Bioengineered Chimeric Spider Silk‐Uranium Binding Proteins

Heavy metals constitute a source of environmental pollution. Here, novel functional hybrid biomaterials for specific interactions with heavy metals are designed by bioengineering consensus sequence repeats from spider silk of Nephila clavipes with repeats of a uranium peptide recognition motif from a mutated 33‐residue of calmodulin protein from Paramecium tetraurelia. The self‐assembly features of the silk to control nanoscale organic/inorganic material interfaces provides new biomaterials for uranium recovery. With subsequent enzymatic digestion of the silk to concentrate the sequestered metals, options can be envisaged to use these new chimeric protein systems in environmental engineering, including to remediate environments contaminated by uranium.

     

重金属的生物吸附机理及吸附平衡模式研究*

各种生物吸附剂包括海洋微生物、发酵工业的菌丝体废渣及活性污泥的提取物等对金属离子的吸附特性已被广泛研究,本文就生物体对金属离子的吸附机理及吸附平衡模式研究进行了综述,阐明了今后的研究方向。     

浙江省主要城市市场中的水产品重金属含量调查研究

对浙江省主要城市市场上销售的水产品进行了调查。结果表明，这些水产品存在重金属的污染，主要的污染元素为Cd、As，超标率分别为4．3％、3．6％。其中，As的污染较为普遍，Cd的污染虽然超标率较高，但潜在污染增长趋势不明显。Pb的潜在污染增长趋势较强，应当密切监控养殖环境中的Pb污染。     

山核桃叶中重金属的含量测定分析

采用紫外分光光度法测定了山核桃叶中重金属的含量,分析波长为299 nm。结果表明,山核桃叶中重金属含量为17.264μg/g,线性范围1～20μg,平均加样回收率为99.87%。为进一步开发利用浙江山核桃叶资源提供了科学依据。     

Sawdust for the Removal of Heavy Metals from Water: A Review

The threat of the accumulation of heavy metals in wastewater is increasing, due to their abilities to inflict damage to human health, especially in the past decade. The world’s environmental agencies are trying to issue several regulations that allow the management and control of random disposals of heavy metals. Scientific studies have heavily focused on finding suitable materials and techniques for the purification of wastewaters, but most solutions have been rejected due to cost-related issues. Several potential materials for this objective have been found and have been compared to determine the most suitable material for the purification process. Sawdust, among all the materials investigated, shows high potential and very promising results. Sawdust has been shown to have a good structure suitable for water purification processes. Parameters affecting the adsorption mechanism of heavy metals into sawdust have been studied and it has been shown that pH, contact time and several other parameters could play a major role in improving the adsorption process. The adsorption was found to follow the Langmuir or Freundlich isotherm and a pseudo second-order kinetic model, meaning that the type of adsorption was a chemisorption. Sawdust has major advantages to be considered and is one of the most promising materials to solve the wastewater problem.     

Removal of Heavy Metals in Effluent by Adsorption and Coagulation

The silicate colloids with an average diameter 100 nm, were prepared by the hydrolysis of tetraethoxysilane (TES), NH4OH (30%) and then modified by (3-mercaptopropyl)trimethoxysilane (APS). The colloids can adsorb heavy metals such as Pb and Cr in effluent and after adsorption the colloids can be separated by coagulation of aluminum sulfate. The removal of heavy metals is up to 99%.     

污染土壤重金属稳定化修复的综合性实验

添加不同种类改良剂对污染农田土壤进行有毒重金属的稳定化修复,内容包括土壤样品制备与培养、pH测定、重金属离子总浓度及有效态浓度测定。首先,学生需要在实验过程中熟练掌握电子天平、pH计、微波消解仪和电感耦合等离子体质谱的操作规程。其次,学生能够在课后利用固化率公式处理数据和评价不同改良剂对重金属的稳定化修复效果,并进行机理解析。本实验不仅可以加强学生对相关专业理论知识的理解和精密化学仪器的使用,还能够培养学生综合运用所学专业知识解决实际应用问题的能力,并进一步激发学生探索化学前沿新知,从而达到拓展创新的培养目标。     

