Accumulation of zinc, cadmium and lead by field populations of Lemanea

A study has been made of the concentrations of zinc, cadmium and lead in populations of the red alga Lemanea growing in fast-flowing rivers in Britain, France. Germany, Ireland and Sardinia (Italy). The sites were selected to provide a wide range of aqueous concentrations of these metals. Many of the sites are influenced by past or present mining activities and Lemanea was found at aqueous concentrations of zinc up to 1.16 mg 1⁻¹. In contrast to previous studies with filamentous green algae, no evidence could be found to support the hypothesis that populations differ genetically in their ability to tolerate these heavy metals. Samples of alga consisted of pooled 2 cm long terminal tips of filaments detached from approx. 1 cm² rock surface. Significant positive correlations were found between the logarithm of the mean concentration of zinc, cadmium and lead in four such samples collected from within 10 m reaches at 59 sites and the logarithm of the concentration of each metal in both unfiltered and filtered water. The enrichment ratios for each metal decreased with increasing aqueous metal concentrations. Although the aqueous concentrations of the three metals were strongly intercorrelated, differences in the ratio of metal concentrations were reflected in the composition of Lemanea filaments. The results suggest that high levels of calcium (and/or magnesium) result in decreased uptake of zinc. Intensive sampling from a single population showed that part of the zinc content of filaments is sensitive to short-term fluctuations in concentrations in the surrounding water. In the particular population studied this was about 20%; a similar percentage could be eluted in the laboratory with EDTA. Transplants of Lemanea were made between reaches with different aqueous concentrations of zinc and in all cases the zinc concentration in filament tips increased or decreased to stabilise at a concentration similar to that in filaments native to the reach. It is suggested that chemical analyses of natural or transplanted populations of Lemanea could provide a valuable aid in monitoring contamination of rivers by zinc, cadmium or lead.     

Use of moss-bags for monitoring heavy metals in rivers

Methods were developed for the use of aquatic mosses in mesh bags to monitor heavy metal pollution by measuring concentrations in 2-cm tips of the widespread species, Rhynchostegium riparioides and (in one experiment) Fontinalis antipyretica. Intermittent pollution events were simulated by transporting moss from streams with low concentrations to ones with high concentrations of zinc, cadmium and lead and also in one case back from high to a low concentration. Factors affecting accumulation were also studied; these included position inside bag, density of packing, mesh size and differences between moss on boulders and in bags. In general these factors influenced accumulation only slightly over a wide range of treatments. The influence of time period for which the moss was exposed to pollution on subsequent loss was tested for zinc: a greater proportion was lost over the first 2 h in moss exposed for 1 h than 24 h. The potential for using the moss-bag technique is discussed: it is robust and convenient to handle and is recommended for monitoring heavy metals in stretches of rivers where there are no natural moss populations.     

The removal of nickel,copper and cadmium from aqueous solution using liver moss (Dumortiera hirsute Sw. nees)

The aim of this study was to investigate the use of liver moss (Dumortiera hirsute Sw. nees) as an alternative adsorbent for the removal of nickel, copper and cadmium from aqueous solution. The results showed that equilibrium contact time was 60?min and acidic pH was favourable for removal of metal ions. Higher initial metal ion concentrations led to lower removal. The data were fitted well both Langmuir and Freundlich isotherms. The monolayer adsorption capacities were 30.675, 35.971 and 53.476?mg/g for nickel, copper and cadmium, respectively. The presence of metal ions such as sodium, potassium and magnesium at concentration of 10?mM was found to have no significant effect on the removal of nickel, copper and cadmium. The removal of nickel, copper and cadmium was markedly inhibited, however, in the presence of calcium ion and heavy metal ions mixture in solutions. The kinetic data for removal processes were described by the pseudo-second-order model. The liver moss shows high potential as an economic and abundant material for the removal of metal ions from aqueous solution.     

