Oak leaves as accumulators of airborne elements in an area with geochemical and geothermal anomalies

The Colline Metallifere (Tuscany) was a major Italian mining district (FeS2, Ag, Cu, Pb, Zn) for centuries, and in the last fifty years it has become the most important area for the exploitation of geothermal resources. Leaves of the widespread oak Quercus pubescens and surface soils were collected from 90 sampling sites in the area and their elemental composition was compared. The results showed that the composition of oak leaves was not significantly affected by the presence of mineral deposits (metal sulphide ores) or soils with high concentrations of Cr, Mg, and Ni (ultramafic). Arsenic was the only element showing higher concentrations in leaves from sites with deposits of metal sulphide ores or As-polluted soils around abandoned smelting plants. Compared to the composition of epiphytic lichens andepigeic mosses from the same sites in the Colline Metallifere, the elemental composition of Q. pubescens leaves was less affected by element contributions from adsorbed soil particles. It was thus easier to evaluate atmospheric inputs of elements in oak leaves than in cryptogams.     

Influence of initial pH on bioleaching of heavy metals from contaminated soil employing indigenous Acidithiobacillus thiooxidans

Bioleaching of heavy metals from contaminated soil was carried out employing indigenous sulfur oxidizing bacterium Acidithiobacillus thiooxidans. Experiments were carried out to assess the influence of initial pH of the system on bioleaching of chromium, zinc, copper, lead and cadmium from metal contaminated soil. pH at the end of four weeks of bioleaching at different initial pH of 3-7 was between 0.9 and 1.3, ORP between 567 and 617mV and sulfate production was in the range of 6090-8418mgl(-1). Chromium, zinc, copper, lead and cadmium solubilization ranged from "59% to 98%" at different initial pH. A. thiooxidans was not affected by the increasing pH of the bioleaching system towards neutral and it was able to utilize elemental sulfur. The results of the present study are encouraging to develop the bioleaching process for decontamination of heavy metal contaminated soil.     

Relation between extracellular polymers' composition and its ability to complex Cd,Cu and Pb

Activated sludges originated from wastewater treatment plants (WWTPs) play an important role in heavy metal removal from effluents. Extracellular polymers (ECP) form a major part of the activated sludge and are heavily involved in biosorption of heavy metals. The complexation of three heavy metals (Cd, Cu and Pb) with ECP extracted from six activated sludges, originated from different WWTPs, was investigated at pH 7.

ECP in the study were shown to be mainly composed of proteins, humic acids, uronic acids and polysaccharides along with smaller amounts of lipids and nucleic acids. IR spectra confirmed the presence of the functional groups usually found in the ECP and the content in each fraction was determined using colorimetric methods. The determination of surface charge was carried out on each ECP sample and allowed two pK_a values characteristic of two distinctive functional groups to be determined. At the pH used in the study, the value of these constants indicates that only one functional group is under protonated form.

A polarographic method was used to determine the complexation parameters (number of binding sites and complexation constant) of ECP solutions towards metals. The following orders were established for the number of binding sites: Cu > Pb  Cd and for the stability of the ECP–metal complex: Cd > Pb  Cu.

A matrix of correlation between the composition of the polymers and the complexation parameters showed that the number of binding sites and the complexation constant were strongly linked to proteins, polysaccharides and humic substances content.     

Field effects of pollutants in dynamic environments. A case study on earthworm populations in river floodplains contaminated with heavy metals

In industrialized countries river floodplains can be strongly polluted with heavy metals. Published studies on effects of heavy metal pollution on soil invertebrates in floodplains, however, are inconclusive. This is unexpected since studies in other less dynamic environments reported clear effects at even lower levels of pollution. Flooding induces extra variation in invertebrate biomass and abundance which may reduce the probability to detect heavy metal effects. In this paper we combine reported data from studies on river floodplains in The Netherlands and Belgium and statistically analyze the effect of heavy metals on species composition, biomass, density and individual weight of earthworms. Interaction effects of heavy metal stress and flooding are also considered. The results suggest clear effects of zinc and copper on all variables and interaction of heavy metals and flooding for individual weight.     