梅州农村饮用水重金属元素监测与分析

对梅州农村饮用水中的重金属元素进行了监测和分析，选择Fe，Mn，Zn，Cu，Ag，Pb，Cd七种元素为检测指标。从实验结果来看，Cu，Ag，Cd含量低，未超标；Fe，Mn，Zn，Pb有超标现象：按其危害程度，Pb，Mn的超标是急需解决的问题。     

消渴丸中重金属铅和砷的含量测定

样品湿法消解后用石墨炉原子吸收法测定了消渴丸中铅含量,用原子荧光法测定了砷含量.结果表明,消渴丸中重金属铅含量在0.23～0.55 mg·kg- 1之间;砷含量在0.55～1.09 mg·kg- 1之间;本法测定消渴丸中重金属铅的平均回收率为96.6%,砷的平均回收率为108.4%,说明该法可用于消渴丸中铅和砷的测定,...     

Characterisation of Screen-Printed Electrodes for Detection of Heavy Metals

 The characterisation of disposable screen-printed electrodes for stripping analysis is described. The graphite surface of the working electrode is used as substrate for plating a thin mercury film, which allows the electrochemical preconcentration of heavy metals. Optimisation procedures and experimental results are presented. Detection limits around the ppb level were obtained for different metals [Pb(II), Cd(II), Cu(II)]. Received June 6, 1998. Revision November 10, 1988.     

Retrospective Analysis of Anthropogenic Inputs of Lead and Other Heavy Metals to the Hawaiian Sedimentary Environment

In this paper we present and discuss heavy-metal concentrations in sediment cores from the Ala Wai Canal, a small urban drainage estuary in Honolulu, Hawaii (Oahu Island), and from selected soils and sediments collected in less impacted areas of Hawaii. We focus on lead and its isotope ratios to document the introduction, proliferation and subsequent phasing-out of alkyl-lead fuel additives in Honolulu over the past 60 years. Sedimentary lead increases from <10 ppm in the oldest (deepest) unimpacted portions of the cores to ˜750 ppm in sediments from the mid-1970s; lead contents then decrease to a range of 100–300 ppm in the most recent deposits. Lead concentrations in the canal sediments closely track the consumption of alkyl-lead fuel additives used on Oahu in the middle of this century. More than 90% of the lead in certain core intervals is of anthropogenic origin. Stable lead isotope ratios reflect changes in the estuary's sources of lead and show that this lead has an isotopic signature distinct from natural samples. Undisturbed layers of sediments in the Ala Wai canal track the average composition of anthropogenic lead used in its Honolulu watershed through time. The distinctive pattern of lead isotopes measured in Ala Wai Canal sediments can be used to distinguish anthropogenic from natural lead in Hawaiian rural locations. Soils located away from point-sources of contamination have isotopic compositions defined by mixtures of locally erupted volcanic rock, atmospheric dust and components similar to Ala Wai Canal anthropogenic lead. Natural lead concentrations in Hawaii are in the range of a few to a few tens of parts per million, with the high-concentration end-member occurring in a few selected intramountain basins where soils contain a significant component of continental dust fines scavenged by rainfall and concentrated by local geological conditions. Rural watershed material exhibits small but discernible elevations in lead concentrations due to anthropogenic effects. Other metals (cadmium, copper and zinc) in the Ala Wai Canal sediments also display patterns consistent with increased fluxes of metals attributable to anthropogenic activity. Unlike lead, no clear maxima are observed in sediments deposited during the mid 1970s. Rather, a continued input of these metals is attributed to expanding anthropogenic activity in the Ala Wai Canal watershed. © 1997 by John Wiley & Sons, Ltd.     

