Bioaccumulation of heavy metals by Phragmites australis cultivated in synthesized substrates

Accumulation of heavy metals from various oxides with adsorbed cadmium by wetland plant Phragmites australis was studied to evaluate the fate of heavy metals in the sediment of constructed wetlands. Hoagland solution was used as nutrition supply, and single metal oxide with adsorbed cadmium was applied as contaminant to study the accumulation characteristics of cadmium and the substrate metals by P. australis. After 45-d treatment, the bioaccumulation degree in root followed the order: Al(OH)3 > Al2O3 > Fe3O4 > MnO2 > FeOOH. Heavy metals absorbed by P. australis were largely immobilized by the roots with little translocation to aboveground parts.     

芦苇与海三棱藨草中重金属的累积及季节变化

通过分析上海滨岸潮滩芦苇和海三棱藨草根系、茎叶中Cu、Pb、Fe、Mn、Zn、Cr、N的含量，发现Fe、Mn、Zn、Cu在芦苇与海三棱藨草根系、茎叶中含量较高，而Pb、Cr、N含量较低；Mn在芦苇与海三棱藨草茎叶中的含量接近或超过根系中的含量，而Fe在茎叶中的百分含量较少；聚类分析表明，Pb、Cr在芦苇和海三棱藨草体内的迁移能力非常相近，Zn、Cd、Cu也表现出类似的规律；芦苇和海三棱藨草分别在夏季和春季开始大量吸收重金属元素，之后含量降低，冬季时重金属元素在这两种潮滩植物根系和茎叶中再次出现富集。在同一采样断面，除Cr以外，其余重金属元素在海三棱藨草体内的含量明显高于芦苇。     

生物氧化锰矿物对几种重金属的吸附作用

从土壤铁锰结核及其附近土壤中分离、培养并筛选到3株锰氧化细菌:芽孢杆菌(Bacillus sp.)WH4和GY16,假单胞菌(Pseudomonas sp.)WHS26,应用这3个菌株大量合成了生物氧化锰.在此基础上,比较研究了这3个菌株催化合成的生物氧化锰与一种化学合成锰氧化物矿物(S-MnOx:Synthesized Mn oxide)对重金属Cu2+、Zn2+、Cd2+的吸附特征.结果表明,3种生物氧化锰对重金属的吸附具有明显优势,其对Cu2+、Zn2+、Cd2+的最大吸附量约为S-MnO2的10～100倍;各种氧化锰对Cu2+、Zn2+、Cd2+的吸附过程均符合Langmuir等温吸附模型,且是一个快速吸附的过程;3种锰氧化物对Cu2+、Zn2+、Cd2+3种重金属的最大吸附量与其比表面积呈正相关,吸附过程受pH影响,最适的pH范围为3～6.     

Bioaccumulation of heavy metals in fishes from Taihu Lake, China

The Cr,Zn,Cu,Cd,Pb contents were determined in Cyprinus carpio Linnaeus,Carassius auratus Linnaeus,Hypophthalmichthys molitrix and Aristichthys nobilis,which were caught from Meiliang Bay,Taihu Lake,a large,shallow and eutrophic lake of China.The results showed that:(1)the Cr,Cu,Pb,Cd contents in the edible parts of the four fish species were much lower than Chinese Food Health Criterion(1994),but the Zn contents were higher than the Criterion;(2)Cd contents were the highest in the liver of fish,Pb contents were almost the same in all organs of fish,Cr contents mainly enriched in the skin and gonads,Zn contents were the highest in the gonad(♀),and Cu contents were the highest in the liver;(3)the total metal accumulation was the greatest in the liver and the lowest in the muscle.The total metal accumulation was the highest in C.auratus L.This investigation indicated that fish products in Taihu Lake were still safe for human consumption,but the amount consumed should be controlled under the Chinese Food Health Criterion to avoid excessive intake of Zn.     

Bioaccumulation of metals in human blood in industrially contaminated area

The consumption of contaminated food crops, meat and milk has significantly increased the concentrations of trace metals in human blood as compared to the control area.     

Removal of heavy metals through adsorption using sand

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A survey of arsenic and other heavy metals in vegetation from markets or mine tailings

This research includes two investigations. The first one is a market basket survey of the levels of arsenic （As） and trace elements in bracken fern （Pteridium aquilinum） originated from three countries： South Korea, China and North Korea. The results showed that the mean As concentrations in stems of samples were significantly higher than those in leaves. As concentrations in all samples did not exceed food safety limits for vegetables. Generally, concentrations of Fe, Mn, Cu and Zn in leaves were higher than those in stems. The second investigation is a survey on the levels of As and other heavy metals in vegetation in the vicinity of Myoungbong mine tailings. The results demonstrated that As, Pb and Cu concentrations and bioaccumulation factors （BCF） in seedlings of the fern（A splenium achilleifolium） were the highest, whereas Marsh horsetail（Equisetum polustre） accumulated the highest levels of Zn. Concentrations of As, Pb, Zn and Cu in vegetable-cress （Lepidium sativum） and the edible herb-aromatic madder （Elasholtzia splendens） were higher than food safety limits. Therefore, a risk assessment of As and other heavy metals in vegetables and herbs on local human health should be conducted in the future.     

