大山包黑颈鹤国家级自然保护区湿地土壤重金属污染评价

2014年9~11月,在测定大山包黑颈鹤国家级自然保护区湿地土壤重金属含量的基础上,分析其重金属的来源;采用内梅罗综合污染指数法和潜在生态危害指数法,评价该区土壤重金属污染特征和潜在的生态危害。结果表明,研究区土壤中的Cu、Zn、Cr、Pb、Cd、Ni、As和Hg的平均质量比分别为159.73 mg/kg、133.35mg/kg、16.53 mg/kg、39.6 mg/kg、1.26 mg/kg、34.76 mg/kg、5.19 mg/kg和0.08 mg/kg;其中,Cd和Hg含量都高于云南省背景值,大多数采样点土壤中的As、Cu、Pb和Zn含量也高于云南省背景值,Cr和Ni含量低于云南省背景值;土壤重金属的污染程度由高到低依次为Cd、Cu、Zn、Pb、Ni、Hg、As和Cr污染,重金属的潜在生态危害由强至弱依次为Cd、Hg、Cu、As、Pb、Zn和Cr生态危害。退耕4 a的土壤综合污染程度和重金属的潜在生态危害指数最高,其次为自然土壤的,退耕10 a土壤的最低;研究区土壤潜在生态危害程度为中等至强等危害程度,土壤重金属污染严重,Cd是第一污染物。土壤退耕年限越长,土壤的污染程度和潜在生态危害越低。研究区湿地土壤重金属污染严重,可能会对黑颈鹤(Grus nigricollis)的取食和健康造成危害。     

哈素海表层沉积物重金属污染特征及生态风险评价

2014年10月10日～20日,在哈素海布设20个采样点,采集表层(0～10 cm深度)的沉积物样品,测定其重金属Cu、Zn、Pb、Cr、Cd、Hg和As含量;采用地累积指数、潜在生态风险指数和生态风险预警指数,分别对沉积物中的重金属污染程度和生态风险进行了评价。研究结果表明,哈素海表层沉积物中的重金属Cu、Zn、Pb、Cr、Cd、Hg和As平均质量比分别为32.29 mg/kg、128.10 mg/kg、28.25 mg/kg、77.14 mg/kg、0.05 mg/kg、0.04 mg/kg和13.76 mg/kg。在湖泊西南部,表层沉积物中的重金属含量较高,特别是在湖泊入水量最大的民生渠入水口处;在湖泊东北部,表层沉积物中的重金属含量中等或偏低。以生态危害临界值(TEL)标准为参考值,哈素海表层沉积物中重金属Cu、Zn、Pb、Cr、Hg和As含量都超标,Cr和As含量超标较严重,Cu、Zn、Cr、As、Pb、Hg和Cd的重金属单因子污染地累积指数依次减小。在20个采样点中,位于湖泊中北部和南部的采样点S6、S18和S20表层沉积物处于中等生态风险,其它17个采样点处于轻微生态风险。生态风险预警指数平均值为5.38,湖泊北部和东部的采样点S2和S11属于轻度重金属生态风险警告,位于湖泊中南部的采样点S14、S15、S17和S19属于中度重金属生态风险警告,其它14个采样点都属于重度重金属生态风险警告,说明哈素海存在重金属污染的生态风险。虽然表层沉积物中的重金属Hg含量并未超标,但由于其生态毒性非常大,不能忽视其污染。因此,应该对哈素海的重金属污染予以重视,特别是As、Cr和Hg污染。     

焦岗湖及入湖河流表层沉积物重金属潜在生态风险评价

以焦岗湖及入湖河流表层沉积物为研究对象,测定其中7种重金属(As、Cd、Cu、Ni、Pb、Zn和Hg)的含量,并结合多种方法评价其潜在生态风险。结果表明,焦岗湖及入湖河流表层沉积物中的7种重金属含量都未超过国家二级标准限值;湖泊沉积物重金属Cd、Hg、Cu、Ni、As、Pb和Zn地质累积评价污染等级的平均值分别为1.89、0.94、0.47、0.25、0、0和0,所有采样点中,Cd、Hg、Cu和Ni表现出一定的污染水平,其它元素为清洁等级;湖泊沉积物中重金属Cd、Hg、Cu、Ni、As、Pb和Zn潜在生态风险指数分别为109.37、76.99、8.17、7.42、6.96、4.44和1.59,湖泊及入湖河流沉积物主要的潜在生态风险因子都为Cd和Hg,湖泊沉积物中重金属的综合潜在生态风险指数的平均值(214.9)高于入湖河流沉积物的平均值(119.5)。焦岗湖及入湖河流表层沉积物中重金属生态风险等级分别为中等和低等。     