Potential health risks of arsenic,antimony and mercury in the Takab geothermal field,NW Iran

This study investigates the bioavailability, water–soil to plant transfer and health risks of arsenic (As), antimony (Sb) and mercury (Hg) in the Takab geothermal field north-west of Iran. Water used for irrigation, surface soils from agricultural lands and cultivated plants were collected from three polluted sites and analysed for As, Sb and Hg to assess associated health risks. As content in irrigation water ranges from 23.4 to 986.4?μg/L, whereas total As content in the surface soil is in the range of 16.3–492?mg/kg^?1. The results agree with other reports that metal (loid) concentrations in leaves are usually much higher than in grain. Most investigated plant species showed a significant correlation between As, Sb and Hg contents in their aerial parts and that available in the soil (r?=?0.82, p?=?0.012; r?=?0.84, p?=?0.004; r?=?0.79, p?=?0.011). Factors influencing the bioavailability of metal (loids) and their occurrences in plants are soil pH, cation exchange capacity, phosphate, calcite and organic matter content, soil texture and interaction between target elements. Available As in analysed soils is relatively low, implying that phosphate, as well as Fe-oxy-hydroxides and calcite are effective in absorbing As. But, sequential extraction analysis indicates that iron oxy-hydroxide surface can bind both As and Sb, with As being more strongly bound. The calculated bioaccumulation factor based on total metal (loids) and available metal (loids) in soil indicates that alfalfa (Medicago sativa L.) and sage (Saliva syriaca L.) are effective accumulators of As, Sb and Hg. The health risk index of the studied plants ranged from 0.0003 to 5.71, with the maximum being in wheat (Triticun aestivum L.), an alarming sign for human health. It is suggested that health risks from long-term consumption of wheat and other As-rich foodstuffs must be managed by monitoring contamination in the water–soil–plant pathway.     

The characterization of metal oxide - Mangifera indica L. matrix and its potential as scavenger of heavy metal pollutant

Widespread pollution by heavy metals requires an efficient, cheap and eco-friendly removal technique. This paper reports the use of discarded leaves of Mangifera indica L. modified to enhance their adsorption efficiency in the removal of heavy metal pollutant. The adsorbent was then characterized through X-ray diffraction study, Fourier transform infrared spectroscopy and application to mathematical models. The adsorption process was found to fit the Langmuir’s isotherm model and pseudo-first-order kinetic model. The intra-particle diffusion model was found to be the rate limiting step for the adsorption process. Its rapid kinetics, high hydrophilicity, and easy regenerability with mild mineral acid (like 0.005 M HCl) make this adsorbent suitable for the fixed bed column technique.     

Pollination ecology and seed production of some species of the genus Pedicularis L. in the highlands of Altai

Abstract

The paper presents data on the pollination ecology and seed production of three Pedicularis L. species in the high mountains of Altai. It was determined that the investigated species are highly specialised entomophiles. Specialisation to entomophily is expressed in a number of adaptations: the presence of nectar in flowers of Pedicularis, pollen and secondary attractants (visual and tactile) that attract insects, as well as specific morphological structures which facilitate the process of pollen hitting a certain area of the body of the insect. Hercogamy and protogyny and gradual explication of the flowers in the inflorescence and their long lifespan in wide ranges of temperature and humidity are also adaptations to cross-pollination. The investigated species have high fertility and viability of the pollen grains. Seed production ranges from 57.1 to 261.3 seeds per stem. The seeds have organic rest. Promoting agents of seeds germination of the investigated species are cold stratification in conjunction with the gibberellic acid treatment. The biology of louseworts is peculiar because they combine autotrophic feeding with parasitism on other higher plants. The lack of strict species specificity in the choice of host plants was discovered. The complex of host plants includes 27 species.     