Degradability of ethylenediaminedisuccinic acid (EDDS) in metal contaminated soils: implications for its use soil remediation

Previous research has identified ethylenediaminedisuccinate (EDDS) as a promising biodegradable alternative for persistent compounds such as EDTA for application in soil washing or enhanced phytoextraction of heavy metals. This study examines heavy metal mobilization in three polluted soils varying in soil composition, with specific attention for competitive behaviour for complexation between the various metals and major elements, such as Al, Fe, Mn, Ca and Mg. In addition, amendment biodegradability was compared between the different soil types. The selected soils included a moderately contaminated calcareous clayey soil, a dredged sediment derived surface soil with similar soil characteristics yet more heavily polluted with Cd, Cr and Zn, and a sandy soil moderately contaminated by historical smelter activity (atmospheric deposition). Biodegradability of EDDS in the three soils varied distinctly. This was mainly expressed in the duration of the lag phase prior to metal complex degradation, and not so much in the half life when degradation effectively did set in. Differences in the lag phase were attributed to differences in soil pollution. However, EDDS was fully degraded within a period of 54 d in all soils regardless of initial delay. Assessment of the cation mobilisation patterns in the three soils under study revealed that mainly Ca, Fe and Al can reduce effectiveness of heavy metal mobilisation by competition for complexation.     

Increasing the recovery of heavy metal ions using two microbial fuel cells operating in parallel with no power output

The present study aimed to improve the performance of microbial fuel cells (MFCs) by using an intermittent connection period without power output. Connecting two MFCs in parallel improved the voltage output of both MFCs until the voltage stabilized. Electric energy was accumulated in two MFCs containing heavy metal ions copper, zinc, and cadmium as electron acceptors by connection in parallel for several hours. The system was then switched to discharge mode with single MFCs with a 1000-Ω resistor connected between anode and cathode. This method successfully achieved highly efficient removal of heavy metal ions. Even when the anolyte was run in sequencing batch mode, the insufficient voltage and power needed to recover heavy metals from the cathode of MFCs can be complemented by the developed method. The average removal ratio of heavy metal ions in sequencing batch mode was 67 % after 10 h. When the discharge time was 20 h, the removal ratios of zinc, copper, and cadmium were 91.5, 86.7, and 83.57 %, respectively; the average removal ratio of these ions after 20 h was only 52.1 % for the control group. Therefore, the average removal efficiency of heavy metal ions increased by 1.75 times using the electrons stored from the bacteria under the open-circuit conditions in parallel mode. Electrochemical impedance data showed that the anode had lower solution resistance and polarization resistance in the parallel stage than as a single MFC, and capacitance increased with the length of time in parallel.

     

Oribatid mite communities and metal bioaccumulation in oribatid species (Acari, Oribatida) along the heavy metal gradient in forest ecosystems

The responses of oribatid communities to heavy metal contamination were studied. Concentration of cadmium, copper and zinc in nine oribatid species along a gradient of heavy metal pollution was measured. Oribatid mites were sampled seasonally during two years in five forests located at different distances from the zinc smelter in the Olkusz District, southern Poland. The most numerous and diverse oribatid communities were found in the forest with moderate concentrations of heavy metals. Analysis by atomic absorption spectrophotometry revealed large differences in metal body burdens among species. All studied oribatid species appeared to be accumulators of copper with Oppiella nova, Nothrus silvestris and Adoristes ovatus characterized by the highest bioaccumulation factors. Most species poorly accumulate cadmium and zinc. The accumulation of heavy metals in the body of oribatids was not strictly determined by their body size or the trophic level at which they operate.     

Effects of heavy metals on sea urchin embryo development. 1. Tracing the cause by the effects

The toxicity of the polluted waters originating from a disused lead mine was evaluated using both sea urchin bioassays and heavy metal analysis. Samples from three polluted waters (a seawater and two freshwaters) were collected from the mine area and one seawater sample was taken from a non-contaminated reference site. The test waters contained higher concentrations of heavy metals such as manganese, lead, cadmium, zinc, chromium, nickel, iron, and copper than did ambient seawater. The three test waters had inhibitory effects, in a dose-dependent manner, on the first cleavage of sea urchin embryos and on pluteus formation during the development. Some malformations, such as a radialized pluteus, exo-gastrula, and spaceship Apollo-like embryos were induced by the test waters without dilution. Zinc alone also induced the same anomaly. Zinc in the test seawater was ascertained as one of the metals that caused the anomalies, but not all of the toxicity was caused by zinc. It was speculated that interactive effects, involving zinc and possibly manganese and nickel, were occurring.     

