盐渍化条件下污灌区土壤重金属的释放特征
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摘要
以受盐渍化和重金属双重胁迫的天津污灌区土壤为研究对象,通过径流实验和淋溶实验,探讨盐渍化土壤重金属的释放特征及对水质安全的影响.研究的盐分种类为污灌区土壤盐渍化进程中的主要盐分Na Cl,设置的盐度梯度为7个,添加质量分数为0(CK)~5%,污染土壤中Cd、Pb和Hg含量分别为2.21、234.1和0.601 mg·kg~(-1).结果表明,(1)不同盐度处理下产流所需时间为(51'25″±15″),盐度对径流产流时间影响不显著;(2)随着Na Cl盐度梯度的提高,土壤径流和淋溶液中Cd、Pb和Hg的累计释放量均显著上升.Cd累计释放量从CK的53.40μg·kg~(-1)(径流)和55.63μg·kg~(-1)(淋溶)分别提高到5%Na Cl盐度处理的122.56μg·kg~(-1)(径流)和135.79μg·kg~(-1)(淋溶),Pb的累计释放量从CK的168.30μg·kg~(-1)(径流)和94.44μg·kg~(-1)(淋溶)分别提高到5%Na Cl盐度处理的340.68μg·kg~(-1)(径流)和201.93μg·kg~(-1)(淋溶),Hg的累计释放量从CK的39.66μg·kg~(-1)(径流)和9.60μg·kg~(-1)(淋溶)分别提高到5%Na Cl处理的89.37μg·kg~(-1)(径流)和11.97μg·kg~(-1)(淋溶).同时,径流及淋溶液中可溶态重金属含量显著上升,颗粒态含量有所下降,其所占比例也显著下降.Cl-含量与重金属累计释放量之间关系可以用线性或对数模型拟合.(3)高盐度处理下径流和淋出液中Cd浓度超过地下水水质Ⅲ类标准,对环境及地下水存在一定威胁;径流和淋溶前期Pb浓度超过Ⅲ类标准;径流和淋溶过程中Hg浓度均超过Ⅲ类标准,风险较高.本研究结果表明高强度降雨强度下污染农田土壤重金属释放风险不可忽视.
This study was designed to understand the release characteristics of Cd,Pb and Hg from soil in the wastewater-irrigated area of Tianjin City,and to assess its risk to groundwater contamination under different salinity level( 0 ~ 5%) by using simulated rainfall tests and leaching experiments. The amounts of metals in tested soil were 2.21 mg·kg~(-1) for Cd,234.1 mg·kg~(-1) for Pb and 0.601 mg·kg~(-1) for Hg,respectively. The results showed that,(1)Runoffs generated at( 51'25″±15″) after simulated rainfall tests started,which were irrelevant to soil salinity levels.(2)As Na Cl spiked into soil,contents of heavy metals in runoffs/leachates markedly increased,from 53.40( runoffs)/55.63( leachates) μg·kg~(-1) at CK to 122.56/135.79 μg·kg~(-1) at 5% Na Cltreatment for Cd,from 168.30/94.44 μg·kg~(-1) to 340. 68/201. 93 μg·kg~(-1) for Pb,and from 39. 66/9. 60 μg·kg~(-1) to 89. 37/11. 97 μg·kg~(-1) for Hg,respectively. It was also found that the dissolved metal in the runoffs/leachates significantly increased,while the particulate metal distinctly decreased with the increasing soil salinity levels. Besides,quantitative release amounts of heavy metals from soils in the runoffs/leachates as functions of Cl-contents in soils could be simulated by the linear or logarithm model.(3)Concentrations of Cd in the runoffs/leachates under the high soil salinity levels( 2% and5%),concentrations of Pb in the early stage of experiments under all studied soil salinity levels,and concentrations of Hg under all studied soil salinity levels were comparatively high,more than Groundwater Quality Standard for Class Ⅲ,which may cause a high risk to groundwater through rainfall.
This study was designed to understand the release characteristics of Cd,Pb and Hg from soil in the wastewater-irrigated area of Tianjin City,and to assess its risk to groundwater contamination under different salinity level( 0 ~ 5%) by using simulated rainfall tests and leaching experiments. The amounts of metals in tested soil were 2.21 mg·kg~(-1) for Cd,234.1 mg·kg~(-1) for Pb and 0.601 mg·kg~(-1) for Hg,respectively. The results showed that,(1)Runoffs generated at( 51'25″±15″) after simulated rainfall tests started,which were irrelevant to soil salinity levels.(2)As Na Cl spiked into soil,contents of heavy metals in runoffs/leachates markedly increased,from 53.40( runoffs)/55.63( leachates) μg·kg~(-1) at CK to 122.56/135.79 μg·kg~(-1) at 5% Na Cltreatment for Cd,from 168.30/94.44 μg·kg~(-1) to 340. 68/201. 93 μg·kg~(-1) for Pb,and from 39. 66/9. 60 μg·kg~(-1) to 89. 37/11. 97 μg·kg~(-1) for Hg,respectively. It was also found that the dissolved metal in the runoffs/leachates significantly increased,while the particulate metal distinctly decreased with the increasing soil salinity levels. Besides,quantitative release amounts of heavy metals from soils in the runoffs/leachates as functions of Cl-contents in soils could be simulated by the linear or logarithm model.(3)Concentrations of Cd in the runoffs/leachates under the high soil salinity levels( 2% and5%),concentrations of Pb in the early stage of experiments under all studied soil salinity levels,and concentrations of Hg under all studied soil salinity levels were comparatively high,more than Groundwater Quality Standard for Class Ⅲ,which may cause a high risk to groundwater through rainfall.
