Genomic analyses of metal resistance genes in three plant growth promoting bacteria of legume plants in Northwest mine tailings, China

To better understand the diversity of metal resistance genetic determinant from microbes that survived atmetal tailings in northwest of China, a highly elevated level of heavymetal containing region, genomic analyses was conducted using genome sequence of three native metal-resistant plant growth promoting bacteria (PGPB). It shows that: Mesorhizobium amorphae CCNWGS0123 contains metal transporters from P-type ATPase, CDF (Cation Diffusion Facilitator), HupE/UreJ and CHR (chromate ion transporter) family involved in copper, zinc, nickel as well as chromate resistance and homeostasis. Meanwhile, the putative CopA/CueO system is expected to mediate copper resistance in Sinorhizobium meliloti CCNWSX0020 while ZntA transporter, assisted with putative CzcD, determines zinc tolerance in Agrobacterium tumefaciens CCNWGS0286. The greenhouse experiment provides the consistent evidence of the plant growth promoting effects of these microbes on their hosts by nitrogen fixation and/or indoleacetic acid (IAA) secretion, indicating a potential in-site phytoremediation usage in themining tailing regions of China.     

极端暴雨条件下广东北江重金属污染特征

以2012年“6.25”暴雨径流过程为对象,研究广东省北江上游高桥断面在极端暴雨条件下水体理化性质与ρ(Pb)、ρ(Cu)、ρ(Zn)、ρ(Cd)(均为溶解态,下同)的变化过程;基于相关分析法,分析北江水质对水文过程的响应关系及各指标间的内联特点. 结果表明:暴雨径流期间,北江水质呈“大流量、高浓度”的特征. 暴雨径流发生前后4个典型阶段中,阶段Ⅰ(局部产流期)ρ(Cd)、ρ(Pb)仅为(0.48±0.09)和(1.91±0.29)μg/L,ρ(Cu)与ρ(Zn)基本未检出;阶段Ⅱ(以地表径流为主的全流域产流期)ρ(Cd)、ρ(Pb)、ρ(Cu)与ρ(Zn)均迅速上升,最高分别达1.80、12.34、6.18、52.57 μg/L;阶段Ⅲ(以浅层地下水径流为主的全流域产流期)重金属质量浓度整体较洪水期有所下降,但ρ(Pb)仍高于阶段Ⅰ正常水平,ρ(Zn)、ρ(Cu)和ρ(Cd)则低于阶段Ⅰ;阶段Ⅳ(深层地下水产流期)ρ(Cu)与ρ(Zn)已回落至未检出水平,ρ(Cd)持续下降,低于阶段Ⅲ和阶段Ⅰ,ρ(Pb)较阶段Ⅲ有所下降,但仍高于阶段Ⅰ. 暴雨径流期间,溶解态重金属质量浓度与流量及浊度间呈显著正相关(P<0.01),ρ(Zn)与ρ(Pb)、ρ(Cd)的相关系数均在0.85以上(P<0.01).      

The role of arbuscular mycorrhiza on change of heavy metal speciation in rhizosphere of maize in wastewater irrigated agriculture soil

To understand the roles of mycorrhiza in metal speciation in the rhizosphere and the impact on increasing host plant tolerance against excessive heavy metals in soil, maize ( Zea mays L. ) inoculated with arbuscular mycorrhizal fungus ( Glomus mosseae) was cultivated in heavy metal contaminated soil. Speciations of copper, zinc and lead in the soil were analyzed with the technique of sequential extraction. The results showed that, in comparison to the bolked soil, the exchangeable copper increased from 26% to 43% in non-infected and AM-infected rhizoshpere respectively; while other speciation (organic, carbonate and Fe-Mn oxide copper) remained constant and the organic bound zinc and lead also increased but the exchangeable zinc and lead were undetectable. The organic bound copper, zinc end lead were higher by 15%, 40% and 20%, respectively, in the rhizosphere of arbuscular mycorrhiza infected maize in comparison to the non-infected maize. The results might indicate that mycorrhiza could protect its host plants from the phytotoxicity of excessive copper, zinc and lead by changing the speciation from bio-available to the non-bio-available form. The fact that copper and zinc accumulation in the roots and shoots of mycorrhia infected plants were significantly lower than those in the non-infected plants might also suggest that mycorrhiza efficiently restricted excessive copper and zinc absorptions into the host plants. Compared to the non-infected seedlings, the lead content of infected seedlings was 60% higher in shoots. This might illustrate that mycorrhiza have a different mechanism for protecting its host from excessive lead phytotoxicity by chelating lead in the shoots.     

