874 resultados para heavy metal stress
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渤海湾沿岸人口密集,工农、航运发达,渤海自身净化能力非常有限。因此,渤海湾 环境污染的压力越来越大,主要污染物包括重金属和持久性有机污染物的。四角蛤蜊广泛 分布于渤海湾海域,是一种重要的经济贝类,对污染物具有较强的富集能力。为了研究不 同站点渤海湾四角蛤蜊软体部重金属含量,选择大港油田、高沙岭码头、涧河村三个断面 进行研究,对不同站点四角蛤蜊软体部重金属含量进行了分析和讨论,最后对水生动物的 POPs 毒理调控通道进行了探索性研究,得到以下结果: 1. 通过比较渤海不同站点四角蛤蜊软体部重金属含量分布特征和方差分析,发现四 角蛤蜊软体部必需重金属元素含量较高,而非必需重金属元素含量较低,这是由于必需重 金属元素具有重要的生理功能作用。侧重比较A、B 两个断面各站位间四角蛤蜊软体部重 金属含量,发现虽然各站位间分布规律不明显,但各站位间差异显著。 2. 利用简单相关回归分析金属元素间及其与生物学性状间的关系,发现Mn 与Zn 之 间,Cu 与Zn 间均存在显著正相关,Se 与As、Cd 间存在显著正相关。另外,A 断面,BL 与Cd 含量显著负相关其回归方程为:Y(Cd)=-1395.97+88.34(BL);R=0.633;在B 断面,利用BW 和BH 分别与Cd 和As 显著负相关和显著正相关,其回归方程分别为:BW 和Cd 的回归方程为:Y(Cd)=-1968.80+220.72(BW);R=0.656。BH 和As 的回归方 程为:Y(As)=1496.86+227.82(BH);R=0.656。 3. 利用PLS(偏最小二乘分析)方法分析,发现五个生物学性状都与Co、As 呈正相 关,而与Cr、Pb、Se 呈负相关,而与必须重金属元素相关不明显。进一步分析表明表明 渤海湾海域中Co、As 含量低于四角蛤蜊正常生长发育的需要,而Cr、Pb、Se 的含量超过 四角蛤蜊正常生长发育所需的量。最后,通过PLS-DA 分析方法,发现C 站点样品能与A、 B 两个断面的站点区分开,而A、B 间未能区分开,反映了渤海湾三个断面的实际污染状 况。 4. 四角蛤蜊软体部重金属含量进行风险评价,首先,利用单因子污染指数法比较分析, 发现从1997 年-2008 年,渤海湾四角蛤蜊软体部Cd 的污染水平在不断降低,现在其含量 已低于《海洋生物质量标准》(第二类)标准。而Cr、As 有污染的趋势,需要引起重视。 然后,利用金属污染指数法进行比较研究,发现B 断面>A 断面>C 断面。最后,利用《人 体消费卫生标准》进行比较分析,发现Cd、Ni 存在轻度污染,因此需要加强其污染源的 控制。 5. 渤海湾污染物除了重金属外,还存在一些典型持久性有机污染物。为进一步揭示 二者间协同毒理机制,利用分子系统学方法,对芳香烃受体通道进行了探索性研究,发现 水生动物AhR通道基因在进化过程中发生了适应性进化,对进一步研究重金属和POPs对双 壳贝类的毒理机制具有参考价值。
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This article presents a laboratory study on the consequences of the application of combined soil stabilization and bioaugmentation in the remediation of a model contaminated soil. Stabilization and bioaugmentation are two techniques commonly applied independently for the remediation of heavy metal and organic contamination respectively. However, for a cocktail of contaminants combined treatments are currently being considered. The model soil was contaminated with a cocktail of organics and heavy metals based on the soil and contaminant conditions in a real contaminated site. The soil stabilization treatment was applied using either zeolite or green waste compost as additives and a commercially available hydrocarbon degrading microbial consortium was used for the bioaugmentation treatment. The effects of stabilization with or without bioaugmentation on the leachability of cadmium and copper was observed using an EU batch leaching test procedure and a flow-through column leaching test, both using deionized water at a pH of 5.6. In addition, the population of hydrocarbon degrading microorganisms was monitored using a modified plate count procedure in cases where bioaugmentation was applied. It was found that while the stabilization treatment reduced the metal leachability by up to 60%, the bioaugmentation treatment increased it by up to 100% Microbial survival was also higher in the stabilized soil samples.
