新疆焉耆盆地平原区地下水化学特征及演化研究

发布时间：2018-03-01 04:37

本文关键词： 地下水水质有机污染评价水文地球化学反向模拟地下水脆弱性 DRAV模型焉耆盆地平原区　出处：《新疆农业大学》2016年博士论文　论文类型：学位论文

【摘要】：焉耆盆地位于新疆天山中段南麓,新疆巴音郭楞蒙古自治州境内,盆地四周环山,呈菱形,地势从西北向东南、周边山岭向盆地中心(博斯腾湖——我国最大的内陆淡水湖)倾斜。地下水资源是焉耆盆地生活、生产及生态用水的主要供水水源。随着工农业生产和城镇化的快速发展,水的供需矛盾日益突出。近几十年来随着不断加剧的人类活动,地下水水质退化日趋严重。如何有效地解决地下水水质变差、水位下降等环境水文地质问题,合理利用地下水资源,成为我们工作的关键。因此,深入研究焉耆盆地地下水水质现状、演化特征及水文地球化学过程对合理开发地下水资源及保护地下水环境具有重要意义。本文以焉耆盆地平原区的焉耆县、博湖县、和静县及和硕县等4县的地下水为主要研究对象,采用地下水质量与污染评价、水文地球化学反向模拟、潜水脆弱性评价等方法,综合分析地下水化学检测数据,结合研究区的水文地质条件,对研究区地下水水质、水化学特征、水文地球化学过程及潜水脆弱性进行系统研究。主要结论如下:(1)2011~2014年焉耆盆地平原区地下水化学类型由HCO3-Ca型过渡到SO4·Cl-Na型。2014年平原区地下水水化学类型均呈现为山前冲洪积扇向博斯腾湖以HCO3→SO4→Cl顺序变化;由山前倾斜平原的HCO3-Ca型水过渡到细土平原的HCO3·SO4-Na·Ca型水,最终过渡为盆地边缘的Cl·SO4-Na·Ca型水。1999~2014年平原区地下水HCO3-Ca型水和HCO3·SO4-Na·Ca型水的面积在逐渐增大,增幅分别为133.5 km2和501.5 km2;Cl·SO4-Na·Ca型水的分区面积逐渐减小,降幅为1537.6 km2。(2)1999年和2014年间地下水TDS差异极显著(P0.01);TDS受宏量阴离子中的Cl-含量及宏量阳离子中的K++Na+含量影响最为显著,与阴离子关系密切程度依次为Cl-、SO42-和HCO3-,与阳离子关系密切程度依次为K++Na+、Ca2+和Mg2+,部分矿物风化溶解是平原区地下水主要的离子来源。在时间尺度上,1983~2014年地下水TDS均值整体呈现先升高再有所降低而后又升高再降低的趋势;在空间尺度上,1999~2014年地下水TDS浓度小于1 g/L区域面积呈增加的趋势。(3)2014年42眼监测井地下水质量评价结果为:焉耆盆地平原区4个潜水监测井,水质较好,均达到III类水质标准;11个浅层承压水监测井中,水质类别属于Ⅴ类的监测井2个,占浅层承压水监测井的18.1%,总监测井的4.8%;27个深层承压水监测井中,水质类别属于Ⅴ类的监测井6个,占深层承压水监测井的22.3%,总监测井的14.3%。2014年焉耆盆地平原区地下水质量从优到劣的顺序是潜水、浅层承压水和深层承压水。(4)首次将地下水有机污染物纳入检测项目,检测有机污染物共计39项,焉耆盆地平原区地下水中检出的有机污染物共有3种,分别是三氯甲烷、1,2-二氯乙烷和1,2-二氯苯,检出率分别为31.0%、2.4%和2.4%,检出的三项有机污染物含量均低于饮用水标准;通过多介质污染评价系统进行地下水有机污染评价,各有机污染物检出点不会对环境造成明显危害。(5)2014年42眼监测井地下水污染评价结果为:焉耆盆地平原区潜水属于未受污染和轻微污染的状态,属于未污染采样点3个、轻微污染采样点1个,分别占潜水采样点的75.0%和25.0%;浅层承压水属于未污染和轻微污染的状态,属于未污染采样点9个、轻微污染采样点2个,分别占浅层承压水采样点的81.8%和18.2%;深层承压水表现为未污染、轻微污染及中度污染状态,属于未污染采样点20个、轻微污染采样点5个、中度污染采样点2个,分别占深层承压水采样点的74.1%、18.5%和7.4%。2014年焉耆盆地平原区地下水污染程度从轻到重的顺序为浅层承压水、潜水和深层承压水。(6)通过对焉耆盆地平原区典型剖面水文地球化学反向模拟,阐明了研究区地下水所经历的水文地球化学作用(水解、蒸发浓缩、阳离子交换、溶解沉淀和氧化还原作用等)。根据地层岩性、离子比例及水文地球化学反向模拟等方面揭示了研究区典型剖面潜水至深层承压水,由浅至深阳离子交换作用越来越强烈。(7)利用DRAV模型对焉耆盆地平原区潜水脆弱性进行了评价,得出极高脆弱性、高脆弱性、中等脆弱性和低脆弱性(脆弱性指数分别为8.0、6.0~8.0、4.0~6.0和2.0~4.0)分区面积分别占研究区总面积的2.5%、21.5%、49.3%和26.7%;脆弱性较高区域包气带岩性主要为颗粒较大的砂砾石。
[Abstract]:Yanqi basin is located in the south of the Middle Tianshan Mountains of Xinjiang, Xinjiang Bayinguoleng Mongolia Autonomous Prefecture, the basin is surrounded by mountains, a diamond, the terrain from the northwest to the southeast, the surrounding mountains to the center of the basin (Bosten Lake, China's largest inland freshwater lake) tilt. Groundwater is the main source of water supply in Yanqi basin of life, production and ecological water with. The rapid development of industry and agriculture and urbanization, the contradiction between supply and demand of water has become increasingly prominent. In recent decades, with the increasing human activities, groundwater quality degradation has become increasingly serious. How to effectively solve the water quality deterioration, water level and so on environmental hydrogeological problems, reasonable utilization of groundwater resources, become the key of our work therefore., a thorough study of the present situation of groundwater quality in Yanqi basin, the evolution characteristics and hydrogeochemical process of protecting groundwater environment for the rational development of groundwater resources and protection Is of great significance. In this paper, taking the plain area of Yanqi basin in Yanqi County, Bohu County, Hejing county and 4 counties in Heshuo County groundwater as the main research object, the groundwater quality and pollution assessment, hydrogeochemical reverse simulation, diving vulnerability evaluation method, comprehensive analysis of groundwater chemical detection data, combined with the hydrogeology conditions in the study area, the groundwater quality in the study area, water chemistry characteristics, systematic study of the hydrogeochemical process and diving vulnerability. The main conclusions are as follows: (1) 2011~2014 in Yanqi plain groundwater basin of type by type HCO3-Ca transition to SO4 - Cl-Na.2014 groundwater water chemistry type showed the Piedmont alluvial fan to Bosten Lake in HCO3 - SO4 - Cl sequence changes; From Piedmont Plain of HCO3-Ca water transition to fine soil plain HCO3 - SO4-Na - Ca water, the final transition Basin The edge of the Cl SO4-Na