利用芦竹修复重金属污染湿地的研究

研究了芦竹(Arundodonaxlinn)对Cu2+、Ni2+、Cr6+重金属污染湿地的响应和对该污染湿地的影响。实验结果表明,芦竹对这3种重金属离子有一定的耐受性,并有不同程度的吸收,Cu2+、Ni2+和Cr6+去除率分别为63.8%,42.3%和34.4%。芦竹在100mg/kg浓度的Cu2+、Ni2+污染湿地中生长正常,在低浓度(55mg/kg)Cr6+污染中能存活,但生长速度较慢。在100mg/kg浓度Cr6+污染湿地中,出现急性中毒现象,半月后致死。在重金属污染环境中,芦竹普遍出现失绿现象,但除高浓度Cr6+(100mg/kg)以外,都能正常存活,表现出较强的适应性。     

Effect of dissolved metal ions on PCE decomposition by gamma-rays

This study investigates the effect of initial tetrachloroethylene (PCE) concentration, irradiation dose and dissolved metal ions such as Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+ and Zn2+ on removal of PCE by gamma irradiation. The amount of removed PCE decreased with increase in initial PCE concentration and increased with increase in irradiation dose. PCE removal reached a maximum in the presence of Fe3+, while Cu2+ strongly hindered PCE decomposition. Except for Cu2+, the amount of removed PCE in the presence of metal ions was linearly dependent on the standard reduction potential of the metal ions. The extraordinary inhibition of Cu2+ in PCE removal was caused by the action of Cu2+ as a strong *OH scavenger, that was directly confirmed by electron paramagnetic resonance spectroscopy.     

Heavy metal ion influence on the photosynthetic growth of Rhodobacter sphaeroides

The potential of purple non-sulphur bacteria for bioremediation was assessed by investigating the ability of Rhodobacter sphaeroides strain R26.1 to grow photosynthetically in heavy metal contaminated environments. Bacterial cultures were carried out in artificially polluted media, enriched with the transition metal ions Hg2+, Cu2+, Fe2+, Ni2+, Co2+, MoO4(2-), and CrO4(2-) in millimolar concentration range. For each investigated ion the effect on growth parameters was evaluated. The analysis of concentration-effect curves revealed a differentiated response, indicating that diverse mechanisms of tolerance and/or resistance are involved. Adaptation or selection procedures were not applied, leading to assess intrinsic abilities of coping with these contaminants. The microorganism proved to be highly tolerant to heavy metal exposure, especially towards Co2+, Fe2+ and MoO4(2-). In addition Ni2+ and Co2+ were found to decrease the cellular content of light harvesting complexes. A characteristic behavior was observed with mercuric ions, which produced a significant increase of the lag-phase.     

Biosorption of copper, cobalt and nickel by marine green alga Ulva reticulata in a packed column

Biosorption of copper, cobalt and nickel by marine green alga Ulva reticulata were investigated in a packed bed up-flow column. The experiments were conducted to study the effect of important design parameters such as bed height and flow rate. At a bed height of 25 cm, the metal-uptake capacity of U. reticulata for copper, cobalt and nickel was found to be 56.3+/-0.24, 46.1+/-0.07 and 46.5+/-0.08 mgg(-1), respectively. The Bed Depth Service Time (BDST) model was used to analyze the experimental data. The computed sorption capacity per unit bed volume (N0) was 2580, 2245 and 1911 mgl(-1) for copper, cobalt and nickel, respectively. The rate constant (K(a)) was recorded as 0.063, 0.081 and 0.275 lmg(-1)h(-1) for copper, cobalt and nickel, respectively. In flow rate experiments, the results confirmed that the metal uptake capacity and the metal removal efficiency of U. reticulata decreased with increasing flow rate. The Thomas model was used to fit the column biosorption data at different flow rates and model constants were evaluated. The column regeneration studies were carried out for three sorption-desorption cycles. The elutant used for the regeneration of the biosorbent was 0.1 M CaCl2 at pH 3 adjusted using HCl. For all the metal ions, a decreased breakthrough time and an increased exhaustion time were observed as the regeneration cycles progressed, which also resulted in a broadened mass transfer zone. The pH variations during both sorption and desorption process have been reported.     

