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摘要:
渗透系数是评价重金属污染液在重塑黄土中迁移扩散作用的一个重要指标。已有研究表明污染液的pH值、可溶性盐浓度、离子含量和饱和渗透系数的变化存在一定的相关关系，但未明晰渗透过程中的地球化学反应机制。基于此，采集了西安白鹿原地区的更新统（Qp）黄土，选取Cu2+溶液作为渗透溶液，开展了重塑黄土的饱和渗透试验，建立了基于Netpath软件的地球化学反演模型。结果表明：试验过程中饱和渗透系数从第1天开始显著降低，且与去离子试验组相比降低幅度较大，极差为5.57×10−5 cm/s；离子来源分析证明了地球化学反应的发生，存在着矿物的溶解、沉淀以及阳离子交换作用；地球化学反演模拟结果显示由于Cu2+的存在，加剧了矿物溶解产生大量的Ca2+，促进碳酸盐矿物溶解平衡左移，从第1天开始方解石和白云石持续形成沉淀，沉淀量分别为1.912，0.958 mmol，从而堵塞渗流孔隙，降低土体的渗透系数。研究结果有助于了解重金属离子侵入过程中重塑黄土饱和渗透系数的变化，同时对于进一步明晰影响渗透系数变化的地球化学机制具有重要的理论意义。
Abstract:The coefficient of permeability is an important index to evaluate the migration and diffusion of heavy metal polluted liquid in remodeled loess. At present, the existing studies have shown that there is a certain correlation among the pH value, the value of electrical conductivity, ion content and saturated coefficient of permeability of the polluted liquid, but the geochemical reaction mechanism during the infiltration process has not been clarified. Therefore, the Qp loess in the Bailuyuan area of Xi’an is collected, and the Cu2+ solution is selected as the infiltration solution to carry out the saturated infiltration test of the reshaped loess, and the geochemical inversion model based on the Netpath software is established. The results show that the saturated coefficient of permeability decreases significantly from the first day during the test, and has a larger decrease compared with the deionized test group, with a range of 5.57×10−5 cm/s. The ion source analysis proves that the geochemical reaction occurs, including mineral dissolution, precipitation and cation exchange. The geochemical inversion simulation results show that the presence of Cu2+ aggravates the mineral dissolution and produces a large amount of Ca2+, which promotes the leftward shift of the carbonate mineral dissolution balance, starting from the first day continual calcite and dolomite precipitation, and the precipitation amounts are 1.912 mmol and 0.958 mmol, respectively, which blocked the seepage pores and reduced the coefficient of permeability of the soil. The results are helpful in understanding the change of the saturated the permeability coefficient of the remodeled loess during the intrusion of heavy metal ions, and are of important theoretical significance for further clarifying the geochemical mechanism affecting the change of the permeability coefficient.
