【作者】 刘琳；

【导师】 潘俊；

【作者基本信息】 沈阳建筑大学 ， 环境科学与工程， 2022， 硕士

【摘要】 河流底泥是污染物质蓄积和扩散的循环中心,底泥沉淀与再悬浮是造成水体污染的重要原因之一。对于闸控河流而言,闸坝不仅改变了水文水质而且极易引起底泥的沉降和释放,对水体造成二次污染,由于闸坝运行形成了复杂的流速场,导致泥水界面污染物的迁移转化机制复杂,因此,要对闸坝河流进行有效的改善防控需重点关注闸坝引起河流内源污染的过程机制。本文首先对浑河谟家堡闸坝河段水文与水环境特征进行调研,进而分析了闸坝前后河流水体指标和底泥各形态氮素的时空分布规律,接着以底泥氨氮吸附释放室内试验及不同环境因子对底泥氮素释放影响试验和PCR扩增测序对闸坝影响下河流底泥氮污染物释放这一现象进行物理、化学、生物角度的全面的剖析,得出闸坝河段底泥氮素的迁移转化机理,最后利用底泥疏浚及闸坝联合控源提出河流污染防控方案,从而有效控制底泥氮素释放并改善水质,也为闸坝河段污染的综合治理提供科学依据。主要研究内容和结果如下:（1）研究区水文与水环境特征分析。收集浑河沈阳站水文资料,分析浑河大闸拦蓄水区水文特征,反映出浑河大闸控制浑河沈阳站的流量水位水质变化。确定研究区水功能类型及水环境容量,采用模糊综合评价法对研究区枯水期及丰水期进行水体评价,结果表明研究区属于过渡区,地表水水质以Ⅳ级为主,部分断面有Ⅴ类的趋向,丰水期水质略好于枯水期,空间上,上游水质稍好于下游,河流水质变化受闸坝运行影响。（2）研究区河段水体及底泥污染物时空分布特征分析。于枯丰平水期对上覆河水的p H、DO、BOD₅、COD、氨氮和硝态氮以及底泥中氮素存在形态进行了时空分布和含量分析。结果表明,闸坝河段整体上属于中性偏碱性,COD、氨氮浓度较高,上游污染高于下游污染,受尾水排放和闸坝运行影响。底泥氮素主要以氨氮和硝态氮存在,表层底泥硝态氮含量较高,随着底泥深度的增加氨氮、亚硝态氮含量也随之增高,硝态氮含量随之降低。（3）研究区底泥氮素的吸附释放研究。对各采样点处的底泥进行氨氮吸附释放动力学和热力学试验,确定最佳吸附释放方程,对比分析不同点位吸附释放特征,通过室内模拟试验,改变温度、p H、DO、扰动和微生物条件探究不同环境因子对底泥释放的影响规律。结果表明氨氮的吸附及释放动力学均符合准二级动力学模型,氨氮吸附热力学过程用Henry模型拟合程度较好。温度升高会促进底泥中氮素释放,p H升高会抑制底泥氮素释放,氨氮随溶解氧升高而降低,硝态氮随溶解氧升高而升高。底泥中氮素释放随扰动强度增大而增大。微生物可抑制氨氮释放,促进硝态氮释放。本研究从底泥污染物释放入手,填补丰富了闸坝河段底泥污染释放的理论,具有一定创新。（4）研究区底泥微生物群落结构与氮的相互作用研究。利用提取DNA,PCR扩增测序方式对枯水期底泥微生物群落多样性进行研究。结果显示,研究区微生物物种丰富,其中C点相对丰度最高,分析了各分类水平下的优势菌种,门水平优势菌种为变形菌门、厚壁菌门及拟杆菌门。纲水平优势菌种γ-变形菌纲、拟杆菌纲、α-变形菌。目水平下优势菌种伯克氏菌目、假单胞菌目、黄单胞菌目。科水平下优势菌种假单胞菌科、嗜氢菌科、黄色单胞菌科。属水平下优势菌种假单胞菌属、硫杆菌属、志贺氏菌属。种水平下优势菌种为大肠杆菌、排硫杆菌、蒂莫内马赛菌。根据预测的功能菌种确定氮循环过程中主要发生固氮反应、硝化及反硝化反应和硝酸盐异化还原反应。由Spearman相关性热图反映出与各形态氮呈显著相关的菌种。（5）研究区底泥氮污染的防控研究。综合上述研究,结合研究区污染和实际情况提出底泥疏浚及闸坝控源联合调度的防控方式。根据流速比及底泥垂向各形态氮含量,确定最佳疏浚深度为0.4～0.5m之间,为闸坝河段污染的治理提供了有效数据,这也是本次研究的创新之处。同时利用MIKE11软件建立水质水量模型,对闸坝不同调控方式和控源方式进行模拟,提出科学有效改善水体的方案,为闸坝河段的综合治理提供了现实意义。更多还原