硫化镍异相结晶法处理含镍废水

针对含络合剂的重金属废水,以含镍废水为例,探索了以气体硫化氢为结晶药剂的硫化镍异相结晶技术。废水以薄层液膜方式铺展于结晶载体表面,硫化氢气体穿过气液界面进入液相,硫离子与金属离子在载体表面异相结晶析出,重金属得以去除。以含酒石酸的模拟化学镀镍废水为对象,静态实验与动态实验均表明该技术具有可行性,硫化镍沉淀在结晶载体表面异相结晶析出,且附着稳定;络合剂对反应影响小;进水流速为4 mL/min,硫化钠流速为0.65 g/min,氮气流速为0.16 L/min时,出水镍浓度为49～53 mg/L,单位面积滤布表面结晶平均去除镍量为0.98 g/(m2.h)。     

Key factors in chemical reduction by hydrazine for recovery of precious metals

Most of the commonly used metal waste treatment approaches only allow removal of metals which are ultimately discarded as sludge and do not permit the reuse of the metals, resulting in a waste of raw materials. In this study, the recovery of precious metals of sliver and copper in a synthesized wastewater in batch reactors was investigated using a reduction method by hydrazine as the reducing agent. Recovery of metal ions was greatest at pH > 11. The presence of humic acid did not have negative effects on the recovery process. Varying dissolved oxygen levels in the hydrazine solution did not significantly affect the recovery of both metals while seeding and ageing processes resulted in an increase in the particle size of the solid obtained. Under competitive conditions between Cu2+ and Ag+ ions, the recovery of silver remained the same, while that of copper was enhanced.     

Selective separation of copper(II) and nickel(II) from aqueous media using the complexation-ultrafiltration process

The polyethylenimine (PEI) as complexing agent was used to study the complexation-ultrafiltration (CP-UF) process in the selective removal of Cu(II) from Ni(II) contained in aqueous media. Preliminary tests showed that optimal chemical conditions for Cu(II) and Ni(II) complexation by the PEI polymer were pH>6.0 and 8.0, respectively, and polymer/metal weight ratio of 3.0 and 6.0, respectively. The effect of some important operating parameters on process selectivity was studied by performing UF tests at different parameters: pH, polymer/metal weight ratio, transmembrane pressure (TMP), and membrane cut-off in a batch experimental set-up. It was observed that process selectivity was achieved by choosing the pH value for obtaining a preferential copper complexation (pH 6.0), and the polymer/metal ratio needed to bound only the copper ion (3.0). The selective separation by UF tests was performed by using both a laboratory aqueous solution and a real aqueous effluent (water from Emoli torrent, Rende (CS)). The Iris 30 membrane at TMP of 200 kPa (2 bar) for both aqueous media gave the best results. A complete nickel recovery was reached, and copper recovery was the highest for this membrane (94% and 92%). Besides at this pressure, a lower water amount was needed to obtain total nickel recovery by diafiltration. A little higher membrane fouling was obtained by using the river effluent due to the presence of dissolved organic and inorganic matter.     

浮游球衣菌对Pb2+、Cu2+、Zn2+、Cd2+的吸附性能研究

研究了浮游球衣菌（Sphaerotilus natans）在不同吸附条件下对溶液中Pb^2＋、Cu^2＋、Zn^2＋、Cd^2＋的吸附规律。结果表明,Sphaerotilus natans对这4种重金属离子均有一定的吸附作用,并在20min内达到吸附平衡,pH对吸附过程影响较大,pH为5.5时Sphaerotilus natans对这4种金属离子的吸附效果最好,Sphaerotilus natans对它们的吸附选择性为Pb^2＋〉Cu^2＋〉Zn^2＋〉Cd^2＋,Pb^2＋、Cu^2＋能部分置换出已被菌体吸附的Zn^2＋、Cd^2＋。HCI和EDTA溶液可有效地将金属离子从菌体上解吸下来,解吸后的菌体可重复使用。     

Multi-tolerance to heavy metals in Plantago arenaria Waldst. & Kit.: adaptative versus constitutive characters

