肠道修复：一种利用益生菌减少重金属积累的新思路

近年来受到重金属工业废水的排放及人类日常活动的影响,我国大面积土壤中重金属含量急剧增高。不同重金属可能通过食物链进入人体,给人类健康带来隐患。因此,减少重金属在动物体肠道中的积累是降低重金属危害的一个重要课题。研究显示,一些益生菌能够在体内外环境中有效地结合重金属,但人们对益生菌结合重金属的能力,及其对重金属的肠道修复机理了解较少。本文针对目前镉、铅、铬等重金属对环境与动物体健康造成严重危害的现状,分析了各类重金属的污染来源,概括了益生菌在环境与动物体肠道中对各种重金属的修复情况及作用机理,重点考察了益生菌在动物体肠道环境中与重金属相互作用的机理研究,同时对未来利用益生菌制剂直接减少人体肠道内重金属积累进行了展望。     

利用生物固定土壤重金属的机理及在农产品安全中的应用

生物固定技术是土壤重金属污染防治和保障农产品安全的有效手段。目前利用生物固定土壤中的重金属主要有三种途径：①利用土壤微生物固定重金属;②利用植物根分泌物固定重金属;③利用植物一微生物联合固定重金属。本文阐述了生物固定技术在解决土壤重金属危害中的重要意义及利用土壤微生物和植物根分泌物固定重金属的机理,提出了农作物选育及改良、高效微生物菌剂的选育及应用等具体措施以保障农产品安全。     

A field lysimeter study of heavy metal movement down the profile of soils with multiple metal pollution during chelate-enhanced phytoremediation

The agricultural soils near a copper smelter in southeast China were found to be highly contaminated with Cu, Pb, Zn, and Cd. Metal migration from the soil to groundwater presents an environmental risk that depends on the physicochemical properties of the contaminated soils. Soil solution samples were obtained using lysimeters from a loam soil with multiple metal pollutions over a period of about 1 yr. A field lysimeter study was also conducted to examine the potential use of (S, S')-ethylenediamine-N, N'-disuccinic acid trisodium salt (EDDSNa3) in chelate-enhanced phytoremedation and to evaluate the leaching of heavy metals. The average heavy metal concentrations in the soil solution (without the addition of EDDS) were high (e.g., 0.15 mg Pb L(-1) at a 50-cm depth) compared to the upper limit for protection of groundwater in China, but varied during the sampling period. Cu concentrations were not correlated with pH or dissolved organic carbon (DOC), but Zn and Cd concentrations were related to soil solution pH. EDDS enhanced metal solubility in the soil, but plant metal uptake by Elsholtzia splendens Nakai did not increase accordingly. There may be an increasing risk of groundwater pollution by Cu and the EDDS enhanced phytoremediation technique needs to be carefully applied to minimize this side effect.     

Estimation of the mean distance of closest approach of some heavy metal ions in aqueous solutions: some experimental and theoretical calculations

The estimation of numerical values of the mean distance of closest approach of ions, a, of heavy metal ion salts in aqueous solutions, determined from activity coefficients, as well as from different theoretical approaches, is presented and discussed.     

Health risks of heavy metals to the general public in Hengyang,China, via consumption of rice

This investigation was conducted to survey the levels of cadmium (Cd), lead (Pb), chromium (Cr), copper (Cu), zinc (Zn), and manganese (Mn) in polished rice collected at supermarkets located in Hengyang, China. The surveyed rice samples were grouped according to their production areas into four different groups—Hunan, Jiangxi, Jilin, and Thailand. The data showed that the highest means of Cd, Pb, Cr, Cu, Zn, and Mn contents were in rice samples produced from Hunan (0.215 mg/kg), Thailand (0.537 mg/kg), Hunan (0.348 mg/kg), Jiangxi (2.472 mg/kg), Thailand (17.259 mg/kg), and Jinlin (9.326 mg/kg), respectively. Average daily intake dose for the six elements through consumption of rice was lower than the oral reference dose. Although the hazard quotient values for all six elements were <1.0, hazard index values in all the production areas (except Thailand) were >1.0, and cancer risk (CR) and total CR values were >10^?4, respectively. Certainly, there are inherent limitations for these health risk values, including actual ingestion rate, exposure duration, and bioavailability of heavy metals. These results indicate that long-term heavy metal exposure by consumption of rice in Hengyang could pose both potential non-carcinogenic and carcinogenic health risks to the local residents.     

