【作者】 李其林；

【导师】 魏朝富； 谢德体；

【作者基本信息】 西南大学 ， 农业资源利用， 2008， 博士

【摘要】 随着现代经济的高速发展,环境污染物的排放量与日剧增,环境污染和生态破坏越来越严重,危及到人类的生存。重金属在环境中不会降解、消失,其通过迁移、转化等过程富积到农作物或其它植物,这些富积的重金属可通过食物链对人类健康造成威胁。区域土壤—作物系统重金属特征是当前重金属污染的研究热点。土壤重金属污染具有普遍性、隐蔽性、表聚性、不可逆性等特点。而关于作物中重金属来源有两种主要观点,一种认为作物主要从土壤中富积重金属而造成污染;另一种认为作物不仅从土壤中富积,从大气中吸附也是重要来源。同时作物重金属的污染受到作物的种类、品种及器官的外部形态及内部结构不同的影响,再次不同作物吸收重金属的生理生化机制不同,累积量差异也较大,使得在重金属污染研究和防治中存在一定的困难。本文对重庆地区的主要作物及其土壤重金属(Cu、Zn、Pb、Cd、Ni、Hg、As、Cr、Fe和Mn)含量进行了调查研究,探讨了该地区土壤重金属与土壤类型和种植模式的关系、土壤和作物体中各重金属间的关系、作物中重金属与土壤中各形态重金属的关系以及作物富积重金属的途径,旨在揭示区域生态系统中土壤—作物系统重金属特征,为重金属污染的防治和进一步研究提供参考。1土壤—水稻系统重金属特征水稻土各重金属的平均含量大小顺序依次为Fe＞Mn＞Zn＞Cr＞Pb＞Cu＞Cd,其中Mn的变异系数最大,Cr的变异系数最小,除Cr、Mn外其余重金属均呈偏态分布。通过聚类分析可将土壤中重金属分为三类,即Zn、Pb、Cu、Cd;Fe、Mn;Cr。水稻土重金属间呈极显著正相关。与国家土壤环境质量二级标准相比,有16%土样Cd含量超标即表明Cd是水稻作物地土壤重金属污染的主要因子。水稻中重金属的平均含量大小顺序为Fe＞Mn＞Zn＞Cu＞Cr＞Pb＞Cd,以Fe的变异系数最大,Zn最小,除Zn外其余重金属均呈偏态分布。Zn含量在水稻中具有正态分布特点,表明长期食用水稻对Zn的丰缺无明显影响。水稻中重金属间正相关明显多于负相关,Mn同其它重金属间均呈极显著正相关,可用主成分分析来表征重金属特征。Cd、Mn在水稻中的相似性也为进一步研究水稻中Cd的行为提供了一种思路。根据国家食品卫生标准,水稻Pb、Cr超标严重。线性回归分析表明水稻中Cd与土壤中Cd呈显著直线相关,表明水稻中Cd主要来源于土壤。2土壤—蔬菜系统重金属特征蔬菜地土壤中重金属Cr、Ni、Cu、Zn、As、Cd、Hg和Pb的平均含量分别为52.12mg/kg、33.44mg/kg、23.04mg/kg、82.27mg/kg、6.757mg/kg、0.291mg/kg、0.056mg/kg、37.04mg/kg,其中Cr、Ni、Zn、Pb变异系数较小。不同土层中各重金属的含量不同。在0～20和20～40cm土层,Cd和Hg有显著差异,其它元素则都没有显著差异。Cr、Ni、Cu和As等重金属在黄棕壤中变异系数较大,Cd、Hg和Pb在其中的变异系数较小。除Cd、As外,其它重金属的平均含量均为黄壤、黄棕壤大于紫色土,这是因为紫色土的粘性明显小于黄壤、黄棕壤,吸附重金属的能力弱。蔬菜地不同土壤类型中重金属间均有较强的相关性,其中以黄壤中的相关性最好;黄壤、黄棕壤中各重金属间均为正相关,紫色土的Ni、Cd与Hg为负相关。紫色土Hg同其它重金属元素的相关性差,这主要是因为紫色土粘性小,孔隙度大,Hg易释放到空气中。不同土壤类型中重金属Cu、Ni、Cr伴生关系均较强。不同区域(污染区和非污染区)蔬菜地土壤重金属分析表明除Hg、Cr、Cd外其它重金属含量在区域间无明显差异,说明菜地土壤重金属受大气污染相对较轻,而同菜地土壤的植物覆盖度关系密切。污染区土壤中重金属间均为正相关,而非污染区中重金属间既有正相关,也有负相关。非污染区土壤中重金属Hg、Cd与其它元素的相关性明显低于污染区,主要原因是非污染区蔬菜地土壤类型主要以紫色土为主,其吸附重金属能力弱,Hg元素易挥发到空气中,Cd元素易淋溶到下层土壤中。不同区域蔬菜地土壤中重金属Ni、Cu、Cr均具有较强的伴生关系。与重庆市土壤背景值相比,其中Cd、Hg、Pb含量大于背景值,Cr、Ni、Cu、Zn、As含量同背景值接近,因此重庆市菜地土壤重金属Cd、Hg、Pb的累积较多,受人类活动影响明显。与国家土壤环境质量二级标准相比,Cd、Hg、Cu、Cr、Zn和Ni含量超标,超标率分别为19.0%、0.8%、1.8%、0.3%、0.3%、7.0%,表明重庆地区蔬菜地土壤中重金属污染较重,特别是Cd污染。蔬菜中Cr、Ni、Cu、Zn、As、Cd、Hg和Pb的平均含量分别为0.14mg/kg、0.22mg/kg、0.77mg/kg、3.52mg/kg、0.020mg/kg、0.024mg/kg、0.0019mg/kg、0.10mg/kg,以Cd的变异系数最大,Cu最小。重金属的平均含量和变异系数在不同蔬菜品种中差异较大。重金属平均含量相对较大的蔬菜品种有苋菜、莴笋、生菜、葱,变异系数相对较大的蔬菜品种有莲白、辣椒、葱。主要蔬菜品种中重金属间相关分析表明不同蔬菜品种在生长过程中对不同重金属的吸收富积行为有较大差异。蔬菜品种中重金属的聚类分析表明蔬菜中重金属含量同其生理形状特征具有较大的关联性。蔬菜种类(果菜类、叶菜类)中重金属的行为特征研究表明叶菜类重金属受到影响因素较多、影响程度较严重;不同蔬菜种类对重金属的行为过程存在较大差异;不同蔬菜种类中重金属伴生关系差异大,叶菜类伴生重金属最多,可能同叶菜类同空气的接触面大,受大气污染影响较大等因素有关。地统计学分析表明蔬菜地土壤中重金属Cr、Ni、Zn、As、Cd、Hg、Pb和Cu的空间变异为各向同性。在各向同性下,Hg和Cu的半方差函数符合高斯模型,其余重金属的的半方差函数符合球状模型。Cr含量的演变趋势分布为渝东高于渝西,高值区域出现在城郊区、北碚、巴南、渝北、长寿、南川、万盛,高值区域含量在51～79mg/kg之间。Ni含量的演变趋势分布无明显规律,高值区域出现在城郊区、合川、万盛、綦江、南川,高值区域含量在35～49mg/kg之间。Zn含量的演变趋势分布无明显的规律性,在东南方向上有一带状高值出现,包括城郊区、巴南、南川、万盛,同时在合川和潼南交界处出现高值分布,高值区域含量在88～140mg/kg之间。As含量的演变趋势分布在北部和东南角有相对高值,高值区域含量在10～25mg/kg之间,但研究区域内As含量的低值分布面积较大。Cd含量的演变趋势分布为北部和南部出现高值,高值区域含量在0.30～0.44mg/kg之间,并且土壤中Cd带状分布明显。Hg含量的演变趋势分布为圆点式扩散状,在北部区域出现高值,包括城郊区、北碚、铜梁、大足,高值区域含量在0.05～0.13mg/kg之间。Pb含量的演变趋势分布为东部明显高于西部,高值区域出现在城郊区、北碚、渝北、长寿、巴南、南川、万盛、綦江,高值区域含量在39～54mg/kg之间。Cu含量的演变趋势分布无明显规律,高值区域出现在城郊区、南川、万盛,高值区域含量在32～64mg/kg之间。3土壤—柑橘系统重金属特征柑橘地黄壤中Cu、As和Cr平均含量较紫色土多了10%以上,Zn、Pb、Cd、Ni和Hg平均含量同紫色土差异不大。除紫色土Hg外,黄壤和紫色土中的其它重金属的变异系数均小于30%。紫色土中所有重金属的变异系数均大于黄壤,说明紫色土中重金属的熟化程度差别较大。