Sorption behavior of Cd, Cu, Pb, and Zn and their interactions in phytoremediated soil

The aim of our study was to compare the sorption properties of a contaminated soil before and after two types of phytoremediation (natural phytoextraction vs. phytostabilization with dolomite limestone (DL) application). Soil from a pot experiment in controlled greenhouse conditions performed for two vegetation periods was used for the study. Lead, as the main contaminant in the studied soil, was easily desorbed by Cu, especially due to the increased affinity of Cu for soil organic matter; hence input of Cu to the studied soil can present another environmental risk in soils contaminated with other metals (such as Pb). In addition, the sorption behavior of chosen metals from single-element solutions differed from multielement solutions. The obtained results proved the different sorption behavior of metals in the single-element solution compared to the multi-element ones. Soil sorption behavior of Cd, Cu, and Zn decreased with the presence of the competitive metals; nevertheless, Pb sorption potential was not influenced by other competitive metals. Natural phytoextraction showed no significant effect on the sorption of Cd, Cu, Pb, and Zn onto the soil On the other hand, phytostabilization associated with DL application improved the soil sorption efficiency of all chosen metals, especially of Cu.     

Induction of a putative metallothionein gene in the blood cockle, Anadara granosa, exposed to cadmium

The relationship between a putative metallothionein gene (MT) and exposure to cadmium (Cd) in blood cockles (Anadara granosa) is reported. In a 96-h dose-response experiment, mortality of cockles was found to proportionately increase in the range of 0.2-5.0 mg/l Cd with a calculated LC(50) of 2.94 mg/l. Exposure to 0.25 mg/l Cd for 16 days caused significant increases (P<0.05) in Cd concentrations in whole tissues, gills and hepatopancreas, and the accumulation of Cd in these tissues increased with the duration of exposure. Two cDNA libraries constructed using the hepatopancreas from control and Cd-treated cockles gave titres of 5.62 x 10(5) and 1.94 x 10(5) pfu/microg vector, respectively. A putative MT gene, AnaMT, of 510 nucleotides in length, was isolated from the treated cDNA library using a heterologous probe MT20 from the blue mussel, Mytilus edulis. Northern analyses using AnaMT as a probe indicated low expression of the MT mRNA in control animals. In cockles treated with 0.25 mg/l Cd for 4 days, MT mRNA level increased to approximately 168%, but declined to 108% at day 8. After 12 and 16 days of Cd treatment, expression of the MT gene was 138% and 187%, respectively, compared to the controls. These observations suggest that induction of the MT gene by a sublethal dose of Cd is rapid, occurring within 4 days of treatment.     

污染条件下VAM玉米元素积累和分布与根际重金属形态变化的关系

为了了解重金属Cu、Zn、Pb、Cd在土壤－根际－植物系统中的行为,揭示VAM植物减弱土壤中过量重金属对植物生理毒的抗性机理,采用原子吸收光谱测定Cu、Zn、Pb、Cd在污灌土壤中生长的VA菌根玉米和无菌根玉米中的积累和分布,并用连接形态分析技术分析了菌根际中Cu、Zn、Pb、Cd的形态分布和变化趋势,结果表明,Cu、Zn、Pb、Cd在菌根玉米中的积累量比非攻根中积累量分别减少10％、18％和29％,Cd积累量没有改变,生长7周后,菌根玉米是非菌根玉米生物量的1．5倍,与对照土壤相比,根际中除Cu交换态显著增加外,Zn、Pb、Cd各形态相对改变量显著大于非菌根,且菌根根际上中Cu、Zn、Pb有机结合态增加量显著大于非根际土,说明菌根际金属向稳定状态转移的程度显著大于非菌根际,同时,讨论了根际金属形态对金属有效性的影响,及其与菌根植物金属抗性机理的关系。     

Epidermal uptake of Pb,Cd, and Zn in tubificid worms

Summary The epidermal uptake of Pb, Cd, and the essential element Zn by tubificid worms was investigated. The animals were starved and contaminated via the water column at 4°C and 25°C. Atomic absorption spectroscopy (AAS), energy-dispersive X-ray microanalysis (EDX), laser induced mass analysis (LAMMA), electron microscopy, and the sulfide-silver method at the electron microscopical level were used. The sulfidesilver method revealed many reaction products indicating heavy metals in membrane-limited lysosomal structures in epidermal cells of contaminated Limnodrilus udekemianus. In these lysosomes, which were particularly abundant in the epidermis of the hind end, Pb, Cd, and Zn were detected by LAMMA and EDX analysis. Beside this distinct occurrence of the three elements a uniform pattern of reaction products was found in epidermal cells after contamination with Cd and Zn, but not after treatment with Pb. As shown by atomic absorption spectroscopy, Cd was the most enriched element at 25°C, followed by Pb and Zn. Simultaneous application of Zn reduced the uptake of Cd, whereas the uptake of Pb was increased. At 4° C uptake of Pb and Cd was slower than at 25° C, while Zn uptake was blocked completely. This shows that heavy metal uptake can be strongly dependent on environmental conditions, which has to be taken into account if animals are used as monitor organisms for heavy metal pollution in the environment.     

