長江三角洲地區(qū)土壤和水稻重金屬污染特征研究_英文_

1、Characteristics and Transformation of Heavy Metal Pollution in Soil and Rice of Yangtze River Delta RegionXIAO Jun-qing 1,YUAN Xu-yin 1,2*,LI Ji-zhou 11College of Environmental Science and Engineering ,Hohai University ,Nanjing 210098;2Key Laboratory of Integrated Regulation and Resource Development

2、 on Shallow Lakes ,Ministry of Education ,Nanjing 210098Abstract Objective Characteristics of heavy metal pollution in soil and rice of Yangtze River Delta Region were studiedMethod Heavy metal contents of more than 150samples in Yangtze River Delta region were determined so as to make the soil envi

3、ronmental quality assessment and study the content distribution ,transformation and distribution characteristics of heavy metals in different regions and different plant partsResult The Yangtze River Delta region was polluted by Cd ,Pb ,Cr ,Cu and Zn ,among them Cd pollution was the most serious ;Pb

4、 ,Cu and Zn took second place ;Cr appears the lightest ;And there was almost no Hg and As pollution in this areaThe Nemero pollution index of soil was0880which was at the alert levelCd ,Cr ,Cu ,Hg and Zn in rice grains exceeded the background valuesHeavy metal pollutions in soils divid-ed by regions

5、 were in order of Taihu Lake region Zhejiang region Yangtze River region and urban areas towns and rural areasHeavy metal pollutions in soil divided by the uptake level were in order of rhizosphere soil rice straw rice grainTransformation coefficients were inorder of Cd Cu Zn As Hg Pb CrDistribution

6、 coefficients were in order of Zn Cr Cd Cu Hg Pb AsConclu-sion There were larger value ranges of contaminated elements in the Yangtze River Delta Region ,moreover individual samples had serious pol-lution ,so the prevention and control of heavy metal pollution should be strengthenedKey words Heavy m

7、etals ;Yangtze River Delta Region ;Soil ;RiceReceived :April 19,2010Accepted :May 19,2010Supported by the Land and Resource Survey Project of China Geo-logical Survey (GZTR20060201;Natural Science Foundation of Hohai University (2008432511*Corresponding authorE-mail :yxy_hjyhhueducnWith the speed up

8、 of industrialization process and the in-crease of population ,heavy metal pollution has become a global problemAgricultural soil is a kind of special soil which is affected by human activities strongly 1,and its environ-mental quality is closely related to human healthSoil pollutant sources mainly

9、come from industry wastes and the massive application of pesticides and chemical fertilizersPollutants can enter into soil through irrigation water and also can result in soil pollution through the dry and wet deposition of particles (including heavy metals ,carcinogenic substances ,etc in airWith t

10、he lapse of time ,the contents of heavy metals like Pb ,Cu ,Zn ,etc in farmland surface soil have a trend of in-crease 2Due to the absorption of crops ,heavy metal ele-ments are transferred from soil into the rhizome ,leaf and grain of crops so as to result in the heavy metal pollution ofcrops and e

11、ndanger human health 3Here ,the distribution of heavy metals in farmland soil and the pollution characteristics of heavy metals in soil-rice system in the Yangtze River DeltaRegion were studiedMaterials and MethodsThe collection and pretreatment of samplesMain cities in the Yangtze River Delta Regio

12、n included Yangzhou ,Taizhou ,Nantong ,Nanjing ,Zhenjiang ,Chang-zhou ,Wuxi ,Suzhou ,Shanghai ,Huzhou ,Jiaxing ,Hang-zhou ,Shaoxing ,Ningbo ,Zhoushan and Taizhou (Fig1Two urban areas and county-level areas were selected fromeach prefecture-level city ,among them the urban areas wereset as class regi

13、on ,and the county-level areas were set as class regionThen ,one sampling site was set in the class region of each sampling region ,and two sampling sites were set in the class region by GPS location ,so sampling sites were distributed in each region uniformlyAbout 500g rhizo-sphere soil was collect

14、ed from each sampling site and oven dried in an incubator (40When impurities like plantroots ,stoneshad be removed ,all soil samples were grinded and went through a 20-mesh sieve ;Besides ,each 500gsample of rice rhizome and rice grain were respectively col-lected ,stored in hermetic bags and then m

