傍河开采驱动下河水入渗地下水过程中铁锰生物地球化学过程研究

发布时间：2018-05-01 10:42

  本文选题：生物地球化学 + 铁锰　； 参考：《吉林大学》2017年博士论文

【摘要】：傍河开采作为重要的地下水开采方式,在促进河水向地下水转化的同时,也影响了河水入渗过程中的生物地球化学作用。由于河水与地下水在温度、酸碱等特征上存在的差异,导致河水入渗补给区域存在明显的物理梯度、化学梯度及生物梯度,从而发生着强烈且复杂的生物地球化学过程。河水入渗补给地下水过程中所发生的这种生物地球化学过程对维持傍河地区地下水水质及生态安全具有重要作用。目前对傍河地下水开采引起的水动力等条件变化如何控制和影响河水入渗地下水过程中生物地球化学作用的机制尚不完全清楚。基于此,本文以沈阳市辽河冲洪积扇黄家傍河水源地为研究区,选择对氧化还原条件和酸碱条件变化极为敏感的铁和锰为研究对象,应用原位监测技术、环境同位素示踪技术、分子生物学技术、室内实验模拟技术和地球化学模拟技术,在调查和分析研究区水文地质条件基础上,查明傍河地下水开采条件下河水与地下水的水力交换特征及交换强度;评价含水介质中铁锰潜在地球化学活性;分析河水入渗补给地下水过程中氧化还原分带的时空演化规律及微生物的响应特征;分析控制河水入渗过程中铁锰生物地球行为的主要影响因素;识别河水入渗过程中铁锰的主要地球化学反应,并评价其对地下水中铁锰迁移转化的贡献。该项研究对于丰富河水-地下水交互作用带生物地球化学研究内容,傍河开采工程地下水资源的合理开采与保护等具有重要的理论意义和实际意义。通过本次研究,得到以下结论:(1)在分析河水入渗带水文地质条件的基础上,利用多重地球化学示踪方法,识别出了河水入渗补给过程中的2条地下水流路径,即浅层水流路径(影响范围10m)和深层水流路径(影响范围10m～50m)。空间上,与浅层水流路径相比,深层水流路径含水层渗透性较好,与河水水力联系密切,河水补给强度相对较大;时间上,与冬季相比,夏季河水水位较高,水力梯度较大,河水入渗速度及入渗通量较高。(2)介质中可交换态锰、可交换态铁、铁锰氧化物结合态铁的地球化学活性相对较强。沿水流路径,有效态铁、有效态锰含量浅层含水介质均高于深层。含水介质中土著微生物物种丰度与多样性表现出强烈的空间异质性。与浅层含水介质相比,深层含水介质中微生物物种及多样性与河床沉积物微生物群落结构表现出较高的相似性。(3)河水与地下水水化学长期动态监测数据显示,河水入渗补给地下水过程中存在明显的顺序氧化还原分带规律,表现为:水平方向上,浅层水流路径氧化还原积极反应带范围为自河岸向漏斗中心延伸至17.0m处,各分带范围较窄;沿深层水流路径,反应范围为自河岸向漏斗中心延伸至200.0m处,各分带范围较宽。垂向上,受降雨与季节性淹没影响,地表以下10.0m范围为氧化还原积极反应带。整体上,介质中微生物群落结构对地下水中氧化还原分带具有一定的协同演化特征。(4)室内实验结果和数值模拟结果表明,河水入渗过程中,铁锰发生了矿物自身溶解度控制的溶解过程、阳离子交换、胶体吸附、Mn(Ⅳ)与Fe(Ⅲ)矿物的还原过程以及配位体的络合等过程。其中,微生物介导下的顺序氧化还原是河水入渗过程中铁锰重要的生物地球化学过程。河水入渗过程中,由水动力条件、微生物及铁锰潜在地球化学活性共同决定了浅层水流路径铁锰的生物地球化学反应程度高于深层水流路径,而铁的反应程度高于锰。(5)自然界中砷多与铁锰共生。在研究区Mn(Ⅳ)与Fe(Ⅲ)还原带,伴随着铁锰的还原,介质表面吸附的砷及晶格内砷释放至地下水中,地下水中砷含量较高,超过30.0μg/L;在硫酸盐还原带,伴随着硫酸盐的还原,HS-和Fe2+形成硫化物(如FeS)吸附或共沉淀砷,地下水中砷降低。建议研究区水源地开采井布设在硫酸盐还原带,以降低砷对地下水二次污染的风险。
[Abstract]:As an important mode of groundwater exploitation, near River Mining promotes the transformation of water into groundwater and affects the biogeochemical effect of water infiltration. Because of the difference in temperature and acid base of water and groundwater, there are obvious physical gradient, chemical gradient and birth in the water infiltration recharge area. It has a strong and complex biogeochemical process. The biogeochemical process in the process of water infiltration and recharge of groundwater has an important role in the maintenance of groundwater quality and ecological safety in the riverside area. The mechanism of biogeochemical action in the process of water infiltration in the river water is not completely clear. Based on this, this paper takes the water source area of the Huang Jia River in the Liaohe alluvial fan, Shenyang city as the research area, chooses iron and manganese, which is extremely sensitive to the change of redox conditions and acid and base conditions as the research image, and applies in situ monitoring technology and environmental isotope tracing. Technology, molecular biology technology, laboratory simulation technology and geochemical simulation technology, based on the investigation and analysis of hydrogeological conditions in the study area, to find out the hydraulic exchange characteristics and exchange strength of water and water under the condition of underground water exploitation, evaluate the potential geochemical activity of iron and manganese in water bearing medium, and analyze the infiltration of river water. The temporal and spatial evolution of Redox Zoning and the response characteristics of microbes in the process of recharging the groundwater, the main factors affecting the iron and manganese biogeochemical behavior in the water infiltration process are analyzed, the main geochemical reactions of iron and manganese in the water infiltration process are identified, and the contribution to the transfer and transformation of iron and manganese in the groundwater is evaluated. It is of great theoretical and