Distribution and Risk Assessment of Soil Heavy Metals in the Main Grain Producing Area of China

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1 Distibution and Risk Assessment of Soil Heavy Metals in the Main Gain Poducing Aea of China Mei Shan* 1,, Xun Wang 3 1 College of Resouces and Envionment, Shandong Agicultual Univesity, Taian, Shandong 71018, China School of Touism, Taishan Univesity, Taian, Shandong 71000, China 3 Taian Envionmental Potection Bueau, Taian, Shandong 71000, China Abstact This study focuses on the soil in Jiangnan city in China using multi-taget geochemical suvey data, with statistical methods and Acgis platfom, togethe with classification map of agicultual land as the base map. We calculate the content of heavy metals in each plot using: the single facto index method, Nemeow index and the potential ecological isk index method to evaluate the isk of 7 kinds of soil heavy metal content. The aveage contents of some metals investigated wee lowe than the cultivated soil backgound values of China. The aea of cultivated soil affected by human activities is not obvious. The single index of heavy metals in ode of size is Hg<Cu<Cd<Zn<C>As<Pb. Cultivated soil envionmental quality of famland with Nemeow index of , shows that the aea of cultivated soil belonging to no degee. In a handful of cultivated soil aeas, heavy metal content and evaluation unit wee used to achieve medium ecological isk level of the content of heavy metal element. Othes ae mild ecological hazads. Cultivated land soil ecological isk does not exist in geneal. Keywods - Famland soil; chaacteistics of heavy metal; isk assessment I. I. INTRODUCTION Famland is the essential mateial foundation fo the agicultual poduction and the most basic living condition fo the mankind[1]. With the apid development of the national economy, the poblem of famland soil, especially the heavy metal is becoming moe and moe seious in China. As the of heavy metals in soil has the chaacteistics of concealment, had degadation, social hamfulness and mobility. Heavy metal effects on soil micobial floa, ecological species and micobial pocess, theeby affecting the ecosystem stuctue and function, though the food chain constitute a potential theat in the human body accumulation []. Accoding to Ministy of Land and Resouces of the People's Republic of China estimation, China's annual heavy metal eached 100 million tons of gain, esulting in the diect economic losses exceeded 00 billion yuan[3]. The heavy metal is one of the main easons on causing the agicultual poduct quality and safety and the poblem of heavy metal has caused the attention of the counties all ove the wold. Thee have been a lot of scholas and pofessionals to cay out a moe in-depth study[4][5][6]. With apid industial poduction of China and agicultual modenization pace acceleate, the aea of aable land soil heavy metal is moe and moe seious as one of the outstanding envionmental poblems[7]. City of Jiangnan in main gain poducing aea should be paid much attention to the distibution of the heavy metals in cultivated soil. The dawing in ode to undestand the degee of human contamination of famland in the study aea, on the basis of domestic and foeign elated eseach. The ecological isk of heavy metals in aable soil was analyzed and evaluated by using many methods. The aim is to find the factos and distibution of heavy metals in the famland of the main gain poducing aeas. II. MATERIALS AND METHODS A. Oveview of Reseach Aea The city is located in Jiangnan. It has a topical monsoon climate, with fou diffeent seasons, plenty of sunshine and good ainfall and vey suitable fo cop gowth. Soil type is divided into thee subclass such as saline soil, fluvo aquic soil and paddy soil. Including five categoies saline soil, paddy soil, gleyed paddy soil etc. The city is the county economic competitiveness hunded counties (cities), and its fist, second and tetiay industies ae elatively well developed. It is vey suitable fo cop cultivation. B. Data Collection and Collation The study use change in the status quo suvey esults figue (1:5000) of the city in 011 as woking map, the evaluation unit is extacted fom the woking base map of famland patten. Using the multi-objective egional geochemical suvey esults data and spatial data intepolation intepolation by AcGIS softwae to get each assessment unit of seven kinds of heavy metal pollutants as cadmium, lead, chomium, coppe, zinc, mecuy, asenic. C. Methods fo Heavy Metal Pollution Assessment of Aable Soil 1) Methods Fo the Assessment of Heavy Metal Pollution in Cultivated Soils In this study, use single facto index method, Geological index accumulates and Nemeow index method to evaluate the famland soil heavy metals index in the city. DOI /IJSSST.a ISSN: x online, pint

2 The single facto index is calculated by the measued values of the heavy metals and the coesponding values of the citeia. This study use the backgound value of soil element in Jiangsu povince as the standad value. The accumulation index of vaious heavy metals is calculated by Equation (1). Igeo=log(Cn/1. 5Bn) (1) evey symbol is expessed as follows: Igeo-cumulative index; Cn-Detemination of a heavy metal element; Bn-Backgound value of a heavy metal element. Nemeow index both to take into account the single heavy metal pollutants of the aveage value and the maximum value, and pominent in the study aea ae the main heavy metals contibutions, but also eflect the contibution of diffeent heavy metal pollutants on soil envionmental quality value. The Equation is : 1 1 n () P [ (p ) ( p ) ] compehens ive i i,max i 1 n evey symbol is expessed as follows: Pcompehensive-Nemeow index; Pi-Pollution index of heavy metals in soil; N- Species numbe of heavy metals in soil; Pi, max-the index of heavy metals in the soil of the fist I species was the maximum. )Ecological isk assessment of heavy metal in famland soil The ecological isk assessment in famland soil heavy metals using potential ecological index evaluation method. The Equation is : i i i i i i i C C / C; E T C ; RI E (3) f measued Evey symbol is expessed as follows: RI-Compehensive ecological hazad index of seven kinds of heavy metal elements in the egion; Ei-Potential ecological isk index of heavy metal elements i; Ti-The toxic coefficient of the heavy metal elements in the I species, which eflects the heavy metal toxicity. The toxic coefficients of As, Cd, Cu, C, Zn, Hg, Pb wee 10, 30,, 5, 40, 5, 1, espectively[8]; Cfi-The coefficient of the heavy metal elements ; Cimeasued-Detemination of heavy metal elements ; Cin-The standad value fo the evaluation of heavy metal elements in the I species, the study used the element backgound value of China. III. MODELRESULTS AND DISCUSSION A. Analysis of heavy metal content in cultivated soil Accoding to the data of the suvey esults of the study aea, the content of heavy metal pollutant in each evaluation unit is obtained by using Acgis softwae. The contents of seven kinds of heavy metals in cultivated soil in the study aea ae shown in table 1. n f 7 i 1 TABLE 1. STATISTICS OF SOIL HEAVY METALS IN THE STUDY AREA (MG. KG -1 ) ( 1-1) heavy metal Cd Hg As Pb content mean value standad deviation coefficient of vaiation (%) skewness kutosis backgound value of Jiangsu Povince national backgound value (1-) heavy metal C Cu Zn content mean value standad deviation coefficient of vaiation(%) skewness kutosis backgound value of Jiangsu Povince national backgound value Table 1. shows, heavy metals such as Hg, Zn, Cu, as, Hg, C content and coefficient of skewness ae less than zeo, indicating that the five elements of the content index value is not concentated, which skewness coefficient of Cu is elatively lage negative , show that the left has a long tail. Compaison of fou indicatos of elatively moe than indicatos of heavy metal content of heavy metal Pb (coefficient of skewness ), Cd (skewness coefficient ) index of skewness coefficient is geate than zeo, indicating that the egion of soil Pb and Cd content was positively skewed, intuitive pefomance fo heavy metal content diagam of cuves on the ight side of the tail on the left side of the tail is slightly longe, namely heavy metals Pb, Cd content of obsevation value is less than the aveage value of evaluation units; Hg, C and Cu kutosis coefficients ae geate than zeo, indicating the than zeo, indicating that the egion of soil Pb and Cd content was positively skewed, intuitive pefomance fo heavy metal content diagam of cuves on the ight side of the tail on the left side of the tail is slightly longe, namely DOI /IJSSST.a ISSN: x online, pint