Spatial characterisation of multi-level in-use copper and zinc stocks in Australia

A methodology has been developed to characterise the in-use stocks of copper and zinc at a variety of spatial levels. The approach employs representative concentrations of copper and zinc in their main in-use reservoirs (which account for virtually all the metal put into service) together with geographic information system (GIS) data sets of the spatial locations and densities of these reservoirs. The authors have applied this methodology to Australia at four spatial levels: central city, urban region, states/territories, and country, to produce what is believed to be the first multi-level spatial characterisations of the in-use stocks of technological materials. The results are presented quantitatively and as a series of stock density maps for Inner Sydney, Sydney Metro, all Australian states/territories, and Australia itself. The total stocks in Australia are estimated at about 4.3 Tg Cu (4.3 thousand million kg) and 3.8 Tg Zn (3.8 thousand million kg), or about 240 kg Cu/capita and 205 kg Zn/capita. A statistical analysis of the data shows that the metal stock density at a given spatial level is largely determined by a small number of high-density components at the next lower level. The spatial analysis of the in-use stocks indicates that 50% of all copper and zinc stock resides in just 10% of Australia's local government areas. The largest stocks occur in large urban regions, which can contain copper and zinc densities more than a hundred times higher than rural areas. These regions are expected to be major Australian “metal mines” in the future.     

Excessive Cu and Zn affecting on distribution of the metals and activities of glycolytic and nitrogen incorporating key enzymes in mycelia of ectomycorrhizal fungi Suillus bovinus

ＩｎｔｒｏｄｕｃｔｉｏｎＥｃｔｏ ｍｙｃｏｒｒｈｉｚａｌｆｕｎｇｉａｒｅｋｎｏｗｎｔｏａｍｅｌｉｏｒａｔｅｍｅｔａｌｔｏｘｉｃｉｔｙｔｏｔｈｅａｓｓｏｃｉａｔｅｄｈｉｇｈｅｒｐｌａｎｔｓ (Ｂｒａｄｌｅｙ ,1981;1982 ;Ｂｒｏｗｎ ,1985;Ｂｕｃｋｉｎｇ ,1995) .Ｔｈｅｉｍｐｒｏｖｅｍｅｎｔｏｆｈｅａｖｙｍｅｔａｌｔｏｌｅｒａｎｃｅｂｙｍｙｃｏｒｒｈｉｚａｌｉｎｆｅｃｔｉｏｎｉｓｒｅｌａｔｅｄｔｏａｒｅｄｕｃｔｉｏｎｏｆｓｈｏｏｔｔｉｓｓｕｅｃｏｎｃｅｎｔｒａｔｉｏｎ ,ｃｏｕｐｌｅｗｉｔｈａｎｉｎｃｒｅａ…     

南海游泳动物重金属含量特征及风险评价

以2019年夏季采自南海的11种游泳动物为研究对象,测定分析其体内重金属（Cu、Pb、Zn、Cd、Cr、As和Hg）的含量,并评估了上述重金属的污染状况和健康风险。结果显示,7种重金属在生物体中的含量,均符合国内相关污染评价标准。单因子污染指数均值依次为Zn>Cr>As>Hg>Pb>Cd>Cu,虽然个别物种的部分元素达到轻度或中度污染水平,但生物体内7种重金属的综合污染评价均属于无污染状态。健康风险评估结果表明,其膳食暴露风险、非致癌与致癌风险都较低。研究结果表明,南海夏季游泳动物体内重金属含量较低,几乎不存在人类食用健康风险。     