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Key words:
- remolded loess /
- heavy mental pollution /
- saturated permeability /
- geochemistry
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表 1 土样的物理性质
Table 1. Physical properties of the soil sample
参数 最优含水率
/%最大干密度
/（g·cm−3）比重 液限/% 塑限/% 粒度分布/% 粉粒 黏粒 砂粒 取值 17.78 1.76 2.6 39.47 19.73 21.32 78.38 0.30 
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表 2 土样的主要化学成分
Table 2. Main chemical components of the soil sample
化学成分 SiO2 Al2O3 Fe2O3 MgO CaO Na2O K2O 其他 质量分数/% 62.15 1.74 12.95 1.96 5.65 2.41 4.89 8.25
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表 3 饱和渗透系数的极差和平均值
Table 3. Range and average value of the saturated coefficient of permeability
溶液类型 最大值/（cm·s−1） 最小值/（cm·s−1） 极差/（cm·s−1） DIW 7.37×10−5 4.97×10−5 2.40×10−5 Cu2+溶液 6.66×10−5 1.09×10−5 5.57×10−5
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表 4 矿物饱和指数（SI）
Table 4. Mineral saturation index (SI)
离子类型 渗透时间/d 矿物相 方解石 白云石 萤石 石膏 岩盐 DIW 0.5 −0.43 −1.44 −0.63 −2.58 −7.14 1.0 −0.71 −1.94 −0.56 −3.13 −7.32 1.5 −0.96 −2.50 −0.40 −3.27 −7.47 2.0 −0.99 −2.57 −0.81 −3.29 −7.79 2.5 −0.50 −3.50 −1.33 −3.24 −8.19 3.0 −0.16 −2.87 −1.45 −3.07 −8.67 3.5 0.05 −2.56 −1.58 −3.04 −9.15 4.0 0.23 −2.73 −1.52 −2.87 −9.42 4.5 0.18 −2.15 −1.50 −2.76 −9.47 5.0 0.09 −2.81 −1.63 −2.89 −9.91 Cu2+ 0.5 −0.22 −1.00 −0.68 −1.06 −6.79 1.0 0.26 0.03 −0.76 −1.83 −7.69 1.5 0.39 0.27 −0.78 −1.88 −8.85 2.0 0.34 0.06 −0.93 −1.88 −9.20 2.5 0.41 0.08 −0.95 −1.87 −9.47 3.0 0.12 −0.57 −1.05 −1.86 −9.58 3.5 0.55 0.23 −1.19 −1.86 −9.64 4.0 0.62 0.35 −1.16 −1.86 −9.62 4.5 0.55 0.2 −1.18 −1.85 −9.71 5.0 0.48 0.04 −1.39 −1.87 −9.66
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表 5 潜在的化学反应
Table 5. Potential chemical reactions
序号 反应相 化学反应 1 方解石 CaCO3=Ca2++CO32− 2 白云石 CaMg（CO3）=Ca2++Mg2++CO32− 3 萤石 CaF2=Ca2++2F− 4 石膏 CaSO4·2H2O=Ca2++SO42−+2H2O 5 钾长石 KAlSi3O8+8H2O=K++Al(OH)4−+3H4SiO4 6 伊利石 K0.6Mg0.25Al2.3Si3.5O10(OH)2+11.2H2O=
0.6K++0.25Mg2++2.3Al(OH)4−+3.5H4SiO4+1.2H+7 岩盐 NaCl=Na++Cl− 8 离子交换 Ca2++2NaX=2Na++CaX2
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[1] 习羽,李同录,江睿君,等. 陇东黄土工程地质分层及其物理特性[J]. 水文地质工程地质,2018,45(4):67 − 72. [XI Yu,LI Tonglu,JIANG Ruijun,et al. Engineering geological stratigraphy and physical properties of the loess in eastern Gansu[J]. Hydrogeology & Engineering Geology,2018,45(4):67 − 72. (in Chinese with English abstract) doi: 10.16030/j.cnki.issn.1000-3665.2018.04.10
[2] XU Panpan,ZHANG Qiying,QIAN Hui,et al. Investigation into microscopic mechanisms of anisotropic saturated permeability of undisturbed Q2 loess[J]. Environmental Earth Sciences,2020,79(18):412 − 426. doi: 10.1007/s12665-020-09152-7
[3] WANG Haike, QIAN Hui, GAO Yanyan. Non-Darcy flow in loess at low hydraulic gradient[J]. Engineering Geology, 2020, 267: 105483.