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Aspartate aminotransferase (E.C. 2.6.1.1.) from the skeletal muscle of fresh water fish Cirrhina mrigala has been purified 40 fold by ammonium sulphate fractionation, adsorption on alumina Csub(8) gel and chromatography using DEAE-cellulose column and the properties of the purified enzyme studied. The pH optimum of the enzyme is 7.8. The Km value of aspartic acid and 2-oxoglutaric acid are found to be 2.8 x 10sub(-3) M and 1.0 x 10sub(-4) M respectively. The activity of enzyme is inhibited by p-chloromercurybenzoate, hydroxylamine hydrochloride and sodium cyanide. The inhibition by pchloromercurybenzoate is reversed by reduced glutathione, B-mercaptoethanol and cysteine. Dicarboxylic acids such as maleic acid, malic acid and succinic acid inhibit the enzyme activity. The enzyme is not activated by any of the metal ions tested and heavy metal ions such as mercury and silver strongly inhibit the enzyme activity.
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Stabilisation, using a wide range of binders including wastes, is most effective for heavy metal soil contamination. Bioremediation techniques, including bioaugmentation to enhance soil microbial population, are most effective for organic contaminants in the soil. For mixed contaminant scenarios a combination of these two techniques is currently being investigated. An essential issue in this combined remediation system is the effect of microbial processes on the leachability of the heavy metals. This paper considers the use of zeolite and compost as binder additives combined with bioaugmentation treatments and their effect on copper leachability in a model contaminated soil. Different leaching test conditions are considered including both NRA and TCLP batch leaching tests as well as flow-through column tests. Two flow rates are applied in the flow-through tests and the two leaching tests are compared. Recommendations are given as to the effectiveness of this combined remediation technique in the immobilisation of copper. © 2005 Taylor & Francis Group.
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This scoping study proposes using mixed nitride fuel in Pu-based high conversion LWR designs in order to increase the breeding ratio. The higher density fuel reduces the hydrogen-to-heavy metal ratio in the reactor which results in a harder spectrum in which breeding is more effective. A Resource-renewable Boiling Water Reactor (RBWR) assembly was modeled in MCNP to demonstrate this effect in a typical high conversion LWR design. It was determined that changing the fuel from (U,TRU)O2 to (U,TRU)N in the assembly can increase its fissile inventory ratio (fissile Pu mass divided by initial fissile Pu mass) from 1.04 to up to 1.17. © 2011 Elsevier Ltd. All rights reserved.
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The release of heavy metals from the combustion of hazardous wastes is an environmental issue of increasing concern. The species transformation characteristics of toxic heavy metals and their distribution are considered to be a complex problem of mechanism. The behavior of hazardous dyestuff residue is investigated in a tubular furnace under the general condition of hazardous waste pyrolysis and gasfication. Data interpretation has been aided by parallel theoretical study based on a thermodynamic equilibrium model based on the principle of Gibbs free energy minimization. The results show that Ni, Zn, Mn, and Cr are more enriched in dyestuff residue incineration than other heavy metals (Hg, As, and Se) subjected to volatilization. The thermodynamic model calculation is used for explaining the experiment data at 800 degrees C and analyzing species transformation of heavy metals. These results of species transformation are used to predict the distribution and emission characteristics of trace elements. Although most trace element predictions are validated by the measurements, cautions are in order due to the complexity of incineration systems.