菌根植物根际环境对污染土壤中Cu、Zn、Pb、Cd形态的影响

采用根垫法和连续形态分析技术,分析了生长在污灌土壤中菌根小麦和无菌根小麦根际Ｃｕ、Ｚｎ、Ｐｂ、Ｃｄ的形态分布和变化趋势。结果表明,下对照土壤相比,菌根际土壤中交换态Ｃｕ含量显著增加,交换态Ｃｄ呈减少的趋势;与非菌根际相比,Ｃｕ、Ｚｎ、Ｐｂ的有机结合态在菌根根际中显著增加,而４种测定金属２的碳酸盐态和铁锰氧化态都没有显著改变,该结果表明,植物根系能影响根际中金属形态的变化,且菌根比无菌根的影响程度大     

White-sided dolphin metallothioneins: purification, characterisation and potential role

Metallothioneins (MTs) were characterised in the kidneys of a white-sided dolphin Lagenorhynchus acutus stranded along the Belgian coast, displaying high levels of cadmium (Cd) and mercury (Hg) in liver and kidney. The protein has two isoforms: MT-1 and MT-2. MT-1 binds Cu, Zn, Hg and Cd, while MT-2 only binds Zn, Hg and Cd. This suggests different metabolic functions for the two isoforms: MT-1 is mainly involved in Cu homeostasis; MT-2, which was four-fold more abundant than MT-1, detoxifies most of the accumulated cadmium.     

农作物体内铅,镉,铜的化学形态研究

本文报道了农作物体内重金属存在的化学形态。用逐步提取法分析了生长在污染土壤上的水稻、小麦的根与叶。结果表明,在两种作物中,根部的铅以活性较低的醋酸可提取态与盐酸可提取态占优势,而叶中的铅以盐酸可提取态占优势。不论根部或叶部,在各种形态镉中,以氯化钠可提取镉所占比例较高,作用较重要。作物体内的铜活性较强,根部以乙醇可提取态占优势,叶中以水提取态占优势。各种结合形态的重金属迁移能力、毒性效应有显著差异。作物体内重金属化学形态特征与其表观毒性效应有密切联系。     

Total nitrogen and pH-controlled chemical speciation,bioavailability and ecological risk from Cd,Cr, Cu,Pb and Zn in the water level-fluctuating zone sediments of the Three Gorges Reservoir

We investigated the distribution and chemical speciation of Cd, Cr, Cu, Pb and Zn in the water level-fluctuating (WLF) zone of the main stream (MS) and tributaries (ZX and MX) of the Three Gorges Reservoir. We evaluated the ecological risk and pollution level from heavy metals based on the Potential Ecological Risk Index (RI), Risk Assessment Code (RAC), and Ratio of Secondary Phase and Primary Phase (RSP). Our results indicated that the total and bio-available heavy metal contents were higher in the tributaries than in the MS. Moderate pollution from Cd and light pollution from Pb were observed both at the MS and ZX sites, whereas the MX site exhibited a pattern of heavy Cd pollution and light Cr and Pb pollution. In our study area, the results indicated that Cd exhibited a higher ecological risk than did the other heavy metals. Finally, the pH and nitrogen content of sediments may play a key role in controlling the amount of heavy metal bioavailability, further inducing a higher potential ecological risk.     

Competitive adsorption of Pb, Cd and Zn ions onto Eichhornia crassipes in binary and ternary systems

A batch sorption technique was used to study the biosorption of Pb²⁺, Cd²⁺ and Zn²⁺ ions onto the vastly abundant water hyacinth weed, Eichhornia crassipes biomass in binary and ternary systems at a temperature of 30 °C and pH 4.84. Mutual interference effects were probed using equilibrium adsorption capacity ratios, , where the prime indicates the presence of one or two other metal ions. The combined action of the metals was found to be antagonistic, and the metal sorption followed the order Pb²⁺  Cd²⁺  Zn²⁺. The behaviour of competitive biosorption for Pb–Cd and Pb–Zn combinations were successfully described by the Langmuir Competitive Model (CLM), whilst the model showed poor fitting to the Cd–Zn data. In conclusion, Pb²⁺ ions could still be effectively removed from aqueous solution in the presence of both Cd²⁺ and Zn²⁺ ions, but removal of the Cd²⁺ and Zn²⁺ ions would be suppressed in the presence of Pb²⁺.     