3 heavy metals Pb, Cd content of obsevation value is less than the aveage value of evaluation units; Hg, C and Cu kutosis coefficients ae geate than zeo, indicating the kind of heavy metal content distibution compaed to the nomal distibution is elatively steep, Cd, as, Hg, Pb and Zn heavy metal coefficient of kutosis is less than zeo, indicating the content distibution and nomal distibution flat[9]. Coefficient of vaiation of the content of heavy metals in cultivated soils: (aveage in Table 1., famland soil Cd, Hg, as, Hg, Pb, C, Cu and Zn in seven kinds of heavy metal elements content values wee , , 8. 00, , , , units:mg. Kg-1), the study aea 7 kinds of heavy metals except Pb, Hg, and the emaining five kinds of heavy metal elements Cd, as, Hg, C, Cu and Zn content values wee geate than in Jiangsu Povince soil element backgound values and the soil element backgound values of the evaluation unit, on the whole the city ae elatively low, one of the lagest coefficient of vaiation fo the heavy metal mecuy of coefficient of vaiation of 3. 5%. The minimum coefficient of vaiation fo the heavy metal chomium coefficient of vaiation of 5. 6%. The distibution of heavy metals in the study aea is elatively unifom, which shows that the heavy metal content in the city is not significantly affected by human activities. B. Assessment esult of heavy metal in famland soil 1 ) Evaluation esults of heavy metal in famland soil The famland soil ph ange , selection of intemediate indicatos of "soil envionmental quality standad" second class standad, using equation 1 to calculate the egion seven kinds of heavy metals (CD, Hg, as, Pb, C, Cu, Zn) of single facto index (Table. ). The calculation esults fom the ode of Hg<Cu<Cd<Zn<C>As<Pb. (-1) TABLE. CULTIVATED SOIL HEAVY METAL POLLUTION INDEX GB heavy metal Cd Hg As Pb index ange index (-) heavy metal C Cu Zn index ange index The single facto in famland soil of the study aea efes to the numeical anged between and combined with the national soil envionmental quality standads (Table 3. ), the single facto of heavy metals in cultivated soil of the city efes to the values ae less than 1 and that fo the seven kinds of heavy metal elements, the famland in the study aea is not contaminated, belonging to non levels ( Table. ). TABLE 3. SINGLE POLLUTION GRADE OF SOIL ENVIRONMENTAL QUALITY STANDARD gade single index assessment 1 Pip 1 non 1<Pip slight 3 <Pip 3 mild 4 3<Pip 5 modeate 5 Pip 5 sevee Note: accoding to the people's Republic of China national agicultual land quality gade standad division. ) Assessment esults of heavy metals accumulation in cultivated soils Combination of Jiangnan and the soil element backgound values of aithmetic aveage (Table 1), use Equation 1-, calculated soil of famland in the study aea of heavy metals accumulation index (Igeo, Table 5. ). Accoding to the heavy metal accumulation index (Igeo) ating citeia [ 10](Table 4. ), and the city of famland soil heavy metal degee of classification and evaluation. TABLE 4. ACCUMULATION OF POLLUTION GRADE STANDARD index (Igeo) gade enichment ( degee Igeo<0 0 gade no enichment (no 0<Igeo<1 1 gade slight enichment (slight 1<Igeo< gade modeate enichment (modeate <Igeo<3 3 gade stong enichment (modeate 3<Igeo<4 4 gade stong enichment (stong 4<Igeo<5 5 gade stonge enichment (stonge 5<Igeo<6 6 gade extemely stong enichment (extemely stong In table 5, the study aea of famland soil heavy metals, only cadmium, chomium and coppe of the vey few evaluation unit of cumulative index geate than zeo, the level 1, is a slightly eniched (slight ; all othe heavy metals such as lead, zinc, mecuy, asenic evaluation unit each tied index value is less than zeo, the level 0, belonging to the no enichment (-fee). In the study aea, except fo the human factos, the natual diagenesis has little effect on the backgound value of heavy metals in soil. TABLE 5. CULTIVATED SOIL HEAVY ETALS ACCUMULATION POLLUTION INDEX STATISTICS element Igeo Igeo<0 0<Igeo<1 change ange mean value atio (%) atio(%) DOI /IJSSST.a ISSN: x online, pint

