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土壤重金属污染是当前人们普遍关注的环境问题之一. 有色金属冶炼活动中原料准备、熔炼和尾气吸收等环节会排放出大量含重金属的废气、废水和废渣,重金属通过迁移、滞留和沉降作用进入地块土壤并进一步污染地下水,对人体健康、周边环境生态安全带来危害和威胁[1 − 3]. 土壤作为迁移通道,对重金属的迁移转化起重要作用. 因此,有必要明确重金属的垂向迁移分布特征及其形成机制和影响因素,以促进有色金属冶炼地块土壤重金属污染的有效防治[4].
目前,一些学者开展了冶炼地块土壤重金属污染垂向分布规律研究. 如秦岭某关闭锌冶炼企业地块土壤剖面0—3 m处As、Cd、Pb和Zn等重金属呈表层聚集和纵向迁移态势[5]. 株洲某废弃大型铅锌冶炼厂不同功能区0—1 m剖面表层(0—20 cm)土壤重金属含量普遍高于深层(80—100 cm),但长期冶炼活动和淋溶会导致部分点位深层土壤重金属含量高于表层[6]. 对某铅锌冶炼地块采集3个土壤剖面(0—6 m)研究发现,土壤重金属含量随剖面深度增加下降,但部分样点4 m深处土壤As和Cd含量仍超过建设用地第一类用地筛选标准值(GB36600-2018)[7]. 株洲某废弃有色冶炼地块不同功能区剖面(0—8 m)土壤重金属垂向分布特征表明,As、Cd、Pb等重金属主要累积于地面以下3 m内土壤[8]. 重金属化学形态直接影响着其迁移能力、生物有效性和对生态环境的危害程度[9],通常冶炼活动导致土壤累积的重金属活性较高. 如白银市某冶炼污染场地表层土壤中Cd含量以弱酸提取态为主,Pb的弱酸可提取态和可还原态比例较高[10]. 株洲某铅锌冶炼地块土壤可还原态Cd含量占比随深度增加而增加[7]. 这表明冶炼活动导致的土壤重金属污染风险较高,更应引起关注. 重金属在土壤中垂向迁移化学行为影响因素复杂,其中,土壤pH值、有机质和铁铝氧化物及矿物组成等均会影响重金属的迁移、有效性和化学形态[3, 11 − 12]. 贵州某铅锌冶炼区土壤Pb、Zn含量主要以铁锰氧化物结合态为主,铁矿物对其有较强固定作用[13]. 以往研究大多集中于冶炼地块土壤浅层剖面(0—3 m)重金属总量和赋存形态的垂直分布,较少关注深层剖面(0—8 m)重金属总量和赋存形态的分布,且影响其不同形态分布的因素尚不明确. 因此,对冶炼地块土壤重金属总量和形态的垂向迁移规律和成因有待进一步研究.
地块剖面土壤层通常由填土层、素填土层、粘土层和全风化基岩层组成,填土是工程建设中常见的特殊性土,地块各层土壤性质存在明显差异. 表层杂填土主要由建筑垃圾和生活垃圾等组成,物质成分复杂. 下层素填土一般经人工扰动,由碎石土、砂土、粉土和黏土等堆填而成,不含或含少量杂质[14]. 冶炼地块土壤大多数经过回填形成不同填土层,地质条件复杂,且由于填土孔隙率较高,更易于重金属的垂向下渗迁移[15]. 因此,探明重金属在不同土壤层中的迁移行为,对于准确评估地块土壤-地下水系统中重金属的生态风险和治理修复至关重要. 但目前对冶炼地块不同土壤层重金属的积累特征研究较少. 本研究拟以某锌冶炼厂沸腾炉生产功能区及周边土壤剖面为研究对象,分析重金属含量和赋存形态垂向分布特征,评价其垂向迁移风险,探讨土壤理化性质对重金属在地块土壤中迁移的影响机制,以期为冶炼地块重金属污染土壤有效防控与治理修复提供科学依据.
