Effects of metal lead on growth and mycorrhizae of an invasive plant species (Solidago canadensis L.)

It is less known whether and how soil metal lead （Pb） impacts the invasion of exotic plants. A greenhouse experiment was conducted to estimate the effects of lead on the growth and mycorrhizae of an invasive species （Solidago canadensis L.） in a microcosm system. Each microcosm unit was separated into HOST and TEST compartments by a replaceable mesh screen that allowed arbuscular mycorrhizal （AM） fungal hyphae rather than plant roots to grow into the TEST compartments. Three Pb levels （control, 300, and 600 mg/kg soil） were used in this study to simulate ambient soil and two pollution sites where S. canadensis grows. Mycorrhizal inoculum comprised five indigenous arbuscular mycorrhizal fungal species （ Glomus mosseae, Glomus versiform, Glomus diaphanum, Glomus geosporum, and Glomus etunicatum）. The ^15N isotope tracer was used to quantify the mycorrhizally mediated nitrogen acquisition of plants. The results showed that S. canadensis was highly dependent on mycorrhizae. The Pb additions significantly decreased biomass and arbuscular mycorrhizal colonization （root length colonized, RLC%） but did not affect spore numbers, N （including total N and ^15N） and P uptake. The facilitating efficiency of mycorrhizae on nutrient acquisition was promoted by Pb treatments. The Pb was mostly sequestered in belowground of plant （root and rhizome）. The results suggest that the high efficiency of mycorrhizae on nutrient uptake might give S. canadensis a great advantage over native species in Pb polluted soils.

Alkaline leaching of metal melting industry wastes and separation of zinc and lead in the leach solution

In this work, a thorough examinations on the extractability of zinc and lead present in the steelmaking dusts using alkaline leaching process and the effectiveness of the zinc and lead separation in the resultant leaching solutions using sulfide precipitation method were made. It was found that only about 53% of zinc and over 70% of the lead could be leached out of the dusts, while the other 47% of zinc and 30% of lead were left in the leaching residues. The zinc and lead in the resultant leaching solution can be effectively and selectively separated. When the weight ratio of sodium sulfide (M.W. = 222-240) to Pb was kept at 1.8, the lead in the solution could be precipitated out quantitatively while all the zinc was remained in the solution. The zinc left in the solution can be further recovered by the addition of extra sodium sulfide with a weight ratio of sodium sulfide to the zinc over 2.6. The resultant filtrate can be recycled to the leaching of dust in the next leaching process.

Study on soil heavy metals contamination of a lead refinery

The contents of Pb, Cd, Cr, As, and Hg was investigated in the neighboring areas of a lead smelting enterprise and the metals contamination of soil was evaluated with the methodologies of the single factor index and Nemerow integrated index. It is found that the content of heavy metals in the neighboring areas has no obvious difference from the reference points. And the soil contamination of heavy metals varies by elements, the contamination index follows the pollution order: Cd>Hg>Cr>As>Pb. The pollution degree of Cd is at high level and Hg at low level, but Cr and As reached the warning level. Therefore, the lead smelting enterprises should not only control lead but also other heavy metals as Cd.

Heavy metal concentrations in soils and plants in the vicinity of Arufu lead-zinc mine, Middle Benue Trough, Nigeria

This study focused on the influence of base metal mining on heavy metal levels in soils and plants in the vicinity of Arufu lead-zinc mine, Nigeria. Soil samples (0-15 cm depth) and plant samples were collected from cul-tivated farmlands in and around the mine, the unmineralized site and a nearby forest (the control site). The samples were analyzed for heavy metals (Fe, Zn, Mn, Cu, Pb, Cr and Cd) by Atomic Absorption Spectrophotometry (AAS). The physical properties of soils (pH and LOI) were also measured. Results showed that soils from cultivated farm-lands have neutral pH values (6.5-7.5), and low organic matter contents (<10%). Levels of Zn, Pb and Cd in culti-vated soils were higher than the concentrations obtained from the control site. These heavy metals are most probably sourced from mining and agricultural activities in the study area. Heavy metal concentrations measured in plant parts decreased in the order of rice leaves>cassava tubers>peelings. In the same plant species, metal levels decreased in the order of Zn>Fe>Mn>Cu>Pb>Cr>Cd. Most heavy metals were found in plant parts at average concentrations normally observed in plants grown in uncontaminated soil, however, elevated concentrations of Pb and Cd were found in a few cassava samples close to the mine dump. A stepwise linear regression analysis identified soil metal contents, pH and LOI as some of the factors influencing soil-plant metal uptake.