植物促生菌在重金属生物修复中的作用机制及应用

重金属污染是导致生态和环境退化的主要因素之一.土壤重金属污染会降低土壤质量、农作物产量和品质,甚至威胁人类健康.因此,优化土壤重金属污染治理措施,对于农业高产优质可持续具有重要意义.诸多国内外学者在重金属污染植物修复方面开展了大量研究,但由于受土壤和气候环境条件的影响,其修复效率受到制约.微生物与植物的协同修复被认为是环境胁迫条件下提高重金属污染修复效率的一种有效手段.耐重金属的植物促生细菌（PGPB）不仅可以促进植物生长,提高对生物胁迫（如病原菌）和非生物胁迫（如干旱、高盐、极端温度和重金属等）的抗性,还可以改变土壤中重金属的生物利用度和毒性,从而提高植物对重金属的修复效率.系统地梳理了耐重金属的PGPB在促进植物生长,增强植物抗逆性和影响重金属生物利用度方面的作用机制,并进一步综述了近年来国内外关于PGPB在生态修复中的应用和研究进展.     

内生菌在修复重金属污染土壤的研究进展

内生菌是生活于植物的各组织、器官内部,但并不使植物表现出有害症状的真菌、细菌或放线菌。因其具有固氮、矿物溶解、光合作用、载运铁、利用1－氨基环丙烷－1羧酸为唯一氮源、传递营养物质等作用,内生菌在修复重金属污染土壤方面具有重要应用潜力。本文综述了内生菌及其抗重金属机理（促进植物生长和拮抗重金属方面）研究进展,以期为修复重金属污染土壤提供新思路。     

攀枝花矿区糙野青茅根际耐铬放线菌筛选及促生能力评价

从攀枝花矿区糙野青茅根际土中分离放线菌,筛选获得对重金属铬具有强耐受性、抗菌促生和产胞外酶能力的放线菌,为微生物-植物联合修复重金属污染提供菌种资源.采用稀释涂布法进行放线菌的分离,通过放线菌在不同铬浓度高氏一号培养基上的生长状况判断其对重金属铬的耐受性,进一步采用原子吸收分光光度法分析菌株对铬耐受性强的菌株耐铬及去铬能力;通过对菌株产铁载体、溶磷、产吲哚乙酸(IAA)、产纤维素酶、产淀粉酶、产木糖酶、产酪蛋白酶能力及抗菌活性的筛选,综合评价菌株抗菌促生能力.结果显示,分离获得的27株根际菌株,光学显微形态及扫描电镜结果均显示为放线菌,其中有14株能在含铬的培养基上生长,具有耐铬能力.16S rRNA基因测序结果显示,14株放线菌分属于链霉菌属(streptomyces)、小单孢菌属(Micromonospora)和冢村氏菌属(Tsukamurella).菌株SCAU9002和SCAU9008在铬浓度为300mg·L~(-1)的处理下培养6 d,去铬率分别达到81.17%和78.41%;菌株SCAU9002、SCAU9006、SCAU9008、SCAU9009、SCAU9013同时具有3种促生功能,盆栽实验结果进一步表明,在重金属胁迫下,经菌株处理后的玉米植株更高,生物量更大,根系更发达,促生效果较好.此外,菌株SCAU9006对6种病原菌具有拮抗作用,5株菌同时具有3种及以上产胞外水解酶的能力,4株菌能在7%的NaCl浓度下生长,13株菌在pH5.0~8.0的范围内均可生长.结果表明,根际放线菌在促进矿区植物生长和铬尾矿污染土壤的生物修复研究中具有很大潜力.     

Recovery of Cu and Fe from Printed Circuit Board waste sludge by ultrasound: Evaluation of industrial application

The paper presents a novel cleaner process for metal recovery from the Printed Circuit Board (PCB) waste sludge by assistance of ultrasound. The process can effectively recover heavy metals at low cost with high separation and recovery efficiency, produce high quality products and also achieve zero waste discharge with operation at industrial scale. With the PCB waste sludge containing (wet content) 3.14–4.85% copper and 3.71–4.23% iron, copper recovery efficiency of 95.2–97.5% and iron recovery efficiency of 97.1–98.5% were achieved, while the purity of copper sulfate produced by the process was 98.0% and the produced ferric chloride had a satisfied quality for using as a coagulant material for the plant on-site wastewater treatment. The process had been successfully scaled up to the industrial scaled applications in a heavy metal recovery plant in city of Huizhou, China for more than two years. The novel cleaner heavy metal recovery process has a great prospect on the applications of resources recovery and environmental protection practices.     