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用不同浓度Hg处理两种基因型小麦种子,较低浓度的Hg对小麦种子萌发影响比较小,对抗旱品种的小麦种子(陕合)的萌发有略微的刺激作用。小剂量、短时间的重金属处理可以提高POD的活性,发芽后受到Hg胁迫的陕合对Hg的耐受性低于发芽前就受到Hg胁迫的陕合,也低于同样胁迫处理的小麦品种(郑引)。发芽后进行Hg胁迫处理情况下,陕合对于Hg胁迫比较敏感,POD活性随着Hg浓度的升高而下降;而郑引,低浓度Hg对其POD活性有促进作用。在小麦发芽前就受到Hg胁迫的情况下,陕合和郑引的POD活性都随着Hg浓度增加表现为先上升而后下降趋势。
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研究食品加工剩余物板栗壳对水中Cu2+的吸附性能,为其用于含铜废水的处理提供理论依据。【方法】研究吸附质溶液pH、Cu2+质量浓度、吸附剂用量、粒径、吸附温度和时间对板栗壳吸附Cu2+效果的影响,探讨吸剂和吸附剂循环利用次数对解吸和再生的影响;并采用穿透曲线和洗脱曲线对动态吸附进行了分析。【结果】吸附质溶液pH值为6、Cu2+起始质量浓度为20 mg/L、吸附剂粒径为0.25 mm时的吸附效果较好,该吸附为放热过程,升高温度虽然可以加快吸附进程,但却降低了吸附量和去除率。Na+和Ca2+对Cu2+的解吸置换能力较弱,0.1mol/L HCl可使96.1%的Cu2+得以解吸回收。通过Thomas模型预测,在固定床柱吸附条件下饱和吸附量为10.94mg/g。【结论】板栗壳对水中Cu2+的吸附性能较好,因而具有很好的应用前景。
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Natural surface coatings sampled (NSCSs) from the surface of shingles and surficial sediments (SSs) in the Songhua River, China were employed to investigate the similarities and difference in fractions of heavy metals (Fe, Mn, Zn, Cu, Pb, and Cd) between NSCSs and SSs using the modified sequential extraction procedure (MSEP). The results show that the differences between NSCSs and SSs in Fe fractions were insignificant and Fe was dominantly present as residual phase (76.22% for NSCSs and 80.88% for SSs) and Fe-oxides phase (20.33% for NSCSs and 16.15% for SSs). Significant variation of Mn distribution patterns between NSCSs and SSs was observed with Mn in NSCSs mainly present in Mn-oxides phase (48.27%) and that in SSs present as residual phase (45.44%). Zn, Cu, Pb and Cd were found dominantly in residual fractions (>48%), and next in solid oxides/hydroxides for Zn, Pb and Cd and in easily oxidizable solids/compounds form for Cu, respectively. The heavy metal distribution pattern implied that Fe/Mn oxides both in NSCSs and SSs were more important sinks for binding and adsorption of Zn, Pb and Cd than organic matter (OM), and inversely, higher affinity of Cu to OM than Fe/Mn oxides in NSCSs and SSs was obtained. Meanwhile, it was found that the distributions of heavy metals in NSCSs and SSs were similar to each other and the pseudo-total concentrations of Zn, Cu, Pb and Cd in NSCSs were greater than those in SSs, highlighting the more importance for NSCSs than SSs in controlling behaviours of heavy metals in aquatic environments.