锌冶炼地块土壤重金属垂向分布特征及影响因素
Vertical distribution of heavy metals in soils and its influencing factors from a zinc smelting site
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摘要: 从湖南某废弃锌冶炼厂火法炼锌区域不同功能区采集6个土壤剖面(0—8 m),分析重金属镉(Cd)、铬(Cr)、铅(Pb)和锌(Zn)含量和赋存形态的垂向分布特征,探讨其与土壤理化性质相互关系. 结果表明,土壤重金属主要累积在0—3 m杂填土层,呈现随土壤深度增加含量下降趋势. 整个剖面Cd含量高,可迁移污染至深层土壤,Cr、Pb和Zn含量表现为0—3 m>3—6 m>6—8 m的显著差异(P<0.05). 欧共体参比司(BCR)制定的三步连续提取法结果表明,剖面土壤Cr含量以残渣态(79.2%—93.0%)为主,随着剖面深度增加,Pb的残渣态比例呈增加趋势,而Cd和Zn的酸可提取态比例增加, 迁移风险高. 电镜扫描能谱仪(SEM-EDS)和X射线衍射仪(XRD)分析结果表明,土层样品含有大量硅铝酸盐和SiO2;但沸腾炉区点位S6的1—1.5 m处土壤样品存在ZnO物相,点位S3号4—5 m和6—8 m深度处出现ZnCO3矿物相,表明核心功能区冶炼活动会加剧土壤Zn富集并向下迁移. 相关性分析表明,剖面土壤重金属全量与其各赋存形态含量呈显著正相关,非晶质Fe2O3含量与Cd、Pb和Zn活性态含量也呈显著正相关(P<0.05),表现出促进迁移的效应. 污染来源、土壤理化性质共同控制重金属的垂向分布及迁移,研究结果可为冶炼地块重金属污染土壤风险管控与修复提供科学依据.Abstract: Six soil profiles were collected from an abandoned zinc smelting site in Hunan Province to study the vertical distribution characteristics of contents and chemical fractions of Cd, Cr, Pb, and Zn, and the influence factors of soil physical and chemical properties were analyzed. The results showed that high content of heavy metals was predominately accumulated in 0—3 m soil layer, and decreased with the increase in soil depth. The Cd content in profiles was high and migrated into the deep soil. The geomean contents of Cr, Pb, and Zn in soil profiles were decreased significantly followed the order of 0—3 m>3—6 m>6—8 m (P<0.05). According to BCR (European Community Bureau of Reference) sequential extraction analysis, soil profile Cr content was predominated with residual fraction, accounting for 79.2%—93.0% of total content. The percentage of acid soluble fraction Cd and Zn, residual fraction Pb was increased with the soil depth increasing, indicating that high potential migration risks of Cd and Zn in soil profiles. The SEM-EDS (scanning electron microscope-energy dispersive spectroscopy) and XRD (X-ray diffraction) analysis results showed that there were much peaks of aluminosilicate minerals and SiO2 in soil. The mineral phase of ZnO were found in 1—1.5 m depth soil from point S6, and that of ZnCO3 appeared at 4—5 m and 6—8 m soil depth from point S3. This result indicated that critical smelting activities would cause the accumulation of Zn in soil. There was significant relationship between total content and chemical fractions of heavy metals in soil. Soil chemical properties of amorphous Fe2O3 promoted the migration of Cd, Pb and Zn in soil profile. The vertical distribution of heavy metals was controlled by pollution sources and soil physical and chemical properties. The results would provide scientific basis for effective prevention, control and remediation of heavy metal contaminated soil from smelting sites.