与重庆市土壤背景值相比,黄壤中As、Cr和紫色土中Cd、Cr含量有一定的增加,但增幅不明显,其余重金属含量同背景值变化不大,说明重庆地区柑橘地土壤重金属的含量相对稳定,受外源性污染影响较小。柑橘地紫色土中Zn与Ni、Cu,Cr与Ni、Pb,Cd与Pb、As间有显著正相关性:Zn与Cr和As,Cd与Hg,As与Cr和Pb有极显著正相关性。紫色土中多个重金属间的显著正相关性说明紫色土受土壤母质影响较大,熟化程度较低。同时,紫色土除Hg与Zn,Hg与Ni为负相关性外,其余重金属元素两两间均为正相关,而黄壤中重金属两两间负相关性明显多于紫色土,说明重金属间的协同作用在紫色土中较明显,颉颃作用在黄壤中较明显,其可能同成土过程有关。柑橘地主要土壤类型中重金属(Cd、Hg、As),(Cu、Ni),(Zn、Cr)与土壤的发育形成过程具有一致性,可能同元素本身的特性和特殊的生态环境有关。柑橘地黄壤和紫色土的0～30cm和30～60cm土层中Cu、Zn和Ni以矿物态含量最多,交换态含量最少;Cd则以铁锰态含量最多,其次是有机态和交换态,水溶态最少;黄壤中Pb在0～30cm和30～60cm土层中以铁锰态为主;紫色土中Pb以矿物态为主,其次是铁锰态,交换态最少。其中紫色土中Cd交换态达14.55%,而其它重金属的生物可利用态非常小,这可能是重庆地区农产品中Cd超标的主要原因。紫色土中Cu水溶态百分比高于其它重金属水溶态,这可能是重庆地区丰水期江河水质Cu超标的重要原因。柑橘地土壤各形态重金属间相关性分析表明黄壤和紫色土中重金属的生物可利用态(水溶态、交换态、碳酸态)受自然环境因素影响大。黄壤和紫色土中水溶态的Cu与Zn,铁锰态的Cu与Ni均达显著正相关,土壤中水溶态Cu与Zn的协同作用可能同其元素本身的性质有关。柑橘地土壤中各重金属形态间相关性分析表明不同土壤类型各重金属形态间的相关性有明显差异,但黄壤中各重金属形态间的显著相关程度明显弱于紫色土,进一步论证了紫色土熟化程度低,受土壤母质影响大。不同柑橘品种(脐橙、锦橙、夏橙)中重金属的含量分析表明重金属间的相关性与柑橘的品种以及器官密切相关。果肉同土壤、叶、果皮中重金属有显著直线关系。部分重金属同土壤重金属形态间有显著相关性,即柑橘叶中Zn与土壤中Zn铁锰态达显著负相关,叶中Ni与土壤中Ni碳酸态达显著正相关:果皮中Zn与土壤中Zn交换态达显著正相关,与土壤中Zn矿物态达显著正相关;果皮中Pb与土壤中Pb有机态达极显著正相关;果皮中Cd与土壤中Cd交换态达显著负相关,与土壤中Cd铁锰态达显著正相关;果肉中Ni与土壤中Ni碳酸态达显著正相关。不同品种柑橘的各部位重金属含量聚类分析表明果肉和叶中重金属的分类具有一致性,无品种差异,而果皮中重金属的分类则同品种关系密切。通过分析所得,重庆地区粮食作物地土壤重金属污染的主要因子是Cd和稻谷中Cd主要来源于土壤;蔬菜地土壤重金属污染较严重,特别是Cd污染,土壤和蔬菜中重金属在区域生态系统中无明显空间分布特征;柑橘地土壤重金属含量相对稳定,受外源性污染较小:水稻作物地和柑橘地中重金属具有明显的相似性,与蔬菜地中重金属有明显差异,即表明蔬菜种植模式下土壤中重金属受人为影响最为突出:重金属Cu、Zn、Cd在蔬菜中富积量明显高于其它植物,柑橘果肉中Cr的富积量明显高于其它植物。水稻、柑橘果肉中重金属Pb、Cd、Cr具有相似性。本文通过对土壤—作物系统重金属特征的研究,获取了大量的研究资料,对重金属污染研究和防治具有一定的科学指导意义。但仍存在一些问题,今后应从不同土壤类型释放重金属的行为特征:不同作物种类(品种)中重金属差异的生理差异原因;不同作物对重金属的生理反应剖析;重金属在区域生态环境中的大循环和作物中的小循环模拟等方面进行进一步的研究。更多还原

【Abstract】 With the rapid economic development of modern society,the discharge of the environmental contamination is increasing steadily.The environmental pollution and ecological damage become more and more serious,which threatens the human life.The heavy metals which could not been degraded and finally disappear in natural environment will accumulate into the crops and other plants by he way of removing and transforming.So the accumulated heavy metals would threaten people’ s health through food cycle. Characteristics of heavy metals in soils-crops of regional system are the hotspot of research at present, which are widespread,however,indistinct,surface-agglomerated,and non-reversible and so on.Heavy metals in plants originate from two sources:one is adsorbing from contaminated soil and the other from air. The degree of the pollutions is influenced by species of plants with their various internal structure and external form of organs.In addition,the adsorbing mechanism and accumulating capacity differ from different plants.All of these mentioned aspects make the researches on heavy metals pollution and prevention so difficult.Based on surveying the content of heavy metals(Cu,Zn,Pb,Cd,Ni,Hg,As,Cr,Fe, and Mn)in soil -crops in Chongqing,this paper discussed their relationships between soils and planting pattern,the forms of heavy metals in crops and in soils,and how these heavy metals accumulating into the crops.From these discussions,the characteristics of the heavy metals in regional soil - crop ecosystems can be revealed and further work on heavy metal pollution and prevention can be made.1 Heavy