铜胁迫对小麦根系微域微生物群落的影响

小麦是我国主要的粮食作物,土壤重金属污染会严重威胁作物生长和粮食安全.大量研究表明根际微生物在调控作物发育和抗逆性方面具有非常重要的作用.因此,本研究通过高通量测序技术研究铜胁迫条件下小麦根际微生物群落的变化,从微生物学角度揭示铜污染胁迫对小麦根际的影响作用.采用盆栽培养试验对铜污染处理中小麦非根际、根际以及根内微生物进行测序后,分别比较小麦不同根系分区环境中的微生物群落结构和多样性.结果发现,所有处理中小麦的根内微生物多样性均显著（P<0.001）低于根际和非根际微生物多样性,表明根表作为微生物进入根内环境的门户,对根内微生物的定殖起着过滤和筛选的作用.铜污染胁迫降低了根际土环境中的微生物多样性,且差异显著（P<0.05）;而在非根际和根内环境中,尽管铜污染胁迫降低了对应根系分区中的微生物多样性,但差异不显著（P>0.05）.变形菌门（Proteobacteria）和放线菌门（Actinobacteria）是小麦根际和非根际环境中的共有优势菌群,通过比较发现铜污染胁迫对这两种优势菌门的影响作用较小.另外,芽孢杆菌属（Bacillus）、假黄色单胞菌属（Pseudoxanthomonas）和鞘氨醇单胞菌属（Sphingomonas）等菌属具有较强的抗逆性,能够在铜污染胁迫下存活且能够为植物提供营养物质.     

7个柳树无性系在Cu/Zn污染土壤中的生长及对Cu/Zn的吸收

通过盆栽试验来评价7个柳树无性系(旱柳?杞柳和金丝柳)修复Cu/Zn污染土壤或矿砂的潜力.研究了7个无性系在2种污染介质中的生长,叶绿素含量?根系形态及其对Cu、Zn的吸收转移.结果表明,150d后,7个柳树无性系在污染介质中都能生长,其中旱柳和金丝柳生长较好,其他无性系生长受到明显抑制.各无性系叶片出现黄化现象,叶绿素相对含量降低.根系发育受到一定程度的抑制.各无性系对Cu的积累主要在地下部,而对Zn的积累主要在地上部,特别是在叶片中.7个无性系在铜土中更容易积累重金属.各无性系生物富集系数(BCF)Cu.Cu的转移系数(TF)值均<1,Zn的TF值在1.36~2.49之间.旱10?旱34和金丝柳对Cu和Zn有较强的耐性和一定积累能力,适合在尾矿区造林和修复.     

Seedling growth and metal accumulation of selected woody species in copper and lead/zinc mine tailings

A greenhouse pot experiment was conducted to evaluate the potential of selected woody plants for revegetation in copper (Cu) and lead/zinc (Pb/Zn) mine tailing areas. Five woody species (Amorpha fruticosa Linn, Vitex trifolia Linn: var. simplicifolia Cham, Glochidion puberum (Linn.) Hutch, Broussonetia papyrifera, and Styrax tonkinensis) and one herbaceous species (Sesbania cannabina Pers) were planted in Cu and Pb/Zn tailings to assess their growth, root morphology, nutrition uptake, metal accumulation, and translocation in plants. Amorpha fruticosa maintained normal growth, while the other species demonstrated stress related growth and root development. Sesbania cannabina showed the highest biomass among the plants, although it decreased by 30% in Cu tailings and 40% in Pb/Zn tailings. Calculated tolerance index (TI) values suggested that A. fruticosa, an N-fixing shrub, was the most tolerant species to both tailings (TI values 0.92–1.01), while S. cannabina had a moderate TI of 0.65–0.81 and B. papyrifera was the most sensitive species, especially to Pb/Zn tailings (TI values 0.15–0.19). Despite the high concentrations of heavy metals in the mine tailings and plants roots, only a small transfer of these elements to the aboveground parts of the woody plants was evident from the low translocation factor (TF) values. Among the woody plants, V. trifolia var. simplicifolia had the highest TF values for Zn (1.32), Cu (0.78), and Pb/Zn (0.78). The results suggested that A. fruticosa and S. cannabina, which have the highest tolerance and biomass production, respectively, demonstrated the potential for tailings revegetation in southern China.     

