Assessing potential dietary toxicity of heavy metals in selected vegetables and food crops

Heavy metals, such as cadmium, copper, lead, chromium and mercury, are important environmental pollutants, particularly in areas with high anthropogenic pressure. Their presence in the atmosphere, soil and water, even in traces can cause serious problems to all organisms, and heavy metal bioaccumulation in the food chain especially can be highly dangerous to human health. Heavy metals enter the human body mainly through two routes namely： inhalation and ingestion, ingestion being the main route of exposure to these elements in human population. Heavy metals intake by human populations through food chain has been reported in many countries. Soil threshold for heavy metal toxicity is an important factor affecting soil environmental capacity of heavy metal and determines heavy metal cumulative loading limits. For soil-plant system, heavy metal toxicity threshold is the highest permissible content in the soil （total or bioavailable concentration） that does not pose any phytotoxic effects or heavy metals in the edible parts of the crops does not exceed food hygiene standards. Factors affecting the thresholds of dietary toxicity of heavy metal in soil-crop system include： soil type which includes soil pH, organic matter content, clay mineral and other soil chemical and biochemical properties; and crop species or cultivars regulated by genetic basis for heavy metal transport and accumulation in plants. In addition, the interactions of soil-plant root-microbes play important roles in regulating heavy metal movement from soil to the edible parts of crops. Agronomic practices such as fertilizer and water managements as well as crop rotation system can affect bioavailability and crop accumulation of heavy metals, thus influencing the thresholds for assessing dietary toxicity of heavy metals in the food chain. This paper reviews the phytotoxic effects and bioaccumulation of heavy metals in vegetables and food crops and assesses soil heavy metal thresholds for potential dietary toxicity.     

Review: Role of soil rhizobacteria in phytoremediation of heavy metal contaminated soils

Heavy metal pollution of soil is a significant environmental problem and has its negative impact on human health and agriculture. Rhizosphere, as an important interface of soil and plant, plays a significant role in phytoremediation of contaminated soil by heavy metals, in which, microbial populations are known to affect heavy metal mobility and availability to the plant through release of chelating agents, acidification, phosphate solubilization and redox changes, and therefore, have potential to enhance phytoremediation processes. Phytoremediation strategies with appropriate heavy metal-adapted rhizobacteria have received more and more attention. This article paper reviews some recent advances in effect and significance of rhizobacteria in phytoremediation of heavy metal contaminated soils. There is also a need to improve our understanding of the mechanisms involved in the transfer and mobilization of heavy metals by rhizobacteria and to conduct research on the selection of microbial isolates from rhizosphere of plants growing on heavy metal contaminated soils for specific restoration programmes.     

Immobilization of heavy metals in sludge using phosphoric acid and monobasic calcium phosphate

The purpose of this research is to investigate the potential of pre-treatment with phosphoric acid(PA) and monobasic calcium phosphate(MCP) for the stabilization of heavy metals in sludge and its bottom ash.The tannery sludge samples were collected in Wenzhou,China and heavily contaminated with heavy metals,such as Pb,Cr and so on.The samples were pre-treated with PA or MCP.Then XRD and TCLP tests were adopted as the evaluating methods to characterize the Pb,Cr,Cu,Zn and Cd immobilization in the pre-treated sludge and its bottom ash.The results showed that this treatment effectively immobilized Pb and Cd in the sludge,lightly stabilized the metal Cu,and adversely,enhanced the leachability of Zn.After incineration at 900℃,Pb and Cr in the bottom ash of pre-treated sludge were significantly stabilized due to the formation of their highly thermostable phosphates and pyromorphite-like minerals during the incineration process.However,an increase of Cu and Zn solubility was observed which might be attributable to the acidification of sludge due to the addition of PA or MCP.     