metals in soil- paddy systemThe average heavy metals’ holding capacity in soils planted with paddy is Fe＞Mn＞Zn＞Cr＞Pb＞Cu＞Cd.For the above heavy metals,the coefficient of variation of Mn is the maximal,and that of Cr is the minimal.The capacities of other heavy metals are in keeping with skew distribution except Cr and Mn. The heavy metals can be classified into 3 groups by the method of clustering:the first group composed of Zn,Pb,Cu,and Cd,the second group of Fe,Mn,and Cr belongs to the third group.The correlation coefficient was clearly positive among all heavy metals in soils planted with the paddy.Comparisiond with the second national standards of soil environment quality,Cd exceeds 16%in soil samples.This result illustrated that Cd is the main pollutant in soils planted with paddy in Chongqing.The average content of heavy metals in paddy is Fe＞Mn＞Zn＞Cu＞Cr＞Pb＞Cd.The coefficient of variation of Fe is the maximal,and that of Zn is the minimal.The capacity of other heavy metals is in keeping with skew distribution except Zn with a normal distribution.This result shows there is no obvious influence on the content of Zn whether it is abundant or scarce if one person only eats one kind of cereal crops for a long time.There are more positive correlations than negative ones among heavy metals in plants. The relationship between Mn and other heavy metals presents remarkable positive correlation,so the characteristics of heavy metals can be analyzed by the principal component method.The comparability between Cd and Mn in paddy provides a new idea for further research on the behavior of Cd.Comparisiond with the national food hygiene criteria,the content of Pb and Cr in paddy seriously exceed the criteria.The linear regression analysis shows a clear linear relationship of Cd content in paddy and in soils.That indicates Cd in paddy roots in soil.2 Heavy metals in soil-vegetable systemIn the soil with the vegetation plantation,the average heavy metals’ contents of Cr,Ni,Cu,Zn,As,Cd, Hg,and Pb are 52.12mg/kg,33.44mg/kg,23.04mg/kg,82.27mg/kg,6.757mg/kg,0.291mg/kg,0.056mg/kg, and 37.04mg/kg,respectively.For these heavy metals,the coefficients of variation for Cr,Ni,Zn,and Pb are the minimal.The contents of heavy metals vary with the different soil horizon.For example,there is remarkable difference in Cd and Hg content in the soil horizon of 0-20cm and of 20-40cm;however,other horizons vary quite little.The coefficient of variation of Cr,Ni,Cu,and As are higher than that of Cd,Hg, and Pb.Apart from Cd and As,the average content of other heavy metals in the yellow soil and yellow brown soil is more than that in the purple soil.That is due to the poor stickiness of the purple soil comparisiond with yellow soil and yellow brown soil,which also leads to the poor ability to absorb heavy metals.Heavy metals in different vegetable plantation soils show superiorer correlation,and the correlation in the yellow soil is the highest.The correlation between different types of heavy,metals in the yellow soil and yellow brown soil shows positive correlation.Ni,Cd in the purple soil show negative correlation to Hg. Hg shows inferior correlation to other