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Key words:
- smelting sites /
- heavy metals /
- chemical speciation /
- vertical distribution /
- influencing factors
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表 1 土壤剖面重金属含量统计结果
Table 1. Contents of heavy metals in soil profiles
元素
Elements剖面
深度/m
Depth含量/(mg·kg−1)
Contens背景值倍数
Background
value
multiple变异系数/%
Coefficient
of variation超标率%
Excess
rate范围
Range算数均值
(标准差)
Arithmetic
mean (SD)几何均值
(标准差) 2
Geometric
mean(SD)中值
Median背景值
Background标准
Standard1)Cd 0—3(n=35) 51.3—1280 483(303) 391(2.01) a2) 419 0.52 172 752 62.7 88.6 3—6 (n=15) 4.79—1033 261(272) 131(4.15) a 161 252 104 40.0 6—8(n=3) 36.3—636 233(237) 138(1.24) a 130 265 102 33.3 Cr 0—3(n=35) 74.2—354 204(63.8) 193(1.4) a 201 95 — 2.03 31.3 — 3—6(n=15) 76.6—254 194(52.7) 185(1.38) a 217 1.95 27.2 6—8(n=3) 72.2—281 188(77) 168(2.82) a 199 1.77 41.0 Pb 0—3(n=35) 150—11933 3619(2898) 2383(2.89) a 2890 60.3 2500 39.5 80.1 60.0 3—6(n=15) 26.1—5596 672(1418) 158(4.73) b 86.7 2.62 211 6.70 6—8(n=3) 31.5—720 238(283) 110(1.68 )b 99.4 1.82 119 0 Zn 0—3(n=35) 5687—165863 64045(40999) 50879(2.1) a 53714 136 — 374 64.0 — 3—6(n=15) 516—148786 31055(37801) 14098(4.4) b 15256 104 122 6—8(n=3) 4988—73843 28233(27334) 17094(3.48) c 17051 126 96.8 注:1), 《土壤环境质量建设用地土壤污染风险管控标准(试行)》(GB 36600-2018)中第二类用地管控值;2), 不同小写字母表示不同剖面深度之间土壤重金属含量有显著差异(P<0.05),有相同字母表示无显著差异. -
[1] 阳安迪, 肖细元, 郭朝晖, 等. 模拟酸雨下铅锌冶炼废渣重金属的静态释放特征[J]. 中国环境科学, 2021, 41(12): 5755-5763. doi: 10.19674/j.cnki.issn1000-6923.20210508.004 YANG A D, XIAO X Y, GUO Z H, et al. Static release characteristics of heavy metals from lead-zinc smelting slag leached by simulated acid rain[J]. China Environmental Science, 2021, 41(12): 5755-5763 (in Chinese). doi: 10.19674/j.cnki.issn1000-6923.20210508.004
[2] 李强, 何连生, 王耀锋, 等. 中国冶炼行业场地土壤污染特征及分布情况[J]. 生态环境学报, 2021, 30(3): 586-595. LI Q, HE L S, WANG Y F, et al. The characteristics and distribution of soil pollution in smelting industry sites in China [J]. Ecology and Environmental Sciences, 2021, 30( 3): 586- 595 (in Chinese).
[3] XU D, FU R, LIU H, et al. Current knowledge from heavy metal pollution in Chinese smelter contaminated soils, health risk implications and associated remediation progress in recent decades: A critical review[J]. Journal of Cleaner Production, 2021, 286: 124989. doi: 10.1016/j.jclepro.2020.124989 [4] KE W, ZENG J, ZHU F, et al. Geochemical partitioning and spatial distribution of heavy metals in soils contaminated by lead smelting[J]. Environmental Pollution, 2022, 307: 119486. doi: 10.1016/j.envpol.2022.119486 [5] 他维媛, 康桢, 孟昭君, 等. 秦岭典型停产关闭锌冶炼企业场地土壤重金属污染特征研究[J]. 生态环境学报, 2021, 30(07): 1513-1521. TA W Y, KANG Z, MENG Z J, et al. Research of pollution characteristics of heavy metals in soil of typical closed zinc smelting enterprises in Qinling Mountains [J]. Ecology and Environmental Sciences, 2021, 30(7): 1513-1521 (in Chinese).