长江三角洲地区土壤重金属污染特征及潜在生态风险评价——以江苏太仓市为例

太仓市表层土壤Zn、Cu属强变异强度,呈对数正态分布;Cd、Ni、Hg、As、Cr和Pb属中等变异强度,呈正态分布。Cu、Hg、Zn、As显著高于当地背景值,以As累积指数和超背景值率最高;8种重金属除As自表层向下递增外,其余元素均为表层向下递减。土壤复合污染严重,土壤潜在生态风险达中等水平,黄泥土生态风险高于沙夹垅;重金属生态风险以印染厂最大,其次为电镀厂和养殖场,产生潜在生态风险为Hg、Cd,而As、Cu、Zn、Cr、Ni、Pb等多属轻微水平。     

博斯腾湖流域绿洲农田土壤重金属污染及潜在生态风险评价

新疆博斯腾湖流域绿洲采集195个农田土壤样品,测定其中As、Cd、Cr、Cu、Mn、Ni、Pb和Zn等8种重金属元素的含量,基于地统计法分析农田土壤重金属空间分布规律,采用污染负荷指数（PLI）和潜在生态风险指数（RI）评价农田土壤重金属污染和潜在生态风险程度,并对重金属的来源进行讨论。结果表明：① 博斯腾湖流域农田土壤Cd、Cr、Cu、Ni、Pb和Zn含量平均值分别超出新疆土壤背景值的1.67倍、1.13倍、1.15倍、1.29倍、2.11倍和1.65倍。② 农田土壤中8种重金属元素空间分布基本呈现岛状分布格局,各金属元素在部分区域出现高值区,表明研究区人类活动对农田土壤环境具有负面效应。③ 农田土壤Pb呈现中度污染,Cd、Cr、Cu、Ni和Zn轻度污染,Mn轻微污染,As无污染。农田土壤重金属污染负荷指数的平均值为1.09,呈现轻度污染态势。④ 各重金属元素单项生态风险指数平均值从大到小依次为：Cd、Ni、As、Cu、Pb、Cr、Zn。综合生态风险指数平均值为18.63,处于轻微生态风险态势。从生态风险程度的区域差异来看,各县生态风险指数从大到小依次为：和硕县、博湖县、焉耆县、和静县。⑤ 农田土壤Cr、Cu、Mn、Ni与Zn主要受到土壤地球化学成因的控制,As、Cd和Pb主要受到人类活动的影响。Cd与Pb是研究区主要的污染因子,研究区农田土壤中Cd与Pb污染必须关注。     

湛江观海长廊红树林土壤-植物体系重金属富集与迁移规律

选取湛江市霞山区观海长廊红树林湿地为研究区域,运用电感耦合等离子体质谱仪（ICP-MS）测定红树林表层土壤及红树植物根、枝、叶中重金属（铜Cu、锌Zn、铅Pb、镉Cd、铬Cr、镍Ni、砷As）的质量分数;运用Hakanson潜在生态风险指数评估红树林土壤的重金属污染风险水平,结合相关性分析和聚类分析探讨重金属的影响因素及来源;应用生物富集系数（BCF）、转运系数（TF）分析重金属在土壤-植物中的富集和迁移能力。结果表明：1）研究区表层土壤7种重金属分布规律为Zn（57.48 mg/kg）>Cr（29.31 mg/kg）>Pb（19.23 mg/kg）>Cu（16.62 mg/kg）>Ni（8.18 mg/kg）>As（6.00 mg/kg）>Cd（0.20 mg/kg）。7种元素平均质量分数均未超过《土壤环境质量标准-农用地土壤风险管控标准》（GB15618-2018）（pH≤5.5）风险筛选值;Cu、Zn、Cd和As平均质量分数分别为广东省土壤背景值的2.08、2.74、6.75和1.11倍。2）重金属中Cd的潜在生态风险系数最高,潜在生态风险程度为很强,其余元素潜在生态风险程度为轻微。研究区土壤重金属的潜在生态风险程度为中等。重金属与有机质、黏土、粉砂呈正相关关系,与pH、砂呈负相关关系。3）Zn、Cr和Cu在红树植物体内质量分数较高,Pb、Ni和As次之,Cd质量分数最低。除无瓣海桑Zn的根-叶转运系数＞1外,重金属在桐花树、木榄和无瓣海桑中的生物富集系数和转运系数均＜1,说明桐花树、木榄和无瓣海桑对重金属的富集和转运能力不强,大部分有毒元素主要积累在根部,降低了有毒重金属通过食物链传递的风险。     

