【作者】 郭金淼；

【导师】 苏小四；

【作者基本信息】 吉林大学 ， 地下水科学与工程， 2012， 硕士

【摘要】 湖泊湿地是干旱沙漠地区水生态系统的重要部分，湖水和地下水之间的交互作用在水生态系统中发挥着重要作用。作为一种重要的生源元素，硫对潜流带的氧化还原、酸碱度、温度等环境极为敏感，是潜流带生物地球化学研究的重要元素。本文利用水化学分析、同位素、多元统计分析和数值模拟相结合的方法，在充分搜集和分析研究区地质和水文地质资料的基础上，开展野外原位监测、室内样品分析测试和数学模拟等工作，调查和分析了库布齐沙漠地区大海子淖潜流带范围、结构、水动力特征和水化学分布特征，分析了大海子淖潜流带水化学形成和演化规律，并在此基础上重点分析了潜流带硫的生物地球化学行为，从而丰富了地表水-地下水交互作用带研究内容。湖水-地下水交互作用带（湖泊潜流带）是联系湖水与地下水相互作用的桥梁和纽带，是湖泊生态系统重要的组成部分，对于维护沙漠高原地区水资源、生物多样性乃至于生态系统具有重要意义。硫是一种重要的生源元素，在湖泊潜流带中，硫与养分循环、碳循环、水体酸化、铁锰矿物的形成、微量金属元素氧化还原、一些有毒重金属及无机物（砷）的迁移转化等密切相关，是湖泊潜流带生物地球化学的重要研究内容。本文以国家自然科学基金项目《沙漠高原地区Hypolentic带中硫的生物地球化学行为研究》为依托，在野外原位监测、室内样品测试和分析的基础上，利用水化学分析方法、多元统计分析方法和数值模拟方法，从湖泊潜流带结构、水动力、水化学、同位素、环境参量、水化学形成、硫的迁移转化等方面出发，来探究大海子淖潜流带中硫的生物地球化学过程。取得如下主要认识：1.大海子淖地形、岩性等结构存在着沿水流方向上的空间分带性，进而使得水动力条件、潜流带剖面孔隙水端元组成和比例存在着沿剖面的一个梯度变化特征。水文地质结构决定水动力特征。利用同位素质量守恒原理可计算出潜流带剖面各点孔隙水的端元组成及混合比例，湖水和地下水混合比例空间分布特征又可以反映湖水和地下水水力联系强弱分布。2.大海子淖湖床沉积物0~-90cm范围内温度、pH等环境参量，孔隙水中各种常规阴阳离子和沉积物中的相关固体组分在沉积物剖面上各自存在着与湖水和浅层地下水不同的浓度梯度，依据这些梯度特征所确定的潜流带范围与单纯依据湖水-地下水混合比例所确定的潜流带范围不同，这是由于潜流带同时具备水文、水化学和生态等方面的性质，并且发生着复杂的物理、化学和生物作用过程，这些作用过程在沉积物剖面上也存在着某种强弱梯度变化特征，这些梯度变化特征与河水-地下水交互作用带相似。因此，在湖泊潜流带范围确定时，应综合考虑地球物理、地球化学和生物指标的空间分布。3.水化学演化和硫生物地球化学循环方面：①混合作用、阳离子交替吸附作用、矿物和盐的溶解沉淀作用、微生物催化作用下的氧化还原作用控制着潜流带水化学和硫的迁移转化过程，其中，硫的非生物过程主要是硫酸盐矿物的溶解及硫化物的沉淀，各种反应过程强弱在垂向剖面上呈现出各自的梯度变化特征。②潜流带中硫的生物地球化学过程主要是微生物催化作用下的一系列氧化还原过程。在Eh高的表层，沉积物中的硫铁矿可被水中溶解氧和活性Fe3+氧化而生成硫酸盐；在Eh低、有机碳充足的深层，硫酸盐还原菌厌氧分解有机物将硫酸盐还原为硫化物并与活性Fe2+结合而沉淀下来，并进一步生成硫铁矿。③硫的迁移转化过程主要与有机碳、溶解氧等氧化还原物质及其所决定的环境氧化还原电位垂向分布梯度有关。在入渗初期，硫酸盐还原速率往下逐渐增大，并在约-0.35m处达到最大；-0.35m以下，因TOC含量减少而减弱。入渗中后期，0~-0.35m的表层，由于TOC的消耗，Eh的增加而使得原来生成的硫铁矿被重新被氧化，并且在最靠近湖床的表层氧化最强烈；在-0.35m以下，由于Eh增加及有机碳消耗而导致硫酸盐还原速率更弱。反应最终使得潜流带垂向剖面上硫化物浓度出现先增大，后减小的分布规律。更多还原

