Removal of metal ions from the complexed solutions in fixed bed using a strong-acid ion exchange resin

Fixed bed removal of equimolar metal ions (Co²⁺, Ni²⁺, Mn²⁺, Sr²⁺) from aqueous solutions using a strong-acid resin was examined. The solution contained a water-soluble complexing agent including ethylenediaminetetraacetic acid, nitrilotriacetic acid, and citric acid. Experiments were performed under different solution pH and molar concentration ratios of complexing agent to the total metals. It was shown from batch studies that the equilibrium exchange of metals and the resin mainly depended on solution pH, and partly on the type of complexing agent used. A mass transfer model was proposed to describe the breakthrough curves of the resin bed, which contained two parameters (τ and k) estimated from the observed breakthrough data. The calculated breakthrough curves agreed well with the measured ones (standard deviation <6%). In fixed bed tests at low pH (=2), the type of complexing agent had little effect on the breakthrough data. For a given complexing agent, the metal with a larger overall formation constant (K_f) showed a smaller exchange capacity. For a given metal ion, the complexing agent with a larger K_f also revealed a smaller exchange capacity.     

Effects of selected metal oxides on the dechlorination and destruction of PCDD and PCDF

OCDD and OCDF spiked silica/graphite based model fly ash containing various copper compounds and metal oxides were thermally treated under oxygen deficient conditions. All copper compounds tested showed a considerable dechlorination/hydrogenation reaction at 260 °C. After 30 min at 340 °C, less than 1% of the spiked OCDD and OCDF was recovered as T₄CDD/F to OCDD/F. Other compounds tested demonstrated a lower rate of dechlorination compared to the copper compounds. However, all other metal oxides showed a small dechlorination effect at 260 °C, which was considerably increased at 340 °C.

The model fly ash containing the different copper compounds or metal oxides showed comparable PCDD and PCDF isomer patterns after thermal treatment. However, small differences were observed among the different tested compounds. The PCDD and PCDF isomer patterns on the model fly ashes were similar to patterns found during dechlorination experiments on fly ashes from waste incineration processes.

Model fly ash containing Ca(OH)₂ exhibited the highest destruction potential, but a low dechlorination potential. In contrast, model fly ash containing any of the remaining compounds tested, was found to predominantly dechlorinate the spiked OCDD and OCDF.     

Soil metal concentrations and productivity of Betula populifolia (gray birch) as measured by field spectrometry and incremental annual growth in an abandoned urban Brownfield in New Jersey

A forested brownfield within Liberty State Park, Jersey City, New Jersey, USA, has soils with arsenic, chromium, lead, zinc and vanadium at concentrations above those considered ambient for the area. Using both satellite imagery and field spectral measurements, this study examines plant productivity at the assemblage and individual specimen level. Longer term growth trends (basal area increase in tree cores) were also studied. Leaf chlorophyll content within the hardwood assemblage showed a threshold model for metal tolerance, decreasing significantly beyond a soil total metal load (TML) of 3.0. Biomass production (calculated with RG - Red/Green Ratio Index) in Betula populifolia (gray birch), the co-dominant tree species, had an inverse relationship with the Zn concentration in leaf tissue during the growing season. Growth of B. populifolia exhibited a significant relationship with TML. Assemblage level NDVI and individual tree NDVI also had significant decreases with increasing TML. Ecosystem function measured as plant production is impaired at a critical soil metal load.     

生物强化技术及其在废水生物处理中的应用

生物强化技术广泛应用于废水生物处理中,而竞争力和适应性强的高效菌株筛选是生物强化技术的决定性因素.论述了利用具有代谢性能的可移动基因片段强化、基因工程菌强化和常规微生物学手段分离菌株的生物强化技术,并阐述了生物强化技术在废水生物处理过程中去除难降解有机物,去除过量的氮、磷等营养物质,维持生物系统稳定性中的应用.     

新乡市大气PM2.5载带金属元素季节分布、来源特征与健康风险

为探究典型工业城市大气PM_2.5载带重金属的季节分布、来源及健康风险,于2019~2020年分季节采集PM_2.5有效样品112个,利用电感耦合等离子体发射光谱法（ICP-AES）测定了19种元素含量.结果表明,PM_2.5及其载带重金属元素的年均浓度分别为（66.25±35.73）μg·m^-3和（1.32±0.84）μg·m^-3.PM_2.5及其元素组分夏季浓度最低,Al、Ca、Fe、Mg和Ti等元素春季浓度最高,其它元素则是冬季浓度最高.利用PMF-PSCF模型共解析出5类排放源,分别为Ni和Co相关排放源（5.8%）、机动车源（13.7%）、Cd相关排放源（5.1%）、燃烧源（18.2%）和扬尘源（57.3%）.风险评价结果表明,每一类排放源的危害指数（HI）值均小于1,不存在明显的非致癌风险;致癌风险均处于10^-6~10^-4范围内,具有一定的致癌风险.与其它排放源相比,燃烧源的致癌风险（8.74×10^-6,36.9%）和非致癌风险（0.60,25.6%）最大,建议优先对燃烧源进行治理以降低区域人群暴露风险.     