Tolerance to Cu, Cd, Ni and Zn was investigated in a population of the pioneer species Plantago arenaria growing in a metallurgical landfill. Tolerance levels were compared with those of two other pioneer species (Coniza sumatrensis and Verbascum densiflorum) growing in the same location, and with a control population taken from an uncontaminated site. Results showed that the metalliferous population of P. arenaria was more tolerant to metal toxicity than C. sumatrensis and V. densiflorum. Comparisons with literature data confirmed that the metalliferous population of P. arenaria was highly tolerant to Cu, moderately tolerant to Cd and Ni, but not particularly tolerant to Zn. The control population of P. arenaria responded the same as the metalliferous one excepted for Cu, for which it was much more sensitive. This suggested that multi-metal tolerances in the metalliferous population of P. arenaria resulted both from constitutive and adaptative traits, depending on the metal. To check whether P. arenaria was able to cope with high internal metal levels, accumulation patterns were evaluated in pot experiments. Results showed that metals accumulated in roots and leaves, at levels proportional to soil content. Metal content was much higher in roots than in leaves and the leaf:root concentration ratio was kept constant over a wide range of soil metal contents. This suggested that metal tolerance was related to the ability to retain metal ions in roots and to tightly control their translocation to leaves. Finally metal tolerance in P. arenaria is discussed in relation to its pioneer and xerophytic characteristics.     

Euglena gracilis as a model for the study of Cu2+ and Zn2+ toxicity and accumulation in eukaryotic cells

We have observed the effect of copper and zinc on the biology of Euglena gracilis. The cells displayed different sensitivities to these metals, as the apparent LC50 for Cu2+ was 0.22 mM, and for Zn2+ it was 0.88 mM. While Zn2+ was able to increase cell proliferation even at 0.1 mM, the minimal CuCl2 concentration tested (0.02 mM) was sufficient to impair cell division. Higher concentrations of these metals not only inhibited cell division in a concentration-dependent manner, but also interfered with the metabolism of E. gracilis. A higher accumulation of proteins and lipids per cell was observed at the DI50 concentration for metal-treated cells. These results suggest that the test concentration of both metals leads to a failure in completing cell division. Ultrastructural analysis indicated a chloroplast disorganization in copper-treated cells, as well as the presence of electron dense granules with different shapes and sizes inside vacuoles. Microanalysis of these granules indicated an accumulation of copper, thus suggesting a detoxification role played by the vacuoles. These results indicate that E. gracilis is an efficient biological model for the study of metal poisoning in eukaryotic cells. They also indicate that copper and zinc (copper being more poisonous) had an overall toxic effect on E. gracilis and that part of the effect can be ascribed to defects in the structure of chloroplast membranes.     

Unexpected toxic interactions in the freshwater amphipod Gammarus pulex (L.) exposed to binary copper and nickel mixtures

To document the toxicity of copper and nickel in binary mixtures, freshwater amphipods Gammarus pulex were exposed to the metals given independently or as mixtures. Toxicity to Cu alone was relatively high: 96-h LC₁₀ and LC₅₀ were found at 91 and 196 μg L^?1, respectively. Toxicity to Ni alone was very low, with 96-h LC₁₀ and LC₅₀ of 44,900 and 79,200 μg L^?1, respectively. Mixture toxicities were calculated from single toxicity data using conventional models. Modeled toxicity was then compared with the measured toxicity of the binary mixture. Two kinds of mixtures were tested. Type I mixtures were designed as combinations of Cu and Ni given at the same effect concentrations, when taken independently, to identify possible interactions between copper and nickel. In type II mixtures, Cu concentrations varied from 0 to 600 μg L^?1 while the nickel concentration was kept constant at 500 μg L^?1 to mimic conditions of industrial wastewater discharges. Ni and Cu showed synergic effects in type I mixtures while type II mixtures revealed antagonistic effects. Low doses of Ni reduced Cu toxicity towards G. pulex. These results show that even for simple binary mixtures of contaminants with known chemistry and toxicity, unexpected interactions between the contaminants may occur. This reduces the reliability of conventional additivity models.     

Screening the phytoremediation potential of desert broom (Baccharis sarothroides Gray) growing on mine tailings in Arizona, USA

The metal concentrations in a copper mine tailings and desert broom (Baccharis sarothroides Gray) plants were investigated. The metal concentrations in plants, soil cover, and tailings were determined using ICP-OES. The concentration of copper, lead, molybdenum, chromium, zinc, arsenic, nickel, and cobalt in tailings was 526.4, 207.4, 89.1, 84.5, 51.7, 49.6, 39.7, and 35.6mgkg(-1), respectively. The concentration of all elements in soil cover was 10-15% higher than that of the tailings, except for molybdenum. The concentration of copper, lead, molybdenum, chromium, zinc, arsenic, nickel, and cobalt in roots was 818.3, 151.9, 73.9, 57.1, 40.1, 44.6, 96.8, and 26.7mgkg(-1) and 1214.1, 107.3, 105.8, 105.5, 55.2, 36.9, 30.9, and 10.9mgkg(-1) for shoots, respectively. Considering the translocation factor, enrichment coefficient, and the accumulation factor, desert broom could be a potential hyperaccumulator of Cu, Pb, Cr, Zn, As, and Ni.     