Physico-chemical characterization of a farmland affected by wastewater in relation to heavy metals

This study investigated selected properties of soils affected by wastewater and its relationship with some heavy metals A free survey technique involving target sampling was used in siting soil profile pits. Soil samples were collected based on horizon differentiation and analyzed using routine and special analytical techniques. Soil data were subjected to correlation analysis using SAS program. Results show that all heavy metals studied had values above critical limits in the polluted soils using known standards and that these biotoxic metals decreased with soil depths. Highly significant （P=0.01 and 0.05） relationships were established between investigated heavy metals and some soil properties, especially soil pH and organic matter. Further studies involving more edaphic properties, biotoxic metals and their bioaccessibility in crops growing on wastewater soils will surely enhance knowledge and management of these highly anthropogenically influenced soils of the study site.     

4城市成人膳食和血液中重金属差异及关系研究

目的:研究成都、镇江、太原、天津4城市的成人膳食和血液中主要重金属的差异以及相关性。方法:用ICP-MS、双道原子荧光光度计测定膳食和血液中的5种重金属元素的浓度,并对重金属元素在城市间的差异以及血液与膳食中重金属的关系进行了统计分析。结果:4城市的成人膳食和血液中重金属含量差异有统计学意义,成都、镇江的膳食重金属含量高于太原、天津,但血液中的重金属含量成都、太原高于天津、镇江;血液中Cd、As分别与膳食中Cd、As的相关有统计学意义;除膳食中Hg与As的比值外,4城市成人血液、膳食中重金属比值差异均有统计学意义,血液与膳食间的多数重金属元素比值相关有统计学意义。结论:4城市成人膳食、血液中重金属含量差异一定程度上反映了城市环境的差异;膳食是血液中Cd、As重要来源,而血液中Cu、Hg、Pb可能与空气污染有关;重金属比值可能是反映血液和膳食中重金属间关系,以及环境污染状况的更好指标。     

Thermal conductivity of soils with heavy metals concentration from the Niger Delta region of Nigeria

INTRODUCTION Knowledge of soil thermal properties is an im- portant factor in understanding mass and energy ex- change processes in the soil-atmosphere system. The chemical composition of the soils will therefore in- directly relate to their thermal conductivities. Ac- cording to Usowicz (1993), this knowledge can also help in controlling the thermal-moisture regime of soils. Soil properties often correlated with metal ad- sorption include soil pH (Christensen, 1984; Harter, 1983), soil …     

Characterization of suspended solids and particle-bound heavy metals in a first flush of highway runoff

To investigate the dynamic characteristics of total suspended solids （TSS） and their particle-bound heavy metals in a first flush, the runoff sampling together with its flow rate measuring was conducted for three rainfall events at outfalls of highway in Shanghai from June to September 2007. Field samples were analyzed to determine the concentrations of TSS and particle-bound heavy metals, such as Zn, Pb, and Cu. Results show that the wash offbehavior of TSS under varying runoffrate condition can be explained by different antecedent dry weather period （ADWP）. Contribution of fine fraction （〈45 μm） to TSS was generally higher than that of coarse fraction （〉45 μm）. When the runoff flow increased obviously, a significant contribution of the coarse fraction was observed for a certain rainfall events with long antecedent dry weather condition. The changes of total metals concentration and particle-bound metal concentrations were strongly dependent on the TSS variation. TSS was generally well correlated with most particulate-bound heavy metals. Of the heavy metals, the concentration of Zn was found considerably high and that of Pb was significantly low at North Zhongshan 2 Road, in Shanghai, China, but they are still within the range reported in the literature. Fluctuation of heavy metal contents in the coarse fraction during a first flush period was more significant compared with that in the fine fraction. The results will assist in the development of effective control strategies to minimize heavy metals and solids in highway runoff.     

Experimental approaches and analytical technique for determining heavy metals in fallen dust at ferrosilicon production factory in Edfu, Aswan, Egypt