practical significance to enrich the Biogeochemical Study of the interaction between river water and groundwater, and the rational exploitation and protection of groundwater resources in the riverside mining project. Through this study, the following conclusions are obtained: (1) on the basis of the analysis of the water geological conditions of the river infiltration zone, the multiple geochemistry is used. The tracing method recognizes 2 groundwater flow paths in the process of water infiltration and recharge, namely, shallow water flow path (influence range 10m) and deep flow path (10m to 50m). In space, the depth of water flow path is better than the shallow water flow path, and the water supply is relatively close to the river water, and the water supply intensity is relatively more than that of the river water. In time, compared with winter, the water level of the river is higher in summer, the hydraulic gradient is larger, the water infiltration velocity and infiltration flux are higher. (2) the exchangeable manganese in the medium, exchangeable iron, and iron manganese oxide bound iron are relatively strong. The shallow water medium with effective state manganese content along the flow path, effective state iron and the effective state manganese content are higher than the deep layer. The aboriginal microbial species abundance and diversity in the aqueous media showed strong spatial heterogeneity. Compared with the shallow water bearing medium, the microbial species and diversity in the deep water bearing medium showed higher similarity to the microbial community structure in the river bed sediments. (3) the long-term dynamic monitoring data of water and water water in the river water and the water were shown in the river water. There is a clear sequential Redox Zoning rule in the process of infiltration and recharge of groundwater, which shows that the range of redox positive reaction zone in the shallow layer is from the riverbank to the 17.0m of the funnel center, and the range of each zoning is narrow. Along the deep flow path, the reaction range extends from the riparian to the funnel center to the 200.0m. The zoning range is wide. Vertical upward, affected by rainfall and seasonal inundation, the range of 10.0m below the surface is a positive redox reaction zone. On the whole, the microbial community structure in the medium has certain coevolution characteristics on the Redox Zoning in the groundwater. (4) laboratory results and numerical simulation results show that the water infiltration process, Iron and manganese occurred in the process of dissolution, cation exchange, colloid adsorption, the reduction process of Mn (IV) and Fe (III) minerals and the complexation of the coordination bodies. The dynamic conditions, microorganism and the potential geochemical activity of iron and manganese determine the superficial flow path of iron and manganese higher than the deep flow path, while the reaction degree of iron is higher than that of manganese. (5) in nature, the arsenic is associated with iron and manganese. In the study area Mn (IV) and the reduction zone of Fe (III), with the reduction of iron and manganese, the absorption of the medium surface. The arsenic and internal arsenic in the lattice are released into underground water, and the arsenic content in groundwater is higher than 30 g/L. In the sulfate reduction zone, with the reduction of sulfate, HS- and Fe2+ form sulphides (such as FeS) to adsorb or copreciate arsenic in the groundwater, and the arsenic in groundwater is reduced. The risk of two water pollution.

【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P641.3
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本文编号：1829026