【Abstract】 Hyporheic zone，which is the interface of groundwater and surface water interaction,has great significance on protecting and preserving water resources, biodiversity andeven ecosystem of desert plateau area, and is important component of lake ecosystem.As an important biogenic element, sulfur is important content in hypolentic zonebiogeochemistry research, which is closely correlated with nutrient cycling, carboncycling, water acidification, origination of ferromanganese minerals, trace metalelements redox, transport and transformation of some toxic heavy metal and inorganicmatter (such as As) etc in hypolentic zone.The thesis relies on National Natural Science Foundation of “Surfur Biogeochemistryin Hypolentic Zone of Lake in Desert Plateau Area”. In the thesis, based on field insitu monitoring and sample analysis in laboratory, coupled of water chemical analysis,multivariate statistical analysis and numerical simulation method are used to exploresulfur geochemistry in hypolentic zone of Da Haizi lake from aspects of structure,hydrodynamic, hydrogeochemistry, isotope, environment parameters,hydrogeochemistry evolve, sulfur migration and transformation etc, from which, thefollowing opinions are obtained:1.There is a spacial zonation of topography, lithology etc along water flow direction inhypolentic zone, which result in gradients of hydrodynamic and ratios of lake watervariatin in pore water along the hypolentic profile. Hydrodynamic is determined byhydrological texture. Components and ratios of each pore water sample of hypolenticprofile, which reflects that: spatial variation of lake-groundwater hydraulic connectioncan be calculated through the mass conservation principle of isotope.2. In the range of0to-90centimeters in sediment profile of DaHaizi Lake,environmental parameters of temperature, pH, each major zwitterion of pore waterand related solid components in sediment all exhibit their respective gradients that aredifferent from surface water and shallow groundwater, ranges of hypolentic zonedetermined by these gradients above are deferment from that determined directly bysurface water-groundwater mixing ratios besides, that is because there are correlativehydrology、geochemistry and biology characteristics in hypolentic zone, and there arephysical, chemical and biological processes in the range of sampling area except for migmatization and diffusion; All of which are similar with hyporheic zone. So,indexes of geophysics, geochemistry and biology should be comprehensivelyconsidered when determining hypolentic zone range.3. In the aspects of geochemistry and sulfur biogeochemistry, the followingconcluctions are drawn:①hydrogeochemistry evolve and sulfur transport and transformation are controlled bymigmatization, cation exchange, dissolution and precipitation of mineral and salt,redox catalyzed by microorganisms, in which inorganic processes of sulfur are mainlydissolving of sulphate mineral and precipitating of sulfide, each process exhibits itsown gradients in vertical profile.②sulfur biogeochemistry in hypolentic zone are mainly a variety of redox processescatalyzed by microorganisms. in surface with high Eh, pyrite in the sediment can beoxidized to sulphate by dissolved O2and active Fe3+; and in deeper layer with lowerEh and a plenty of organic carbon, sulphate is reduced to sulphide that currentlyprecipitated with active Fe2+by the activity of sulfur reducing bacteria decompositingorganic matter anaerobically and further transformed to pyrite.③Transport and transformation of sulfur are mainly correlated with redox matters oforganic carbon, DO etc and the respecting vertical Eh gradient of environmentdetermined by them. In early of surface water infiltration, sulfate reducing rateincreasing with depth, and reaches the maximum at depth of about-30centimeter,below-30centimeter, reduces with TOC reduces. In late infiltration and in the surface0to about-30centimeter, pyrite formed previously is oxidized again because of TOCconsumption and Eh increasing, and the oxidizing rate is highest in the nearest lakebed; below-30centimeter, sulfate reducing gets more weaker as Eh increasing andTOC consumption. The result is that: concentration of pyrite in vertical hypolenticprofile first increase and then decrease with depth.更多还原