Contributions of heavy metals from municipal runoff to the sediments of Lake Pontchartrain, Louisiana

A study was conducted to determine the distribution and sources of heavy metal pollutants in the sediments of Lake Pontchartrain. Sediment samples were collected from the northern and southern shorelines and analyzed for heavy metals by atomic absorption spectrometry. The heavy metals of interest were barium, copper, nickel, lead, and zinc. The concentrations of these metals indicate that the principal source of heavy metal pollution is associated with urban stormwater runoff and municipal discharges.     

Recovery of elemental sulfur from zinc concentrate direct leaching residue using atmospheric distillation: A pilot-scale experimental study

Recovery of elemental sulfur from zinc concentrate direct leaching residue (DLR) using atmospheric distillation was systematically investigated on a pilot-scale system for the first time. Batch operating mode was suggested for recovery of elemental sulfur from water-rich DLR using atmospheric distillation. Elemental sulfur with purity higher than 99% was obtained under certain conditions in batch operating mode. With an appropriate feed amount of 1,200 kg, batch experiment conducted at 460°C resulted in sulfur purity of 96.22% and a recovery rate higher than 85%. Only 0.59 and 1.24 kWh power was needed to handle 1.0 kg DLR and produce 1.0 kg elemental sulfur, respectively. The results suggest that recovery of elemental sulfur from zinc concentrate DLR using atmospheric distillation is technologically and economically feasible. Moreover, other metal elements such as zinc were enriched in the distillation concentrate, which could be used for metal refining. Technologies could effectively lower the moisture content of DLR, and lowering the distillation temperature would be of great value for recovery of elemental sulfur from DLR using a distillation method.

Implications:

Distillation is a promising solution for recovery of elemental sulfur from DLRs. This work revealed the possibility of separation of elemental sulfur from zinc concentrate DLR using atmospheric distillation. Such knowledge is of fundamental importance in developing field-scale separation and purification technologies and devices in which simultaneous sulfur recovery and precious metal enrichment are possible. Important tasks for follow-up research are also suggested.     

Air pollution assessment based on elemental concentration of leaves tissue and foliage dust along an urbanization gradient in Vienna

Foliage dust contains heavy metal that may have harmful effects on human health. The elemental contents of tree leaves and foliage dust are especially useful to assess air environmental pollution. We studied the elemental concentrations in foliage dust and leaves of Acer pseudoplatanus along an urbanization gradient in Vienna, Austria. Samples were collected from urban, suburban and rural areas. We analysed 19 elements in both kind of samples: aluminium, barium, calcium, copper, iron, potassium, magnesium, sodium, phosphor, sulphur, strontium and zinc. We found that the elemental concentrations of foliage dust were significantly higher in the urban area than in the rural area for aluminium, barium, iron, lead, phosphor and selenium. Elemental concentrations of leaves were significantly higher in urban than in rural area for manganese and strontium. Urbanization changed significantly the elemental concentrations of foliage dust and leaves and the applied method can be useful for monitoring the environmental load.     

Modified SBA-15 mesoporous silica for heavy metal ions remediation

N-Propylsalicylaldimino-functionalized SBA-15 mesoporous silica was prepared, characterized and used as an adsorbent for heavy metal ions. The organic-inorganic hybrid material was obtained using successive grafting procedures of SBA-15 silica with 3-aminopropyl-triethoxysilane and salicylaldehyde, respectively. For comparison an amorphous silica gel was functionalized using the same procedure. The structure and physicochemical properties of the materials were characterized by means of elemental analysis, X-ray diffraction (XRD), nitrogen adsorption-desorption, thermogravimetric analysis and FTIR spectroscopy. The organic functional groups were successfully grafted on the SBA-15 surfaces and the ordering of the support was not affected by the chemical modification. The behavior of the grafted solids for the adsorption of heavy metals ions from aqueous solutions was investigated. The hybrid materials showed high adsorption capacity and high selectivity for copper ions. Other ions, such as nickel, zinc, and cobalt were adsorbed by the modified SBA-15 material. The adsorbent can be regenerated by acid treatment without altering its properties.     