Novel Metal-organic Framework Compound Pb(C_5H_4NCOO)_2 Showing One-dimensional Channel Defined as Four Leads and Four Nicotinic Acids

A novel metal-organic framework（MOF） compound of Pb（C5H4NCOO）2 was hydrothermally synthesized and structurally determined by X-ray single-crystal diffraction. The data of unit cell： orthorhombic space group Pccn, a=1.0325（2） nm, b=1.3597（3） nm, c=0.8499（2） nm, V=1.1931（4） nm^3, Z=4, Dc=2.513 g/cm^3, R1=0.047 were obtained on the basis of 1365 reflections with Fo〉2σ（Fo）. PbN2O6 polyhedron adopts the distorted cubic configuration which is assigned to the holodirected geometry. These PbN2O6 polyhedra can form the zigzag chain by edge-sharing mode along（001） direction. Pb atom is connected by six nicotinic acid molecules, leading neutral 3D metal-organic framework with a channel defined by four Pb atoms and four nicotinic acid molecules.

Analysis and Evaluation of Bioavailable Heavy Metals in Surface Soil of the Abandoned Lead-zinc Mine in Changhua,Hainan Province

[Objectives] The research was conducted to study characteristics of bioavailable levels pollution of heavy metals in the surface soil of the lead-zinc mine in Changhua.[Methods] A total of 56 surface samples were collected from the 3 study zones （peripheral zone, reclamation zone and tailing zone） located at the lead-zine mine in Changhua. Based on total and bioavailable heavy metals （Pb, Zn, Cu and Cd） in soils, the correlation of total content with bioavailable content was analyzed, and their pollution characteristics were assessed by methods of single factor pollution index, Nemerow pollution index, geological accumulation index and potential ecological risk index.[Results] （i） The surface soils were polluted by Pb, Zn, Cu, Cd in different degrees, and the overall trend of the contents of the 4 heavy metals was in order of Cd 〉 Pb 〉 Zn 〉 Cu. The average excess multiple of heavy metals of total and bioavailable content in soils were in the order of peripheral zone 〉 tailing zone 〉 reclaimed zone, and their pollution degrees were tailing zone 〉 peripheral zone 〉 reclaimed zone. （ii） In general, the total and bioavailable contents of Pb, Zn, Cu, Cd showed a significant correlation, but were not correlated in each study zone. （iii） Pollution degrees of the study zones were in the order of tailing zone 〉 peripheral zone 〉 reclamation zone. The pollutions of heavy metals Pb and Cd were more serious, especially Cd reached high levels of pollution degree, and the pollution degrees of Zn, Cu were lighter. Contributors of ecological risk were mainly Cd, Pb and Cu, and the contribution of Cd achieved more than 90 %, making it the main source of pollution.[Conclusions] The results not only revealed the pollution status of heavy metals in the surface soil of the abandoned coal mine, but also could provide scientific guidance for reasonable utilization and ecological recovery of the land.

Spin-flip process through double quantum dots coupled to two half-metallic ferromagnetic leads

We investigate the spin-flip process through double quantum dots coupled to two half-metallic ferromagnetic leads in series. By means of the slave-boson mean-field approximation, we calculate the density of states in the Kondo regime for two different configurations of the leads. It is found that the transport shows some remarkable properties depending on the spin-flip strength. These effects may be useful in exploiting the role of electronic correlation in spintronics.