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沉积物中的重金属,与无机、有机胶体通过吸附、配位体交换、络合、共沉淀等作用与沉积物中不同组分结合,由于污染来源、环境条件、赋存时间的不同,重金属可以有不同的化学形态。不同赋存形态的重金属具有不同的生物环境地球化学过程及生物有效性规律。 5种氧化物矿物吸附态Cd的富集实验表明,芦苇对吸附在含铝矿物表面的Cd吸收最多,其次为铁锰矿物。比表面积较大、等电点较低的矿物与Cd的吸附强度和稳定性较强,进而造成Cd的植物有效性较低。可能对Cd的吸附解吸产生影响的是植物根系分泌的有机酸,有机酸对不同矿物吸附Cd的解吸规律与芦苇对Cd的吸收规律一致。有机酸本身性质,如羧基数量、电离常数等影响Cd解吸量。 环境中与水合氧化物结合(吸附和共沉淀)的Cd生物有效性研究表明,两种结合形式的Cd均被芦苇富集,不同处理体系中富集强度不同,根中富集量9.1 ~ 37.8 mg/kg;地上部分富集量为0 ~ 10.0 mg/kg。由于共沉淀处理增加了矿物的比表面积和吸附位点密度,并且在预先混合的过程中Cd进入氧化物内部使结合了Cd的水合氧化物更加稳定,因此吸附态Cd的植物有效性大于共沉淀。老化处理可使Cd向水合氧化物晶格内部扩散,因而显著地降低吸附态Cd的富集。由于Fe(OH)3的等电点较低、阳离子交换容量较大,因此与Fe(OH)3 结合的Cd有效性较低。采用2种低分子量有机酸对Cd进行解吸,Cd的解吸规律与芦苇对镉的富集规律一致。 与无定形铁氧化物结合(吸附和共沉淀)的多金属富集实验表明,芦苇对不同金属的富集强度不同。金属离子与铁氧化物的亲合力由金属阳离子水合半径和水化数决定,本研究中金属与铁矿物结合亲合力遵循:Pb > Cd > Cu > Ni,因此芦苇对金属的富集规律大致为Ni > Cu > Cd > Pb。在多金属处理体系中,金属之间往往竞争相同的吸附位点,形成相似络合物,从而改变吸附强度和稳定性。Ni和Cd在根中富集量较少,可能是体系中Pb的投加产生了竞争作用。此外,植物对金属的选择性吸收也影响金属的植物有效性。解吸实验表明,吸附处理的金属解吸量大于共沉淀,单一金属投加体系中,重金属的解吸量:Ni > Cu > Cd > Pb;多种金属投加体系中,Pb的解吸量增加,Cd的解吸量下降。根系分泌的低分子量有机酸对沉积物中的重金属有重要的活化作用,这可能是植物吸收污染沉积物或土壤中重金属的重要因素之一。 针铁矿和不溶性腐殖酸吸附态Cd的富集实验表明,水溶态金属的有效性最大,其次为针铁矿吸附态,最难被植物吸收的是腐殖酸吸附态金属。由于腐殖酸结构复杂、表面多官能团和吸附位点,因此与金属的亲合力较大,结合牢固,不易被芦苇吸收富集。解吸实验验证了相同条件下,柠檬酸对腐殖酸吸附态金属的解吸量小于针铁矿结合态。pH值是影响金属与沉积物中活性组分结合强度和稳定性的重要因素。较低的pH值,水相中H+浓度较高,与金属离子竞争吸附位点,降低针铁矿或腐殖酸对金属离子的吸附容量和稳定性。另外,环境pH值较低(低于矿物等电点)时,矿物表面趋于带正电,增加了金属离子吸附的难度。 水体-沉积物体系中,可溶性腐殖酸影响重金属的迁移和生物有效性。不同的腐殖酸浓度和投加顺序对金属的生物有效性影响研究表明,单一金属投加体系中,金属在芦苇体内的富集规律为:Cu > Cd > Ni > Pb,金属在植物不同部位的分布遵循:根 > 叶 > 茎 > DCB,腐殖酸浓度的增加降低了金属的富集(除Ni外)。混合金属投加体系中,金属的富集遵循:Ni > Cu > Cd > Pb(HA 5 ppm);Cd > Ni > Cu > Pb(HA 20 ppm)。与单一金属投加相比,金属的富集量降低,DCB提取态金属含量增加。腐殖酸浓度的增加降低了金属的生物有效性。腐殖酸加入顺序显著影响的金属与针铁矿的吸附,进而影响金属的生物有效性。