heavy metals due to its easy release into air,and the stickiness of the purple soil is poor and with high porosity.Cu,Ni,Cr accompany each other strongly in all types of soil. The analysis showed notable diversity in other heavy metals except for Hg,Cr,and Cd in different area of vegetable plantation(polluted zone and non-polluted zone).That illustrates vegetable soil suffers relatively less from air pollution because of its vegetation coverage.The correlations are all positive between different types of heavy metals in polluted zoning;however those in non-polluted zone show either positive or negative.The correlations between Hg,Cd,and other heavy metals in non-polluted zone are much inferior to in polluted zone.The main reason is that the soil in non-polluted zone is purple soil with a poor absorption,which makes Hg volatilizes into air and Cd go to deeper soil.Ni,Cu,and Cr showed strongly accompaniment in different part of vegetable plantation.Comparisiond with Chongqing’s soil background value,the content of Cd,Hg,and Pb is higher,and that of Cr,N,Cu,and Zn,As are almost the same.So Cd, Hg,and Pb accumulate fairly more in vegetable plantation of Chongqing,and human actions obviously affect the content of heavy metals.Comparisiond to the second level of national standards of soil environment quality,the content of Cd,Hg,Cu,Cr,Zn,and Ni exceed seriously,with the values of 19.0%, 0.8%,1.8%,0.3%,0.3%,and 7.0%,respectively.All this indicated vegetable plantations in Chongqing were seriously contaminated by heavy metals,and Cd should appeal to higher concern particularly.The average content of heavy metals in vegetable for Cr,Ni,Cu,Zn,As,Cd,Hg,and Pb are 0.14mg/kg,0.22mg/kg,0.77mg/kg,3.52mg/kg,0.020mg/kg,0.024mg/kg,0.0019mg/kg,and 0.10mg/kg, respectively.The coefficient of variation of Cd is the maximal,and that of Cu is the minimal.The mean and the coefficient of variation of heavy metals’ content show remarkably distinctness in different types of vegetable.The average content of heavy metals is higher in amaranth,asparagus,lettuce and onion.While the variation coefficient of cabbage,capsicum,and onion are higher.Correlation analysis among heavy metals in the main types of vegetables indicated that there are clear difference on absorption in heavy metals by different sorts of vegetables at the process of growth.And cluster analysis among heavy metals in different types of vegetables indicated that there was more superior correlation between the content of heavy metals and physiologic morphologic character.Research on characteristics of different kinds of vegetables(leaf vegetables、fruit vegetables)indicated that leaf vegetables are affected by more factors and on higher degree.There is markedly difference on the behaviors of heavy metals in all kinds of vegetables as well as accompanying relationship.The quantity of the accompanying heavy metals is the most in the leaf vegetables,and that is because the interface of leaf vegetables is larger which makes serious air pollution on the leaf vegetables.The analysis of geo-statistics showed the distributions of heavy metals such as Cr、Ni、Zn、As、Cd、Hg、Pb and Cu in the vegetable