Enhanced removal of heavy metals in primary treatment using coagulation and flocculation.

The goal of this study was to determine the removal efficiencies of chromium, copper, lead, nickel, and zinc from raw wastewater by chemically enhanced primary treatment (CEPT) and to attain a total suspended solids removal goal of 80%. Operating parameters and chemical doses were optimized by bench-scale tests. Locally obtained raw wastewater samples were spiked with heavy metal solutions to obtain representative concentrations of metals in wastewater. Jar tests were conducted to compare the metals removal efficiencies of the chemical treatment options using ferric chloride, alum, and anionic polymer. The results obtained were compared with those from other studies. It was concluded that CEPT using ferric chloride and anionic polymer is more effective than CEPT using alum for metals removal. The CEPT dosing of 40 mg/L ferric chloride and 0.5 mg/L polymer enhanced heavy metals removal efficiencies by over 200% for chromium, copper, zinc, and nickel and 475% for lead, compared with traditional primary treatment. Efficient metals capture during CEPT can result in increased allowable headworks loadings or lower metal levels in the outfall.     

村镇小型生活垃圾热处理炉底渣的理化特性

小型垃圾热处理设备可实现就地处置,节约运输成本,目前在中国山区、丘陵地带的村镇得到广泛应用.为了解村镇小型生活垃圾热处理炉底渣的理化特性及其影响因素,对中国云南、贵州、安徽村镇实际运行的小型生活垃圾热处理设备产生的底渣进行取样,分析其热灼减率、物理组成、化学组成、晶相组成、重金属含量和浸出特性,探讨处理工艺、地域及季节...     

Characterization of trace metal particles deposited on some deciduous tree leaves in an urban area

In 1996 and 1997 horse chestnut (Aesculus hippocastanum L.) and Turkish hazel (Corulys colurna L.) leaves were sampled at 2 m height in the Belgrade Botanic Garden, located in an urban area with heavy traffic. Using a scanning electron microscope with an energy dispersive X-ray spectroscopy (SEM-EDAX), the size, size distribution, morphology and chemical composition of individual particles were examined on the adaxial and abaxial surfaces of leaf discs of both species. The majority of particles observed on leaves belonged to a class of fine particles (D < 2 microm). Morphological and chemical composition indicated that the most abundant particles were soot and dust with minor constituents such as Pb, Zn, Ni, V, Cd, Ti, As and Cu. Using an electrochemical technique (DPASV), it was possible to measure trace metal concentrations (Pb, Cu, Zn) in a water-soluble fraction of deposits on each single leaf. Trace metal contents in the leaf deposits, increased during the vegetation period for both species and were considerably higher in A. hippocastanum due to different epidermal characteristics. The higher trace metal concentrations in deposits in 1997 reflected greater atmospheric pollution in the Belgrade urban area.     

Compartmentation of metals in foliage of Populus tremula grown on soils with mixed contamination. I. From the tree crown to leaf cell level

In order to achieve efficient phytoextraction of heavy metals using trees, the metal allocation to aboveground tissues needs to be characterised. In his study, the distribution of heavy metals, macro- and micronutrients and the metal micro-localisation as a function of the leaf position and heavy metal treatment were analysed in poplars grown on soil with mixed metal contamination. Zinc was the most abundant contaminant in both soil and foliage and, together with cadmium, was preferentially accumulated in older foliage whereas excess copper and lead were not translocated. Changes in other element concentrations indicated an acceleration in aging as a consequence of the metal treatment. Excess zinc was irregularly accumulated inside leaf tissues, tended to saturate the veins and was more frequently stored in cell symplast than apoplast. Storage compartments including metabolically safe and sensitive subcellular sites resulted in sizable metal accumulation as well as stress reactions.     