淋洗法修复化工厂遗留地重金属污染土壤的可行性

通过室内模拟试验,采用振荡淋洗的方法研究了蒸馏水、HCl、H₃PO₄、草酸、CaCl₂等淋洗剂对化工厂遗留地污染土壤中重金属的淋洗效果,探讨了淋洗剂浓度、淋洗时间、淋洗次数等对淋洗效果的影响,并研究了HCl处理前后土壤中重金属形态的变化.结果表明：蒸馏水、H₃PO₄、CaCl₂等对Cr、Pb、Zn、Cu、Cd的去除率较低,大多数条件下重金属去除率均在1%以下,最大去除率仅为3.58%.2 mol·L^-1 HCl在土水比为1∶3、反应时间为1 h、2次淋洗的条件下可以达到最佳淋洗效果,Cr、Pb、Zn、Cu、Cd的去除率分别达到80.75％、88.69％、98.00％、79.33％和95.52％.形态分析结果表明,HCl能有效去除土壤中各种结合形态的重金属.     

Genetic improvement of heavy metal tolerance in plants by transfer of the yeast metallothionein gene (CUP1)

Cauliflower (Brassica oleracea var. botrytis) tolerates treatment with 25 µM CdCl2 for eight days, but is killed by that with a 50 µM concentration. However, even 15 µM CdCl2 is toxic in the presence of 1 mM L-buthionine sulfoximine (BSO), suggesting the presence of a Cd-inducible phytochelatin and its involvement in Cd-tolerance in cauliflower. To develop heavy metal-tolerant transgenic plants, we ligated the structural gene of yeast metallothionein gene (CUP1) downstream of CaMV35S promoter and introduced the fused gene into cauliflower. A Cd-tolerant transgenic cauliflower was selected, which grew well in the presence of 400 µM or less Cd, whereas the non-transformed cauliflower tolerated only up to 25 µM Cd. The transgenic cauliflower accumulated more Cd, especially in the upper leaves, than the non-transformed plant.In conclusion, by transfer of the yeast metallothionein gene into cauliflower increased Cd-tolerance and Cd-accumulating ability can be conferred to the plant.     

Cadmium accumulation by a Citrobacter sp. immobilized on gel and solid supports: Applicability to the treatment of liquid wastes containing heavy metal cations

Polyacrylamide gel-immobilized cells of a Citrobacter sp. removed cadmium from flows supplemented with glycerol 2-phosphate, the metal uptake mechanism being mediated by the activity of a cell-bound phosphatase that precipitates liberated inorganic phosphate with heavy metals at the cell surface. The constraints of elevated flow rate and temperature were investigated and the results discussed in terms of the kinetics of immobilized enzymes. Loss in activity with respect to cadmium accumulation but not inorganic phosphate liberation was observed at acid pH and was attributed to the pH-dependent solubility of cadmium photsphate. Similarly high concentrations of chloride ions, and traces of cyanide inhibited cadmium uptake and this was attributed to the ability of these anions to complex heavy metals, especially the ability of CN(-) to form complex anions with Cd(2+). The data are discussed in terms of the known chemistry of chloride and cyanide-cadmium complexes and the relevance of these factors in the treatment of metal-containing liquid wastes is discussed. The cells immobilized in polyacrylamide provided a convenient small-scale laboratory model system. It was found that the Citrobacter sp. could be immobilized on glass supports with no chemical treatment or modification necessary. Such cells were also effective in metal accumulation and a prototype system more applicable to the treatment of metal-containing streams on a larger scale is described.     

