the pH is small. (2) The methane production rate of the bottom mud and the water body is obtained by using the top empty bottle, the methane production rate of the water body is very small, almost zero, the methane production rate of the bottom mud is increased, and the methane production rate of the bottom mud is at the maximum of 0.0056 mg 路 g-1 at the fifth day. The rate of methane production after the 15th day was very small. Under the condition of anaerobic and 25 鈩，
本文编号：2487139
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