福建土壤重金属地积累污染特征及潜在生态危害评价

基于地理信息系统软件,使用地积累指数和潜在生态危害指数分别研究了福建省土壤重金属(As、Cd、Cr、Cu、Hg、Ni、Pb、Zn)的地积累污染特征和潜在生态危害程度。通过分析结果表明:研究区土壤中各重金属元素均出现不同程度的累积污染状况,污染强弱为:CdPbHgAsZnCrNiCu,总体上累积污染主要处于0~3级,有小部分点位的累积污染程度在重度以上。主要污染元素为Cd、Hg、Pb和As,而Cr、Cu、Ni和Zn的累积污染程度相对较轻。土壤中Cd和Hg具有中等潜在生态危害,其他元素具有轻微潜在生态危害,各重金属元素潜在生态危害强弱为:CdHgAsPbNiCuCrZn,其中As、Cd、Cu和Hg有部分点位具有严重潜在生态危害。研究区主要土地利用类型土壤重金属综合潜在生态危害的强弱为:水田果园滩涂旱地林地茶园草地。研究认为人类活动包括农药、施肥、灌溉、交通、采矿等是造成研究区土壤重金属污染的主要原因。     

盐城滨海湿地表层沉积物重金属分布特征与污染评价

于2014~2016年,采集并测定盐城滨海湿地陆域和海域表层沉积物样品,测定其中的重金属(Cu、Pb、Zn、Cr、Cd、As、Hg)含量,分析其空间分布特征;利用内梅罗综合污染指数法,进行污染评价。研究结果表明,盐城滨海湿地表层沉积物中,重金属Cr、Cu、Zn、Cd、Pb、As和Hg的平均质量比分别为64.78μg/g、23.33μg/g、67.70μg/g、0.17μg/g、20.14μg/g、10.4μg/g和0.05μg/g,都低于国家Ⅰ类土壤质量标准和Ⅰ类海洋沉积物标准。Cd在王港乡附近海域为中等污染,局部地区存在轻度污染现象。内梅罗综合污染指数评价显示,研究区大部分地区为清洁区,中山河口至灌河口沿海一带、新洋港、大丰港附近为尚清洁区,轻污染区仅在新洋港、王港乡以及斗龙港附近有零星分布。     

农田、退耕还湿地、天然草本沼泽土壤重金属和农药的分布及潜在生态风险评价——以抚远市乌苏镇东兴村为例

为了解三江平原农田、退耕还湿地、天然草本沼泽土壤中重金属含量和农药残留状况,以黑龙江省抚远市乌苏镇东兴村为研究区,采集农田、退耕还湿地和天然草本沼泽土壤样品,分析了这些土壤中重金属含量和农药残留量;采用潜在生态风险指数法和风险商值法,分别评价了土壤中的重金属潜在生态风险水平和农药残留潜在生态风险水平。研究结果表明,研究区土壤中As、Cd、Cr、Ni和Cu的平均含量都低于国家土壤环境质量二级标准(GB15618—1995);农田土壤中的As、Cd、Cr、Cu和Ni平均质量比分别为12.4 mg/kg、0.24 mg/kg、97.06mg/kg、24.08 mg/kg和36.46 mg/kg,退耕还湿地土壤中的Cr和Ni平均质量比为95.13 mg/kg和31.43 mg/kg。农田、退耕还湿地和天然草本沼泽土壤中的滴滴涕残留以4.4'—滴滴伊为主,其4.4'—滴滴伊平均残留质量比分别为6.13 ng/g、6.80 ng/g和4.47 ng/g;农田土壤中检测出阿特拉津平均残留质量比达到了79.32 ng/g;农田土壤中的Cd含量达到了中等潜在生态风险水平;农田、退耕还湿地和天然草本沼泽土壤中5种重金属综合潜在生态风险处于轻度潜在生态风险水平;农田土壤中残留的阿特拉津的污染风险商大于1,说明阿特拉津残留可能有潜在的生态风险。     