15、ade screening ,dry ,classification and labelling in labsFig1Distribution of sampling sites in Yangtze River Delta RegionResources and EnvironmentAgricultural Science Technology ,2010,11(4:148151,163Copyright 2010,Information Institute of HAASAll rights reservedSample analysisContents of Cd,Pb,Zn,Cr

16、and Cu were determined by mass spectrometric method,and the instrument was plasma mass spectrometer(XSERIES ICP-MSContents of As and Hg were determined by atomic fluorescence spectrometry, and the instrument was atomic fluorescence spectrometer (AFS-230ESoil environmental quality assessmentPresent s

17、ituation of soil environmental quality was evalua-ted by the method of single factor pollution index and Nemer-ow comprehensive pollution index recommended by China Green Food Development CenterThe calculation formula of single factor index method was:Pi =ci/SiWhere Piwas the environmental quality i

18、ndex of pollutanti in soil;ciwas the measured concentration(mg/kgof pollu-tant i;Siwas the evaluation standard(mg/kgof pollutant i, and the evaluation was conducted by taking environmental background value and the national secondary standard for soilenvironment as reference;Pi 1,pollution;Pi1or Pi=1

19、,no pollutionThe calculation formula of Nemerow comprehensive pol-lution index method was:Pc =Max Pi2+(1/nPi2/21/2Where Pcwas Nemerow comprehensive pollution indexSoilclassification standard was showed in Table1(where Pcvalue was by taking the national secondary standard as referenceTable1Soil class

20、ification standardLevel Pollution level1P c07Safe and clean207P c1Alert level but clean31P c2Light pollutionSoil was polluted lightly;Crops began to be polluted42P c3Medium pollutionSoil and crops wereboth polluted moderately5P c3Heavy pollutionSoil and crops hadbeen both polluted seriouslyThe distr

21、ibution,transformation and allocation of heavy metal elementsThe transformation coefficient and distribution coefficient of every heavy metal in soil,stem and fruit were calculated as follows:Transformation coefficient=Element content in rice rhi-zome/Elernent content in rhizosphere soilDistribution

22、 coefficient=Element content in rice fruit soil/Elernent content in rice rhizomeResults and AnalysisThe distribution law of heavy metals in soil and rice fruit The distribution of heavy metals in soil samples Deter-mination results of heavy metals in soil samples were showed in Table2Table2Content o

23、f heavy metals in soilElements Samples Meanmg/kgRangemg/kgBackgroundvalue4mg/kgMean/backgr-ound valueSamples excee-ded backgr-ound valueSoil quality stan-dard(levelmg/kgExceededsamplepercentageHg15701400407801608944056 As1577801901800800099622500 Cd157033008138150142391420351 Pb157323011128968243013

24、31213000 Cr15774522214191907094105943000 Cu993600990265802590139771002 Zn99105603060470407750136702002Results(Table2showed that the means of Hg and As in soil in the Yangtze River Delta Region were all less than their background values,but Cd,Pb,Cr,Cu and Zn all had different degrees of pollutionThe

25、 means of metal elements of many samples were more than their environmental back-ground values,among them Cd,Pb,Cu and Zn were the most obvious,which were239,133,139and136times of their background values,respectivelyAmong all samples, compared with the national secondary standard for soil quali-ty,C

26、d had the most number of exceeding standard samples, which reached51and accounted for325%in total number of samples;Pb had no exceeding standard samples,but77%of them had exceeded the background valuePb pollution mainly came from the waste gas of traffic emission5,arrived in farmland soil by the dry

27、 and wet deposition of pollutants and aggravated by the increasingly developmental transportation net of the Yangtze River Delta RegionBesides,the pollution of heavy metals in soil was closely related to the soil type6, irrigation water and industrial activities7The distribution of heavy metals in r

28、ice fruit Content analysis on heavy metal elements in rice fruit was showed in Table3Results showed that rice rhizosphere soil had been polluted by heavy metals,and rice fruits also suffered from different degrees of heavy metal pollutionThe means of Cd, Cr,Cu,Hg and Zn were313,268,149,114and109 tim