小清河干流底质有毒金属形态分布

以小清河干流底质为研究对象，为了更好地了解固体颗粒物上有毒金属被浸取进入液相情况．分析了三种不同浸取剂(DTPA、EDTA、NTA)的提取液中有毒金属Pb、Cr、Cu、Zn、Cd的含量。结果表明．金属浓度因浸取剂种类及金属本身类型不同而不同。由于固体颗粒物上金属的毒性及其可流动性与其存在形态密切相关。选取连续浸取法来考察底质样品中金属形态分布情况。结果表明．底质中Pb主要以氧化物键合态和碳酸键合态存在；Cr主要以有机键合态存在；Cu以有机键合态为优势存在；Zn主要以有机键合态和氧化物键合态存在；Cd主要以可交换态存在。     

Immobilization study of biosorption of heavy metal ions onto activated sludge

Activated sludge was immobilized into Ca-alginate beads via entrapment, and biosorption of three heavy metal ions, copper(Ⅱ), zinc(Ⅱ), and chromimum(Ⅱ), from aqueous solution in the concentration range of 10-100 mg/L was studied by using both entrapped activated sludge and inactivated free biomass at pH≤5. A biphasic metal adsorption pattern was observed in all immobilized biomass experiments. The biosorption of metal ions by the biosorbents increased with the initial concentration increased in the medium. The adsorption rate of immobilized pre-treated activated sludge(PAS) was much lower than that of free PAS due to the increase in mass transfer resistance resulting from the polymeric matrix. Biosorption equilibrium of beads was established in about 20 h and the adsorbed heavy metal ions did not change further with time. No significant effect of temperature was observed in the test for free biomass while immobilized PAS appeared to be strong temperature dependent in the test range of 10 and 40℃.Besides, the content of activated sludge in the calcium alginate bead has an influence on the uptake of heavy metals. The sorption equilibrium was well modeled by Langmuir isotherm, implying monomolecular adsorption mechanism. Carboxyl group in cell wall played an important role in surface adsorption of heavy metal ions on PAS.     

Beneficial reuse of chicken feathers in removal of heavy metals from wastewater

Natural and chemically treated chicken feathers (CF) were tested for their ability, as adsorbents, to remove copper and zinc from wastewater. Alkaline solutions of 0.2 N NaOH were found to be the best for the sorption process and a 0.6 wt% solution of dodecyl sulfate, as anionic surfactant, also gave best adsorption results. Treatment of CF with alkaline solutions adsorb more metal ions than those treated with the anionic surfactant followed by the untreated CF. Generally, the kinetics of the removal process by all tested sorbents was fast. The Freundlich isotherm model was found to represent the equilibrium results, of all adsorbents toward copper and zinc, reasonably well.     

不同养分对磷酸盐固定的污染土壤中铜锌生物有效性的影响

采用盆栽试验,在磷酸盐固定铜、锌单一及复合的三级污染(Cu 200 mg·kg^-1、Zn 400 mg·kg^-1)红壤和水稻土中,种植黑麦草40　d,测定不加养分、加入KCl和NH₄Cl、K₂SO₄和(NH₄)₂SO₄后土壤中有效态铜锌含量、黑麦草生物量及其铜锌吸收量,以讨论养分对污染土壤中磷酸盐固定态铜锌的活化作用.结果表明,磷酸盐固定的铜单一、锌单一和铜锌复合污染红壤中,增加养分,有效态铜锌的含量都较未加入养分的增高,并且养分KCl和NH₄Cl的增高幅度大于K₂SO₄和(NH₄)₂SO₄,其中在磷酸盐固定的锌单一污染红壤中,有效态锌含量较未加入养分时增幅高达133.4%.虽然加入K₂SO₄和(NH₄)₂SO₄,促进了红壤中黑麦草植株的生长,最大增幅达22.2%,但同时也增加了植株21.5%～112.6%的铜锌吸收量.调节养分对水稻土中铜锌的生物有效性没有显著影响.施入氮钾等养分能够改变磷酸盐固定的污染红壤中铜锌的生物有效性,对固定的铜锌都有活化作用.因此,在重金属污染土壤的修复中要充分考虑施肥等养分条件对固定钝化的重金属活性的影响.     