衡水湖底泥中7种重金属元素含量的分布及其潜在生态风险评价

于2018年6月25～27日,在河北省衡水湖设置了22个采样点,采集0～50 cm深度的底泥样品,测定底泥样品中的7种重金属元素含量;并采用地累积指数法和潜在生态危害指数法,对7种重金属元素潜在生态风险进行评价。研究结果表明,衡水湖底泥中的7种重金属元素Cd、Hg、As、Pb、Cr、Cu和Zn的质量比分别为0.046～0.290 mg/kg、0.010～0.064 mg/kg、4.31～10.70 mg/kg、11.7～29.5 mg/kg、48.5～87.5 mg/kg、10.7～24.7 mg/kg和35.2～198.0 mg/kg;在22个采样点中,有9个采样点底泥中的Cd元素含量的地累积指数大于0,即这9个采样点存在轻微的Cd污染,处于轻微危害等级;每种重金属元素含量分别与其它大多数金属元素含量显著相关,表明这些重金属元素可能具有同源性,各重金属元素含量都分别与底泥中的有机质、全氮含量显著相关,Hg、Pb和Zn元素含量与全磷含量显著相关;衡水湖底泥中的7种重金属元素综合潜在生态风险指数为90.23,表明衡水湖底泥中的重金属元素存在轻微的潜在生态风险。     

Contaminations of Heavy Metals in Surface Soils of Various Lands and Their Health Risks in Tianjin Qilihai Ancient Lagoon Wetlands,China

A total of 36 surface soil profiles were set at the wetlands in Qilihai Ancient Lagoon Wetlands,Tianjin,the surface soils of 0-20 cm depth were sampled at various use types of lands to provide information on the concentrations of heavy metals in the coastal wetlands.Total concentrations of arsenic(As),cadmium(Cd),copper(Cu),lead(Pb),chromium(Cr)and zinc(Zn)were determined using inductively coupled plasma atomic absorption spectrometry(ICP-AES)to address the pollution levels in the sampling sites.The results showed that the concentrations of Cd,Cu in the soils disturbed by human activities intensively,the Phragmites australis marshes,the farmland,the brushes decreased in turn;among the sites,the concentrations of As,Cd and Cu were the highest in the soil of build-up areas,while the concentrations of Pb and Zn were the higher in the soil of farmland.The mean concentrations of Cu,Cr,Cd,Pb,Zn and As in the soils of 0-20 cm depth were 38.74 mg/kg,83.52 mg/kg,0.19 mg/kg,34.27 mg/kg,121.7 mg/kg and 18.77 mg/kg,respectively.The contamination indices of As were on the high pollution level in the soils of farmland and disturbed by human activities intensively;the concentrations of Cd in the soils of the marshes and farmland were at the moderate pollution level,while that in the soil disturbed by human activities intensively was at high pollution level.The values of comprehensive contamination index demonstrated that the variation of As contents was the maximum in the soils,Cd pollution reached to a high level.Geoaccumulation index showed that As pollution was at moderate level,and Cd,Cu and Zn pollution were at slight level,and the Pb and Cr pollution wasn't found in the build-up areas.     

青海湖流域沙柳河下游沉积物中重金属污染风险评价

对青海湖流域沙柳河下游沉积物中As、Cd、Pb、V、Cr、Mn、Ni、Cu和Zn 9种重金属元素的含量进行了分析测定,采用污染系数、富集系数、地累积指数和潜在生态危害指数评估了其污染程度。结果表明：无论在横向还是纵向上,重金属元素含量均低于青海湖土壤背景值;重金属元素污染系数和富集系数均小于2,且大多数样品的值低于1（高于1者多为Cd、Cu、Ni、Zn,且具高值）;地累积指数均为负值（除QB-19中Cd和Cu分别为0.10和0.02）;潜在生态风险因子大多低于30,潜在生态危害指数大多低于70。沙柳河下游沉积物尚未出现重金属污染,具有低的生态风险,但该流域重金属的人为排放确实存在（主要是Cd、Cu、Ni、Zn等）,而且在近代排放更为显著。     