soil is isotropy and the semi variance function of Hg and Cu coincides with Gaussian model and the other heavy metals coincides with Spherical Model.The evolution trend of the content of Cr is distributed in the east of Chongqing rather than in the west and the higher content region appears in the suburb area、Beibei、Banan、Yubei、Changshou、Nanchuan、Wangsheng.No apparent changes of evolution trend of the content of Ni is detected and the higher content region appear in the suburb area、Hechuang、Wangsheng、Qijiang、Nanshuan.And the concentrations of Ni in these region are 35～49mg/kg.No apparent regularities of evolution trend of the Zn contents are detected and higher contents region appear in the southeast areas including the suburb area、Banan、Nanchuan、Wangsheng and the junction between Hechuang and Tongnan.The concentrations of Ni in these region are 88～140mg/kg. The evolution trend of the contents of As is distributed highly in the north and southeast of Chongqing.The concentrations of As in these region are 10～25mg/kg and the contents of As in the study area are relatively low.The evolution trend of the contents of Cd was highly distributed in the north and south of Chongqing. The concentrations of Cd in these regions are 0.30～0.44mg/kg.The contents of Cd appear in zonal distribution.The evolution trend of the contents of Hg is diffused in circular point style and higher contents region appear in the north areas including the suburb area、Beibei、Banan、Liangtong、Dazhu.The concentrations of Hg in these regions are 0.05～0.13mg/kg.The evolution trend of the contents of Pb is distributed in the east of Chongqing rather than in the west and the higher contents region appear in the suburb area、Beibei、Yubei、Changshou、Nanchuan、Banan、Wangsheng、Qijiang.The concentrations of Pb in these region are 39～54mg/kg.No apparent changes of evolution trend of the contents of Cu are detected and higher contents region appear in the suburb area、Nanshuan、Wangsheng.The concentrations of Cu in these region are 32～64mg/kg.3 Heavy metals in soil-citrus systemThe mean contents of Cu、As and Cr in the yellow soil of the Citrus field are 10%more than those in purple soil.While the mean contents of Zn、Pb、Cd、Ni and Hg have not obvious diversity.Except for Hg in the purple soil,the coefficient of variation of all other heavy metals in the yellow soil and the purple soil is lower than 30%.The coefficient of variation of all heavy metals in purple soil is higher than that in the yellow soil,which indicates that the heavy metals in purple soil differ greatly in the degree of ageing. Comparisiond with the soil background level of Chongqing,the contents of As and Cr in the yellow soil and that of Cd and Cr in the purple soil have increased in certain extent but the difference isn’t obvious,and the contents of the other metals have little change.That explains the contents of heavy metals in the Citrus field in Chongqing are relatively steady and hardly influenced by the exogenous pollution.There are significant positive correlations between Zn and Ni、Cu,the same between Cr and Ni、Pb,and also Cd and Pb、As in the purple soil of the citrus field;Zn with Cr、As,Cd with