An experimental study on metal precipitation driven by fluid mixing: implications for genesis of carbonate-hosted lead–zinc ore deposits

A type of carbonate-hosted lead–zinc(Pb–Zn)ore deposits, known as Mississippi Valley Type(MVT)deposits, constitutes an important category of lead–zinc ore deposits. Previous studies proposed a fluid-mixing model to account for metal precipitation mechanism of the MVT ore deposits, in which fluids with metal-chloride complexes happen to mix with fluids with reduced sulfur, producing metal sulfide deposition. In this hypothesis, however, the detailed chemical kinetic process of mixing reactions, and especially the controlling factors on the metal precipitation are not yet clearly stated. In this paper, a series of mixing experiments under ambient temperature and pressure conditions were conducted to simulate the fluid mixing process, by titrating the metal-chloride solutions, doping withor without dolomite, and using NaHS solution. Experimental results, combined with the thermodynamic calculations, suggest that H_2S, rather than HS^-or S^(2-),dominated the reactions of Pb and/or Zn precipitation during the fluid mixing process, in which metal precipitation was influenced by the stability of metal complexes and the pH. Given the constant concentrations of metal and total S in fluids, the pH was a primary factor controlling the Pb and/or Zn metal precipitation. This is because neutralizing or neutralized processes for the ore-forming fluids can cause instabilities of Pb and/or Zn chloride complexes and re-distribution of sulfur species, and thus can facilitate the hydrolysis of Pb and Zn ions and precipitation of sulfides. Therefore, a weakly acidic to neutral fluid environment is most favorable for the precipitation of Pb and Zn sulfides associated with the carbonate-hosted Pb–Zn deposits.

Biosorptive Removal of Lead Ions from Aqeuous Stream by Using Leaves, Stems and Roots of Momordica charantia Biomass

Water pollution is one of the most important issues of the 21st century. It takes place when the pollutants are being entered into a water reservoir without any treatment. Heavy metals are one of the major harmful pollutants that exist in the water;therefore, it is necessary to remove these toxic metals to keep our environment safe. Biosorption is an ecofriendly and economical technique for the elimination of these toxic metals from polluted water. In this research work roots, stems, and leaves of Momordica charantia (Bitter gourd) were used as biosorbent for the elimination of Pb (II) ions from aqueous solution. Many different parameters such as metal ion solution pH, biomass dosage, initial metal ions concentration and contact time were optimized in the batch experiments. The calculated results revealed that biosorption of Pb (II) was maximum at solution pH 5, biosorbent dosage of 0.1 g and 100 ppm of initial metal ions concentration within 240 minutes of contact time. M. charantia’s leaves showed the highest level of lead biosorption capacity (47.62%), followed by stems (42.36%) and roots (38.47%). The Freundlich isotherm and pseudo-second order kinetics model fitted well for the analytical data. The results indicated that Momordica charantia is an effective biosorbent for Pb (II) ions elimination from wastewater.

Risk Assessment of Heavy Metals in Food Crops at Abandoned Lead-Zinc Mining Site at Tse-Faga, Logo, Lga, Benue State, Nigeria

Hundreds of children died in 2010 due to suspected lead poisoning from mining sources in Zamfara State among epidemiological concerns. Evaluating ecological and human health risks of heavy metals levels in sampled food crops harvested near two abandoned Lead-Zinc mining sites at Logo Benue State is crucial. Abelmoschus esculentus, Carica papaya, Manihot esculenta, and Zea mays were sampled, prepared, and analyzed for four heavy metals using the Atomic Absorption Spectrophotometric method. The mean data from the analysis of variance was subjected to ecological and health risk models. Pb means value ranged from Carica papaya Peel 0.46 ± 0.011 mg/kg to 1.30 ± 0.01 mg/kg in Zea mays seed. Zn was highest in Carica papaya flesh 0.50 ± 0.01 mg/kg, and lowest in Manihot esculenta peels and its flesh 0.12 ± 0.000 mg/kg. Hg and Cd were below detectable levels. Zea mays seeds (1.001) had the highest Pd bioaccumulation factor. BAF of zinc and ecological indices were <1. Daily Intake of Metals were all <1, however, Hazard Quotient (HQ) of Pb was ≥1 in Manihot esculenta flesh 1.143 and Zea mays at 1714. Cancer Risks were within permissible range (10-4 - 10-6). Health Risk result indicates communities around the mining area may be at risk of lead poisoning therefore due to high contamination of samples, routine checks on heavy metals especially lead is recommended to prevent excessive bioaccumulation in the body.