In this study aimed to evaluate the pollution extent of metals and nonmetals inside and outside the ferrosilicon production factory in Edfu, Aswan, Egypt, raw materials (quartz, cokes, iron oxides), ferrosilicon alloy, silica fume, dust and suspended dust (at different sites) samples were collected from the factory, and fallen dust samples were collected from outside the factory, horizontally (at different sites and different distance and directions) and vertically (at different floors in the selected buildings). Gravimetric methods, X-ray fluorescence (XRF), flame photometer, wide range carbon determinator and atomic absorption spectroscopy tools were used for elements determination. The results indicating that the fallen dust and its element contents on southern factory walls being higher than those on eastern factory walls may be due to the nature of the dusts and effects of wind force and wind direction. Fallen dust levels in different regions outside the factory were found to be affected by the distance, direction and floors. The nature of dust samples was affected by gravity and the suspended dust in different factory units depended on the work capacity and method of handling materials by personnel in different production units. Silica fume was a complicated problem, had dangerous effect against the workers' health, and was characterized by high concentrations of SiO2(90.6%～93.6%) and heavy metals (Mn, 420.6×10-6～520.3×10-6; Fe, 2354×10-6～2685×10-6; Co, 80.7×10-6～101.6×10 6 and Ni,5.3× 10-6～6.05× 10-6). The TSP (Total Suspended Particulate) levels in all factory units were higher than the recommended air quality value (70 μg/m3) under Egyptian law. The effect of ferrosilicon factory fallen dust on the surrounding regions decreased with increasing distance between the factory and these regions. The suspended dust samples in the factory units and their components greatly exceeded national and international standards, so health and environmental criteria must be enforced on these units.     

Phytoremediation of heavy metal polluted soils and water：Progresses and perspectives

Environmental pollution affects the quality of pedosphere, hydrosphere, atmosphere, lithosphere and biosphere. Great efforts have been made in the last two decades to reduce pollution sources and remedy the polluted soil and water resources. Phytoremediation, being more cost-effective and fewer side effects than physical and chemical approaches, has gained increasing popularity in both academic and practical circles. More than 400 plant species have been identified to have potential for soil and water remediation. Among them, Thlaspi, Brassica, Sedum alfredii H., and Arabidopsis species have been mostly studied. It is also expected that recent advances in biotechnology will play a promising role in the development of new hyperaccumulators by transferring metal hyperaccumulating genes from low biomass wild species to the higher biomass producing cultivated species in the times to come. This paper attempted to provide a brief review on recent progresses in research and practical applications of phytoremediation for soil and water resources. Project supported by the Higher Education Commission, Government of Pakistan for the faculty training under the R & D Project “Strengthening Department of Soil Science and Soil and Water Conservation” at the University of Florida, USA, a grant from the St. Lucie River Water Initiative (SFWMD contract No. OT060162), USA, in part, and the Program for Changjiang Scholars and Innovative Research Team in University (No.IRT0536), China     

Role of soil rhizobacteria in phytoremediation of heavy metal contaminated soils

Heavy metal pollution of soil is a significant environmental problem and has its negative impact on human health and agriculture. Rhizosphere, as an important interface of soil and plant, plays a significant role in phytoremediation of contaminated soil by heavy metals, in which, microbial populations are known to affect heavy metal mobility and availability to the plant through release of chelating agents, acidification, phosphate solubilization and redox changes, and therefore, have potential to enhance phytoremediation processes. Phytoremediation strategies with appropriate heavy metal-adapted rhizobacteria have re-ceived more and more attention. This article paper reviews some recent advances in effect and significance of rhizobacteria in phytoremediation of heavy metal contaminated soils. There is also a need to improve our understanding of the mechanisms in-volved in the transfer and mobilization of heavy metals by rhizobacteria and to conduct research on the selection of microbial isolates from rhizosphere of plants growing on heavy metal contaminated soils for specific restoration programmes.     

Science Letters： Simultaneous removal of nitrate and heavy metals by iron metal

INTRODUCTION Nitrate and heavy metals commonly found ingroundwater pollutants constitute significant healthrisk to humans and a burden on the environment.Mixtures of these compounds often exist in soils andgroundwater at numerous contaminated sites. Highnitrate (NO3 ) levels in drinking water supplies sig- ?nificantly endanger human health, as they are directlyresponsible for methemoglobinemia in infants (bluebaby syndrome) and may play a role in the develop-ment of som…     