Hg,As with Cr、Pb also have significantly positive correlation.The significantly positive correlations among all kinds of heavy metals in the purple soil explain that the purple soil has been greatly influenced by the parent soil materials and the degree of ageing is lower.Meanwhile except that Hg and Zn,Hg and Ni show the negative correlations, there exists the positive correlations between one type of heavy metals and the other,but the negative correlations in yellow soil are more than those in the purple soil.That illustrates the synergistic reaction among the heavy metals in the purple soil is more obvious,while the antagonism in the yellow soil is more obvious,which may be related to the soil formation.The heavy metals(Cd、Hg、As),(Cu、Ni),(Zn、Cr)in the main types of soil in the Citrus field accord with the process of developing and forming of the soil,which may be related to the character of the elements and to the special eco-environment.In the soil horizon from the depth of 0-30cm and of 30-60cm of the yellow soil and the purple soil in the Citrus field, the heavy metals such as Cu、Zn end Ni are the main forms of mineral,but the contents in the form of exchange is lowest.And the contents of Cd in the form of ferro-manganese are the most,organic form and exchange form follows,and the water soluble matters are the least.In the soil horizon from the depth of 0-30cm and of 30-60cm of the yellow soil,the contents of Pd are mainly in the form of ferro-manganese, but in the purple soil,the contents of Pd are mainly in the form of mineral,the form of ferro-manganese follows,and the exchange form is the least.The contents of Cd in the form of exchange form in the purple soil reaches to 14.55%,and the other metals as the available form are few,that may be the main reason of exceedance about Cd in the agricultural products in Chongqing.The content of Cu in the form of the water soluble in the purple is higher than other heavy metals,which may be the main reason of exceedance about Cu in the river of Chongqing with the high flow period.Correlation analysis among all forms of heavy metals in the soil of the Citrus field explains that the biological available forms(the water soluble form, exchange form,and carbonic acid form)in the yellow soil and the purple soil are greatly influenced by the natural environmental factors.In the yellow soil and the purple soil,the content of Cu and Zn in the form of the water soluble and Cu and Ni in the form of ferro-manganese show the markedly positive correlation. The synergistic reaction of Cu and Zn in the soil may be related to the properties of the elements.In the Citrus field,correlation analysis among all forms of heavy metals in the soil of the Citrus field explains that the correlations among all forms of heavy metals in all types of the soil have markedly differences.The significant correlations among all forms of heavy metals in the yellow soil is more inferior,which further demonstrates the purple soil has been greatly influenced by the parent soil materials and the degree of ageing is lower.Analysis of the concentration of metals in different breeds of Citrus(Jincheng Citrus,Navel