Role of Melatonin in Plant Tolerance to Soil Stressors: Salinity,pH and Heavy Metals

Melatonin (MT) is a pleiotropic molecule with diverse and numerous actions both in plants and animals. In plants, MT acts as an excellent promotor of tolerance against abiotic stress situations such as drought, cold, heat, salinity, and chemical pollutants. In all these situations, MT has a stimulating effect on plants, fomenting many changes in biochemical processes and stress-related gene expression. Melatonin plays vital roles as an antioxidant and can work as a free radical scavenger to protect plants from oxidative stress by stabilization cell redox status; however, MT can alleviate the toxic oxygen and nitrogen species. Beyond this, MT stimulates the antioxidant enzymes and augments antioxidants, as well as activates the ascorbate–glutathione (AsA–GSH) cycle to scavenge excess reactive oxygen species (ROS). In this review, we examine the recent data on the capacity of MT to alleviate the effects of common abiotic soil stressors, such as salinity, alkalinity, acidity, and the presence of heavy metals, reinforcing the general metabolism of plants and counteracting harmful agents. An exhaustive analysis of the latest advances in this regard is presented, and possible future applications of MT are discussed.     

Ornamental Plant Efficiency for Heavy Metals Phytoextraction from Contaminated Soils Amended with Organic Materials

Accumulation of heavy metals (HMs) by ornamental plants (OPs) from contaminated agriculture soils is a unique technique that can efficiently reduce the metal load in the food chain. Amaranthus tricolor L. has attractive characteristics acquiring a higher growth rate and large biomass when grown at heavy metal contaminated soils. Site-specific detailed information is not available on the use of A. tricolor plant in metal phytoremediation from the polluted sites. The study aimed to enhance the uptake of HMs (Pb, Zn, and Cu) via amending poultry litter extract (PLE), vinasse sugarcane (VSC), and humic acid (HA) as natural mobilized organic materials compared to ethylene diamine tetraacetic acid (EDTA), as a common mobilized chemical agent by A. tricolor plant. The studied soils collected from Helwan, El-Gabal El-Asfar (Cairo Governorate), Arab El-Madabeg (Assiut Governorate), Egypt, and study have been conducted under pot condition. Our results revealed all organic materials in all studied soils, except EDTA in EL-Gabal El-Asfar soil, significantly increased the dry weight of the A. tricolor plant compared to the control treatment. The uptake of Pb and Zn significantly (p > 0.05) increased due to applying all organic materials to the studied soils. HA application caused the highest uptake as shown in Pb concentration by more than 5 times in Helwan soil and EDTA by 65% in El-Gabal El-Asfar soil while VSC increased it by 110% in El-Madabeg soil. Also, an increase in Zn concentration due to EDTA application was 58, 42, and 56% for Helwan, El-Gabal El-Asfar, and El-Madabeg soil, respectively. In all studied soils, the application of organic materials increased the remediation factor (RF) than the control. El-Madabeg soil treated with vinasse sugarcane gave the highest RF values; 6.40, 3.26, and 4.02% for Pb, Zn, and Cu, respectively, than the control. Thus, we identified A. tricolor as a successful ornamental candidate that, along with organic mobilization amendments, most efficiently develop soil health, reduce metal toxicity, and recommend remediation of heavy metal-contaminated soils. Additionally, long-term application of organic mobilization amendments and continued growth of A. tricolor under field conditions could be recommended for future directions to confirm the results.     

Characterization of Compost with Respect to its Content of Heavy Metals. Part II: Sample Preparation

Abstract

This paper forms part of a study aimed at the development of a procedure for the determination of heavy metals in compost. The present paper deals with the sample preparation stage, including subdividing laboratory samples and reduction of the particle size.

The effect of particle size reduction on the random error due to the analysis of test portions was examined. It was found that milling for 20min in a quartz planet ball mill yields sufficiently homogeneous test samples. As the milling capacity of this device is too small, prior to milling subdivision of the laboratory sample is required. Subdivision before drying is recommended for practical reasons.     

Coarse Metal Powder-Assisted pulsed CO2 Laser-induced Breakdown Spectroscopy for the Direct Determination of Heavy Metals in Soil

A novel method of laser-induced plasma spectroscopy utilizing a pulsed transversely excited atmospheric CO₂ laser has been developed for the high-sensitivity determination of heavy metals in soil. A coarse metal powder was used to trap the soil and to assist with plasma generation. When the CO₂ laser (10.6?µm, 1.5?J, 200?ns) was irradiated on the metal and soil powder, a high-temperature and long-lifetime luminous plasma was induced. Fine particles of soil were dissociated and were excited in the plasma region. The method was used for the rapid determination of Cr, Pb, and Hg in loam. The limits of detection for Cr, Pb, and Hg were approximately 0.8, 15, and 0.7?mg/kg, respectively.     