引文
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Yong R N,Sheremata T W.2011.Effect of chloride ions on adsorption of cadmium from a landfill leach[J].Canadian Geotechnical Journal,28(3):378-387
张宇峰,姚敏,邵春燕,等.2005.酸雨和有机配体(EDTA)对已污染红壤中稀土元素释放的研究[J].农业环境科学学报,24(1):64-68
Zheng Y,Luo X,Zhang W,et al.2016.Transport mechanisms of soilbound mercury in the erosion process during rainfall-runoff events[J].Environmental Pollution,215:10-17
朱昌宇,黄道友,朱奇宏,等.2012.模拟降雨条件下污染土壤中重金属元素径流迁移特征[J].水土保持学报,26(4):49-53
Zuo X J,Fu D F,Li H.2013.Variation Characteristics of Mercury in Speciation during Road Runoff for Different Rainfall Patterns[J].Clean-Soil Air Water,41(1):69-73
Antonious G F,Turley E T,Sikora F,et al.2008.Heavy metal mobility in runoff water and absorption by eggplant fruits from sludge treated soil[J].J Environ Sci Health B,43(6):526-532
Bayraktar S,Yilmaz T.2008.Measures to diminish leaching of heavy metals to surface waters from agricultural soils[J].Desalination,226(1):89-96
Boekhold A E,Temminghoff E J M,Van der Zee S E A T.2010.Influence of electrolyte composition and p H on cadmium sorption by an acid sandy soil[J].European Journal of Soil Science,44(1):85-96
Bonten L T C,R9mkens P F A M,Brus D J.2008.Contribution of heavy metal leaching from agricultural soils to surface water loads[J].Environmental Forensics,9(2/3):252-257
Chen W,Hou Z,Wu L,et al.2010.Evaluating salinity distribution in soil irrigated with saline water in arid regions of northwest China[J].Agricultural Water Management,97(12):2001-2008
高扬,朱波,汪涛,等.2008.人工模拟降雨条件下紫色土坡地生物可利用磷的输出[J].中国环境科学,28(6):542-547
Ghallab A,Usman A.2007.Effect of sodium chloride-induced salinity on phyto-availability and speciation of Cd in soil solution[J].Water Air and Soil Pollution,185(1/4):43-51
He Z L,Zhang M K,Calvert D V,et al.2004.Transport of heavy metals in surface runoff from vegetable and citrus fields[J].Soil Science Society of America Journal,68(5):1662-1669
Kibet L C,Allen A L,Church C,et al.2013.Transport of dissolved trace elements in surface runoff and leachate from a Coastal Plain soil after poultry litter application[J].Journal of Soil&Water Conservation,68(May/June 2013):212-220
Linde M,9born I,Gustafsson J P.2007.Effects of changed soil conditions on the mobility of trace metals in moderately contaminated urban soils[J].Water,Air,&Soil Pollution,183(1):69-83
鲁如坤.2000.土壤农业化学分析方法[M].北京:中国农业科技出版社
罗璇,李军,张鹏,等.2013.中国雨水化学组成及其来源的研究进展[J].地球与环境,41(5):566-574
Muyen Z,Moore G A,Wrigley R J.2011.Soil salinity and sodicity effects of wastewater irrigation in South East Australia[J].Agricultural Water Management,99(1):33-41
农业部环境监测总站.1999.1996-1999第二次中国污水灌溉普查报告[Z].
Smith S R.2009.A critical review of the bioavailability and impacts of heavy metals in municipal solid waste composts compared to sewage sludge[J].Environment International,35(1):142-156
Tian H,Kong L,Megharaj M,et al.2017.Contribution of attendant anions on cadmium toxicity to soil enzymes.[J].Chemosphere,187:19-26
王美丽,李军,岳甫均,等.2011.天津盐渍化农田土壤盐分变化特征[J].生态学杂志,30(9):1949-1954
王婷,王静,孙红文,等.2012.天津农田土壤镉和汞污染及有效态提取剂筛选[J].农业环境科学学报,31(1):119-124
王祖伟,张辉.2005.天津污灌区土壤重金属污染环境质量与环境效应[J].生态环境,14(2):211-213
尹建道,吴春森,杨进军,等.2006.天津市盐碱土面积考证及其动态分析[J].天津农业科学,12(1):1-4
Yong R N,Sheremata T W.2011.Effect of chloride ions on adsorption of cadmium from a landfill leach[J].Canadian Geotechnical Journal,28(3):378-387
张宇峰,姚敏,邵春燕,等.2005.酸雨和有机配体(EDTA)对已污染红壤中稀土元素释放的研究[J].农业环境科学学报,24(1):64-68
Zheng Y,Luo X,Zhang W,et al.2016.Transport mechanisms of soilbound mercury in the erosion process during rainfall-runoff events[J].Environmental Pollution,215:10-17
朱昌宇,黄道友,朱奇宏,等.2012.模拟降雨条件下污染土壤中重金属元素径流迁移特征[J].水土保持学报,26(4):49-53
Zuo X J,Fu D F,Li H.2013.Variation Characteristics of Mercury in Speciation during Road Runoff for Different Rainfall Patterns[J].Clean-Soil Air Water,41(1):69-73