[6] LI S, ZHAO B, JIN M, et al. A comprehensive survey on the horizontal and vertical distribution of heavy metals and microorganisms in soils of a Pb/Zn smelter[J]. Journal of Hazardous Materials, 2020, 400: 123255. doi: 10.1016/j.jhazmat.2020.123255 [7] XU L, DAI H, SKUZA L, et al. Comprehensive exploration of heavy metal contamination and risk assessment at two common smelter sites[J]. Chemosphere, 2021, 285: 131350. doi: 10.1016/j.chemosphere.2021.131350 [8] YANG J, GUO Z, JIANG L, et al. Cadmium, lead and arsenic contamination in an abandoned nonferrous metal smelting site in southern China: Chemical speciation and mobility[J]. Ecotoxicology and Environmental Safety, 2022, 239: 113617. doi: 10.1016/j.ecoenv.2022.113617 [9] RODRÍGUEZ L, RUIZ E, ALONSO-AZCÁRATE J, et al. Heavy metal distribution and chemical speciation in tailings and soils around a Pb–Zn mine in Spain[J]. Journal of Environmental Management, 2009, 90(2): 1106-1116. doi: 10.1016/j.jenvman.2008.04.007 [10] 陈任连, 蔡茜茜, 周丽华, 等. 甘肃某冶炼厂区土壤重金属铅、镉污染特征及其对微生物群落结构的影响[J]. 生态环境学报, 2021, 30(3): 596-603. CHEN R L, CAI X X, ZHOU L H, et al. Characteristics of soil contamination with heavy metals (Pb and Cd) in a smelting plant of Gansu and their effects on microbial community structure [J]. Ecology and Environmental Sciences, 2021, 30(3): 596-603 (in Chinese).
[11] LI F, FAN Z, XIAO P, et al. Contamination, chemical speciation and vertical distribution of heavy metals in soils of an old and large industrial zone in Northeast China[J]. Environmental Geology, 2009, 57(8): 1815-1823. doi: 10.1007/s00254-008-1469-8 [12] ZHONG X, CHEN Z, LI Y, et al. Factors influencing heavy metal availability and risk assessment of soils at typical metal mines in Eastern China[J]. Journal of Hazardous Materials, 2020, 400: 123289. doi: 10.1016/j.jhazmat.2020.123289 [13] 杨元根, 刘丛强, 张国平, 等. 铅锌矿山开发导致的重金属在环境介质中的积累[J]. 矿物岩石地球化学通报, 2003(4): 305-309. YANG Y G, LIU C Q, ZHANG G P, et al. Heavy metal accumulations in environmental media induced by lead and zinc mine development[J]. Bulletin of Mineralogy Petrology and Geochemistry, 2003(4): 305-309 (in Chinese).
[14] 刘凌青, 肖细元, 郭朝晖, 等. 锌冶炼地块剖面土壤对镉、铅的吸附特征及机制[J]. 环境科学, 2021, 42(8): 4015-4023. Liu L Q, XIAO X Y, GUO Z H, et al. Adsorption characteristics and mechanism of Cd and Pb in tiered soil profiles from a zinc smelting site[J]. Environmental Science, 2021, 42(8): 4015-4023 (in Chinese).
[15] Di SANTE M, MAZZIERI F, PASQUALINI E. Assessment of the sanitary and environmental risks posed by a contaminated industrial site[J]. Journal of Hazardous Materials, 2009, 171(1-3): 524-534. doi: 10.1016/j.jhazmat.2009.05.145 [16] 鲁如坤. 土壤农业化学分析方法[M]. 北京: 中国农业科技出版社, 2000. LU R K. Methods for agricultural chemical analysis of soil[M]. Methods for agricultural chemical analysis of soil, 2000 (in Chinese).
[17] SHI L, GUO Z, LIU S. Effects of combined soil amendments on Cd accumulation, translocation and food safety in rice: a field study in southern China[J]. Environmental Geochemistry and Health, 2022, 44(8): 2451-2463. [18] DAVIDSON C M, DUNCAN A L, LITTLEJOHN D, et al. A critical evaluation of the three-stage BCR sequential extraction procedure to assess the potential mobility and toxicity of heavy metals in industrially-contaminated land[J]. Analytica Chimica Acta, 1998, 363(1):45-55. [19] GUO Z, ZHANG Y, XU R, et al. Contamination vertical distribution and key factors identification of metal(loid)s in site soil from an abandoned Pb/Zn smelter using machine learning[J]. Science of The Total Environment, 2023, 856: 159264. doi: 10.1016/j.scitotenv.2022.159264 [20] ZHANG X Y, LIN F F, WONG M T F, et al. Identification of soil heavy metal sources from anthropogenic activities and pollution assessment of Fuyang County, China[J]. Environmental Monitoring and Assessment, 2009, 154(1-4): 439-449. doi: 10.1007/s10661-008-0410-7 [21] 郭佳雯, 廖敏, 谢晓梅, 等. 铅锌冶炼厂冶炼渣淋溶释放的铅在红壤中垂直迁移特征[J]. 环境污染与防治, 2021, 43(8): 990-996, 1009. GUO J W, LIAO M, XIE X M, et al. Characteristics of vertical migration of Pb released from smelting slag of lead-zinc smelter in red soil area[J]. Environmental Pollution & Control, 2021, 43(8): 990-996, 1009 (in Chinese).