[4] 王艳,唐晓武,刘晶晶,等. 黄土对锰离子的吸附特性及机理研究[J]. 岩土工程学报,2012,34(12):2292 − 2298. [WANG Yan,TANG Xiaowu,LIU Jingjing,et al. Adsorption behavior and mechanism of loess soil towards Manganese ions[J]. Chinese Journal of Geotechnical Engineering,2012,34(12):2292 − 2298. (in Chinese with English abstract)
[5] LI Zhenze,TANG Xiaowu,CHEN Yunmin,et al. Sorption behavior and mechanism of Pb(II) on Chinese loess[J]. Journal of Environmental Engineering,2009,135(1):58 − 67. doi: 10.1061/(ASCE)0733-9372(2009)135:1(58)
[6] TANG Xiaowu, LI Zhenze, CHEN Yunmin, et al. Removal of Cu（Ⅱ） from aqueous solution by adsorption on Chinese Quaternary loess: Kinetics and equilibrium studies[J]. Environmental Letters, 2008, 43（7）: 779-791.
[7] TANG Xiaowu, LI Zhenze, CHEN Yunmin. Behavior and mechanism of Zn（II） adsorption on Chinese loess at dilute slurry concentrations[J]. Journal of Chemical Technology and Biotechnology, 2008, 83: 673–682.
[8] 米栋云,李熠,董晓强. 重金属Pb2+污染土的渗透性能研究[J]. 中国科技论文,2016,11(15):1778 − 1781. [MI Dongyun,LI Yi,DONG Xiaoqiang. Study on hydraulic permeability of heavy metal Pb2+ contaminated soil[J]. China Sciencepaper,2016,11(15):1778 − 1781. (in Chinese with English abstract) doi: 10.3969/j.issn.2095-2783.2016.15.018
[9] 杨波. 重金属污染重塑黄土的抗剪强度与渗透性研究[D]. 太原: 太原理工大学, 2016
YANG Bo. Study on shear strength and permeability of remolded loess polluted by heavy metal[D]. Taiyuan: Taiyuan University of Technology, 2016. （in Chinese with English abstract）
[10] 李熠. Pb（Ⅱ）、 Zn（Ⅱ）污染土特性研究[D]. 太原: 太原理工大学, 2016
LI Yi. Study on Pb（Ⅱ）or Zn（Ⅱ） contaminated soil[D]. Taiyuan: Taiyuan University of Technology, 2016. （in Chinese with English abstract）
[11] 郭争争. 重金属离子对膨润土防水毯防渗性能影响研究[D]. 武汉: 武汉理工大学, 2020
GUO Zhengzheng. Study on the influence of heavy metal ions on the impermeability of geosynthetic clay liner[D]. Wuhan: Wuhan University of Technology, 2020. （in Chinese with English abstract）
[12] HAGE J T,MULDER E. Preliminary assessment of three new European leaching tests[J]. Waste Management (New York,N Y),2004,24(2):165 − 172. doi: 10.1016/S0956-053X(03)00129-6
[13] PLUMMER L N,PRESTEMON E C,PARKHURST D L. An interactive code (NETPATH) for modeling net geochemical reactions along a flow path,version 2.0[J]. Water-Resources Investigations Report,1994,94:4169.
[14] XU Panpan,ZHANG Qiying,QIAN Hui,et al. Exploring the geochemical mechanism for the saturated permeability change of remolded loess[J]. Engineering Geology,2021,284:105927. doi: 10.1016/j.enggeo.2020.105927
[15] XU Panpan, ZHANG Qiying, QIAN Hui, et al. Effect of sodium chloride concentration on saturated permeability of remolded loess[J]. Minerals,2020,10(2):199. doi: 10.3390/min10020199
[16] AL-GHANIMY M A, AL-MUTAWKI K G, FALAH H H. Geochemical modeling of groundwater in AL Teeb area （North East Missan Governorate）[J]. Journal of Physics: Conference Series, 2019, 1294（8）: 082002.
[17] ZHENG Xiuqing, ZANG Hongfei, ZHANG Yongbo, et al. A study of hydrogeochemical processes on Karst groundwater using a mass balance model in the Liulin Spring area, North China[J]. Water. 2018, 10（7）: 903.