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随着工农业的快速发展,土壤重金属尤其Cd和Pb污染日益严重。筛选和培育具有重金属低积累特性的农作物排异品种被认为是当前应对土壤重金属污染最为合理和有效的途径之一。本文通过盆栽试验、大田试验和砂培试验,研究了大白菜品种对Cd和Pb的吸收和积累的品种差异、对Cd、Pb胁迫的响应以及大白菜安全生产的调控技术,得出以下结论: 1) 盆栽梯度试验中,80种大白菜地上部对Cd的吸收存在显著差异(p < 0.05)。在3种Cd处理下(1.0, 2.5和5.0 mg/kg),80种大白菜Cd含量浓度范围分别为(mg/kg) 0.22–2.46, 0.90–14.10和2.03–18.01, 其平均值分别为 0.79, 3.76 和6.79 mg/kg DW。大白菜对Cd胁迫具有较强的耐性。大田试验中,15种大白菜的富集系数和转运系数与盆栽梯度试验的结果基本一致。排异植物的筛选和鉴定标准包括:(1)该植物的地上部和根部的Cd含量都很低或者可食部位低于有关标准;(2) 富集系数(BF) < 1.0;(3) 转运系数(TF) < 1.0;(4)该植物具有较高的Cd耐性,在较高的Cd污染下能够正常生长且生物量无显著下降。采用此标准,结合盆栽梯度试验和大田试验结果,北京新3号、绿星70和丰源新3号可鉴定为Cd排异品种。秋傲和赛新5号具有排异Cd特性,但其对Cd的耐性较差。 2) 盆栽梯度试验中,在Pb投加浓度为500和1500 mg/kg处理下,30种大白菜地上部对Pb的吸收存在显著差异 (p < 0.05),其Pb浓度的范围分别为:0.52–8.68 和1.86–16.20 mg/kg, 其平均值分别为3.01 和6.87 mg/kg DW。并且,随着Pb浓度的增加,白菜地上部Pb含量有随之增加的趋势。大白菜对Pb具有较强的耐性。低浓度的Pb处理对大白菜的生物具有一定的促进作用。结合盆栽试验和大田试验的结果,秋傲、世博秋抗和福星80可鉴定为Pb排异大白菜品种。 3) 砂培试验中,在Cd和Pb胁迫下,大白菜地上部的丙二醛(MDA)含量增加,随着Cd处理浓度的增加,超氧化物歧化酶(SOD)活性呈现先下降后上升接着下降的趋势,酸菜王的SOD活性要高于北京新3号SOD的活性。随着Pb处理浓度的增加,福星80地上部的SOD活性随之增加,而绿星大棵菜地上部的SOD活性先下降后增加。在不同梯度的Cd处理下,大白菜地上部的可溶性蛋白(SP)含量未见显著降低,甚至有所增加,而在不同梯度的Pb处理下,大白菜地上部的SP含量有所降低。 4) 施用改良剂可升高土壤的pH值和降低土壤中的有效态Cd,从而对大白菜的生长具有促进作用。施用改良剂可显著降低大白菜对Cd和Pb的吸收和累积。
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综合运用环境地球化学、土壤学、生态学和统计学的方法开展了矿山废弃物尾矿石的堆置对土壤造成的污染以及矿区土壤重金属污染对白菜(Brassica Chinensis)的卫生品质和营养品质的影响研究。静态培养试验和动力学淋溶试验证明:在环境因素(如降水)的作用下,尾矿石的堆置将对下伏土壤的重金属含量产生长久影响,随着降水量以及酸度的增加,土壤中Cu、Cd、Pb、Zn的全量和有效态含量都有所升高并且土层间的差异减小。有机酸能不同程度地促进土壤中的重金属转化为有效态,增强重金属的生物有效性;多元梭酸比一元梭酸的转化率高。另外,有机酸对重金属的转化作用随其浓度的增大而增强,在低温范围内,随温度的升高而增加。通过网室盆栽试验,研究了土壤受Cu、Cd、Pb,Zn单一重金属污染后对大白菜吸收Cu、Cd、Pb、Zn以及植物体内粗纤维和维生素C含量的影响;同时还进一步对Cd-P交互作用影响大白菜吸收Cd、P以及植物体内粗纤维和维生素C含量的情况进行了研究,结果表明大白菜从污染的土壤吸收重金属与土壤中目标元素的含量呈极显著正相关,对非目标重金属的吸收情况复杂,因不同元素间的相互作用机制而异;白菜体内粗纤维和抗坏血酸含量随土壤重金属浓度的增加而降低,它们之间呈极显著的负相关关系。在采用大白菜进行高等植物毒性试验的基础上,首次运用典型相关分析方法对Cu、Cd、Pb、Zn复合污染土壤的生态毒性进行了评价,分别建立了由4元素共同组成的复合污染土壤毒性的线性组合函数和由芽生物量抑制率和根伸长抑制率组成的植物学表征的线性组合函数,并计算了其第一典型变量Toxl(土壤毒性)和BloL(植物学表征)之间的相关系数为0.94(p<0.01)。典型相关分析是介质毒性评价的有效方法之一。
