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湿地享有“地球之肾”的美名,被人类视为地球上最重要的自然生存环境之一[1]. 由于地势低洼,湿地易在水动力作用下持续汇集人类活动产生的重金属,而成为重金属的重要汇源地之一[2-4]. 因此,湿地土壤重金属已成为众多学者关注的对象之一. 本世纪以来,广大学者在重金属富集[5]、空间分布[6]、赋存形态[7]、生态风险评价[8]等方面对湿地表层土壤开展一系列的研究,结果表明当前世界各地湿地土壤均存在不同程度的重金属累积,并呈现稳步增长的态势. 对湿地表层土壤中重金属的研究不足以解释自然和人为双重作用下的重金属分布特征,更难以阐明重金属在剖面土壤中的垂向迁移特征及其对生态环境的潜在污染风险等问题.
重金属在进入土壤后受耕种、淋滤和翻耕等因素综合影响会向土壤的不同方向发生迁移转化,从而导致不同土层受到污染[9],这不仅阻碍农作物健康生长,而且会对地下水的安全构成严重威胁. 同时,重金属在不同深度土壤中的垂向迁移特征是展现重金属迁移能力和土壤污染状况最直观的指标之一[10-11]. 据研究报道,国内外对剖面土壤重金属研究多集中在工矿业场地[12]、城市土壤[13]、农田土壤[14]以及喀斯特地区[15]. 但是,目前对于湿地土壤剖面重金属分布特征及其迁移规律的研究报道较少. 此外,湿地周边不同类型土壤所处环境不同,其性质差异较大,以本研究的草滩和泥滩为例,二者在植被类型、土壤质地及水位变化条件等方面都存在较大差异,其重金属含量特征及迁移规律也必然有所不同. 因此,开展湿地土壤重金属的垂向分布特征及其影响因素研究,对揭示重金属在湿地土壤中的分布特征及迁移规律是十分必要的.
菜子湖作为长江中下游典型的沿江湿地,其生态环境质量对长江生态环境保护至关重要. 菜子湖湿地是国家工程“引江济淮”线路中重要节点之一,该工程完工后主要用以保障城乡供水和农业灌溉用水、促进航运发展、改善水生态环境,对沿途地区社会经济的发展至关重要[16-17]. 前人研究表明,菜子湖湿地周边土壤已累积了部分重金属,并存在不同程度的生态风险[2,18]. 基于此,本研究以菜子湖湿地为案例地,以湿地周边不同类型垂直剖面土壤为研究对象,阐明湿地土壤重金属在垂直方向上的分布特征及其迁移规律,以期为沿江湿地生态环境保护提供基础数据和科学依据.
菜子湖湿地不同类型土壤重金属的垂直分布特征及迁移规律
Vertical distribution and migration of heavy metals in different types of soils in Caizi Lake wetland
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摘要: 湿地是全球三大生态系统之一,而重金属污染已经成为桎梏湿地生态功能的重要环境问题. 本文以菜子湖湿地草滩和泥滩两种不同类型0—100 cm垂直剖面土壤为研究对象,通过对比实验方法,分析菜子湖湿地土壤剖面8种重金属元素(As、Co、Cr、Cu、Ni、Pb、V、Zn)的垂向分布特征及迁移规律. 结果表明,从整体剖面来看,除Cr、Cu和Pb外,其余重金属元素均不同程度超过安庆市土壤背景值,尤以表层土壤较为严重,说明当地存在重金属累积现象;根据土壤垂直分布来看,草滩和泥滩土壤重金属含量垂向变化较一致,总体表现出随土层深度的增加而逐渐减少的趋势,其中,草滩变化规律较为明显,而泥滩变化规律则稍显复杂;As、Co、Ni和V在草滩和泥滩整个剖面中的迁移系数均大于0,表明存在不同程度的富集,尤以As较为严重;Cu和Cr在两种类型土壤剖面中以富集为主,部分土层深度流失;Pb和Zn在垂直剖面土壤中的迁移特征较相似,均表现为在土壤表层富集,在中底层流失. 研究结果可为沿江湿地环境保护提供理论支撑和科学依据.Abstract: Wetland is one of the three major ecosystems in the world, and heavy metal pollution has become an important environmental problem restricting wetland ecological function. In this study, two different types of vertical profile soil (0—100 cm) from Caizi Lake wetland grassland and mudflat were collected and the vertical distribution characteristics and migration rules of eight heavy metals (As, Co, Cr, Cu, Ni, Pb, V, Zn) in the profile soil were analyzed by comparative experimental methods. The results showed that :(1) Except for Cr, Cu and Pb, all the other heavy metals in the profile soils exceeded the background values of the soil in Anqing city to varying degrees, especially in the surface soil, indicating that there was heavy metal accumulation in the local area. (2) According to the vertical distribution of soil, the vertical variation of heavy metal content in soil of grass flat and mud