Ca.1999~2014 type water groundwater water type HCO3-Ca and HCO3 - SO4-Na - Ca type water area increases gradually, an increase of 133.5 km2 and 501.5 km2; Cl - SO4-Na - Ca type water partition area gradually decreases, a decline of 1537.6 km2. (2) between 1999 and 2014 groundwater TDS significant difference (P0.01); TDS was affected by the K++Na+ content and Cl- content of macro cationic macro anions in the most significant, and the relationship between the close degree of anion were Cl-, SO42- and HCO3-, and the relationship between the close degree of cation were K++Na+, Ca2+ and Mg2+, part of mineral weathering dissolution is ion source groundwater mainly. In the time scale, 1983~2014 TDS presents the overall mean groundwater increased first and then decreased and then increased and then decreased; in the spatial scale, 1999~2014 groundwater concentration of TDS is less than 1 g/L area Product showed an increasing trend. (3) the results for 2014 42 monitoring wells of groundwater quality evaluation: 4 diving monitoring wells, the plain area of Yanqi basin, better water quality, have reached the class III water quality standard; 11 shallow confined water monitoring wells, water quality monitoring wells belongs to the category V 2, accounting for shallow confined water monitoring wells 18.1%, director of the 4.8% logging 27; deep confined water monitoring wells, water quality belongs to the category V monitoring wells 6, accounting for deep confined water monitoring wells 22.3%, director of the 14.3%.2014 logging groundwater in plain area of Yanqi basin, the quality of good to bad order is diving, shallow confined water and deep confined water. (4) for the first time, the organic pollutants in groundwater into the detection project, a total of 39 organic pollutants, organic pollutants detected in groundwater in Yanqi basin area in a total of 3 species, namely chloroform, 1,2- two and 1,2- two chlorobenzene chloroethane, detection rate Were 31%, 2.4% and 2.4%, three organic pollutants were detected were lower than the standard of drinking water; Groundwater Organic Pollution Evaluation by evaluation of multi medium pollution system, the organic pollutants detection point will not cause significant harm to the environment. (5) in 2014 42 monitoring wells of groundwater pollution evaluation results: the plain area of Yanqi basin is diving without pollution or light pollution, no pollution belongs to the 3 sampling points, slightly polluted sampling point 1, accounted for 75% and 25% diving sampling points; the state of shallow confined water was not polluted and slight pollution, no pollution belongs to the 9 sampling points, slightly polluted sampling point 2 respectively, shallow confined water sampling points 81.8% and 18.2%; the deep confined water is not contaminated, slight pollution and moderate pollution, pollution did not belong to the 20 sampling points, 5 sampling points are slightly polluted, moderately polluted sampling point 2, Respectively, the deep confined water sampling points 74.1%, 18.5% and 7.4%.2014 in Yanqi basin area groundwater pollution degree from mild to severe order of shallow confined water and phreatic water and confined water. (6) through the simulation of the plain area of Yanqi basin typical section of hydrogeochemical reverse, the hydrogeochemical action of groundwater experience (hydrolysis, evaporation, ion exchange, dissolution and precipitation and oxidation reduction etc.). According to lithology, ion ratio and hydrogeochemical reverse simulation reveals the typical profile of diving to deep confined water in the study area, from shallow to deep cation exchange more and more intense. (7) to dive plain area of Yanqi basin vulnerability was evaluated by the DRAV model, the high vulnerability to high vulnerability, moderate vulnerability and low vulnerability (fragility index was 8.0,6.0~8.0,4.0~6.0 and 2 respectively. ~4.0) zoning area accounts for 2.5%, 21.5%, 49.3% and 26.7% of the total area of the study area, and the lithology of high fragile zone gas zone is mainly sand gravel.

【学位授予单位】：新疆农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P641.3;X523

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