海河低平原区农田重金属含量的空间变异性——以河北省肥乡县为例

随着工业和农业的快速发展,农田受到重金属污染的压力越来越大,其土壤环境质量的及时监测和掌握重金属在其空间的变异规律对农业生产具有十分重要的意义。利用地统计学和GIS技术对海河低平原区（肥乡县）农田土壤耕层（0—20Cm）8种重金属含量空间变异性进行了研究。结果表明：去除异常值后,8种重金属含量都符合正态分布,且其含量算术平均值未超过国家土壤环境质量二级标准。通过变异函数分析,Ph和Cr具有纯块金效应,Cu和Zn符合指数模型,Ni和Cd符合球状模型,地和As符合带基台值的线性模型。在该地区以2．0km为取样间距较大,以后调查时应该缩小间隔。Zn和Cd的空间变异性受人为因素影响较小,而Cu、Ni、Hg和As的空间变异性受人为因素影响较大,Ph和Cr在整个研究尺度上具有恒定的变异。Cu、Zn、Ni、Hg、As和Cd的变程差异较大,在2．5—13．7km之间。通过普通kriging法局部插值,Cu、Zn、Ni和As含量由西南部向东北部含量逐步升高,但是Hg却表现出相反的分布趋势。这将为当地正在开展的优势农产品区域布局规划提供理论依据。     

Cadmium and copper uptake and accumulation by Sesbania rostrata seedling, a N-fixing annual plant: implications for the mechanism of heavy metal tolerance

Sesbania rostrata,an annual tropical legume,has been found to be tolerant to heavy metals,with an unknown mechanism.It is a promising candidate species for revegetation at mine tailings.In this study,sequential extractions with five buffers and strong acids were used to extract various chemical forms of cadmium and copper in S.rostrata,with or without Cd or Cu treatments,so that the mechanisms of tolerance and detoxification could be inferred.Both metals had low transition rates from roots to the aboveground of S.rostrata.The transition ratio of Cd (4.00%) was higher than that of Cu (1.46%).The proportion of NaCl extracted Cd (mostly in proteinbinding forms) increased drastically in Cd treated plants from being undetectable in untreated plants.This suggests that Cd induced biochemical processes producing proteinlike phytochelatins that served as a major mechanism for the high Cd tolerance of S.rostrata.The case for Cu was quite different,indicating that the mechanism for metal tolerance in S.rostrata is metal-specific.The proportion of water-insoluble Cu (e.g.oxalate and phosphate) in roots increased significantly with Cu treatment,which partially explains the tolerance of S.rostrata to Cu.However,how S.rostrata copes with the high biotic activity of inorganic salts of Cu,which increased in all parts of the plant under Cu stress,is a question for future studies.Sesbania rostrata is among the very few N-fixing plants tolerant to heavy metals.This study provides evidence for the detoxification mechanism of metals in Sesbania rostrata.     

A new index for assessing heavy metal contamination in sediments of the Beijing-Hangzhou Grand Canal (Zaozhuang Segment): A case study

Zaozhuang Segment of the Beijing-Hangzhou Grand Canal is an important water conveyance line on the eastern route of the South-North Water Transfer Project in China and its water environment condition can exert a significant influence on diversion water quality safety. This paper analyzed contents of five heavy metals such as Cd, Cu, Ni, Pb and Zn as well as their chemical forms in surface sediments in this region. Methods including Threshold Effects Level-Probable Effects Level (TEL-PEL), Risk Assessment Code (RAC) and Acid Volatile Sulfide- Simultaneously Extracted Metals (AVS-SEM) were also employed to evaluate the quality of sedimentary environment in this region. With the aim to assess the eco-environmental risk revealing the information of the concentration, the chemical fractionation, the toxicity of heavy metals, a new assessment index known as Multivariable Evaluation Index (MEI) was introduced into this paper. Results indicated that contents of such five heavy metals in surface sediments were generally low. Overall, ecological risk was in the medium-low grade in addition to several locations where the level of risk was high. However, certain differences still existed among various assessment results. Comparing with other single evaluation methods, MEI may be able to reflect contamination status and ecological risks of heavy metals in sediments of a specific region more comprehensively. MEI also seemed able to overcome the limitations of other prevalent aggregated indexes to assess potential sediment pollution risk in aquatic systems.     