flat was consistent, and it gradually decreased with the increase of soil depth. The variation pattern of grass flat was more obvious, while that of mud flat was slightly more complex. (3) The migration coefficients of As, Co, Ni and V in the whole section of grass and mud flats were all greater than 0, indicating that they were enriched in varing degrees , especially in As. Cu and Cr were mainly enriched in the two types of soil profiles, and part of the soil depth was lost. The migration characteristics of Pb and Zn in vertical profile soil were similar, both of which were enriched in the surface layer and lost in the middle and bottom layer. The results can provide theoretical support and scientific basis for the environmental protection of wetland along the Yangtze River.
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Key words:
- wetland soil /
- heavy metals /
- vertical distribution /
- migration law /
- Caizi Lake
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表 1 湿地土壤剖面理化性质总体特征 (n=170)
Table 1. Overall characteristics of physical and chemical properties of soil in wetland profile (n=170)
项目
ItempH SOM/(g·kg−1) TN/(g·kg−1) TP/(g·kg−1) 砂粒/%
Sand粉粒/%
Silt黏粒/%
Clay平均粒径/μm
Average grain diameter最大值 7.96 61.94 5.37 0.32 9.75 86.18 30.72 10.40 最小值 4.45 1.16 0.39 0.02 0.04 59.11 12.00 4.07 平均值 5.83 16.41 1.51 0.11 1.58 77.87 20.55 6.77 标准差 0.70 14.77 1.05 0.05 1.49 3.54 3.29 1.33 变异系数 0.12 0.90 0.70 0.45 0.94 0.05 0.16 0.20 表 2 湿地土壤剖面重金属总量特征(mg·kg−1,n=170)
Table 2. Characteristics of Total heavy metals in soil of wetland profile
项目
ItemAs Co Cr Cu Ni Pb V Zn 最小值 2.74 0.62 17.44 2.44 4.65 0.08 38.18 19.14 最大值 70.33 48.09 125.36 101.29 81.36 61.73 216.32 301.28 平均值 28.81 16.65 59.42 24.21 36.19 19.35 111.59 77.22 标准差 11.55 8.30 22.27 11.64 14.96 10.63 30.91 41.58 变异系数 0.40 0.50 0.37 0.48 0.41 0.55 0.28 0.54 土壤背景值 9.41 12.35 63.38 30.30 23.75 26.92 93.79 74.41 注:土壤背景值参考依据来源于安徽省环境监测中心-1992.
Note: The reference basis of soil background value is from Anhui Environmental Monitoring Center-1992. -
[1] SHAN V, SINGH S K, HARITASH A K. Evaluation of water quality and potential metal contamination in ecologically important Bhindawas bird sanctuary, India [J]. Applied Water Science, 2021, 11(1): 1-9. doi: 10.1007/s13201-020-01330-z [2] 徐明露, 方凤满, 林跃胜. 安庆菜子湖退耕湿地土壤中的重金属含量及其污染评价 [J]. 湿地科学, 2015, 13(4): 437-443. XU M L, FANG F M, LIN Y S. Contents and pollution evaluation of heavy metals in soils of wetlands after returning farmland to lake in Caizi lake in Anqing City [J]. Wetland Science, 2015, 13(4): 437-443(in Chinese).