Evaluation of zeolites synthesized from fly ash as potential adsorbents for wastewater containing heavy metals

Both pure-form zeolites (zeolites A and X) were synthesized by applying a two-stage method during hydrothermal treatment of fly ash prepared initial gel. The difference of adsorption capacity of both fly ash-synthesized zeolits was assessed under the same adsorption conditions. Copper and zinc were chosen as target heavy metal ions. It was found that adsorption capacity of zeolite A showed much higher value than that of zeolite X. Thus, attention was focused on investigating the removal performance of heavy metal ions in aqueous solution on the synthetic pure-form zeolite A from fly ash, zeolite HS (hydroxyl-solidate) prepared from the residual fly ash (after synthesis of pure-form zeolite A from fly ash) and a commercial grade zeolite A. Batch method was employed to study the influential parameters such as initial pH value, adsorbents dosage and adsorption temperature on the adsorption process. The equilibrium data were well fitted by the Langmuir model and showed the affinity: Cu2+ > Zn2+ (adsorbent FA-ZA). The removal mechanism of metal ions followed adsorption and ion exchange processes. Attempts were also made to recover heavy metal ions and regenerate adsorbents (adsorbent FA-ZA).     

Modified accumulation of selected heavy metals in Bt transgenic rice

Safety assessment of genetically modified crops generally does not take into account the potential hazard of altered patterns of heavy metal accumulation in plants. A pot experiment was conducted under greenhouse conditions to evaluate the impact of heavy metal amendments on the accumulation of Cd, Cu, Pb and Zn in a Bt transgenic rice Ke-Ming-Dao (KMD) and its wild-type Xiushui 11 (Xs11). In control soils, significant di erence was only found in contents of Cu (p < 0.01) and Pb (p < 0.05) in straw between KMD and Xs11. At three levels of Cd amendments (5, 10, and 20 mg/kg), the Cd contents in grain and straw of KMD were significantly higher than those of Xs11, and all grain Cd contents were significantly higher than the International Criteria (0.2–0.4 mg/kg) as specified by the Codex Alimentarius Commission (CAC). These results implied that it may be unsafe for growing Bt transgenic rice in heavily Cd-polluted areas. No significant di erence in Zn was found between the two varieties with the exception of roots at Zn amendment level of 600 mg/kg, while Pb contents in KMD were much higher in the straw at the lead amendment level of 1000 mg/kg and in the root at 250 mg Pb/kg. Data on the heavy metal accumulation patterns for the genetically modified rice may be used for the selection of growing areas as well as for plant residue management for Bt rice.     

Removal of heavy metals from aqueous solution by carbon nanotubes: adsorption equilibrium and kinetics

IntroductionWastewatersfrombatterymanufacturing ,printing ,painting ,dyeingandotherindustrialprocessesoftencontainconsiderableamountsofheavymetalsthatwouldendangerpublichealthifdischargedwithoutadequatetreatment.Long termingestionofwatercontaininghigherco…     

北京耕作土壤重金属含量的空间自相关分析

以北京市耕作土壤中重金属元素为例,采用Moran's I统计量研究了土壤重金属含量的空间自相关关系、空间相关尺度以及空间分布规律.结果表明:北京市耕作土壤中8种重金属含量均存在空间自相关性.Cr、Ni、Zn、Hg、Cu、Pb、As、Cd的空间自相关尺度分别为57、75、57、55、55、65、74、37km.以cr和Hg为例,用区域空间自相关指标结合Moran散点图分析了重金属含量空间聚集区和空间孤立区在研究区内的分布规律.其中"高-高"空间聚集和"低-高"空间孤立区域存在潜在的污染风险,对土壤重金属环境质量评价和重金属污染防治有着重要的作用.     

城市交通大气与土壤重金属对小蜡生物富集作用的影响

选择合肥市区交通干道、城郊公路和森林公园作为具有不同交通流量的路段,通过火焰原子吸收法,测定土壤和小蜡叶片中的w(Cu),w(Zn),w(Pb),w(Cd)和w(Cr);运用统计方法研究土壤和小蜡叶片中重金属含量的差异和相关性,以及与城市交通大气污染的关系.结果表明:市区交通干线和城郊公路的土壤中w(Cu),w(Zn),w(Pb),w(Cd)和w(Cr)均高于对照点(森林公园),且市区交通干线与对照点的土壤中重金属含量差异显著;小蜡叶片对5种重金属富集量与土壤中的相应重金属含量没有明显相关性,这表明叶片富集的重金属主要来源于道路交通产生的大气重金属污染物,而非主要从土壤中吸收获得;小蜡叶片对大气中的Pb和Cr的富集能力较强,其生物浓缩系数分别为5.50和3.43,说明小蜡可能是Pb和Cr的良好指示植物,可用于环境监测.     