Comparison and Analysis of Estimation Methods for Heavy Metal Pollution of Farmland Soils

Heavy metal pollution of farmland soils is a serious environmental problem. The accurate estimation of heavy metal pollution levels of farmland soils is very crucial for sustainable agriculture. Concentrations of heavy metal elements (As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn) in farmland soils at 186 sampling sites in the Baghrash Lake Basin, NW China, were determined and analyzed based on the pollution index (P_i), the geo-accumulation index (I_geo), the enrichment factor (EF), the ecological risk index (ER), and the environmental risk index (I_er). The results of these five different estimation methods were compared and discussed. The obtained results indicated that the average concentrations of all the heavy metals in the farmland soils of the study area were lower than the Soil Environmental Quality of China (GB 15168-2018) levels, but the average concentrations of Cd, Cr, Ni, Pb, and Zn exceed the corresponding background values. Significant differences in estimation results existed between the five estimation methods. Based on the identified concentrations, the average P_i, I_geo, and EF values of the heavy metals in farmland soils decreased in the order of: Zn > Pb > Cd > Cr > Ni > Cu > As, whereas the average ER values decreased in the order of: Cd > As > Cu > Pb > Ni > Cr > Zn, and the average I_er values decreased in the order of: Cd > Cu > Zn > As = Pb > Cr > Ni. The pollution class values with different estimation methods were ranked as: P_i > I_geo = EF > ER = I_er. The obtained results suggest that the most appropriate estimation method and soil background values of farmlands should be used for better understanding the environmental quality of farmland soils. Overall, the EF and ER methods are recommended for assessing heavy metal pollution risks of farmland soils.     

Heavy metal concentrations of agricultural soils and vegetables from Dongguan, Guangdong

A total of 118 of agricultural soil and 43 of vegetable samples were collected from Dongguan City, Guangdong, China. The spatial distribution, sources, accumulation characteristics and potential risk of heavy metals in the agricultural soils and vegetables were depicted in details by three different approaches, including total contents of eight metal elements in soils and vegetables, GIS maps and multivariate analysis of heavy metals in soils in the study. The results show that there are higher accumulation of heavy metals such as Cu, Zn, Ni, Pb, Cd and Hg in agricultural soils, and the contents of Pb (65.38 mg kg?1) and Hg (0.24 mg kg?1) are 1.82 and 2.82 times of the background contents of the corresponding heavy metals in soils of Guangdong Province, respectively. There are about 3.4% of Cu, 5.9% of Ni, 1.7% of Cd and 28% of Hg in all collected soil samples from all investigated sites which have overran the contents for heavy metals of the China Environmental Quality Standard for Soils (GB15618-1995, Grade Ⅱ). The pollution characteristics of multi-metals in soils are mainly reflected by Hg. There are different sources to eight metal elements in soils, Cu, Zn, Ni, Cr and As are predominantly derived from parent materials, and Pb, Hg and Cd are affected by anthropogenic activities. The spatial distribution shows that the Cu, Zn, Ni, Cr, Pb, As and Hg contents of agricultural soils are high in the west and low in the east, and Cd contents are high in the northwest, southeast and low in the southwest in Dongguan. The ratios of vegetable samples which Ni, Pb and As concentrations higher than the Maximum Levels of Contaminants in Foods (GB2762-2005) are 4.7%, 16.3% and 48.8%, respectively. The order of bio-concentration factors (BCF) of heavy metals in vegetables is Cd > Zn > Cu > As > Ni > Hg > Cr > Pb. It is necessary to focus on potential risk of heavy metals for food safety and human’s health from agricultural soils and vegetables in Dongguan City, Guangdong Province.     