[3] 李亚瑾, 孙志高, 李晓, 等. 闽江大樟溪下游沿线湿地沉积物中重金属分布特征及生态风险评价 [J]. 水土保持学报, 2020, 34(2): 331-339. LI Y J, SUN Z G, LI X, et al. Distribution characteristics and ecological risk of heavy metals in sediments of wetland along the lower reach of the Dazhang stream(Min River) [J]. Journal of Soil and Water Conservation, 2020, 34(2): 331-339(in Chinese).
[4] 李伟, 布多, 孙晶, 等. 拉萨巴嘎雪湿地土壤重金属分布及生态风险评价 [J]. 环境化学, 2021, 40(1): 195-203. doi: 10.7524/j.issn.0254-6108.2019092006 LI W, BU D, SUN J, et al. Distribution and ecological risk assessment of heavy metal elements in the surface sediments of Bagaxue wetlands in Lhasa [J]. Environmental Chemistry, 2021, 40(1): 195-203(in Chinese). doi: 10.7524/j.issn.0254-6108.2019092006
[5] RAMOS-MIRAS J J, ROCA-PEREZ L, GUZMÁN-PALOMINO M, et al. Background levels and baseline values of available heavy metals in Mediterranean greenhouse soils (Spain) [J]. Journal of Geochemical Exploration, 2011, 110(2): 186-192. doi: 10.1016/j.gexplo.2011.05.009 [6] HARIKUMAR P S, NASIR U P, RAHMAN M P M. Distribution of heavy metals in the core sediments of a tropical wetland system [J]. International Journal of Environmental Science & Technology, 2009, 6(2): 225-232. [7] HOQUE R R, GOSWAMI K G, KUSRE B C, et al. Distribution and solid-phase speciation of toxic heavy metals of bed sediments of Bharali tributary of Brahmaputra River [J]. Environmental Monitoring and Assessment, 2011, 177(1/2/3/4): 457-466. [8] CUI J, ZANG S Y, ZHAI D L, et al. Potential ecological risk of heavy metals and metalloid in the sediments of Wuyuer River Basin, Heilongjiang Province, China [J]. Ecotoxicology (London, England), 2014, 23(4): 589-600. doi: 10.1007/s10646-014-1182-1 [9] 何梦媛, 董同喜, 茹淑华, 等. 畜禽粪便有机肥中重金属在土壤剖面中积累迁移特征及生物有效性差异 [J]. 环境科学, 2017, 38(4): 1576-1586. HE M Y, DONG T X, RU S H, et al. Accumulation and migration characteristics in soil profiles and bioavailability of heavy metals from livestock manure [J]. Environmental Science, 2017, 38(4): 1576-1586(in Chinese).
[10] 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 [11] 刘洪莲, 李恋卿, 潘根兴. 苏南某些水稻土中Cu Pb Hg As的剖面分布及其影响因素 [J]. 农业环境科学学报, 2006, 25(5): 1221-1227. doi: 10.3321/j.issn:1672-2043.2006.05.026 LIU H L, LI L Q, PAN G X. Profile distribution of total Cu, Pb, Hg, as in some paddy soils from the southern Jiangsu, China and the influencing factors [J]. Journal of Agro-Environment Science, 2006, 25(5): 1221-1227(in Chinese). doi: 10.3321/j.issn:1672-2043.2006.05.026
[12] YOUNG G, CHEN Y Q, YANG M. Concentrations, distribution, and risk assessment of heavy metals in the iron tailings of Yeshan National Mine Park in Nanjing, China [J]. Chemosphere, 2021, 271: 129546. doi: 10.1016/j.chemosphere.2021.129546 [13] 姜玉玲, 阮心玲, 杨玲, 等. 开封市城市土壤剖面Hg、As和Sb分布特征分析 [J]. 环境化学, 2017, 36(5): 1036-1046. doi: 10.7524/j.issn.0254-6108.2017.05.2016112903 JIANG Y L, RUAN X L, YANG L, et al. Distribution of Hg, As and Sb concentrations in urban soil profiles of Kaifeng City, Henan Province [J]. Environmental Chemistry, 2017, 36(5): 1036-1046(in Chinese). doi: 10.7524/j.issn.0254-6108.2017.05.2016112903
[14] 窦韦强, 安毅, 秦莉, 等. 农田土壤重金属垂直分布迁移特征及生态风险评价 [J]. 环境工程, 2021, 39(2): 166-172. DOU W Q, AN Y, QIN L, et al. Characteristics of vertical distribution and migration of heavy metals in farmland soils and ecological risk assessment [J]. Environmental Engineering, 2021, 39(2): 166-172(in Chinese).