小球藻对多种重金属吸附性能的研究

微藻是一种广泛存在、生长速度快、适宜大规模养殖的结构简单的植物.近年来,基于微藻的水污染控制技术被广泛研究并得到认可,其中,利用藻类吸附污染水体中的重金属类物质更被看作是一种极具前景的水处理手段.然而,当前的研究始终对藻类吸附重金属性能的决定性影响因素缺乏相对全面的探究,同时对藻类表面官能团在吸附过程中所起的作用也不明确.对此,本研究采取静态实验的方法,选取常见的淡水藻类小球藻Chlorella sp.和典型重金属Ni （Ⅱ）、Cr （VI）、Cd （Ⅱ）,以藻细胞密度、重金属离子浓度、温度、pH作为影响因素,探究其对小球藻细胞吸附性能的影响.结果表明,小球藻对Ni （Ⅱ）、Cr （VI）、Cd （Ⅱ）均显示出了很好的吸附能力.在所选的几种藻细胞密度下,小球藻吸附性能差异不大.当溶液处于中性偏酸性、重金属浓度低于5 mg·L^-1的情况下,小球藻吸附效果最好.在20~30℃范围内升高温度对吸附会产生有利影响.对小球藻进行红外光谱检测发现,官能团C—O、C=O、—COOH、—NH—在对重金属离子的吸附过程中起主要作用.     

Removal of heavy metals from aqueous solution by sawdust adsorption

The adsorption of lead, cadmium and nicel from aqueous solution by sawdust of walnut was investigated. The effect of contact time, initial metal ion concentration and temperature on metal ions removal has been studied. The equilibrium time was found to be of the order of 60 min. Kinetics fit pseudo first-order, second-order and intraparticle diffusion models, hence adsorption rate constants were calculated. The adsorption data of metal ions at temperatures of 25, 45 and 60~C have been described by the Freundlich and Langmuir isotherm models. The thermodynamic parameters such as energy, entropy and enthalpy changes for the adsorption of heavy metal ions have also been computed and discussed. Ion exchange is probably one of the major adsorption mechanisms for binding divalent metal ions to the walnut sawdust. The selectivity order of the adsorbent is Pb（I1）~Cd（II）〉Ni（I1）. From these results, it can be concluded that the sawdust of walnut could be a good adsorbent for the metal ions from aqueous solutions.     

石墨烯材料去除重金属及放射性核素的研究

石墨烯及其改性材料具有比表面积大、吸附能力强、抗辐射性能好、耐高温、耐酸碱等优点,近年来在去除重金属和放射性核素领域得到了广泛关注.本文简要介绍了石墨烯的合成及改性方法,综述了石墨烯材料去除水中重金属离子和放射性核素的研究进展,包括吸附容量、影响因素、吸附动力学、吸附热力学模型和吸附机理,分析了该研究领域目前存在的问题,探讨了今后的研究方向.     

环境修复中锰氧化物与变价重金属交互作用的研究进展

氧化-还原过程是影响重金属环境行为的重要过程.锰氧化物作为重要的天然氧化剂,通过对变价重金属的氧化还原和吸附作用,影响着其在环境中的形态、生物有效性乃至归趋,具有很高的环境修复潜力和应用价值.近年来对锰氧化物和变价重金属元素的研究主要集中在以下几个方面:生物氧化锰的形成与多铜氧化酶体系的关系;锰氧化物与变价重金属的交互作用的机制及其影响因素,尤其锰氧化物的空间结构和作用位点的影响.目前,锰氧化物在环境修复中的应用主要集中在水环境修复方面,土壤体系及土壤微界面还很鲜见.同时土壤体系中影响锰氧化物与重金属交互作用的因素更多,其过程也更为复杂.本文通过总结锰氧化物与变价重金属交互作用的研究进展,对比不同重金属种类之间反应机制的差别,为更好的理解锰氧化物的环境作用提供基础,也期望能够进一步拓展其在污染环境的修复中的应用范围.     