[18] ZHANG Qiying,XU Panpan,QIAN Hui,et al. Hydrogeochemistry and fluoride contamination in Jiaokou Irrigation District,Central China:Assessment based on multivariate statistical approach and human health risk[J]. The Science of the Total Environment,2020,741:140460. doi: 10.1016/j.scitotenv.2020.140460
[19] CUISINIER O,AURIOL J C,LE BORGNE T,et al. Microstructure and hydraulic conductivity of a compacted lime-treated soil[J]. Engineering geology,2011,123(3):187 − 193. doi: 10.1016/j.enggeo.2011.07.010
[20] MULLER E,GAUCHER E C,DURLET C,et al. The origin of continental carbonates in Andean salars:A multi-tracer geochemical approach in Laguna Pastos Grandes (Bolivia)[J]. Geochimica et Cosmochimica Acta,2020,279:220 − 237. doi: 10.1016/j.gca.2020.03.020
[21] LI Peiyue,ZHANG Yuting,YANG Nuan,et al. Major ion chemistry and quality assessment of groundwater in and around a mountainous tourist town of China[J]. Exposure and Health,2016,8(2):239 − 252. doi: 10.1007/s12403-016-0198-6
[22] LI Peiyue,LI Xinyan,MENG Xiangyi,et al. Appraising groundwater quality and health risks from contamination in a semiarid region of Northwest China[J]. Exposure and Health,2016,8(3):361 − 379. doi: 10.1007/s12403-016-0205-y
[23] 朱洲洋,肖长来,梁秀娟,等. 安图县玄武岩区偏硅酸型天然矿泉水水化学特征及形成机理[J]. 水利水电技术(中英文),2021,52(10):146 − 156. [ZHU Zhouyang,XIAO Changlai,LIANG Xiujuan,et al. Hydrochemical characteristics and formation mechanism of metasilicic acid type natural mineral water in basalt area of Antu County[J]. Water Resources and Hydropower Engineering,2021,52(10):146 − 156. (in Chinese with English abstract)
[24] 张春潮,侯新伟,李向全,等. 三姑泉域岩溶地下水水化学特征及形成演化机制[J]. 水文地质工程地质,2021,48(3):62 − 71. [ZHANG Chunchao,HOU Xinwei,LI Xiangquan,et al. Hydrogeochemical characteristics and evolution mechanism of karst groundwater in the catchment area of the Sangu Spring[J]. Hydrogeology & Engineering Geology,2021,48(3):62 − 71. (in Chinese with English abstract) doi: 10.16030/j.cnki.issn.1000-3665.202004059
[25] 张鸿,周权平,姜月华,等. 长江干流水化学成因与风化过程CO2消耗通量解析[J]. 水文地质工程地质,2022,49(1):30 − 40. [ZHANG Hong,ZHOU Quanping,JIANG Yuehua,et al. Hydrochemical origins and weathering-controlled CO2 consumption rates in the mainstream of the Yangtze River[J]. Hydrogeology & Engineering Geology,2022,49(1):30 − 40. (in Chinese with English abstract)
[26] ZHANG Qiying,XU Panpan,QIAN Hui. Assessment of groundwater quality and human health risk (HHR) evaluation of nitrate in the central-western Guanzhong Basin,China[J]. International Journal of Environmental Research and Public Health,2019,16(21):4246. doi: 10.3390/ijerph16214246
[27] 魏晓鸥. 柳林泉域岩溶地下水水文地球化学形成演化规律[D]. 太原: 太原理工大学, 2013
WEI Xiaoou. Hydrochemical formation and evolution of the karstic groundwater in Liulin Spring catchment[D]. Taiyuan: Taiyuan University of Technology, 2013. （in Chinese with English abstract）
[28] ZANG Hongfei,ZHENG Xiuqing,JIA Zhenxing,et al. The impact of hydrogeochemical processes on karst groundwater quality in arid and semiarid area:A case study in the Liulin Spring area,North China[J]. Arabian Journal of Geosciences,2015,8:6507 − 6519. doi: 10.1007/s12517-014-1679-1
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