Citrus, Valencia Citrus)shows the correlations among heavy metals are closely related to the breed and part of the citrus.The heavy metals in the flesh with those in soil、in leaves and in seedcase show the significant linear correlations.There are significant correlations between some heavy metals and forms of heavy metals in soil.For example,Zn in the citrus leaves shows significant negative correlations with Zn in the form of ferro-manganese in the soil,while Ni of the leaves shows significant positive correlations with Ni in the form of carbonic acid in the soil,and Zn of the seedcase shows significant positive correlations with Zn in the form of exchange in the soil as well as in the form of mineral,and Pb of the seedcase shows significant positive correlations with Pb organic form in the soil,and Cd of the seedcase shows significant negative correlations with Cd exchange form in the soil but shows significant positive correlations with Cd in the form of ferro-manganese in the soil,and also Ni of the flesh shows significant positive correlations with Ni carbonic acid form in the soil.The cluster analysis of metals in different parts of all breeds of Citrus indicates that in flesh and leaf,sorts of metals are accordant,no diversity for breed,while sorts of heavy metals in flesh is closely related to the breed.From what we analyzed in this study,we can draw the conclusion that Cd is the main element of heavy metals pollution in soil planted paddy in Chongqing and Cd in paddy mainly comes from soil;the soil of vegetable plantations in Chongqing were seriously contaminated by heavy metals and Cd should appeal to high concern particularly,and there are no obvious spatial distribution characteristics about the heavy metals in the soil-vegetable of regional ecosystem;the contents of heavy metals in the Citrus field are relatively steady and are hardly influenced by the exogenous pollution.The heavy metals in soil planted with paddy show obvious comparability with those in the Citrus field but distinguish with that in the vegetable plantation,which indicates that the heavy metals in soil is seriously influenced by human-induced factors.The contents of heavy metals as Cu、Zn and Cd accumulated into the vegetable as well as the contents of Cr into the Citrus flesh are obviously higher than those into other plants.The heavy metals such as Pb、Cd and Cr in the paddy present the comparability with those in citrus flesh.This paper obtained lots of research data by studying the Characteristic of heavy metals in soil and crop of regional system so as to provide the scientific guidance for the research and prevention work on the heavy metals pollution.However,there are also some problems.And in the future,we should do further research on the behavior characteristics of releasing the heavy metals from all kinds of soils and on the reason for the physico-diversity of the heavy metals in different kinds(breeds)of the crops,and on taking apart the physiological reaction of sorts of crops to the heavy metals,and also on simulating the general circulation of the heavy,metals on the regional ecosystem and the small size circulation on the crops.更多还原