Phytostabilization of heavy metals by the emergent macrophyte Vossia cuspidata (Roxb.) Griff.: A phytoremediation approach

The present study was conducted to investigate the potential of Vossia cuspidata as a phytoremediator to accumulate heavy metals from polluted water bodies. Thirty-two quadrats, distributed equally in eight sites (six polluted sites along the Ismailia canal and two unpolluted sites along the Nile River) were selected seasonally for plant, water, and sediment investigations. Winter plants recorded the highest values of shoot height, diameter, and leaf width, but the lowest shoot density. Plants collected in autumn had the lowest values of leaf length, width, and area, while those collected in spring had the highest shoot density, with the lowest shoot height. Summer populations had the highest fresh and dry plant biomass, while winter plants had the lowest. Fresh production and dry biomass of V. cuspidata in the unpolluted Nile were significantly higher than those in polluted canals. Chlorophyll a and carotenoid concentrations were reduced under pollution stress. Spring plants accumulated the highest concentrations of Cr, Cu, and Pb in their root, and the lowest concentrations of Al, Cd, Cr, and Zn in their shoot. The bioaccumulation factor for most investigated metals, except Al, Cr, and Fe was greater than 1, while the translocation factor of all metals was less than 1, therefore this plant is considered to be a potential for these metals phytostabilization.     

A novel approach to study variable heavy chain gene usage in response to the capsular polysaccharide of Neisseria meningitidis serogroup C

The molecular mechanisms involved in the relatively poor immune response in the elderly are not clearly understood. Qualitative aspects of the immune response could be a possible explanation for the differential response to T-independent antigens in young adults and elderly. This study is directed towards elucidating the differential usage of variable heavy chain by young adult and elderly derived sequences in response to the capsular polysaccharide of Neisseria meningitidis serogroup C. We currently report findings of a preliminary study designed to test the feasibility of a novel approach to isolate antigen-specific B cells. Paramagnetic beads coated with an anti-idiotypic antibody, which mimics the capsular polysaccharide of N. meningitidis serogroup C, were used to select B cells. Analysis of the gene usage data indicates some unexpected differences in the use of variable chain heavy chain in the case of young adult versus elderly sequences. The elderly derived sequences use a more diverse array of V_H gene families in contrast to the young adult sequences, where the V_H gene family usage is restricted. Nearly half the young adult sequences utilize V_H3-15 germline sequence while only 25% of the elderly sequences use this germline sequence. There were interesting differences in the types of JH chain and the composition and length of CDR3 utilized by the two groups. Together, these significant differences may contribute towards the poor immune response to T-independent antigens in the elderly. These data validate the techniques used for these studies and suggest that it is pertinent to use this approach towards future investigations to elucidate gene usage in response to an antigen.     

崇明东滩盐沼土壤重金属含量的高光谱估算模型

高光谱遥感技术现已被广泛应用于地表矿物成份的识别以及它的含量、植物化学成份的估测,土壤调查等方面的研究。利用地物光谱仪测定了长江口崇明东滩盐沼土壤的光谱信息,根据EO-1卫星Hyperion高光谱仪的波段设置,提取各波段平均波长的光谱反射率,并结合实验室实测的土壤重金属含量,应用偏最小二乘法(PLS),预测盐沼土壤重金属含量。结果表明,盐沼土壤重金属Zn、Cr、Cu预测值与实测值相关系数分别达到0.822**、0.761**和0.775**,均为极显著相关,其实测值与预测值的平均相对误差为4%、3%和4%。研究结果可以为高光谱遥感技术反演盐沼土壤重金属含量,进一步应用空间或航空遥感进行大尺度环境污染遥感、遥测信息提取和反演提供技术支撑。     

Assessment of heavy metal toxicity related with human health risk in the surface water of an industrialized area by a novel technique

This study innovates an assessment technique to evaluate heavy metal toxic load (HMTL). Assessment of surface water in Durgapur industrial area, West Bengal India illustrates that heavy metals in majority of sampling locations exceed the drinking water quality standards. Therefore, pollution status and health impact were predicted by heavy metal pollution index (HPI) and hazard index (HI). More than 50% of sampling locations were marked as polluted. Moreover, 5% and 90% of sampling locations near the industries have health risk to adult and child on ingestion. The study of specific exposure-time and exposure-duration affirms the suitability of water for fishing and regular activities. However, HPI or HI does not quantify heavy metal concentrations that pose threat to human health. Therefore, the proposed assessment technique, HMTL, determines the concentration of heavy metals responsible for health hazard. HMTL identifies Mn, Pb, and Co as toxic metals and estimates 85%, 63%, and 70% removal of these metals from surface water to limit pollution. Origins of metals were also investigated through statistical techniques, which revealed that Fe has geogenic and anthropogenic source, while other metals originate by anthropogenic activities solely. This study demonstrates that HMTL will help the planning authority to document effective water quality management plan.     