The effects of decreasing heavy metal concentrations on the biota of Buttle Lake, Vancouver Island, British Columbia

Since 1966, a copper-lead-zinc mine operated by Westmin Resources Limited has been a source of heavy metal input into Buttle lake. Metal levels increased in the lake, peaking in 1980/1981; thereafter improved treatment and collection systems at the mine site have resulted in steadily decreasing metal levels throughout the lake system. The increase in metal concentrations in the lake water was accompanied by increased metal concentrations in salmonid muscle and liver tissues, by elevated levels of hepatic metallothionein and by declines in both species diversity and population for phytoplankton, periphyton and zooplankton. However, recovery of the biota of Buttle lake with decrease in metal concentrations has not followed a simple reversal of the earlier trends.While metal levels in rainbow trout muscle tissue have improved significantly, copper and cadmium liver tissue levels remain significantly higher than for the control lakes. Hepatic metallothionein levels in rainbow trout have declined steadily from a maximum of 269 ± 23 nmol/g in 1981 to a low of 64 ± 22 nmol/g in 1985, which is similar to the control lake.Interspecies comparison of muscle and liver tissue levels both for Buttle lake and for uncontaminated British Columbia lakes found that rainbow trout (Oncorhynchus mykiss), cutthroat trout (Oncorhynchus clarki) and Dolly Varden char (Salvelinus malma) respond differently to metals in the environment. It is apparent that trends in rainbow trout data should not be generalized to include all three groups.As metal concentrations decreased, the phytoplankton community began to change so that beginning in 1983 and continuing well into 1985, a continuous phytoplankton bloom consisting of a virtual monoculture of Rhizosolenia eriensis was present throughout the lake. Accompanying the bloom was a scarcity of zooplankton. However, as levels of R. eriensis peaked in 1985, zooplankton and phytoplankton diversity and species number are improving as previously dominant species begin to reappear.     

The accumulation of La,Ce and Y by Lemna minor and Lemna gibba in the Keban gallery water,Elazig Turkey

This study investigated the phytoremediation ability of Lemna minor and Lemna gibba to accumulate lanthanum, cerium and yttrium from gallery water polluted by metals. L. minor and L. gibba were settled in the mining water and adapted to separate reactors. During the experiment, the water and plant samples were daily taken and the temperature, electric conductivity and pH of the water were daily measured in situ. These plants were firstly washed, dried in and then ashed at 300°C for 24 h in an oven. Both water and ashed plant samples were measured by ICP‐MS to detect the concentrations of lanthanum (La), cerium (Ce) and yttrium (Y). Although these elements are at low concentrations in gallery water, they were accumulated at the highest levels in L. gibba and in L. minor. This study showed that both plants have high ability to remove lanthanum, cerium and yttrium in gallery water polluted by different elements.     

Potential of citric acid to alter pH and metal uptake in reeds in acid mine drainage solutions

Phragmites australis (common reed) is often used to treat acid mine drainage (AMD) sites contaminated with high concentrations of heavy metals and low pH. This study investigated the effects of different levels (low 0.34 g/L, middle 17.86 g/L and high 33.62 g/L) of the biodegradable chelator citric acid (CA) on pH change, metal (i.e. Fe, Al and Mn) accumulation and translocation in reeds cultured in aqueous AMD contaminated media for 4 and 12 weeks. The results indicated that CA inhibited further deceases in AMD pH as well as increased Fe and Mn accumulation in both belowground and above ground tissues of reeds. As expected, increasing CA dosage and treatment time increased metal accumulation in plants. By 12 weeks, 0.18 ± 0.01 mg Mn/g, 56.78 ± 7.63 mg Fe/g and 0.60 ± 0.01 mg Al/g were accumulated in roots; while 0.06 ± 0.01 mg Mn/g; 6.38 ± 0.06 mg Fe/g; and 0.19 ± 0.01 mg Al/g were sequestered in stems of reeds treated with 33.62 g/L CA. Further research is needed to study the application of CA to enhance the phytoremediation efficiency of AMD contaminated field.     