野生食用牛肝菌的重金属富集研究

研究探讨了5种野生牛肝菌(灰褐牛肝菌,双色牛肝菌,全褐牛肝菌,美味牛肝菌,皱盖疣柄牛肝菌)对重金属Cd、Pb、Zn、Cu和Hg的富集特征。结果表明:5种牛肝菌子实体Cd含量为<0.10～19.00 mg/kg,Pb的含量为<0.10～9.34 mg/kg,Zn、Cu和Hg含量为0.000 09～0.1mg/kg。5种牛肝菌子实体中Cd、Pb和Hg含量均超标。与牛肝菌子实体相比,Cd和Pb在牛肝菌非菌根根和菌根根中含量处于中等偏高水平。在牛肝菌子实体中,除Pb外,Cd、Zn、Cu和Hg更易向灰褐牛肝菌子实体的菌盖中迁移。Cd、Pb、Zn、Cu和Hg更易于富集在全褐牛肝菌、美味牛肝菌和皱盖疣柄牛肝菌子实体的菌盖中;Zn和Cu容易富集于双色牛肝菌菌盖,Cd、Pb和Hg更容易富集于双色牛肝菌柄。5种牛肝菌对Cd的富集能力最强,生物富集系数(Bioaccumulation factor,BCF)范围为1.00～79.17。对Pb和Hg的BCF分别在0.010～0.18和0.10～0.38;对Zn和Cu的BCF不足0.001。生长牛肝菌的土壤Cd含量提高,从不足0.1 mg/kg提高到(0.24±0.04)mg/kg,Pb含量从(52±3)mg/kg提高到(53±3)mg/kg,而Zn含量从(94±6)mg/kg降低到(61±5)mg/kg,Cu含量从(26±5.6)mg/kg升高至(40±5.57)mg/kg,对Hg含量影响不大。     

基于PMF模型的兰州耕地土壤重金属来源解析

为了分析Pb、Cd、Cr、Hg、As、Cu、Zn、Ni等8种重金属的污染状况、空间分布及污染来源.2019年9月共采集382个兰州耕地表层土壤样品,并测定其重金属含量.结果表明：①兰州市耕地土壤重金属Pb、Cd、Cr、Hg、As、Cu、Zn、Ni的平均含量分别为20.96,0.24,0.05,6.40,8.36,48.57,101.92,34.34mg/kg,其中Hg的均值超过国家土壤污染风险筛选值,Cd、Hg、Cu、Zn、Ni的均值超过兰州市土壤背景值.内罗梅综合指数表明研究区耕地52.62%样点呈现轻度污染,37.70%样点呈现中度污染,3.66%样点呈现重度污染,无重金属污染的样点占6.02%.潜在生态风险指数表明13.09%的样点属于轻微生态风险,68.85%的样点属于中等生态风险,17.54%的样点属于强生态风险,0.52%的样点属于很强生态风险.②基于PMF模型可知8种重金属有4种主要来源,其中Pb、Cd、Zn、Ni以交通运输源为主,贡献率分别为52.4%、50.7%、56.7%和50.2%;Hg以农业活动和医疗设备源为主,贡献率为83.7%;Cr、Cu和Ni以自然源为主,贡献率分别为81.2%和61.3%和49.8%;As以工业活动源为主,贡献率为68.3%.③从空间分布来看,研究区内除Cr外,Pb、Cd、As、Cu、Zn、Ni在城关区和七里河区都有高值区出现,其中Zn和Ni的高值范围较广,可能与人为影响有关;Hg在城关区、安宁区、七里河区以外的研究区内均有高值出现.     

长江口滨岸潮滩无齿相手蟹体内重金属元素的时空分布及其在环境监测中的指示作用

对长江口滨岸带无齿相手蟹体内的重金属元素分析表明:无齿相手蟹体内的Zn、Cr、Ni三种元素季节分布的总体趋势是夏季>春季>秋季。无齿相手蟹对重金属元素的累积也存在着地点间的差异。青龙港、浒浦两地的无齿相手蟹对Cu、Pb、Cr、Ni的累积量都很高,东海农场和崇明东滩的无齿相手蟹对Zn的累积量较高。对无齿相手蟹、沉积物、悬浮颗粒物中的重金属含量分析表明,无齿相手蟹对重金属Cu有一定的富集能力,适于做长江口滨岸带Cu的指示生物。     

电化学方法去除污泥中重金属的研究

分析了河东污水处理厂污泥中Pb、Cd、Cu、Ni的含量和形态分布特征,并以PbO2/Ti电极板为阳极、铜板为阴极通电处理污泥,考察了电压、通电时间等因素对污泥pH及重金属去除效果的影响.结果表明,污泥中Cd和Ni的含量超过了国家农用标准(GB4284—1984),同时,Cd和Ni也具有较高的生态可利用性.不同电压对污泥重金属去除率影响较大,当电压为35 V,电流为80 mA,反应时间为6 h时,对污泥的处理效果与费用最佳,在此电压下对污泥进行处理,Cu、Pb、Cd和Ni的去除率分别为57.35%、48.42%、68.63%和49.85%.此时,阳极区污泥中的重金属含量已有较大程度的降低,均能达到国家农用标准(GB4284—1984).