Evaluation of the effectiveness of phosphate treatment for the remediation of mine waste soils contaminated with Cd, Cu, Pb, and Zn

The effectiveness of phosphate treatment for Cd, Cu, Pb, and Zn immobilization in mine waste soils was examined using batch conditions. Application of synthetic hydroxyapatite (HA) and natural phosphate rock (FAP) effectively reduced the heavy metal water solubility generally by about 84-99%. The results showed that HA was slightly superior to FAP for immobilizing heavy metals. The possible mechanisms for heavy metal immobilization in the soil involve both surface complexation of the metal ions on the phosphate grains and partial dissolution of the phosphate amendments and precipitation of heavy metal-containing phosphates. HA and FAP could significantly reduce Cd, Cu, Pb, and Zn availability in terms of water solubility in contaminated soils while minimizing soil acidification and potential risk of eutrophication associated with the application of highly soluble phosphate sources.     

Levels and interactions of heavy metals in sea birds from Svalbard and the Antarctic

Samples of liver and kidney from 92 seabirds of ten species collected on Spitsbergen and in the Antarctic, were analysed for their content of copper, zinc, cadmium, lead, mercury and selenium. Significantly higher levels of copper and zinc were observed in birds from Spitsbergen than in those from the Antarctic, while the opposite was true for selenium. The highest cadmium levels were found in fulmar Fulmarus glacialis and macaroni penguin Eudyptes chrysolophus. A possibility of kidney damage due to cadmium exists. The highest mercury levels were recorded in brown skua Catharacta lonnbergi collected at Bouvet?ya. Lead was not detected in any of the birds. Significant correlations were observed between levels of several of the metals studied, especially between cadminum and zinc and between mercury and selenium. However, for all birds, the highest correlation coefficients were observed when the molar concentrations of cadmium plus mercury, and selenium plus zinc, were used in the calculations. Thus several protective mechanisms may operate to diminish effects of heavy metal contaminants.     

Assessment of metal availability to vegetation (Betula pendula) in Pb-Zn ore concentrate residues with different features

In this work, characterisation of several ore concentrate remains from an abandoned Pb-Zn mining factory was performed determining chemical and physical properties such as pH, organic carbon content, particle size distribution, total heavy metal content (Pb, Zn, Cu, As and Cd) as well as mineralogical composition which showed, in most cases, the oxidization of the parent ore material (mostly galena: PbS and sphalerite: ZnS) to more mobile fractions as anglesite (PbSO(4)) and goslarite (ZnSO(4)). Moreover, two operational defined extraction procedures commonly used in soil and sediment studies (first and second steps of BCR procedure and DTPA extraction protocol) were applied in the different mining wastes in order to study Pb and Zn mobility and likely bioavailability to Betula pendula growing on the same mining spoils, which presents lead and zinc contents in leaves over ten times background values.     

Metal availability and uptake by sorghum plants grown in soils amended with sludge from different treatments

Several factors depending on the sludge, the soil, or the combination of both substrates, may affect element availability to plants. In this study, an assessment was done of the effect of two sludges obtained by different processes (activated sludge and facultative stabilization pond) on heavy-metal availability and uptake by sorghum plants in soils with high and low copper contents. Results obtained for DTPA-extractable metal indicated higher metal availability in sludge-amended soils. In addition, sludges caused changes in copper and zinc distribution in soil, indicating in most cases a discrete increase in the more labile metal forms. However, observed changes did not increase heavy metal concentration in plant leaves, indicating that assessment of metal availability by a chemical procedure (single extraction or metal fractionation) would not permit a good prediction of metal bioavailability. On the other hand, sludge application at a rate of 100 t ha⁻¹ to high-copper agricultural soils would not imply greater mobility of this metal on account of a greater sorbing capacity provided by the sludges. Such results would indicate that sludges from wastewater treatment plants, meeting the standards of heavy metal contents, regardless of the process by which they were obtained, may be applied to several kinds of soil, even to high-copper soils, with no risk of increasing heavy metal bioavailability to phytotoxic levels in the short range.