Heavy Metals in Acrylic Color Paints Intended for the School Children Use: A Potential Threat to the Children of Early Age

Heavy metals are the harmful elements, regarded as carcinogens. Nevertheless, owing to their physical and chemical properties, they are still used in the production of several commercial products. Utilization of such products increases the chance for the exposure of heavy metals, some of them are categorized as probable human carcinogens (Group 1) by the International Agency for Research on Cancer. Exposure of heavy metals to school children at early age can result severe life time health issues and high chance of emerging cancer. Thus, we have performed study relating to the presence of heavy metals in acrylic color paints commonly used by the school children. Acrylic paints of different colors were assayed for seven potential heavy metals manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn), arsenic (As), cadmium (Cd) and lead (Pb) using microwave digestion and iCAPQ inductively coupled plasma mass spectrometry (ICP-MS) system. The optimized method including paints digestion reagents nitric acid (HNO₃, 65%, 5 mL) and hydrofluoric acid (HF, 40%, 2 mL) have offered excellent method performance with recovery values ranged between 99.33% and 105.67%. The elements were identified in all of the analyzed samples with concentrations ranged from 0.05 to 372.59 µg/g. Cd constitutes the lower percentage (0.05%), whereas Zn constitutes high ratio contribution which was tremendously high (68.33%). Besides, the paints contamination was also color specific, with considerably total heavy metal concentrations found in brunt umber (526.57 µg/g) while scarlet color (12.62 µg/g) contained lower amounts. The outcomes of our investigation highlight the necessity for guidelines addressing the heavy metals in acrylic color paints intended for the school children usage.     

烟草制品及烟气中重金属检测方法的研究进展

从烟草制品及其烟气的前处理方法和检测方法两方面对烟草中重金属含量测定的研究进展进行了综述。重点介绍了湿法消解、微波消解、萃取和悬浮进样技术等样品前处理方法,以及原子光谱法、质谱法和液相色谱法等测定方法。列举了不同方法的灵敏度、准确性和适用范围,对各方法的优缺点进行了比较,并对烟草中重金属检测方法的发展进行了展望。     

Speciation Characteristics and Ecological Risk Assessment of Heavy Metals in Municipal Sludge of Huainan,China

In order to fully understand the morphological characteristics and pollution status of heavy metals in the dewatered sludge of Huainan Municipal sewage treatment plant, the physical and chemical properties were analyzed, and the content and occurrence forms of heavy metals (As, Cu, Zn, Pb, Cd, Cr, and Ni) in the sludge were studied using the geological accumulation method (Igeo), risk assessment coding method (RAC), and potential ecological risk index method to evaluate the ecological risk. The results showed that the municipal sludge in Huainan was rich in nutrients, with good prospects for agricultural utilization. There were differences in the morphological distributions of different heavy metals. The Igeo values for Ni, As, Cr, and Pb were below 0. The results of RAC indicated that the risk level of Cr in sludge was a low risk, and those of other heavy metals were moderate risks. The potential ecological risk of Cd had the highest potential ecological risk, and the other six metals were of low ecological risk. This conclusion can provide basic data and a theoretical reference for the comprehensive utilization of sludge in sewage treatment plants.     

Identification of Two Distinct Sites for Antagonist and Biased Agonist Binding to the Human Chemokine Receptor CXCR3

The chemokine receptor CXCR3 is a G protein‐coupled receptor that conveys extracellular signals into cells by changing its conformation upon ligand binding. We previously hypothesized that small‐molecule allosteric CXCR3‐agonists do not bind to the same allosteric binding pocket as 8‐azaquinazolinone‐based negative allosteric modulators. We have now performed molecular‐dynamics (MD) simulations with metadynamics enhanced sampling on the CXCR3 system to refine structures and binding modes and to predict the CXCR3‐binding affinities of the biased allosteric agonist FAUC1036 and the negative allosteric modulator RAMX3. We have identified two distinct binding sites; a “shallow” and a second “deeper” pocket to which the biased allosteric agonist FAUC1036 and negative allosteric modulator RAMX3 bind, respectively.