Evaluation of metal contamination and risk assessment to human health in a coal mine region of India: A case study of the North Karanpura coalfield

The present study aimed to evaluate metal contamination level in coal mine water of the North Karanpura coalfields and assess the possible health risk due to the intake of untreated mine water. Fourteen coal mine water samples were collected from the study area and analyzed for Al, As, Ba, Cr, Cu, Fe, Mn, Ni, Se, and Zn using inductively coupled plasma-mass spectroscopy (ICP-MS). The heavy metal pollution index (HPI) was used to calculate metal pollution level in the coal mine water. The hazard quotient (HQ) and hazard index (HI) were estimated for health risk to child and adult by using the United States Environmental Protection Agency (USEPA) methods. The concentrations of Al, Fe, Mn, and Ni in coal mine water were exceeding the acceptable as well as the maximum permissible limits specified for drinking and domestic uses. The HPI values were below the critical pollution index level of 100 except at one location. The estimated HQ and HI values for adult and children were greater than the standard limits in nearly half of the water samples. High HQ and HI values suggest that suitable treatment of coal mine water will require before its utilization in domestic and drinking purposes.     

A comparison of heat shock protein genes from cultured cells of the cabbage armyworm, Mamestra brassicae, in response to heavy metals

Heat shock protein (HSP) genes, hsp90, hsp70, hsc70, hsp20.7, and hsp19.7, were cloned and sequenced from cultured cells of the cabbage armyworm, Mamestra brassicae. Analyses of the cDNA sequences revealed open reading frames of 2,151, 1,914, 1,962, 540, and 465 bp in lengths, which encode proteins with calculated molecular weights of 82.5, 69.9, 71.6, 20.7, and 19.7 kDa, respectively. An increased expression was observed in all five genes after exposure to a high temperature. The induction of gene expression was not observed during a low temperature exposure, but was observed when the cells were recovered at ambient temperature. Expression of hsp90, hsp70, and hsp20.7 was induced after exposure to 2 microM of cadmium, while the minimum cadmium concentration for induction of hsp19.7 was 5 microM. The induction of hsp90 expression was somewhat masked by basal levels of expression. Only hsp20.7 expression was induced by exposure to copper. Lead did not induce expression of any of the HSP genes tested. Cadmium-induced up-regulation of hsp70 expression was lasted longer than heat-induced one. These results suggest that hsp70 could be useful to assess the cellular distress or injury induced by cadmium.     

Cadmium and copper uptake and accumulation by Sesbania rostrata seedling, a N-fixing annual plant: implications for the mechanism of heavy metal tolerance

Sesbania rostrata, an annual tropical legume, has been found to be tolerant to heavy metals, with an unknown mechanism. It is a promising candidate species for revegetation at mine tailings. In this study, sequential extractions with five buffers and strong acids were used to extract various chemical forms of cadmium and copper in S. rostrata, with or without Cd or Cu treatments, so that the mechanisms of tolerance and detoxification could be inferred. Both metals had low transition rates from roots to the aboveground of S. rostrata. The transition ratio of Cd (4.00%) was higher than that of Cu (1.46%). The proportion of NaCl extracted Cd (mostly in protein-binding forms) increased drastically in Cd treated plants from being undetectable in untreated plants. This suggests that Cd induced biochemical processes producing protein-like phytochelatins that served as a major mechanism for the high Cd tolerance of S. rostrata. The case for Cu was quite different, indicating that the mechanism for metal tolerance in S. rostrata is metal-specific. The proportion of water-insoluble Cu (e.g. oxalate and phosphate) in roots increased significantly with Cu treatment, which partially explains the tolerance of S. rostrata to Cu. However, how S. rostrata copes with the high biotic activity of inorganic salts of Cu, which increased in all parts of the plant under Cu stress, is a question for future studies. Sesbania rostrata is among the very few N-fixing plants tolerant to heavy metals. This study provides evidence for the detoxification mechanism of metals in Sesbania rostrata.