Pb和Cd在塿土不同剖面土壤中的竞争吸附作用
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摘要
多种金属离子的共存影响土壤对重金属离子的吸附作用,从而影响其生物有效性和迁移特征。利用等温吸附方法研究了塿土不同发育层次土壤对Pb~(2+)、Cd~(2+)单一离子和两种离子共存的吸附特征。对于单一的离子吸附,Pb~(2+)在塿娄土耕层、黏化层和钙积层的分配系数为8.0、8.1和6.1,Langmuir方程最大吸附量为6.1、5.8和6.0 mmol kg~(-1);而Cd~(2+)的分配系数为4.2、7.1和4.7,最大吸附量为5.5、4.8和2.9 mmol kg~(-1);三种土壤对Pb~(2+)的吸附性能均强于对Cd~(2+)的吸附。当Pb~(2+)、Cd~(2+)共存时,两种离子间存在竞争吸附作用,致使Pb~(2+)、Cd~(2+)的吸附量均降低,Pb~(2+)、Cd~(2+)互为竞争性吸附离子的亲和力效应在0.8~0.9之间,竞争性的Langmuir吸附方程可用于描述Pb~(2+)、Cd~(2+)的竞争吸附。
The coexistence of various metal ions can affect their adsorption by soil, thus will affect the bioavailability and migration of these ions. The adsorption characteristics of single and competitive adsorption of Pb~(2+)and Cd~(2+)by different layers of Tier Soil were studied through batch adsorption experiences. The distribution coefficient of Pb~(2+)were, respectively, 8.0, 8.1 and 6.1, the maximum adsorption capacities of Langmuir equation were, respectively, 6.1,5.8 and 6.0 mmol kg~(-1), the distribution coefficient of single Cd~(2+)were, respectively, 4.2, 7.1 and 4.7, and the maximum adsorption capacities of Langmuir equation were, respectively, 5.5, 4.8 and 2.9 mmol kg~(-1)at cultivated, claying and calcic layer of Tier Soil. Pb~(2+)had stronger adsorption capacity than Cd~(2+)in three soils. The adsorption capacities of Pb~(2+)and Cd~(2+)decreased due to their competitive adsorption when they coexisted. The affinity effect between Pb~(2+)and Cd~(2+)was 0.8-0.9. And the competitive Langmuir adsorption equation could be employed to describe the competitive adsorption of Pb~(2+)and Cd~(2+)with high determined coefficient.
The coexistence of various metal ions can affect their adsorption by soil, thus will affect the bioavailability and migration of these ions. The adsorption characteristics of single and competitive adsorption of Pb~(2+)and Cd~(2+)by different layers of Tier Soil were studied through batch adsorption experiences. The distribution coefficient of Pb~(2+)were, respectively, 8.0, 8.1 and 6.1, the maximum adsorption capacities of Langmuir equation were, respectively, 6.1,5.8 and 6.0 mmol kg~(-1), the distribution coefficient of single Cd~(2+)were, respectively, 4.2, 7.1 and 4.7, and the maximum adsorption capacities of Langmuir equation were, respectively, 5.5, 4.8 and 2.9 mmol kg~(-1)at cultivated, claying and calcic layer of Tier Soil. Pb~(2+)had stronger adsorption capacity than Cd~(2+)in three soils. The adsorption capacities of Pb~(2+)and Cd~(2+)decreased due to their competitive adsorption when they coexisted. The affinity effect between Pb~(2+)and Cd~(2+)was 0.8-0.9. And the competitive Langmuir adsorption equation could be employed to describe the competitive adsorption of Pb~(2+)and Cd~(2+)with high determined coefficient.
引文
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[23]王维君,邵宗臣,何群.红壤粘粒对Co、Cu、Pb和Zn吸附亲和力的研究[J].土壤学报,1995,32(2):167-178.
[24]COVELO E F,VEGA F A,ANDRADE M L.Competitive sorption and desorption of heavy metals by individual soil components[J].Hazardous Materials,2007,140:308-315.