改性黑药类捕收剂强化浮选玉龙铅锌矿中伴生银的无碱工艺研究

针对玉龙铅锌矿浮选过程中伴生银矿物回收率不高等问题,进行了新型捕收剂下无碱铅银浮选工艺研究。研究结果表明,在磨矿细度为-74μm占65%时,抑制剂采用亚硫酸钠与硫酸锌,捕收剂采用改性黑药类捕收剂CY-1,可实现无碱条件下铅银精矿中银回收率的显著提升。闭路实验获得了含Pb 52.05%、Ag 4 866 g/t的铅银精矿,铅、银回收率分别为91.76%和84.43%。与乙硫氮+丁铵黑药为组合捕收剂时的高碱工艺相比,铅、银回收率分别提高了2.5和6百分点。该工艺消除了浮选过程中石灰对银矿物的抑制,有助于强化铅锌矿伴生稀贵金属的综合回收,提升资源的综合利用效率。

新质生产力与我国有色金属产业高质量发展的关系:以铅锌产业为例

高质量发展是发展新质生产力的首要任务,发展新质生产力的过程中要处理好新兴产业和传统产业的关系,决不能忽视和放弃传统产业。有色金属作为我国国民经济、国防工业、科学技术发展必不可少的基础原材料和重要战略物资,是建设现代化强国的重要支撑和保障,也是最具代表性的传统产业之一。生产过程的特性导致有色金属行业在发展过程中面临更严峻的能耗、排放和污染的问题和困难。创新是引领发展的第一动力,在近十年的发展过程中,有色金属行业产业遵循国家政策指引、积极响应国家号召,依托技术创新和改造在工艺升级、节能减排、绿色低碳等方面取得长足的进步,为行业实现现代化高质量发展奠定了坚实的基础。进入新发展阶段后,有色金属行业上下游、左右岸交叉关联融合程度更深,绿色化、数字化、智能化、高端化转型升级需求更加迫切,此时,新质生产力的提出为行业未来面向高质量发展、重塑竞争新优势提供了全新动力和根本指引。有色金属品种多、应用广、生产流程和规模差异化较为明显,但是全行业产业借力新质生产力实现转型升级和高质量发展的需求和目标是一致的。我国是世界上最大的铅锌生产国和消费国,铅锌产业是有色金属产业最具代表性的传统产业之一。本文以铅锌产业为例,结合铅锌产业近年来在国家支持和指导下取得的发展成果,肯定和明确创新赋能传统产业发展和转型的重大意义以及传统产业未来借力和发展新质生产力的需求和潜力;从政策研究角度梳理近三年与有色金属行业高质量发展紧密相关的针对性政策文件,分析国家在未来对有色金属行业特别是铅锌产业发展新质生产力的支持和指引;针对铅锌产业在新发展阶段发展新质生产力方面已经或未来可能面临的问题和挑战,提出政策需要与时俱进、持续的技术创新能力培育、高素质人才培养和造就,以及坚持不懈地推进国际合作等相关建议。

铅锌冶炼重金属重污染土壤稳定化研究

针对部分铅锌冶炼场地遭受严重重金属污染的问题,采用基于铁的稳定化材料FeCl_(3)+CaCl_(2)+NaOH+Ca(OH)_(2),FeCl_(3)+CaCl_(2)+NaOH+Ca(OH)_(2)+Na_(2)S及FeCl_(3)+Na_(2)HPO_(4)进行修复。根据TCLP浸出法评估效果,选出最佳组合为FeCl_(3)+Na_(2)HP0_(4),该组合在3个场地中使Pd浸出浓度分别下降96%,63%,61%,显著减少重金属迁移。研究突显了合适材料的选择对有效土壤稳定化的重要性。