[22] 龙永珍, 戴塔根, 邹海洋. 长沙、株洲、湘潭地区土壤重金属污染现状及评价[J]. 地球与环境, 2008(3): 231-236. LONG Y Z, DAI T G, ZOU H Y. The status quo and evaluation of heavy metal pollution of soils in the Changsha, Zhuzhou and Xiangtan areas[J]. Earth and Environment, 2008, 36(3) : 231-236 ( in Chinese) .
[23] 李勖之, 姜瑢, 孙丽, 等. 不同国家土壤生态筛选值比较与启示[J]. 环境化学, 2022, 41(3): 1001-1010. LI X Z, JIANG R, SUN L, et al. Ecological soil screening values among different countries and implication for China[J]. Environmental Chemistry, 2022, 41 (3): 1001-1010 (in Chinese).
[24] OKONKWO S I, IDAKWO S O, AMEH E G. Heavy metal contamination and ecological risk assessment of soils around the pegmatite mining sites at Olode area, Ibadan southwestern Nigeria[J]. Environmental Nanotechnology, Monitoring & Management, 2021, 15: 100424. [25] 陈丹丹, 谭璐, 聂紫萌, 等. 湖南典型金属冶炼与采选行业企业周边土壤重金属污染评价及源解析[J]. 环境化学, 2021, 40(9): 2667-2679. doi: 10.7524/j.issn.0254-6108.2021010901 CHEN D D, TAN L, NIE Z M, et al. Evaluation and source analysis of heavy metal pollution in the soil around typical metal smelting and mining enterprises in Hunan Province[J]. Environmental Chemistry, 2021, 40 (9): 2667-2679 (in Chinese). doi: 10.7524/j.issn.0254-6108.2021010901
[26] ZENG J, LUO X, CHENG Y, et al. Spatial distribution of toxic metal(loid)s at an abandoned zinc smelting site, Southern China. [J]. Journal of Hazardous Materials, 2022, 425: 127970. doi: 10.1016/j.jhazmat.2021.127970 [27] TIBANE L V, MAMBA D. Ecological risk of trace metals in soil from gold mining region in South Africa[J]. Journal of Hazardous Materials Advances, 2022, 7: 100118. doi: 10.1016/j.hazadv.2022.100118 [28] STERCKEMAN T, DOUAY F, PROIX N, et al. Vertical distribution of Cd, Pb and Zn in soils near smelters in the north of France[J]. Environmental Pollution , 2000, 107(3): 377-389. doi: 10.1016/S0269-7491(99)00165-7 [29] LI P, LIN C, CHENG H, et al. Contamination and health risks of soil heavy metals around a lead/zinc smelter in southwestern China[J]. Ecotoxicology and Environmental Safety, 2015, 113: 391-399. doi: 10.1016/j.ecoenv.2014.12.025 [30] GUO Z, YANG J, SARKODIE E K, et al. Vertical distribution of the toxic metal(loid)s chemical fraction and microbial community in waste heap at a nonferrous metal mining site[J]. Ecotoxicology and Environmental Safety, 2021, 228: 113037. doi: 10.1016/j.ecoenv.2021.113037 [31] YU Z, LIU E, LIN Q, et al. Comprehensive assessment of heavy metal pollution and ecological risk in lake sediment by combining total concentration and chemical partitioning[J]. Environmental Pollution, 2021, 269: 116212. doi: 10.1016/j.envpol.2020.116212 [32] LIU W, HU T, MAO Y, et al. The mechanistic investigation of geochemical fractionation, bioavailability and release kinetic of heavy metals in contaminated soil of a typical copper-smelter[J]. Environmental Pollution, 2022, 306: 119391. doi: 10.1016/j.envpol.2022.119391 [33] DU H, LI Y, WAN D, et al. Tungsten distribution and vertical migration in soils near a typical abandoned tungsten smelter[J]. Journal of Hazardous Materials, 2022, 429: 128292. doi: 10.1016/j.jhazmat.2022.128292 [34] ZHONG Q, YIN M, ZHANG