[2]孙波,周生路,赵其国.基于空间变异分析的土壤重金属复合污染研究[J].农业环境科学学报,2003,22(2):248-251.
[3]陈怀满.土壤一植物系统中的重金属污染[M].北京:科学出版社,1996.
[4]郑国璋.农业土壤重金属污染研究的理论与实践[M].北京:中国环境科学出版社,2007.
[5]宋伟,陈百,刘琳.中国耕地土壤重金属污染概况[J].水土保持研究,2013,20(2):203-208.
[6]ELLIOT H A,LIBERATI M R,HUANG C P.Competitive adsorption of heavy metals by soils[J].Environ.Qual,1986,15(3):214-219.
[7]ADHIKARI T,SINGH M V.Sorption characteristics of lead and cadmium in some soils of India[J].Geoderma,2003,114(1-2):81-92.
[8]SERRANO S,GARRIDO F,CAMPBELL C G,et al.Competitive sorption of cadmium and lead in acid soils of Central Spain[J].Geoderma,2005,124(1-2):91-104.
[9]LU S G,XU Q F.Competitive adsorption of Cd,Cu,Pb and Zn by different soils of Eastern China[J].Environ Geol,2009,57:685-693.
[10]GOMES P C,FONTES M P F,SILVA A G DA,et al.Selectivity sequence and competitive adsorption of heavy metals by Brazilian soils[J].Soil Sci.Am.J,2001,65:1115-1121.
[11]APPEL C,MA L Q,RHUE R D,REVE W.Sequential sorption of lead and cadmium in three tropical soils[J].Environmental Pollution,2008,155:132-140.
[12]QIN F,WEN B,SHAN X-Q,et al.Mechanisms of competitive adsorption of Pb,Cu,and Cd on peat[J].Environmental Pollution,2006,144:669-680.
[13]JALALI M,MORADI F.Competitive sorption of Cd,Cu,Mn,Ni,Pb and Zn in polluted and unpolluted calcareous soils[J].Environ Monit Assess,2013,85:8831-8846.
[14]王岚,王亚平,徐春雪,等.水稻土中重金属元素Cd、Pb的竞争吸附[J].地质通报,2012,31(4):601-607.
[15]林青,徐绍辉.土壤中重金属离子竞争吸附的研究进展[J].土壤,2008,40(5):706-711.
[16]LIMOUSIN G,GAUDET J-P,CHARLET L,et al.Sorption isotherms:A review on physical bases,modeling and measurement[J].Applied Geochemistry,2007,22:249-275.
[17]MURAL V,AYLMORE L A G.Competitive adsorption during solute transport in soils.I.Mathematical models[J].Soil Sci,1983,135(3):143-150.
[18]XUE W B,YIA H,ZHANG Z Q,et al.A new competitie adsorption isothermal model of heavy metals in soils[J].Pedosphere,2009,19(2):251-257.
[19]BRADL H B.Adsorption of heavy metal ions on soils and soils constituents[J].Journal of Colloid and Interface Science,2004,277:1-18.
[20]MESQUITA M E,SILVA J M V E.Preliminary study of p H effect in the application of Langmuir and Freundlich isotherms to Cu-Zn competitive adsorption[J].Geoderma,2002,106:219-234.
[21]PARDO M.T.Sorption of lead,copper,zinc,and cadmium by soils:effect of nitriloacetic acid on metal retention,Communications in Soil Science and Plant Analysis,2006,31(1-2):31-40.
[22]APPEL C,MA L Q.Concentration,p H,and Surface Charge Effects on Cadmium and Lead Sorption in Three Tropical Soils[J].Environ.Qual,2002,31(2):581-589.
[23]王维君,邵宗臣,何群.红壤粘粒对Co、Cu、Pb和Zn吸附亲和力的研究[J].土壤学报,1995,32(2):167-178.
[24]COVELO E F,VEGA F A,ANDRADE M L.Competitive sorption and desorption of heavy metals by individual soil components[J].Hazardous Materials,2007,140:308-315.