Trace elements and rare earth elements in wet deposition of Lijiang, Mt. Yulong region, southeastern edge of the Tibetan Plateau

In order to investigate the compositions and wet deposition fluxes of trace elements and rare earth elements (REEs) in the precipitation of the southeastern edge of the Tibetan Plateau, 38 precipitation samples were collected from March to August in 2012 in an urban site of Lijiang city in the Mt. Yulong region. The concentrations of most trace elements and REEs were higher during the non-monsoon season than during the monsoon season, indicating that the lower concentrations of trace elements and REEs observed during monsoon had been influenced by the dilution effect of increased precipitation. The concentrations of trace elements in the precipitation of Lijiang city were slightly higher than those observed in remote sites of the Tibetan Plateau but much lower than those observed in the metropolises of China, indicating that the atmospheric environment of Lijiang city was less influenced by anthropogenic emissions, and, as a consequence, the air quality was still relatively good. However, the results of enrichment factor and principal component analysis revealed that some anthropogenic activities (e.g., the increasing traffic emissions from the rapid development of tourism) were most likely important contributors to trace elements, while the regional/local crustal sources rather than anthropogenic activities were the predominant contributors to the REEs in the wet deposition of Lijiang city. Our study was relevant not only for assessing the current status of the atmospheric environment in the Mt. Yulong region, but also for specific management actions to be implemented for the control of atmospheric inputs and the health of the environment for the future.     

北京冬季PM2.5中金属元素浓度特征和来源分析

为了解北京冬季细颗粒物中金属元素的浓度水平及其来源,于2014年12月至2015年1月使用中流量PM_(2.5)采样器在北京城区开展了为期30 d的连续采样,采用滤膜称重法检测PM_(2.5)浓度,电感耦合等离子体质谱法(ICP-MS)分析PM_(2.5)中16种元素总量,并采用富集因子法和因子分析法分析元素污染特征及其来源.结果表明,观测期间PM_(2.5)中主要金属元素为K、Ca、Fe、Al和Mg,占16种元素总量的90.7%.与白天相比,地壳元素如Mg和Al等在夜间的浓度下降30%以上,而人为源金属元素如Cu和Pb等的浓度则上升40%以上.从优良天到重污染天气,上述16种金属元素的总浓度上升1倍,但其在PM_(2.5)中的比例却逐渐降低,说明金属元素的富集不是PM_(2.5)上升的主要原因.随着污染程度的加剧,Cu、Zn、As、Se、Ag和Cd等主要来自人为源的金属元素浓度上升较快,重度污染天与优良天的浓度比值范围为2.9~5.3;而Al、Mg、Ca、Mn和Fe等地壳元素浓度上升则较缓,重度污染天与优良天的浓度比值范围为1.2~1.8.北京冬季PM_(2.5)中金属元素主要来源于燃煤和生物质燃烧、交通和工业排放以及地面扬尘,贡献率分别为34.2%、25.5%和17.1%.     

大气颗粒物中无机元素特性的研究

介绍用ICP-MS方法分析大气颗粒物中的无机元素,研究了部分污染元素在不同粒径颗粒物中的富集特征以及不同季节的浓度变化,并采用富集因子法对颗粒物的来源进行初步探讨。     

微塑料及金属在黄浦江地表水环境的赋存特征及与金属抗性基因的相关性分析

城市河流是微塑料(MPs)及重金属污染的“热点”区域,在污染迁移中起到重要作用.然而同样作为抗性基因赋存及释放的重要媒介,鲜有研究考察了流域MPs、金属与金属抗性基因(MRGs)的关联.为此,调研了10个黄浦江站点水样的金属及MPs的污染特征,并基于宏基因组学对水样及提取的MPs上的MRGs及可移动遗传元件(MGEs)进行分析.结果显示,表层水中ρ[锑(Sb)]平均值最高,为(3.16±0.419)μg·L^-1. MPs的丰度平均值为(1.78±0.84)n·L^-1,位于工业区和人口密集区的MPs丰度显著高于农业区和低人口密度的区域.纤维状、“小粒径”(<0.5 mm)的聚对苯二甲酸乙二醇酯(PET)是最主要的MPs类型.所有样本中共检出18类MRGs,其中水样中MRGs的相对丰度为1.68±0.21.最主要的MRGs亚型是merR和ruvB,分别为汞和多重金属抗性基因的亚型.相关性分析表明,水中的铬和镍与MRG-Cr、MRG-Ni和多重金属抗性基因之间存在显著正相关.MPs上MRGs的相对丰度为1.63±0.53,最主要的MRGs亚型...     

大连市园林绿地土壤化学元素分异特征研究

以大连市单位附属绿地、公共绿地、住宅区绿地、道路绿地4种典型城市绿地类型8个取样点的表层土壤为研究对象,采用野外土样采集和室内分析相结合的研究方法,就大连市城区不同绿地类型表层土壤大量元素、微量元素及重金属元素的分异特征进行系统研究.结果表明:大连市园林绿地土壤在养分特征上具有明显的空间变异性,但土壤化学元素多呈无规律分布.