Q, et al. Cadmium isotopic fractionation in lead-zinc smelting process and signatures in fluvial sediments[J]. Journal of Hazardous Materials, 2021, 411: 125015. doi: 10.1016/j.jhazmat.2020.125015 [35] KANG M, YU S, JEON S W, et al. Mobility of metal(loid)s in roof dusts and agricultural soils surrounding a Zn smelter: Focused on the impacts of smelter-derived fugitive dusts[J]. Science of The Total Environment, 2021, 757: 143884. doi: 10.1016/j.scitotenv.2020.143884 [36] TUHÝ M, HRSTKA T, ETTLER V. Automated mineralogy for quantification and partitioning of metal(loid)s in particulates from mining/smelting-polluted soils[J]. Environmental Pollution, 2020, 266: 115118. doi: 10.1016/j.envpol.2020.115118 [37] XU D, FU R. A typical case study from smelter–contaminated soil: new insights into the environmental availability of heavy metals using an integrated mineralogy characterization[J]. Environmental Science and Pollution Research, 2022, 29(38): 57296-57305. doi: 10.1007/s11356-022-19823-6 [38] LIN H, TANG Y, DONG Y, et al. Characterization of heavy metal migration, the microbial community, and potential bioremediating genera in a waste-rock pile field of the largest copper mine in Asia[J]. Journal of Cleaner Production, 2022, 351: 131569. doi: 10.1016/j.jclepro.2022.131569 [39] BUATIER M D, SOBANSKA S, ELSASS F. TEM-EDX investigation on Zn- and Pb-contaminated soils[J]. Applied Geochemistry, 2001, 16(9): 1165-1177. [40] BOLAN N, KUNHIKRISHNAN A, THANGARAJAN R, et al. Remediation of heavy metal(loid)s contaminated soils – To mobilize or to immobilize?[J]. Journal of Hazardous Materials, 2014, 266: 141-166. doi: 10.1016/j.jhazmat.2013.12.018 [41] SHAHEEN S M, TSADILAS C D, RINKLEBE J. A review of the distribution coefficients of trace elements in soils: Influence of sorption system, element characteristics, and soil colloidal properties[J]. Advances in Colloid and Interface Science, 2013, 201-202: 43-56. doi: 10.1016/j.cis.2013.10.005 [42] LI Y, LIU J, WANG Y, et al. Contribution of components in natural soil to Cd and Pb competitive adsorption: Semi-quantitative to quantitative analysis[J]. Journal of Hazardous Materials, 2023, 441: 129883. doi: 10.1016/j.jhazmat.2022.129883 [43] KUBIER A, WILKIN R T, PICHLER T. Cadmium in soils and groundwater: A review[J]. Applied Geochemistry, 2019, 108: 104388. doi: 10.1016/j.apgeochem.2019.104388 [44] MILER M, GOSAR M. Characteristics and potential environmental influences of mine waste in the area of the closed Mežica Pb–Zn mine (Slovenia)[J]. Journal of Geochemical Exploration, 2012, 112: 152-160. doi: 10.1016/j.gexplo.2011.08.012 [45] WILSON S C, LOCKWOOD P V, ASHLEY P M, et al. The chemistry and behaviour of antimony in the soil environment with comparisons to arsenic: A critical review[J]. Environmental Pollution, 2010, 158(5): 1169-1181. doi: 10.1016/j.envpol.2009.10.045 [46] 王璐莹, 秦雷, 吕宪国, 等. 铁促进土壤有机碳累积作用研究进展[J]. 土壤学报, 2018, 55(5): 1041-1050. WANG L Y, QIN L, LV X G, et al. Progress in researches on effect of iron promoting accumulation of soil organic carbon[J]. Acta Pedologica Sinica, 2018, 55(5): 1041-1050 (in Chinese).