[15] 孙子媛, 文雪峰, 吴攀, 等. 喀斯特地区典型风化剖面重金属超标程度及元素迁移特征研究 [J]. 地球与环境, 2019, 47(1): 50-56. SUN Z Y, WEN X F, WU P, et al. Excessive degrees and migration characteristics of heavy metals in typical weathering profiles in Karst areas [J]. Earth and Environment, 2019, 47(1): 50-56(in Chinese).
[16] 王钟, 范中亚, 杨忠勇, 等. “引江济淮”工程对安徽菜子湖水龄分布的影响 [J]. 湖泊科学, 2018, 30(6): 1576-1586. doi: 10.18307/2018.0609 WANG Z, FAN Z Y, YANG Z Y, et al. Effects of Water Diversion Project from the Yangtze River to Huaihe River on the water age distribution of Lake Caizi, Anhui Province [J]. Journal of Lake Sciences, 2018, 30(6): 1576-1586(in Chinese). doi: 10.18307/2018.0609
[17] LI C, DING S M, YANG L Y, et al. Diffusive gradients in thin films: Devices, materials and applications [J]. Environmental Chemistry Letters, 2019, 17(2): 801-831. doi: 10.1007/s10311-018-00839-9 [18] JIANG Z G, XU N, LIU B X, et al. Metal concentrations and risk assessment in water, sediment and economic fish species with various habitat preferences and trophic guilds from Lake Caizi, Southeast China [J]. Ecotoxicology and Environmental Safety, 2018, 157: 1-8. doi: 10.1016/j.ecoenv.2018.03.078 [19] 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: 13-14, 107-108. LU R K. Analysis method of soil agrochemistry[M]. China Agriculture Scientech Press, 2000: 13-14, 107-108(in Chinese).
[20] 董智今, 展秀丽, 丁小花. 毛乌素沙地西南缘不同土地利用类型土壤颗粒分形特征 [J]. 水土保持研究, 2022, 29(3): 43-48,56. doi: 10.3969/j.issn.1005-3409.2022.3.stbcyj202203007 DONG Z J, ZHAN X L, DING X H. Fractal features of soil particles under different land uses in the southwestern edge of the Mu Us sandy land [J]. Research of Soil and Water Conservation, 2022, 29(3): 43-48,56(in Chinese). doi: 10.3969/j.issn.1005-3409.2022.3.stbcyj202203007
[21] 方凤满, 武慧君, 姚有如, 等. 鸟粪对同里湿地公园土壤重金属及其形态的影响 [J]. 生态学报, 2018, 38(8): 2925-2933. FANG F M, WU H J, YAO Y R, et al. Heavy metal concentrations and speciation of soil affected by bird droppings in Tongli Wetland Park, East China [J]. Acta Ecologica Sinica, 2018, 38(8): 2925-2933(in Chinese).