The effect of soil type and degree of metal contamination upon uptake of Cd,Pb and Cu in bush beans (Phaseolus vulgaris L.)

Summary Five soils of increasing specific surface area (SSA) were loaded to five levels of contamination with Cd, Pb and Cu, and bean plants (Phaseolus vulgaris L.) were grown on the soils for 30 days. A linear correlation was found between the concentration of Cd in the soil solutions and the amount absorbed by the plant per gram root material for four out of the five soils, and, in the case of Cu, for all five soils. Quantitatively, there was insufficient Cd or Cu in the soil solution to account for plant uptake of these metals. The amount of Cd absorbed by plants could also be related to the adsorption density (concentration/SSA soil) of the metal in four of the five soils, whereas the Cu content of plants could be related to the adsorption density of all five soils. It is thought that the metals were removed from the soil solution by root absorption and replenished by metal cations adsorbed onto surface sites in the soil. Consideration of the adsorption density of these metals in the soil may be a useful means to determine the permissible limits for heavy metal application for a wide range of soils. Lead uptake was significantly correlated to total Pb in soils, but not to the adsorption density or soil solution concentrations. The possible interpretation of the results are discussed.     

Distribution patterns of Cd,Cu, Mn,Pb and Zn in wood fly ash emitted from domestic boilers

Abstract

Wood fuels being a renewable source of primary energy have been considered environmentally friendly. However, wood combustion in domestic boilers is a source of air pollution. The lack of a dust collection device is the reason why flue gases emit a significant load of particulate pollutants into the air, including heavy metals. The aim of this research was to assess the environmental hazard caused by both emissions of heavy metals during wood combustion in domestic boilers and their chemical forms present in fly ash.

From the various wood fuels burnt in domestic boilers, the fly ash selected for this study came from the combustion of briquettes of softwood from non-polluted areas, and from burning hardwood fuel from trees exposed to pollutants from heavy traffic. The wood fuels satisfy the quality demands determined in the EN 14961 Solid Biofuels - Fuel quality assurances. However, the concentrations of Cd, Cu, Pb and Zn in the fly ash are considerably higher than the appropriate limit values determined for soil improvers. Sequential extraction shows that Cd and Zn are associated mainly with the water leaching and carbonate fractions, regarded as mobile and bioavailable, and pose the potentially greatest hazard to the environment and human health. Cu, Mn and Pb associated with less mobile fractions may not pose a direct air quality hazard but, due to their high concentrations, medium-term and long-term effects on soils and surface and subsurface waters should be considered.     

人工湿地处理重金属Pb,Cd污水的机理探讨

1 引言 人工湿地系统是70年代提出,80年代得到迅速发展的一种污水处理新技术,具有投资少,处理效果好,运转费用低和能耗少等优点,已用于污水处理,我们对人工湿地处理污水技术进行了初步研究,结果表明,该技术对氮、磷、BOD、COD和重金属Pb、Cd等均有良     

Phytoremediation of Cd,Ni, Pb and Zn by Salvinia minima

Most metals disperse easily in environments and can be bioconcentrated in tissues of many organisms causing risks to the health and stability of aquatic ecosystems even at low concentrations. The use of plants to phytoremediation has been evaluated to mitigate the environmental contamination by metals since they have large capacity to adsorb or accumulate these elements. In this study we evaluate Salvinia minima growth and its ability to accumulate metals. The plants were cultivated for about 60 days in different concentrations of Cd, Ni, Pb and Zn (tested alone) in controlled environmental conditions and availability of nutrients. The results indicated that S. minima was able to grow in low concentrations of selected metals (0.03 mg L^?1 Cd, 0.40 mg L^?1 Ni, 1.00 mg L^?1 Pb and 1.00 mg L^?1 Zn) and still able to adsorb or accumulate metals in their tissues when cultivated in higher concentrations of selected metals without necessarily grow. The maximum values of removal metal rates (mg m² day^?1) for each metal (Cd = 0.0045, Ni = 0.0595, Pb = 0.1423 e Zn = 0.4046) are listed. We concluded that S. minima may be used as an additional tool for metals removal from effluent.     