Adsorption and desorption of heavy metals in bottom mud of urban rivers

An adsorption experiment has been carried out to determine the factors affecting the uptake of heavy metals by bottom mud in urban rivers. The adsorption of Cu, Zn, Cd, and Pb was described using the Freundlich adsorption equation. The Freundlich constant (K) was related to the grain size and organic matter content of bottom mud. It was found that the main factor controlling the adsorption of metal was organic matter, since the adsorbed metals decreased remarkably due to the destruction of organic matter from the fine bottom mud. The desorption experiment proved that the metals adsorbed by mud were extracted approx. 100% with dilute HCI. Therefore, the amount of heavy metal adsorbed per 1 g of TOC can be calculated from the acid soluble metal content of bottom mud. Moreover, the method of extraction by 2 N CH₃COONH₄ can be used to distinguish between an ion exchangeable form by minerals and a chemical form by organic matter.The adsorption and desorption experiments indicated that fine bottom mud with a high organic matter content contributes to the uptake of metals in urban rivers and that such metals can be extracted with 0.5 N HCI.     

New species of Platygastrinae and Sceliotrachelinae (Hymenoptera,Platygastroidea: Platygastridae) from Australia

The following 20 species and one new subgenus are described as new to science: Acerotella australica, Amblyaspis canberrensis, Amitus teres, Leptacis australica, L. gloriosa, L. piliclava, L. powerae, Metanopedias australicus, Platygaster amblyaspoides, P. (Austroplatygaster subgen. n.) breviclava, P. gibsoni, P. mediolobata, P. pilosithorax, Synopeas alternatum, S. bangmadseni, S. carlseni, S. eucalypti, S. salicorniae, S. striolagaster and S. triangulatum.     

Role of bacterial extracellular polymers in metal uptake in pure bacterial culture and activated sludge—II Effects of mean cell retention time

A gel filtration technique afforded a good separation between metal complexed with bacterial extracellular polymers and free metal ions. The complexation of polymers extracted from cultures of Klehsiella aerogenes and activated sludge with cadmium, nickel, manganese and cobalt was demonstrated. The extraction of extracellular polymers from cultures of K. aerogenes and activated sludge reduced the capacity of the cells and flocs to adsorb metal. Adsorption and complexation of metals by cells of K. aerogenes and extracellular polymers extracted from activated sludge were fitted to Freundlich equilibrium isotherms. Saturation of activated sludge polymer binding sites occurred at 10 mg 1⁻¹ metal additions for all the metals studied except manganese which was complexed to a very limited extent. Cells of K. aerogenes exhibited no saturation effects in the range of metal concentrations studied.Precipitation of metals below a concentration of 1 mg 1⁻¹ was minimal, with the exception of cadmium precipitation. At a concentration of 10 mg 1⁻¹, precipitation of cadmium, cobalt and manganese may have been the major mechanism of metal removal. The more soluble metals generally displayed the lowest removals. Concentrations of extracellular polymers and soluble chelating agents may be important in controlling removals of metals which are largely soluble in activated sludge.     

Screening wheat and other small grains for acid soil tolerance

Aluminum (Al) toxicity in acid soils is a major growth-limiting factor for cereal crops in many parts of the world. The most striking effect of high Al concentration in acid soils is stunting of the root system. Liming reduces Al toxicity in surface soils; however, cereal breeders must be prepared to develop cultivars that have tolerance to soil acidity. A 4 day root bioassay, originally used to identify Al toxics soils, was adapted to evaluate tolerance to soil acidity of cereal species and genotypes. Acid soil tolerance was related to the extent of inhibition of root elongation in an Al-toxic soil (pH 4.2) relative to root elongation in the same soil treated with lime (pH5.2). Of the entries, 18% were tolerant or moderately tolerant, and 48% were susceptible or moderately susceptible when 75 bread wheat (Triticum aestivum L.) genotypes were tested. None of the 22 entries of durum wheat (Triticum durum Desf.) were tolerant or moderately tolerant, indicating much lower adaptability to soil acidity than bread wheat. The following ranking of acid soil tolerance of cereal species was obtained: rye (Secale cereale L.) #62;oats (Avena sativa L.) #62;millet(Panicum miliaceum L.) #62;bread wheat (Triticum aestivum L.) #62;barley (Hordeum vulgare L.) #62;durum wheat (Triticum durum Desf.). Variation in tolerance within the other cereal species was much lower than within bread wheat species. The root bioassay method is relatively quick, simple and inexpensive. The method can also be used to screen early-generation populations because assayed seedlings are still viable and can be transplanted for growing until harvest.     