4 As Cd C Cu Hg Pb Zn ) Nemeo index evaluation of famland soil Because of the heavy metal contamination in the egion, the phenomenon is elatively ae[11]. In ode to fully eflect the diffeent pollutants on soil envionmental quality of famland, pominent in the study aea, the highest content of pollutants on soil envionment have impotant effect, taking into account the to soil in a vaiety of heavy metal pollutants in the aveage value and the maximum value, the analysis of compehensive study aea soil heavy metals by Nemeow index method (Nemeow) (equation ), using Nemeow index gading standads (Table 6. ) of heavy metal classification and evaluation[1]. compehensive index Pcompehensive Pcompehensive < < Pcompehensive < < Pcompehensive <. 0. 0< Pcompehensive <3. 0 Pcompehensive <3. 0 TABLE 6. NEMEROW INDEX GRADING STANDARD Polluti on gade one gade two gade thee gade fou gade five gade degee non mild middle level modeate stong standad soil cleaning soil cleane soil is ove backgound, the cop begins to pollute soil and cops ae modeately polluted soil and cops have been seiously polluted. C. Soil ecological isk assessment of cultivated land Accoding to the famland soil of the study aea in the sediments of seven kinds of heavy metal element backgound value, combined with the biological toxicity coefficient, ecological effect and peliminaily using of Equation (1)-(3) to calculate seven kinds of heavy metals in soil of famland in the study aea of potential ecological isk index (Ei) values (Table 8. ). The compehensive ecological hazad index (RI) and the classification standad of individual ecological hazad index (Ei) wee found in table 7. [13]. TABLE 7. ECOLOGICAL RISK COEFFICIENT OF HEAVY METALS ERI AND ITS POTENTIAL ECOLOGICAL RISK DEGREE RI VALUE RELATIONSHIP(HUA JUN TANG, ETC. 004) E i potential ecological hazad RI potential ecological isk <40 light <10 light modeate modeate stong stong stonge >480 stonge >30 stongest The potential ecological isk index of seven kinds of heavy metals fom big to small in the ode of Cd>Hg>As>Pb>Cu>C>Zn(Table 8), the heavy metal cadmium (Cd) the ecological isk index is the lagest, most egional ecological isk facto contibution [14]. The potential ecological hazad, the coefficient ange of 11-48, belonging to the modeate ecological ham degee, potential ecological isk index of othe six kinds of heavy metal elements Hg, As, Pb, Cu, C, Zn ae less than 40, belonging to slight ecological ham degee; the othe seven kinds of heavy metal ecological evaluation in the study aea the unit inteval hazad index fo 1-48, wee less than 80, belonging to modeate ecological isk level (Table 7. ). TABLE 8. FARMLAND SOIL HEAVY METAL POTENTIAL ECOLOGICAL RISK INDEX (ERI) (8-1) heavy metal Cd Pb C Cu (8-) E i mean value heavy metal Zn Hg As E i mean value Compehensive ecological eseach in the aea of each evaluation unit of heavy metal hazad index (RI) inteval was 41, showing a law inceases gadually fom the south to the noth of the index value, the RI of the maximum value appeas in the nothen egion. But thoughout the egion of heavy metal compehensive ecological isk index wee less than 10, belonging to slight ecological isk level (Table 7), by the method of esult evaluation and Nemeow index evaluation esults ae consistent, an oveall eseach on the aea of famland soil envionment quality is good. IV. CONCLUSIONS A. The content of seven kinds of heavy metal elements of aable soil in the study aea, in addition to the thee elements of Se, Pb and Hg, the emaining fou heavy metal elements only vey individual evaluation unit content value is geate than in Jiangsu Povince and the soil element backgound values. But the aveage content DOI /IJSSST.a ISSN: x online, pint