29、es of their background values,rspectively,among them 2950%,576%and144%of As,Cd and Pb samples had exceeded the National Standard for Grain Sanitation of ChinaThereby,rice in the Yangtze River Delta Region had com-monly suffered from the pollution of heavy metal elements, even some samples had suffer

30、ed from heavy pollution,which had exceeded the limit valueThe mean of As was less than its background value in rhizosphere soil and was also less than its background value in rice fruit,but the grain sanitation standard of As was relatively low,and it still had many sam-ples to exceed the sanitation

31、 standardThe absorption of As in rice was related to the pH value of soil and the effect of phosphorus elementSome researches suggested that phos-phorus could inhibit the absorption of As by plants89,but the uptake of As by plants would increase with the increase of phosphorus concentration under th

32、e same concentration of As10The content of Pb in rice seed was relatively small, which was related to its bioavailability941XIAO Jun-qing et alCharacteristics and Transformation of Heavy Metal Pollution in Soil and Rice of Yangtze River Delta RegionTable3Contents of each heavy metal in rice grainEle

33、ments Samples Meanmg/kgRangemg/kgBackgroundvaluemg/kgMean/backg-round valueSamples excee-ded backgr-ound valueFood hygienestandardmg/kgSamplesexceededstandardHg139000660001800174000581138690020 As1390130000300034000185007033601541 Cd1390065700054069240021031291030208 Pb139009720039502330028800338002

34、02 Cr139019040057508066007102682137Cu139520001800090100349101490123Zn139227300138700416400207900109387Soil environmental quality assessmentBecause the pollution of soil heavy metals was closely re-lated to industrial economic activities,the research area was divided into three regions,Yangtze River

35、region(Nanjing, Yangzhou,Taizhou,Nantong,Zhenjiang,Changzhou,Jian-gyin,Zhangjiagang and Taicang,Taihu Lake region Shanghai,Wuxi(except for Jiangyin,Suzhou(except for Zhangjiagang and Taicang,Huzhou and Jiaxingand Zhe-jiang region(Hangzhou,Shaoxing,Ningbo,Zhoushan and TaizhouThe evaluating index for

36、soil heavy metal pollution of studied regions was showed in Table4Table4Evaluating index for soil heavy metal pollutionRegion BenchmarkPiHg As Cd Cr Pb Cu ZnPcYangtze River region A054098153130118148160143 B020031080024009031044061 Taihu Lake region A067087253121135154168205 B03403214302601003406110

37、7 Zhejiang region A089061268115153368240291 B034023129023012070083099 Whole basin A090098239105133139136194 B029029117024011037054088 A and B are with background value4and national secondary standard as benchmark respectivelyResults(Table4showed that Piof As and Hg were lessthan1,which indicated tha

38、t soil in the studied area didn't suf-fer from the pollution of the2elements basically,while Piof Cd,Zn,Pb,Cu and Cr were more than1,which indicated that pollutants had entered into soilAccording to Pc,soilquality of the Yangtze River region was relatively good(Pc07,and it was at the level of sa

39、fe and cleanThe biological toxicity of Cd was much higher than those of the other ele-ments11,so the main pollutant in this region was CdThe mean of Cd had exceeded its background value,but it didn't exceed standardTaihu Lake region belonged to light pollutiongenerally(Pc1,and its main pollutant

40、 was Cd which had exceeded standardZhejiang region was at alert level(07Pc1,and its main pollutants were Cd,Cu and Zn,among them Cd had exceeded standardOn the whole,the soil com-prehensive index of whole basin was088,which was at alert level,and heavy metal pollutions in soil divided by regions wer

41、e in order of Taihu Lake regionZhejiang regionYan-gtze River region,furthermore there was significant spatial difference in the distributions of heavy metal elementsThe distribution,transformation and allocation of heavy metal elementsThe content distribution,transformation and distribution coeffici

42、ent of heavy metal elements in different regions and dif-ferent parts of plant were showed in Table56Table5Distribution of heavy metal content in different region and different parts of rice mg/kg Region Hg As Cd Cr Pb Cu ZnSoil01620690038072270325705430128700137073003407317031140323010310 Whole bas