缺陷型巯基功能化MOF的制备及其重金属离子吸附性能

水中的重金属离子对人体伤害巨大,特别是Pb(Ⅱ)和Hg(Ⅱ)离子,因此需要去除Pb(Ⅱ)和Hg(Ⅱ)离子。通过调节合成过程中浓盐酸的用量,合成了具有不同缺陷程度的巯基功能化锆基金属有机框架(zirconium-based metal-organic frameworks, Zr-MOF)材料,简称UiO-66-(SH)_2,并将其用于液相中Pb(Ⅱ)和Hg(Ⅱ)离子的吸附去除。通过UiO-66-(SH)_2对Pb(Ⅱ)和Hg(Ⅱ)离子的吸附实验,发现随着制备过程中盐酸用量的增大,MOF的缺陷程度升高,其对Pb(Ⅱ)和Hg(Ⅱ)离子的吸附能力也有所增强。缺陷型UiO-66-(SH)_2对较低质量浓度的Pb(Ⅱ)(50 mg/L)和Hg(Ⅱ)(70 mg/L)离子的最大吸附量分别可达45和259 mg/g,且对这2种重金属离子具有较好的吸附选择性。经过3次循环吸附后,缺陷型UiO-66-(SH)_2对Pb(Ⅱ)和Hg(Ⅱ)离子的吸附能力没有明显下降,表明该材料在水中重金属离子去除应用上具有一定的潜力。

喀斯特地区尾矿库周边植物重金属富集特征及空间分布

目的:了解典型喀斯特地区尾矿库周边植物的重金属富集特性和空间分布特征,筛选优势植物品种。方法:计算富集系数来判断不同植物对不同重金属的富集能力;采用地理信息分析软件(GIS)通过普通克里金插值和半变异函数分析,建立植物重金属空间分布模型;计算皮尔逊相关系数,以分析植物体内各重金属之间及与土壤pH值的相关性。结果:该尾矿库周边28种植物中,茄科植物红丝线、菊科的野茼蒿和荨麻科的八角麻对Cd有较强富集能力,植物中Cd污染严重;乌毛蕨科的苏铁蕨、海金沙科的小叶海金沙和大戟科的禾串树对Pb有较强富集能力;各植物对Cu和Zn均无富集作用。重金属空间分布模型显示,Cd主要分布在尾矿库南面、西南面、东南面和西北面;Pb主要分布在东南部、坝下小溪及正南面;Cu主要分布在正南、西南和坝下小溪方向;Zn主要分布在西面、西南、西北和正北面。在半变异函数模型参数中,Cd和Zn以随机性因素误差为主,各点的空间相关性弱,Pb、Cu以结构性因素误差为主,空间相关性较强;植物体内重金属含量空间变异性和空间相关性排序为Zn<Cd<Cu<Pb。Cd与Cu存在中等程度正相关关系,Cd与Pb、Zn呈正弱相关关系;植物体内各重金属含量与土壤pH值相关性不强。结论:筛选出的部分优势植物可作为矿区土壤重金属富集转移和生物修复的备选品种,初步了解了该区域重金属在土壤和植物之间的迁移规律,为开展矿区重金属污染治理提供了依据。

造纸黑液源类黄腐酸对水体中铅的吸附作用研究

造纸黑液占整个造纸业污染的90%以上,对环境造成严重影响,造纸黑液中大量的有机质可以作为黄腐酸的合成前体,黄腐酸对重金属有良好的吸附作用。根据国际腐植酸协会推荐方法,自两种不同造纸工艺的黑液中成功提取出了碱法类黄腐酸(JFLA)和铵法类黄腐酸(AFLA);通过平衡络合试验,在不同Pb^(2+)浓度和pH的重金属水溶液中,研究了两种类黄腐酸对铅的吸附效果与规律,AFLA在低Pb^(2+)浓度、高pH条件下具有更好的吸附能力,且AFLA比JFLA的吸附能力更强。研究结果表明了黑液类黄腐酸有修复Pb^(2+)污染水体的可能性,为相关研究开展奠定了理论基础。