纳米材料与农作物之间的相互作用：食品安全与启示

研究目的：通过综述作物对纳米材料的吸收途径和积累,以及纳米材料对农作物生长和营养的影响,为纳米污染在农业中的风险提供理论分析和启示。 创新要点：归纳了纳米材料被作物吸收的路径和对作物生理、遗传、营养各水平上产生的胁迫。重要结论：当前纳米与作物的研究应集中在食品安全相关的问题上,考虑农业实际情况和环境因素,分析纳米材料通过食物链富集和传递的可能性,探讨纳米材料与其他土壤有机污染物可能产生的复合污染。     

四川省西部山区农作物生产潜力研究——以石棉县为例

在分析石棉县自然条件的基础上,对该县农作物的光合、光温、光温水及光温水土生产潜力进行了估算,并在计算农作物的土地自然生产潜力和实际生产力的基础上,结合石棉县农业生产存在问题,提出了石棉县农业可持续发展的对策.     

螯合离子色谱法测定茶叶中过渡金属及重金属含量

利用选择性螯合树脂和磺酸型交换树脂，在线将样品中的阴离子，碱金属，碱土金属，三价金属离子除去，同时浓缩富集待测的过渡金属，选择适当的梯度淋洗体系，将pb^2 ,Cu^2 ,Cd^2 ,Co^2 ,Zn^2 和Ni^2 等六种金属离子分离，继用在线柱后检测，检测限（信噪比为3：1）为ngmL^-1级甚至更低，并成功地应用于茶叶中过渡金属的测定。     

苏州河底泥重金属形态分析

Nine elements （As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn） in sediment samples at 7 sites （Site 1-7） from Suzhou Creek in Shanghai were analyzed with the Community Bareau of Reference （BCR） （sequential extraction （SE）） protocol and simultaneously extracted metals （SEM）/acid volatile sulfide （AVS） procedure to assess the metal bioavailability and toxicology in this area. The results showed that the BCR extraction can be utilized as an additional tool with the AVS method for assessing the potential bioavailability and toxicity of metals in sediments. Pollution from S5 （Site 5） was more severe than from other sites, especially Pb, Cu and Zn. Among all the sites, more than 80% of the total concentration of Fe existed in the residual fraction, As, Cr, Mn also dominated in the residual fraction （more than 50%）. While Cd, Ni and Zn （more than 35%） were mainly in the non-stable phase. Cu had a strong affinity with oxidizable phase and Pb varied from site to site. The SEM/AVS ratio was less than one in these sediments and results implied that the majority of Zn and Ni （〉 40%） were bound to AVS. In contrast, Pb, Cu and Cd were little bound to AVS due to their low ration of SEM-Pb, Cu, Cd to corresponding total concentration and relatively high Dorewater concentration.     

胶州湾沉积物重金属分布特征及生态风险评价

为探明胶州湾沉积物重金属的时空分布特征、关键影响因素及生态风险,分别于2015年4个季节调查采集了胶州湾表层沉积物样品,测定了As、Cd、Cr、Cu、Ni、Pb和Zn 7种重金属质量比。通过多元回归分析确定了影响重金属分布的主要因素,并采用潜在生态危害指数法(potential ecological risk index,PERI)与沉积物质量基准法(sediment quality guidelines,SQGs)结合法对7种重金属生态风险进行评价。结果表明,胶州湾表层沉积物中重金属高值区主要出现在海泊河和李村河口等东部河口附近。多元回归分析结果表明,Cu和Ni人为输入影响较大,As、Cr和Zn主要受沉积物理化性质控制,Cd和Pb人为输入与沉积物理化性质影响作用相当。风险评估结果显示,Cd、Cr、Cu和Ni是胶州湾污染较为严重的重金属。     

南京市城郊零散菜地土壤及青菜中重金属含量特征

采集了南京市城郊零散菜地土壤和青菜配对样品各18个,用原子吸收光谱仪测定了其中铜、锌、铅、镉的含量,结果表明:南京市城郊菜地土壤中Cu、Zn、Pb、Cd全量高于农区菜地土壤,Cu、Zn达到显著差异,重金属含量在土样之间有较大的变异性,反映了人为活动已对南京城郊土壤重金属产生了明显影响。城郊土壤上种植的青菜其可食部分重金属含量高于农区,尤其是对人体健康影响较大的Pb、Cd含量与农区相比存在显著差异,大大超过国家食品卫生标准。     