Effects of Cu,Pb and Zn on two Potamogeton species grown under field conditions

Two common macrophyte species, Potamogeton perfoliatus L. and Potamogeton pectinatus L. were grown for 12 weeks at shallow depths in sediments contaminated with 1250 or 2500 g Pb or Cu and/or Zn (gDW sediment)^-1. Control experiments were run at background levels of 4, 13, and 38 g Pb, Cu and Zn (gDW sediment)^-1, respectively. Effects of heavy metals on biomass production and metal uptake and distribution in plants are presented in relation to total amount and plant-available fraction of metals in the sediment.All three studied metals gave reduced biomass production, and the toxicity of the metals decreased in the order Zn>Cu>Pb. The root/shoot biomass ratio increased for P. pectinatus, but decreased for P. perfoliatus with metal treatment. The content of any single metal was higher in shoots than in roots of plants grown on sediments not contaminated with that specific metal, but addition of that metal increased the proportion in roots. The uptake by plants of any of the heavy metals increased with increased metal addition. The magnitude of the plant-available fraction of metals of untreated sediment was Zn>Cu>Pb, and increased in contaminated sediments. Addition of Cu decreased both the plant-available fraction and the total concentration of Zn in the sediment, while increased the uptake of Zn by the plants. The opposite was found for Cu when Zn was added. P. pectinatus accumulated about twice as much Cu as P. perfoliatus. On the other hand, the concentration of Pb was higher in P. perfoliatus than in P. pectinatus, and was negligible in P. pectinatus when cultivated in untreated sediments.     

Serum levels of Cd, Pb, Cu and Zn in cigarette smokers

In order to show the accumulation of Cd, Pb, Cu and Zn in smokers, levels of these metals in serum were determined in 108 subjects: 32 non-smokers, 37 average cigarette smokers and 39 heavy cigarette smokers. The analysis was carried out by potentiometric stripping analysis (PSA) with the Tecator "Striptec System". Backward oxidation time of the amalgamated metals, by means of electrolysis, in a thin "film" of mercury in an electrode, gives their concentration measure. Our data showed an increase in average values of Cd and Pb in the serum of heavy smokers compared with average and non-smokers. Instead, as regards Cu and Zn, no differences were found in the two groups of smokers compared with the non-smokers used as controls. Results obtained of the Cd and Pb levels in serum are compatible with the presence of these metals in cigarette tobacco and inhaling them could contribute to disease connected with their accumulation in the human organism. For these subjects the increase in Cd values is of particular importance as it could predispose pulmonary emphysema.     

Use of bryological communities as a diagnostic tool of heavy metal soil contamination (Cd,Pb, Zn) in northern France

Correlations between terricolous bryophyte flora and edaphic parameters (pH, organic nitrogen (ON), C/N, Cation Exchange Capacity (CEC), Organic Matter (OM) and Pb, Cd and Zn soil contents) of metalliferous wastes in northern France were performed using statistical analysis (FCA, PCA and FCMA). The significant correlation between the classification based on the bryophyte flora and that based on edaphic variables shows that bryophyte groupings have a strong bioindicative value. More information was obtained by taking into account other parameters such as physiological stages (sterility, fertility, maturation, vitality). Three bryophyte classes were distinguished according to Cd, Pb and Zn soil contents.     

Evaluation of cadmium,lead and metallothionein contents in the tissues of mussels (Mytilus galloprovincialis) from the Campania coast (Italy): Levels and seasonal trends

The biological effect of seasonality on cadmium, lead and metallothionein contents was assessed in mussels Mytilus galloprovincialis from natural banks located along the coastline of the Gulf of Naples (Campania, Italy). Heavy metals and metallothionein concentrations were measured in digestive and reproductive glands. The results showed a clear correlation between metallothionein content and the reproductive gland status determined during the seasons; on the contrary, no correlation was found between metallothionein and metal contents. Data allow us to hypothesize that metallothionein functions go beyond metal detoxification, thus opening new scenarios for these proteins in invertebrates. The effect of seasons on metals concentration in mussel tissues showed similar seasonal patterns between the sites, regardless of their anthropogenic impacts. Cadmium content was not strictly related to seasonal periods, whereas lead content was significantly lower in summer. The results also indicate that the metal contents in mussels from the Gulf of Naples do not represent a risk to human health, even in the period of their maximum accumulation, and that the relaying of mussels before marketing could improve the animal stress conditions, but having a slight effect on metal excretion.     

Litter accumulation in woodlands contaminated by Pb,Zn, Cd and Cu

Summary Close to a primary lead-zinc-cadmium smelter the standing crop of litter in woodlands was found to be elevated relative to more distant sites. The total litter accumulation is similar to that from contaminated sites reported by other authors but in this case the concentrations of heavy metals are considerably lower than those reported for other sites. Evidence is provided to support the hypothesis that within the woodlands studied, litter accumulation is not closely pH dependent, but is clearly related to both cadmium and zinc concentrations in litter. Litter accumulation occurs in certain particle size ranges and fractionation shows that the weight of accumulated litter in these size ranges is highly correlated to cadmium concentrations. These results are discussed in relation to the reported possible long term effects of metal contamination on decomposition processes and the possibility of adaptation to these adverse effects.