【Abstract】 River sediment is the circulation center of pollutant accumulation and diffusion.Sediment sedimentation and re-suspension is one of the important causes of water pollution.For gating rivers,such not only change the hydrology and water quality and easy to cause the settlement of sediment and release,cause secondary pollution to water,due to such formed the velocity field of complex operation and lead to mud interface migration mechanism of pollutants is complex,therefore,to effectively improve the prevention and control of the sites for river must focus on the process of such cause endogenous pollution mechanism.In this thesis,the hydrology and water environment characteristics of mojiapu sluice and dam reach of Hunhe River were investigated,and then the temporal and spatial distribution of river water indexes and nitrogen forms in sediment before and after sluice and dam were analyzed.Then,through laboratory experiment of ammonia nitrogen adsorption and release from sediment,experiment of nitrogen release from sediment by different environmental factors and PCR amplification sequencing,the phenomenon of nitrogen pollutant release from sediment of river under the influence of sluice dam is comprehensively analyzed from physical,chemical and biological perspectives,and the migration and transformation mechanism of nitrogen in sediment of sluice dam section was obtained.Finally,the river pollution prevention and control scheme is put forward by using sediment dredging and sluice dam combine source control,so as to effectively control nitrogen release from sediment and improve water quality,and also provide scientific basis for comprehensive pollution control of sluice dam section.The main research contents and results are as follows:（1）Analysis of hydrological and water environment characteristics in the study area.Collect the hydrological data of the Hunhe Shenyang Station,analyze the hydrological characteristics of the water storage area of the Hunhe Gate,and reflect the change of the flow,water level and water quality of the Hunhe Gate to control the Hunhe Shenyang Station.Determine the water function type and water environment capacity of the study area,and use the fuzzy comprehensive evaluation method to evaluate the water in the dry and wet periods of the study area.The results show that the study area belongs to the transition area,and the surface water quality is mainly grade IV,and some sections have grade V.The trend of water quality in the wet season is slightly better than that in the dry season.Spatially,the water quality in the upstream is slightly better than that in the downstream.The changes in the water quality of the river are affected by the operation of the gates and dams.（2）Analysis of temporal and spatial distribution characteristics of river water and sediment pollutants in the study area.The temporal and spatial distribution and content of p H,DO,BOD₅,COD,ammonia nitrogen and nitrate nitrogen in the overlying river water and nitrogen in the sediment are analyze in dry,wet and flat water periods.The results show that the sluice and dam reaches are generally neutral and alkaline,with higher concentrations of COD and ammonia nitrogen,and the upstream pollution is higher than the downstream pollution,which is affected by tail water discharge and sluice and dam operation.Nitrogen in the bottom sediment mainly exists as ammonia nitrogen and nitrate nitrogen,and the nitrate nitrogen content in the surface sediment is relatively high.（3）Study on the adsorption and release of nitrogen in the sediment in the study area.The adsorption and release kinetics and thermodynamic tests of ammonia nitrogen are carry out on the sediment collect at each sampling point,the optimal adsorption and release equation is determine,and the adsorption and release characteristics of different points were compared and analyzed.Microbial conditions explore the influence of different environmental factors on sediment release.The results show that the adsorption and release kinetics of ammonia nitrogen conformed to the pseudo-second-order kinetic model,and the Henry model is well fitted for the thermodynamic process of ammonia nitrogen adsorption.The increase of temperature will promote the release of nitrogen in the sediment,the increase of p H will inhibit the release of nitrogen in the sediment,the ammonia nitrogen will decrease with the increase of dissolved oxygen,and the nitrate nitrogen will increase with the increase of dissolved oxygen.Nitrogen release in sediments increased with the increase of disturbance intensity.Microorganisms can inhibit the release of ammonia nitrogen and promote the release of nitrate nitrogen.This study starts with the release of sediment pollutants,filling in and enriching the theory of sediment pollution release in the sluice and dam reaches,and has certain innovations.（4）Research on the interaction between the microbial community structure and nitrogen in the study area.The diversity of sediment microbial community in dry season was studied by DNA extraction and PCR amplification and sequencing.The results show that the study area is rich in microbial species,of which point C have the highest relative abundance.The dominant bacterial species at each taxonomic level were analyzed,and the dominant bacterial species at the phylum level were Proteobacteria,Firmicutes and Bacteroidetes.The dominant bacteria at the class level areγ-Proteobacteria,Bacteroidetes,andα-Proteobacteria.The dominant bacteria at the order level are Burkholderia,Pseudomonas and Xanthomonas.The dominant bacteria at the family level are Pseudomonas,Hydrogenobacteriaceae and Xanthomonas.The dominant bacteria at the genus level are Pseudomonas,Thiobacillus and Shigella.The dominant bacteria at the species level are Escherichia coli,Thiobacillus spp,and Marseille Timone.According to the predict functional bacteria,it is determine that nitrogen fixation reaction,nitrification and denitrification reaction and nitrate dissimilatory reduction reaction mainly occur in the nitrogen cycle process.The Spearman correlation heat map reflect the bacterial species that are significantly correlate with each form of nitrogen.（5）Research on the prevention and control of nitrogen pollution in sediments in the study area.Based on the above research,combine with the pollution and the actual situation in the study area,the governance method of sediment dredging and joint source control of gates and dams is proposed.According to the flow rate ratio and the vertical nitrogen content of the sediment,the optimal dredging depth is determined to be between 0.4m and 0.5m,which provides effective data and practical significance for the pollution control of the sluice and dam reaches,which is also the innovation of this research.place.Using MIKE11 software to establish a water quality and quantity model,simulate different regulation methods and source control methods of gates and dams,and put forward a scientific and effective plan to improve the water,which provides practical significance for the comprehensive management of gates and dams.更多还原