Childhood maltreatment and high dietary fat intake behaviors in adulthood: A birth cohort study

Childhood maltreatment has been associated with a wide range of chronic medical conditions including obesity, other metabolic events and eating disorders. However, little is known about the association between childhood maltreatment and high dietary fat intake. This study addresses the extent to which co-occurring and specific forms of substantiated childhood maltreatment are associated with self-reported high dietary fat intake in adulthood and whether there is a gender–childhood maltreatment interaction in predicting this association. The study also examines the association between age at substantiation of maltreatment, number of childhood maltreatment substantiations and high dietary fat intake-related behaviors. The data were from a prospective Australian pre-birth mother-child dyads study, the Mater-University of Queensland Study of Pregnancy. The study followed 7223 mother-child dyads following the birth of a live, singleton baby at the Mater hospital. Recruitment was early in pregnancy, and then follow-ups at 3–5 days postpartum and again when the child was 6 months, 5, 14 and 21 years of age. The data were linked to agency-substantiated cases of childhood maltreatment 0–14 years. This study extended the data linkage to 3766 (47.4% female) participants who had complete data on dietary fat intake behaviors at the 21-year follow-up. Consecutive logistic regressions were used to estimate odds ratios with respective 95% confidence intervals for high dietary fat intake for multiple and specific forms of childhood maltreatment, as well as age at and number of childhood maltreatment substantiations. Finally, a gender–childhood maltreatment interaction term was used to predict the outcome. In both unadjusted and adjusted analyses, substantiated childhood maltreatment including physical abuse were associated with high dietary fat intake-related behaviors. Similarly, substantiation of childhood maltreatment between the ages of 5 and 14 years was significantly associated with high dietary fat intake-related behaviors as were two or more substantiations of maltreatment. Inclusion of gender–childhood maltreatment interaction only had a minor impact on the size and direction of the association. Chronic and severe forms of childhood maltreatment including physical abuse are associated with a higher rate of dietary fat intake in young adulthood. Further research to replicate this association might focus on possible neuro-hormonal mechanisms that might explain this behavior.     

一种用于山区土壤重金属评估的集成RBF空间插值算法(英文)

提出了一种在山区能够准确、稳定地预测未采样点土壤重金属浓度的集成径向基函数神经网络空间插值方法(IRBFANNs).该方法集成径向基函数神经网络和神经网络集成技术的优点.为了研究所提IRBFANNs方法的性能,进行了3组不同采样密度条件下的实验.通过M n元素插值的均方根误差和分布估计图对IRBFANNs和其他6个插值方法进行了比较.实验结果表明:IRBFANNs方法在精确性和稳定性方面优于其他参评方法,且在采样密度稀疏条件下该方法能够提供细节较丰富的分布估计图.     

Competitive adsorption of Cd, Cu, Hg and Pb by agricultural soils of the Changjiang and Zhujiang deltas in China

Soils can often be contaminated simultaneously by more than one heavy metal. The sorption-desorption behavior of a metal in a soil will be affected by the presence of other metals. Therefore, selective retention and competitive adsorption of the soils to heavy metals can affect their availability and movement through the soils. In this study, the simultaneous competitive adsorption of four heavy metals (Cd, Cu, Hg, and Pb) on ten agricultural soils collected from the Changjiang and Zhujiang deltas, China was assessed. The results showed that the competition affected the behavior of heavy metal cations in such a way that the soils adsorbed less Cd and Hg, and more Pb and Cu with increasing total metal concentrations, regardless of the molar concen- tration applied. As the applied concentrations increased, Pb and Cu adsorption increased, while Cd and Hg adsorption decreased. The adsorption sequence most found was Pb>Cu>Hg>Cd. The maximum adsorption capacity for the heavy metal cations was calculated, and affected markedly by soil properties. The results suggest that Hg and Cd have higher mobility associated to the lower adsorption and that Pb and Cu present the opposite behavior. Significant correlations were found between the maximum adsorption capacity of the metals and pH value and exchangeable acid, suggesting that soil pH and exchangeable acid were key factors controlling the solubility and mobility of the metals in the agricultural soils.