[22] ZHANG H H, CHEN J J, ZHU L, et al. Anthropogenic mercury enrichment factors and contributions in soils of Guangdong Province, South China [J]. Journal of Geochemical Exploration, 2014, 144: 312-319. doi: 10.1016/j.gexplo.2014.01.031 [23] GUAN Q Y, WANG F F, XU C Q, et al. Source apportionment of heavy metals in agricultural soil based on PMF: A case study in Hexi Corridor, northwest China [J]. Chemosphere, 2018, 193: 189-197. doi: 10.1016/j.chemosphere.2017.10.151 [24] 赵津, 刘汝海, 金嘉欣, 等. 子牙新河下游湿地土壤重金属垂直分布及形态特征 [J]. 环境化学, 2016, 35(10): 2044-2050. doi: 10.7524/j.issn.0254-6108.2016.10.2016022001 ZHAO J, LIU R H, JIN J X, et al. Vertical distribution and speciation characteristics of heavy metals in wetlands soils of Ziyaxin River downstream [J]. Environmental Chemistry, 2016, 35(10): 2044-2050(in Chinese). doi: 10.7524/j.issn.0254-6108.2016.10.2016022001
[25] 郑国璋. 关中娄土剖面中重金属元素的垂直分布规律研究 [J]. 地球学报, 2008, 29(1): 109-115. doi: 10.3321/j.issn:1006-3021.2008.01.014 ZHENG G Z. The vertical distribution regularity of heavy metal elements in Guanzhong tier soil profile [J]. Acta Geoscientica Sinica, 2008, 29(1): 109-115(in Chinese). doi: 10.3321/j.issn:1006-3021.2008.01.014
[26] WARNKEN J, OHLSSON R, WELSH D T, et al. Antimony and arsenic exhibit contrasting spatial distributions in the sediment and vegetation of a contaminated wetland [J]. Chemosphere, 2017, 180: 388-395. doi: 10.1016/j.chemosphere.2017.03.142 [27] 张国伟, 张永波, 吴艾静, 等. 湿地植物对煤矿老窑水污染土壤中重金属的富集能力研究 [J]. 环境污染与防治, 2021, 43(10): 1244-1248. doi: 10.15985/j.cnki.1001-3865.2021.10.005 ZHANG G W, ZHANG Y B, WU A J, et al. Study on the accumulation ability of wetland plants to heavy metals in the soil polluted by acid mine drainage [J]. Environmental Pollution & Control, 2021, 43(10): 1244-1248(in Chinese). doi: 10.15985/j.cnki.1001-3865.2021.10.005
[28] 唐世琪, 刘秀金, 杨柯, 等. 典型碳酸盐岩区耕地土壤剖面重金属形态迁移转化特征及生态风险评价 [J]. 环境科学, 2021, 42(8): 3913-3923. doi: 10.13227/j.hjkx.202101066 TANG S Q, LIU X J, YANG K, et al. Migration, transformation characteristics, and ecological risk evaluation of heavy metal fractions in cultivated soil profiles in a typical carbonate-covered area [J]. Environmental Science, 2021, 42(8): 3913-3923(in Chinese). doi: 10.13227/j.hjkx.202101066
[29] KOSTASCHUK R, CHEN Z Y, SAITO Y, et al. Sedimentation rates and heavy metals in a macrotidal salt marsh: Bay of Fundy, Canada [J]. Environmental Geology, 2008, 55(6): 1291-1298. doi: 10.1007/s00254-007-1077-z [30] 史锐, 岳荣, 张红. 有色金属采选冶基地周边土壤中重金属纵向分层研究 [J]. 土壤通报, 2016, 47(1): 186-191. doi: 10.19336/j.cnki.trtb.2016.01.029 SHI R, YUE R, ZHANG H. Research on vertical distribution of heavy metal in soil around non-ferrous metal industry area [J]. Chinese Journal of Soil Science, 2016, 47(1): 186-191(in Chinese). doi: 10.19336/j.cnki.trtb.2016.01.029
[31] 张响荣, 罗红, 祝安安, 等. 武汉市某旱地自然土壤剖面中重金属迁移规律研究 [J]. 资源环境与工程, 2022, 36(3): 274-279. doi: 10.16536/j.cnki.issn.1671-1211.2022.03.002 ZHANG X R, LUO H, ZHU A N, et al. Study on the migration of heavy metals in natural soil profile of a dryland in Wuhan City [J]. Resources Environment & Engineering, 2022, 36(3): 274-279(in Chinese). doi: 10.16536/j.cnki.issn.1671-1211.2022.03.002
[32] 赵玉庭, 孙珊, 由丽萍, 等. 莱州湾沉积物粒度与重金属分布特征 [J]. 海洋科学, 2021, 45(3): 43-50. ZHAO Y T, SUN S, YOU L P, et al. Distribution characteristics of grain size and heavy metals of sediments in Laizhou Bay [J]. Marine Sciences, 2021, 45(3): 43-50(in Chinese).