湘江中下游农田土壤和蔬菜的重金属污染

A total of 219 agricultural soil and 48 vegetable samples were collected from the midstream and downstream of the Xiangjiang River（the Hengyang-Changsha section）in Hunan Province.The accumulation characteristics,spatial distribution and potential risk of heavy metals in the agricultural soils and vegetables were depicted.There are higher accumulations of heavy metals such as As,Cd,Cu,Ni,Pb and Zn in agricultural soils,and the contents of Cd（2.44 mg kg^-1 ）,Pb（65.00 mg kg^-1 ）and Zn（144.13 mg kg^-1 ）are 7.97,3.69 and 1.63 times the corresponding background contents in soils of Hunan Province,respectively. 13.2%of As,68.5%of Cd,2.7%of Cu,2.7%of Ni,8.7%of Pb and 15.1%of Zn in soil samples from the investigated sites exceeded the maximum allowable heavy metal contents in the China Environmental Quality Standard for Soils（GB15618-1995,Grade Ⅱ）.The pollution characteristics of multi-metals in soils are mainly due to Cd.The contents of As,Cd,Cu,Pb and Zn in vegetable soils are significantly higher than the contents in paddy soils.95.8%, 68.8%,10.4%and 95.8%of vegetable samples exceeded the Maximum Levels of Contaminants in Foods（GB2762-2005）for As,Cd,Ni and Pb concentrations,respectively.There are significantly positive correlations between the concentrations of Cd,Pb and Zn in vegetables and the concentrations in the corresponding vegetable soils（p〈0.01）.It is very necessary to focus on the potential risk of heavy metals for food safety and human health in agricultural soils and vegetables in the midstream and downstream of the Xiangjiang River,Hunan Province of China.     

东莞市农田土壤和蔬菜重金属的含量特征分析

从东莞市采集118 个农田土壤样品和43 个蔬菜样品, 测试其中Cu、Zn、Ni、Cr、Pb、 Cd、As 和Hg 等8 种重金属元素的含量, 并结合GIS 制图和数据统计, 对农田土壤中重金属 的空间分布和来源、土壤和蔬菜中重金属的富集特征及其潜在风险进行了分析。结果表明, 农田土壤中Cu、Zn、Ni、Pb、Cd 和Hg 等元素含量均高于相应元素的广东省土壤背景值, 其中, Pb (65.38 mg kg^-1) 和Hg (0.24 mg kg^-1) 含量分别为其对应背景值的1.82 和2.82 倍。与我国《土壤环境质量标准》中II 级标准(pH < 6.5) 相比, 土壤中Cu、Ni、Cd 和Hg 含量样本超标率分别为3.4%、5.9%、1.7%和28%, 表现为以Hg 为主的多种重金属共同污染。土壤 中8 种重金属中Cu、Zn、Ni、Cr 和As 等元素主要来源于成土母质, Pb、Hg 和Cd 等元素主要与人类活动有关。空间分布上, Cu、Zn、Ni、Cr、Pb、As 和Hg 等7 种重金属含量呈现出西部高、东部低的特点, Cd 含量在西北部和东南部较高, 西南部较低。与《食品中污染物限量》(GB2762-2005) 等相关标准比较, 蔬菜中Ni、Pb 和As 含量的样本超标率分别为4.7%、16.3%和48.8%。蔬菜中重金属富集系数的顺序为: Cd > Zn > Cu > As > Ni > Hg > Cr > Pb。     

东莞市农田土壤和蔬菜重金属含量分析(英文)

A total of 118 of agricultural soil and 43 of vegetable samples were collected from Dongguan City,Guangdong,China. The spatial distribution,sources,accumulation charac-teristics and potential risk of heavy metals in the agricultural soils and vegetables were de-picted in details by three different approaches,including total contents of eight metal ele-ments in soils and vegetables,GIS maps and multivariate analysis of heavy metals in soils in the study. The results show that there are higher accumulation of heavy metals such as Cu,Zn,Ni,Pb,Cd and Hg in agricultural soils,and the contents of Pb (65.38 mg kg-1) and Hg (0.24 mg kg-1) are 1.82 and 2.82 times of the background contents of the corresponding heavy metals in soils of Guangdong Province,respectively. There are about 3.4% of Cu,5.9% of Ni,1.7% of Cd and 28% of Hg in all collected soil samples from all investigated sites which have overran the contents for heavy metals of the China Environmental Quality Standard for Soils (GB15618-1995,Grade Ⅱ ). The pollution characteristics of multi-metals in soils are mainly reflected by Hg. There are different sources to eight metal elements in soils,Cu,Zn,Ni,Cr and As are predominantly derived from parent materials,and Pb,Hg and Cd are affected by anthropogenic activities. The spatial distribution shows that the Cu,Zn,Ni,Cr,Pb,As and Hg contents of agricultural soils are high in the west and low in the east,and Cd contents are high in the northwest,southeast and low in the southwest in Dongguan. The ratios of vegetable samples which Ni,Pb and As concentrations higher than the Maximum Levels of Con-taminants in Foods (GB2762-2005) are 4.7%,16.3% and 48.8%,respectively. The order of bio-concentration factors (BCF) of heavy metals in vegetables is Cd Zn Cu As Ni Hg Cr Pb. It is necessary to focus on potential risk of heavy metals for food safety and hu-man's health from agricultural soils and vegetables in Dongguan City,Guangdong Province.     