黄河流域典型铅锌冶炼企业重金属废水管控与碳排放协同研究

黄河流域作为国家生态安全的重要屏障,重金属污染一直以来备受关注.为提升重金属重点排放源铅锌冶炼行业废水排放管控水平,本文聚焦黄河流域中上游典型地区某铅锌冶炼企业,研究了不同产污环节排放废水中重点重金属排放特征及达标情况,并从行业绿色低碳发展方面测算了不同冶炼工艺流程碳排放强度、不同产污环节排放废水处理过程碳排放强度.结果表明:(1)采用氧化法+硫化钠除汞+石灰中和+生物制剂法+除铊稳定剂的组合处理工艺,污酸废水中总铅、总镉、总汞和总砷的排放浓度均可稳定达到《铅、锌工业污染物排放标准》(GB 25466-2010)特别排放限值要求,以处理后各重金属日最大检出浓度的90%分位数作为参比浓度,该处理工艺对总铅、总镉、总汞的去除率分别为98.2%、99.8%、99.9%.(2)铅锌冶炼企业污酸车间地面冲洗水应全部纳入污酸车间污水处理系统进行集中处理,避免铅、镉、汞、铊等重金属废水稀释排放,长期汇入黄河干流富集造成潜在环境风险.(3)锌冶炼过程重金属主要富存于固相颗粒和液相颗粒中,污酸废水(废气洗涤制酸废水)中总铅、总镉、总汞、总砷产污系数分别为4.83、4.33、7.02、0.01 g/t(以产品计),较实际流向废气中相应重金属产污系数低10^(3)量级.(4)鉴于污酸废水处理碳排放强度约为一般性生产废水的7.93倍,建议加强评估并推广应用2022年《国家先进污染防治技术目录(水污染防治领域)》提出的有色冶炼烟气洗涤污酸废水治理与资源化利用技术,研究提出基于资源化利用途径的污酸废水排放控制要求.(5)湿法炼锌工艺碳排放强度为3.08 t/t(冶炼1 t锌的CO_(2)排放量),相对属于绿色低碳冶炼工艺.研究显示,黄河流域中上游部分典型铅锌冶炼企业已采用相对绿色低碳冶炼工艺,鉴于黄河流域的国家战略定位,需进一步提升末端重金属废水风险管控和减污降碳协同治理力度,引领沿黄冶炼产业高质量发展.

退役铅酸蓄电池铅膏回收策略及研究进展

推动再生铅产业的高质量发展,是铅资源实现生产-消费-再生良性循环的重要保障,缓解铅资源枯竭的同时,有效降低铅的生产成本和改善环境污染,对促进铅工业可持续发展具有重要的战略意义。本文概述了近年来铅酸蓄电池铅膏回收的最新研究进展,基于铅酸蓄电池的资源特点和再生产品的经济效益,详细总结了以金属铅、氧化铅、硫化铅及功能性铅基材料为目标的回收工艺技术,重点分析了不同铅产品回收方法的优缺点及需注意的关键环节。结合铅产业链的下游应用,介绍了废铅酸蓄电池再生产品在电池及传感器等领域的应用。最后从实际应用角度出发,展望了未来废铅酸蓄电池铅膏回收及再生铅产品的发展方向。

钐钴永磁流量计研制与锂铅自然对流回路流速测量

介绍了钐钴永磁流量计的研制过程,包括材料选取、结构设计、运行原理及内部磁场分布状态。利用镓铟锡高温冲刷回路与商用流量计对其进行了校准比对,结果显示校准后的平均流速约为钐钴永磁流量计测量值的1.8倍。将校准后的结果运用于液态锂铅自然对流回路的流速测量,并与商业软件ANSYS Fluent模拟计算结果进行对比,二者之间的误差约为23.3%,并对误差进行了分析。通过实验与分析,确定锂铅自然对流回路的流速范围约为0.05~0.06m·s^(-1)。

西南某铅锌冶炼废渣堆放场地周边土壤重金属污染特征与风险评价

为探究西南某铅锌废堆渣场地及其周围土壤中重金属空间分布特征和生态风险,以西南某废弃铅锌冶炼废渣堆放场地为研究目标,通过检测其土壤中As、Pb、Zn、Cd、Cr、Cu、Hg、Ni共8种元素,概括其空间分布特征,分析重金属存在形态对其迁移与渗透的影响,并采用多个污染评价方法对该废渣堆放场的重金属状况进行污染风险评估。结果表明:堆渣场地重金属元素分布与地表径流方向一致,且向深层土壤渗透;As、Cd、Cu已很难再以离子形态随地表径流进一步迁移,而Pb、Zn目前仍具有较大的离子迁移性能,仍会进一步向周边及深层土壤扩散;按照综合污染指数评价上层堆渣区属于重污染,污染元素主要来源于As;同时As、Cd含量表现出极强的生态毒性,使该区域存在很强的生态风险。研究结果为该区域土壤的进一步修复提供了理论依据和参考。