43、in0143072003507297031450369010850 Rhizome00408355023308411854273859060068034703370825202326296506 Whole basin0061534703320833190226396350 Fruit000590140050020201005292222000670130067018900955202326 Whole basin000660130066019000975222273Result(Table5showed that whetherclass region orclass region,cont

44、ents of determined elements were in order of rhizosphere soilrice strawrice grainThereby,every part in rice all had interception effects on the heavy metal ele-mentsTransformation coefficient and allocation coefficient embodied the degree of interception effectResult(Table6 showed that transformatio

45、n coefficients were in order of CdCuZnAsHgPbCr,and allocation coefficients were in order of ZnCrCdCuHgPbAs, which indicated that soil-rice system had the strongest inter-051Agricultural ScienceTechnology Vol11,No4,2010ception effect on Cr and Pb ,but had the weakest interception effect on CdIn contr

46、ary ,the pollution of Cd in soil was most harmful to human body and biosphereThe degree of inter-ception effect and the severity of soil heavy metals didn't de-pend on the total content completely ,and also depended on the chemical speciation 12,so the available fraction of Cd in soil was highTa

47、ble 6Transformation and allocation coefficient of heavy metals in different regionElement Conversion coefficient Whole basin Distribution coefficient Whole basinHg 025050043014010010As 051048048004004004Cd 061099095021020020Cr 001001001024023023Pb 006007006005005005Cu 050081072019020020Zn04606305903

48、8036036In rhizosphere soil ,contents of Hg ,Cd ,Pb ,Cu and Zn were in order of class region class region ,and the con-tent of As was in order of class region class region ,but there was little difference in Cr content between class region and class region ,which was related to human activities and i

49、ndustrial typeclass region was mostly distrbuted in subur-ban area around which there were many industrial and com-mercial districts ,and human activities were frequent ;class region was mostly distributed in country-level farmland protec-tion area ,where pollution sources were relatively fewAmong t

50、he studied elements ,the ratios of mean /background value of As and Cr were the minimum ,which were 098and 105,re-spectively ,and there were almost no extraneous pollution ,so their content levels in class region and class region were mostly caused by the background-value differenceThe distri-bution

51、 of Cu in rice rhizome was the same as that in rhizo-sphere soil ,and it was in order of class region class re-gionExcept Cu ,distributions of the other elements in rice rhizome were contrary to those in rhizosphere soil ,while the distributions of them in grains agreed with those in rhizosphere soi

52、l ,that was ,contents of heavy metals in the rhizosphere soil of class region were relatively high ,while contents of them in rice rhizome and grain were relatively low ,which indi-cated that the interception effect of rice in class region was more than that in class regionExcept As and Cr ,the tran

53、s-formation coefficients of the other elements were in order of class region class region ,which was related to the pH value and use patterns of landConclusionThe rapid development of urbanization ,industrialization and agricultural intensification in the Yangtze River Delta Re-gion has made soil su

54、ffer from different degrees of pollution ,the degree and characteristics of pollution and the accumula-tion ability of crops are closely related to the pollution charac-teristics of typical industries ,parent materials and soil typesThere is significant spatial differences in the distribution of hea

55、vy metal in soilsThere is the most serious heavy metal pollution in Taihu Lake region ,which has belonged to lightpollution level ,and crops begin to be polluted with increasing health riskGenerally ,the pollution of heavy metals in class region is more than that in class regionTransformation coeffi

56、cients are in order of Cd Cu Zn As Hg Pb Cr ,and allocation coefficients are in order of Zn Cr Cd Cu Hg Pb AsCd pollution is the most serious ,so it is sug-gested that related institutions should strengthen the supervi-sion for Cd inputBesides ,the ranges of contaminated ele-ments are relatively large ,and individual samples have seri-ous pollution ,so the control and prevention for heavy metal pollution should be enhancedReferences1LI XL (李秀蘭,HU XF (胡雪峰Study on pollution situation andenrichment regulations of some popular vegetables for heavy met-als in Shanghai (上海郊區(qū)蔬菜重金屬污染現(xiàn)狀及累積規(guī)律研究J Chem