陕西西部某工业园区采暖期大气降尘重金属特征

为了解陕西省某工业园区采暖期大气降尘重金属元素特征,于2012年11月20日至2013年3月20日,通过被动采样的方式,采集该区域采暖期的大气降尘样品,利用火焰原子吸收分光光度法测定其中重金属元素Cu、Pb、Zn、Cd、Ni、Cr和Fe的含量,并分别计算各元素采暖期的日沉降通量和富集因子.结果表明:研究区采暖期大气降尘量普遍较高,并且受园区人为污染源和道路扬尘影响明显;大气降尘中重金属含量分布不均,位于园区内部点位的重金属含量明显大于上风向点位和对照点;各元素之间也有很大的差异,其中,Fe的含量远高于其他6种元素,Pb、Zn含量次之,Cu、Cd、Ni、Cr的含量较小;从采暖期日沉降通量来看,Fe、Zn、Pb的沉降通量较大,Cu、Cr、Ni、Cd的沉降通量较小.而根据富集因子分析结果可知,Zn、Pb、Cu、Cd主要来自人为源,Fe、Cr、Ni与当地的自然地质背景有关.     

A meta-analysis of heavy metals pollution in farmland and urban soils in China over the past 20 years

A total of 713 research papers about field monitor experiments of heavy metals in farmland and urban soils in China, published from 2000 to 2019, were obtained. A meta-analysis was conducted to evaluate the level of China's heavy metal pollution in soils, mainly focusing on eight heavy metals. It was found that the average concentrations of cadmium (Cd), lead (Pb), zinc (Zn), copper (Cu), mercury (Hg), chromium (Cr), nickel (Ni), and arsenic (As) in China were 0.19, 30.74, 85.86, 25.81, 0.074, 67.37, 27.77 and 8.89 mg/kg, respectively. Compared with the background value (0.097 mg/kg), the Cd content showed a twofold (0.19 mg/kg) rise in farmland soils and a threefold (0.29 mg/kg) rise in urban soils. The decreasing order of the mean I_geo was Cd (1.77) > Pb (0.62) > Zn (0.60) > Cu (0.58) > Hg (0.57) > Cr (0.54) > Ni (0.47) > As (0.28). Nearly 33.54% and 44.65% of sites in farmland and urban soils were polluted with Cd. The average concentrations of eight heavy metals were not sensitive change in recent two decades in farmland and urban soils. The average P_n values for urban (2.52) and farmland (2.15) soils showed that heavy metal pollution in urban soils was more serious than that in farmland, and the middle Yangtze River regions, where industrial activity dominates, were the most polluted. The meta-analysis comprehensively evaluated the current pollution situation of soil heavy metal, and provided important basis for soil management and environment prevention in China.     

十溴联苯醚的热解及其影响因素研究

在200~300℃的温度范围内研究了十溴联苯醚(BDE-209)的热降解及其影响因素.结果表明,温度、时间以及硝酸铜、三氯化铁、氯化铝和氯化锌等处理线路板过程中产生的金属盐对BDE-209热降解有不同的影响.升高温度或延长热解时间均能促进BDE-209的热解,且温度对BDE-209降解的影响程度大于时间对其降解的影响;硝酸铜、三氯化铁和氯化铝对BDE-209的热解均起促进作用,促进作用的顺序为:硝酸铜 >三氯化铁 >氯化铝;氯化锌对BDE-209的热解有抑制作用;随着温度的升高,氯化铝和氯化锌对BDE-209热降解的影响减弱.该研究结果可为深入探究电子垃圾热处理过程中BDE-209的释放及降解提供科学依据.