Removal of Cu and Pb by tartaric acid modified rice husk from aqueous solutions

A study on the modification of rice husk by various carboxylic acids showed that tartaric acid modified rice husk (TARH) had the highest binding capacities for Cu and Pb. The carboxyl groups on the surface of the modified rice husk were primarily responsible for the sorption of metal ions. A series of batch experiments using TARH as the sorbent for the removal of Cu and Pb showed that the sorption process was pH dependent, rapid and exothermic. The sorption process conformed to the Langmuir isotherm with maximum sorption capacities of 29 and 108 mg/g at 27 +/- 2 degrees C for Cu and Pb, respectively. The uptake increased with agitation rate. Decrease in sorbent particle size led to an increase in the sorption of metal ions and this could be explained by an increase in surface area and hence binding sites. Metal uptake was reduced in the presence of competitive cations and chelators. The affinity of TARH for Pb is greater than Cu.     

Simultaneous heavy metal removal mechanism by dead macrophytes

The use of dead, dried aquatic plants, for water removal of metals derived from industrial activities as a simple biosorbent material has been increasing in the last years. The mechanism of simultaneous metal removal (Cd2+, Ni2+, Cu2+, Zn2+ and Pb2+) by 3 macrophytes biomass (Spirodela intermedia, Lemna minor and Pistia stratiotes) was investigated. L. minor biomass presented the highest mean removal percentage and P. stratiotes the lowest for all metals tested. Pb2+ and Cd2+ were more efficiently removed by the three of them. The simultaneous metal sorption data were analysed according to Langmuir and Freundlich isotherms. Data fitted the Langmuir model only for Ni and Cd, but Freundlich isotherm for all metals tested, as it was expected. The K(F) values showed that Pb was the metal more efficiently removed from water solution. The adsorption process for the three species studied followed first order kinetics. The mechanism involved in biosorption resulted ion exchange between monovalent metals as counter ions present in the macrophytes biomass and heavy metal ions and protons taken up from water. No significant differences were observed in the metal exchange amounts while using multi-metal or individual metal solutions.     

Microbial ecotoxicity and mutagenicity of 1-hydroxypyrene and its photoproducts.

1-Hydroxypyrene (1-HP) is a carcinogenic and slightly water-soluble polycyclic aromatic hydrocarbon. Ecotoxicity and mutagenicity of 1-HP and its photoproducts, and the effect of Mn2+ and Cu2+ on their mutagenicity were measured with microbial assay in this study. The assay includes spread plate counting, direct counting, microbial mineralization of 14C-UL-D-glucose and Mutatox Test. At the concentration examined (0.8 microM), the photoproducts (after 1.5 h solar irradiation) of 1-HP inhibited microbial glucose mineralization activity (by 64%) after microbial assemblages of a local reservoir site were exposed for 1 day. However, heterotrophic bacteria were able to utilize 1-HP photoproducts as the growth substrates and increase viability counts by up to 4.75-folds. 1-HP exhibited positive response to Mutatox Test in both direct medium and S-9 medium, with the lowest observable effective concentration of 0.625 microM in the test with direct medium. After photolysis, 1-HP decreased its mutagenicity. Mn2+ (312.5 microM-5 mM) and Cu2+ (6.25-100 microM) themselves are not mutagenic. However, addition of the metal ions before or after photolysis modifies the light readings of 1-HP during the test. Therefore, presence of metal ions could affect the genotoxicity of 1-HP in aquatic environments, depending on timing of the addition.     

Characterization and lead(II), cadmium(II), nickel(II) biosorption of dried marine brown macro algae Cystoseira barbata

Purpose

The objectives of this research are to identify the functional groups and determine corresponding pK _a values of the acidic sites on dried brown algae Cystoseira barbata using FTIR and potentiometric titrations, and to investigate the biosorption ability of biomass towards divalent nickel, cadmium, and lead ions. Adsorption was studied as a function of solution pH and contact time, and experimental data were evaluated by the Langmuir isotherm model.

Methods

CaCl₂ pretreatment was applied to the sorbent for enhancing the metal uptake capacity. The effect of solution pH on biosorption equilibrium was investigated in the pH range of 1.5?C5.0. Individual as well as competitive adsorption capacity of the sorbent were studied for metal cations and mixtures.