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超积累植物是植物提取修复的核心,同时也是污染环境修复领域研究的热点与前沿。针对目前已发现的超积累植物数量与对重金属提取种类较少的现状,并根据修复实践的需求,本研究确立了以超积累植物的筛选为主要研究内容并就一些强化措施进行了初步探索,同时根据已报道的植物修复研究的阶段性成果,对污染土壤植物修复的基本概念、原理、方式、强化机制等相关的修复过程进行了系统总结,结果如下:(1)超积累植物应同时具有四个基本特征,即临界含量特征、转移特征、耐性特征和富集系数特征。(2)龙葵和球果掉菜是Cd超积累植物,在Cd投加浓度为259/kg条件下,其茎和叶中Cd含量分别为103.80mg/kg和124.57mg/kg及107.7Omg/kg和150.10mg/kg。植物体内积累的Cd主要分布在茎和叶中。这2种植物不具有同时超积累Pb、Cu或Zn的能力。(3)施加鸡粪后植物对Cd的提取率提高了35.7%~97.0%;采用开花期收获超积累植物的复种方式,植物提取率可以提高到1.43倍和1.75倍。(4)以杂草为筛选对象,将成为筛选超积累植物的一个突破口。(5)盆栽筛选试验具有可操作性强、易于实施等优点,是筛选超积累植物值得尝试的一种方法。(6)现发现的超积累植物几乎均来源于污染区,本研究表明,未污染区也可能存在超积累植物。(7)栽培措施对植物修复效果有较大影响,与现代农业高新技术相结合是植物修复技术成功应用于修复实践的一条捷径。
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Electron Cyclotron Resonance (ECR) ion source is regarded as the most efficient machine to produce stable multiple charge state ion beams. Because of the special characteristics, all-permanent magnet ECR ion sources have been widely adopted around the world to produce stable ion beams of multiple charge state with good repetition have been widely adopted around the world to produce stable ion beams of multiple charge state with good repetition and high duty factor for compact research platforms and ion beam implanters. In this paper, all-permanent magnet ECR ion sources developed at IMP are presented, and typical parameters and performances are discussed. The high charge state source, LAPECR2, is mainly used to produce intense high charge state ion beams, and the LAPECR1 source is designed to produce intense ion beams of medium and low charge state. An improved LAPECR1-M is specially designed to produce heavy metal ion beams of low charge state. These ECR ion sources have been adopted by different experimental terminals at IMP and, with their nice performance, many experimental studies could be possible. 中文文摘:ECR(电子回旋共振)离子源是产生稳定的强流多电荷态离子束流最有效装置。全永磁ECR 离子源因其独特的特点为很多中小型多电荷态离子束流实验平台与离子注入机等系统所采用,为后者产生重复性好、稳定性强的多电荷态离子束流。本文着重论述了中国科学院近代物理研究所研制的几台全永磁多电荷态ECR 离子源及其特性与典型性能,如能产生强流高电荷态离子束流的高性能全永磁离子源LAPECR2,能产生强流中 低电荷态离子束流的LAPECR1,能产生多电荷态重金属离子束流的LAPECR1-M 等。这些性能稳定的离子源为提高近代物理研究所相关试验平台的性能提供了关键的束流品质保障。