5 of these seven heavy metals is lowe than the soil backgound value in Jiangsu povince and the whole county, which shows that the soil in the egion is not obvious. B. Reseach aea soil heavy metals accumulation index, only cadmium, chomium and coppe of the vey few evaluation unit of cumulative index geate than zeo, othe values ae less than zeo that in the study aea in addition to the influence of human factos, have little effect of diagenes is on the soil heavy metal backgound values. C. The single index of heavy metals in soil fom famland in the ode of Hg <Cu<Cd<Zn<C>As<Pb. The soil envionmental quality of famland in the study aea is , which indicates that the soil in the whole aea is unde the condition of no. D. Region in cultivated soil of seven kinds of heavy metal elements of potential ecological hazad index size is of the ode of Cd>Hg>As>Pb>Cu>C>Zn, which heavy metal cadmium (Cd) is the city soil the main ecological isk facto. The compehensive ecological hazad index (RI value) of soil heavy metals is 41-58, the aveage value is 49. 5, which is a mild ecological isk level. E. Thee is no absolute optimal method in using a vaiety of methods of heavy metal in famland soils wee evaluated, including the single facto index method, the cumulative index method, Nemeow index and potential ecological isk index method, egadless of what kind of methods have cetain limitations, so of heavy metals wee evaluation. Due to the coastal plain aea and majo gain poducing aeas of the study aea unde the juisdiction of the factos of human activity is the main souce of heavy metal in famland soils, in tun to famland soil contaminated by food chain effects to human health. Theefoe, the evaluation method of the heavy metal in the study aea, the degee of heavy metal in the study aea using the potential ecological isk index method is moe easonable. By calculating the heavy metal potential ecological isk index to detemine the egion focus on pevention and contol object, the need of heavy metal cadmium (Cd) pioity to develop the coesponding pevention and contol measues. REFERENCES [1] Feng Zhiming, the establishment of China's famlandpotection zone, and Technology Review Science 1993 fist: 4-43 [] FA Jing Tang, pogenito IEEE. Spatial vaiability of heavy metals in soil eseach methods[j]. Jounal of Yunnan Agicultual Univesity, 008, 3 (4): [3] Zhang Jiantai. Reseach on the poblem of ual envionmental tot in China unde the pespective of hamonious society[d]. Nanchang. Nanchang Univesity [4] Li X D, Lee S L, Wong S C, et al. The Study of Metal Contamination in Uban Soil of Hong Kong Using a GIS based Appoach[J]. Envionmental Pollution, 004, 19: [5] Chao S Z. Using Multivaiate Analyses and GIS to Identify Pollutants and Thei Spatial Pattens in Uban Soils in Galway, Ieland[J]. Envionmental Pollution, 006, 14: [6] Katin I, Wolfgang W, Gigoij S. Heavy Metal Distibution in Soil Aggegates:A Compaison of Recent and Achived Aggegates fom Russia[J]. Geodema, 004, 13: [7] Hu Miao, Wu Jiaqiang, Peng Peiqin, et al. Evaluation model and case study of heavy metal in famland soil in mining aea [J]. Jounal of envionmental science,. 014, 34 (): [8] Hakanson L. An Ecological Risk Index fo Aquatic Pollution Contol A Sedimentological Appoach[J]. Wate Reseach, 1980, 14(8): [9] Lai Guoyi, Chen Chao. SPSS commonly used functions and application examples[m]. Beijing. Electonics Industy Pess, 010: [10] Hu Yanxia, Zhou Liandi, Wei Changshan, et al. The spatial vaiation of heavy metals in soil and chaacteistics[j]. Beijing. 013, 44 (6): [11] Peng Kunguo, Yao Na, Liu Zugen, et al. Chaacteistics and isk assessment of heavy metals in soil in Beijiao. Shijiazhuang, (): [1] Yu Bin. Study on agicultual land health evaluation [D]. Kaifeng, Henan Univesity [13] Chen Youqi, Tang Huajun, Qiu Jianjun et al. Reseach on the change of land use / land cove in China [M]. China Agicultual Science and Technology Pess. Beijing: 004, [14] Wang Qi. Hefei city nea suface dust heavy metal isk identification and isk assessment [D]. Nanjing. Nanjing Univesity 01. DOI /IJSSST.a ISSN: x online, pint