Results

The retention of the tested metal ions was mostly influenced from pH in the range of 1.5?C2.5, then stayed almost constant up to 5.0, while Ni(II) uptake showed the highest variation with pH. Potentiometric titrations were performed to find the number of strong and weak acidic groups and their acidity constants. The density of strong and weak acidic functional groups in the biomass were found to be 0.9 and 2.26?mmol/g, respectively. The FTIR spectra of the sorbent samples indicated various functionalities on the biomass surface including carboxyl, hydroxyl, and amino and sulphonate groups which are responsible for the binding of metal ions.

Conclusions

The capacity of the biomass for single metal ions (around 1?mmol/g) was increased to 1.3?mmol/g in competitive adsorption, Pb(II) showing the highest Langmuir intensity constant. Considering its extremely high abundance and low cost, C. barbata may be potentially important in metal ion removal from contaminated water and industrial effluents.     

Trace metal accumulation and fish pathologies in areas affected by mining and metallurgical enterprises in the Kola Region, Russia

Throughout the Kola region of Russia there has been a substantial increase of metal concentrations in water, which are related to local discharges from metallurgical and mining industry, transboundary transmissions as well as indirect leaching of elements by acid precipitation. This study presents data on the levels of Ni, Cu, Sr, Al, Zn, Co, Mn, Pb, Cd, Hg in the organs and tissues of fish, and evaluates relationships with water chemistry. Special attention is paid to fish pathologies, whose aetiology is related to the accumulation of metals and the associated changes of the elementary ratios within the organism. Ecotoxicological assessment of the copper nickel, strontium and acidification regimes also is considered in this article. In general we observed a large number of lakes that are heavily contaminated by Ni and Cu. Fish in these lakes contain high concentrations of Ni and Cu and display frequent pathologies, mostly associated with the kidneys. In lakes contaminated with Sr, there also are high Sr levels in fish and pathologies associated with skeletal tissues. Exposure to acidified water appears to increase the transport of metals (including Al, Ni and Cu) into fish and hence the toxic effects.     

Microbial enhancement of Cu2+ removal capacity of Eichhornia crassipes (Mart.)

Bacteria resistant to Cu2+, Ni2+ or Zn2+ were isolated from the rhizosphere of water hyacinth (Eichhornia crassipes (Mart.)) and their metal ion removal capacities (RCs) were determined. The Ni2+ and Zn2+ RCs of the respective metal ion-resistant bacteria were less than 4.1 mg g(-1), while one of the Cu2+-resistant bacteria (Strain CU-1) showed a significant high Cu2+ RC of 10.6 mg g(-1). The effect of inoculating water hyacinth with Strain CU-1 on its Cu2+ RC was further studied. Water hyacinths were treated with an antibiotic, oxytetracycline (OTC), to remove most rhizospheric bacteria of plant roots. Inoculation of Strain CU-1 increased the Cu2+ RC of the plant root by 1.91 (OTC-treated) and 1.56 (OTC-untreated) folds respectively when compared with the control. Results also showed that Strain CU-1 colonized onto the plant root and led to the increase of Cu2+ RC of the roots of water hyacinth.     

Effects of past sewage sludge additions on heavy metal availability in light textured soils: implications for crop yields and metal uptakes

The effect of heavy metal additions in past sewage sludge applications on soil metal availability and the growth and yield of crops was evaluated at two sites in the UK. At Gleadthorpe, sewage sludges enriched with salts of zinc (Zn), copper (Cu) and nickel (Ni) had been applied to a loamy sand in 1982 and additionally naturally contaminated Zn and Cu sludge cakes in 1986. At Rosemaund, sewage sludges naturally contaminated with Zn, Cu, Ni and chromium (Cr) had been applied in 1968-1971 to a sandy loam. From 1994 to 1997, the yields of both cereals and legumes at Gleadthorpe were up to 3 t/ha lower than the no-sludge control where total topsoil Zn and Cu concentrations exceeded 200 and 120 mg/kg, respectively, but only when topsoil ammonium nitrate extractable metal levels also exceeded 40 mg/kg Zn and 0.9 mg/kg Cu. At Rosemaund, yields were only decreased where total topsoil Cu concentrations exceeded 220 mg/kg or 0.7 mg/kg ammonium nitrate extractable Cu. These results demonstrate the importance of measuring extractable as well as total heavy metal concentrations in topsoils when assessing likely effects on plant yields and metal uptakes, and setting soil quality criteria.