[33] ZHOU W X, HAN G, LIU M, et al. Vertical distribution and controlling factors exploration of Sc, V, Co, Ni, Mo and Ba in six soil profiles of the Mun River Basin, Northeast Thailand [J]. International Journal of Environmental Research and Public Health, 2020, 17(5): 1745-1759. doi: 10.3390/ijerph17051745 [34] 胡青青, 沈强, 陈飞, 等. 重构土壤垂直剖面重金属Cd赋存形态及影响因素 [J]. 环境科学, 2020, 41(6): 2878-2888. doi: 10.13227/j.hjkx.201911023 HU Q Q, SHEN Q, CHEN F, et al. Reconstructed soil vertical profile heavy metal Cd occurrence and its influencing factors [J]. Environmental Science, 2020, 41(6): 2878-2888(in Chinese). doi: 10.13227/j.hjkx.201911023
[35] 李晋昌, 张红, 石伟. 汾河水库周边土壤重金属含量与空间分布 [J]. 环境科学, 2013, 34(1): 116-120. doi: 10.13227/j.hjkx.2013.01.027 LI J C, ZHANG H, SHI W. Concentrations of soil heavy metals and their spatial distribution in the surrounding area of Fenhe reservoir [J]. Environmental Science, 2013, 34(1): 116-120(in Chinese). doi: 10.13227/j.hjkx.2013.01.027
[36] BAI J H, XIAO R, CUI B S, et al. Assessment of heavy metal pollution in wetland soils from the young and old reclaimed regions in the Pearl River Estuary, South China [J]. Environmental Pollution, 2011, 159(3): 817-824. doi: 10.1016/j.envpol.2010.11.004 [37] 李俊莉, 宋华明. 土壤理化性质对重金属行为的影响分析 [J]. 环境科学动态, 2003, 28(1): 24-26. LI J L, SONG H M. Effects of soil physicochemical properties on heavy metal behavior [J]. Environmental Science Trends, 2003, 28(1): 24-26(in Chinese).
[38] ZHANG P Y, QIN C Z, HONG X, et al. Risk assessment and source analysis of soil heavy metal pollution from lower reaches ofYellow River irrigation in China [J]. Science of the Total Environment, 2018, 633: 1136-1147. doi: 10.1016/j.scitotenv.2018.03.228 [39] 王国梁, 周生路, 赵其国, 等. 菜地土壤剖面上重金属元素含量随时间的变化规律研究 [J]. 农业工程学报, 2006, 22(1): 79-84. doi: 10.3321/j.issn:1002-6819.2006.01.017 WANG G L, ZHOU S L, ZHAO Q G, et al. Spatial and temporal changes of soil heavy metal concentrations in vegetable cultivation land [J]. Transactions of the Chinese Society of Agricultural Engineering, 2006, 22(1): 79-84(in Chinese). doi: 10.3321/j.issn:1002-6819.2006.01.017
[40] 石东平, 刘秋荣. 工业园道路两侧土壤及行道树的叶片Cr富集与污染评价 [J]. 安全与环境学报, 2019, 19(5): 1803-1809. doi: 10.13637/j.issn.1009-6094.2019.05.043 SHI D P, LIU Q R. Chromium(Cr) enrichment and pollution assessment in soil and leaves of street-by trees on both sides of industrial park roads [J]. Journal of Safety and Environment, 2019, 19(5): 1803-1809(in Chinese). doi: 10.13637/j.issn.1009-6094.2019.05.043
[41] 戴树桂. 环境化学[M]. 2版. 北京: 高等教育出版社, 2006: 283-284. DAI S G. Environmental chemistry [M]. 2nd Edition. Beijing: Higher Education Press, 2006: 283-284(in Chinese).
[42] 王敬国. 生物地球化学: 物质循环与土壤过程[M]. 北京: 中国农业大学出版社, 2017: 369-370. WANG J G. Biogeochemistry-material cycle and soil process[M]. Beijing: China Agricultural University Press, 2017: 369-370(in Chinese).