湘江中下游农田土壤和蔬菜的重金属污染

从湖南省湘江中下游衡阳-长沙段沿岸采集219 个农田土壤样品和48 个蔬菜样品, 测 试其中As、Cd、Cr、Cu、Ni、Pb、Zn 等7 种重金属元素的含量, 并结合GIS 作图与数据统 计, 对农田土壤中重金属空间分布、土壤和蔬菜中重金属富集特征以及其潜在风险进行分析。 结果表明, 农田土壤中As、Cd、Cu、Ni、Pb 和Zn 含量均大于湖南省相应土壤重金属含量背 景值, Cd (2.44 mg kg^-1)、Pb (65.00 mg kg^-1)、Zn (144.13 mg kg^-1) 含量分别超标7.97、3.69 和 1.63 倍。与我国《土壤环境质量标准》(GB15618-1995) 中II 级标准(pH 6.5~7.5) 比较, 土壤 As、Cd、Cu、Ni、Pb 和Zn 含量的超标率分别为13.2%、68.5%、2.7%、2.7%、8.7%和 15.1%, 表现为以Cd 为主的多种重金属混合污染。菜地土壤中As、Cd、Cu、Pb 和Zn 的含 量( 几何均值) 分别高于水稻土As、Cd、Cu、Pb 和Zn 含量。与《食品中污染物限量》 (GB2762-2005) 等标准比较, 蔬菜As、Cd、Ni、Pb 含量的样本超标率分别为95.8%、68.8%、 10.4%和95.8%; 蔬菜Cd、Pb、Zn 含量与相应土壤的Cd、Pb、Zn 含量存在极显著的相关性 (P < 0.01)。湘江中下游的农田土壤和蔬菜中重金属污染的潜在风险值得关注。     

澜沧江-湄公河重金属污染评价及大坝影响(英文)

The resource development and changes of hydrological regime,sediment and water quality in the Mekong River basin have attracted great attentions.This research aimed to enhance the study on transboundary pollution of heavy metals in this international river.In this study,eight sampling sites were selected to collect the bed sand samples along the mainstream of the Mekong River.In addition,the contents of 5 heavy metal elements and their spatial variability along the mainstream of the river were analyzed.The geoaccumulation index(I geo) and potential ecological risk analysis were employed to assess heavy metal pollution status in the mainstream of the Mekong River.The results show that the average content of the heavy metal elements Zn is 91.43 mg/kg,Pb is 41.85 mg/kg,and As is 21.84 mg/kg in the bed sands of the Upper Mekong River,which are higher than those(Zn 68.17 mg/kg,Pb 28.22 mg/kg,As 14.97 mg/kg) in the Lower Mekong.The average content of Cr in the Lower Mekong is 418.86 mg/kg,higher than that in the Upper Mekong(42.19 mg/kg).Luang Prabang has a very high Cr concentration with 762.93 mg/kg and Pakse with 422.90 mg/kg.The concentration of Cu in all of the 8 sampling sites is similar,except for in Jiajiu with 11.70 mg/kg and Jiebei with 7.00 mg/kg.The results of the geoaccumulation index reveal that contaminations caused by Zn and Pb while Pb and As are more than those by Zn in Upper Mekong.Cr is the primary pollutant in the Lower Mekong,especially at Luang Prabang and Pakse.Slight pollution with As also occurs in Pakse.The potential ecological risk index indicates that the potential ecological risk of heavy metals in the mainstream of the Mekong River is low.We argue that the pollution of water quality and contamination of heavy metals in bed sediment caused by mining of mineral resources or geochemical background values in the Mekong is not transmitted from the Upper to the Lower Mekong because of the reservoir sedimentation and dilution along the river.