Removal of tetracycline antibiotic by Lemna gibba L. from aqueous solutions

In this study, the efficiency of Lemna gibba L. on tetracycline (TC) removal from the solutions prepared at various initial TC concentrations (50, 100 and 300 µg/L) was investigated. The study was conducted in the reactors planted with Lemna gibba L. plants. Lemna gibba L. plants in the reactors were harvested at various hydraulic retention times. Then, the concentrations of TC were determined by using LC/‐MS‐MS. The maximum removal efficiencies for the TC50, TC100 and TC300 in the planted reactors were 99.8 ± 4.1; 99.9 ± 4.9 and 99 ± 4.9%, respectively. The harvesting times for Lemna gibba L. at TC50, TC100 and TC300 concentrations were determined to be 12, 8 and 12 hours, respectively. First‐, second‐ and pseudo‐first‐order kinetics are determined in the planted reactors (with Lemna gibba L.). According to the study results, second‐order kinetics were obtained at TC50, TC100, TC300 concentrations. As a result, the Lemna gibba L. plant can be used as an alternative treatment method to other advanced treatment methods and it can be done with a cheap method by adapting to existing treatment plants. Lemna gibba L. plants can be used to remove pollutants by applying them to polluted lakes and water bodies.     

Treatment of wastewater containing high concentrations of terephthalic acid by Comamonas sp. and Rhodococcus sp.: kinetic and stoichiometric characterization

In this work, terephthalic acid degradation was studied with two strains that were isolated and identified as closely related to Comamonas (99%) and Rhodococcus (99%) genus. A characterization of both strains was carried out during batch experiments performed at two oxygen transfer capacities (0.094 ± 0.011 and 0.538 ± 0.042 g O₂/L/h) and five concentrations of terephthalic acid (2.5 to 15.0 g/L). Maximum degradation rates of 0.073 ± 0.004 and 0.062 ± 0.003 g TOC/L/h, were observed, for Comamonas sp. and Rhodococcus sp., respectively. However, a degradation rate of 0.159 ± 0.011 g TOC/L/h was reached with a mixed culture. Haldane, Aiba, Edwards and Andrews models were used to fit terephthalic acid degradation kinetics, being Haldane the model that best fitted the results. Several parameters were determined including, maximum growth rate, growth yield, substrate affinity and inhibition constant.     

Biosorption of mercury and lead by dried Aspergillus niger Tiegh. isolated from estuarine sediments

The sorption of Hg and Pb from mono‐metal and bi‐metal solution under different concentrations (20ppm–80ppm) was studied using dried Aspergillus niger biomass. The biosorption of Hg and Pb from the mono‐metal solution was found to be much better than from the bi‐metal solution. The maximum sorption of heavy metals was observed at pH 5–6 and at temperature 25°C–26°C. Biosorption of heavy metals from mono‐metal and bi‐metal solutions followed the Langmuir and Freundlich isotherm. The role of different functional groups like amine, hydroxyl, carboxyl and the phosphate group was confirmed by FTIR. The adsorption of metal ions on the biomass surface and the possible ion exchange mechanism was confirmed using SEM‐EDAX studies. A. niger can be used as a good biosorption agent for removing Hg and Pb from aqueous solution when present individually or in combination.     

Potentially harmful secondary metabolites produced by indoor Chaetomium species on artificially and naturally contaminated building materials

The presence of the fungal genus Chaetomium and its secondary metabolites in indoor environments is suspected to have a negative impact on human health and well‐being. About 200 metabolites have been currently described from Chaetomium spp., but only the bioactive compound group, chaetoglobosins, have been screened for and thus detected in buildings. In this study, we used a liquid chromatography high‐resolution mass spectrometry approach to screen both artificially and naturally infected building materials for all the Chaetomium metabolites described in the literature. Pure agar cultures were also investigated to establish differences between metabolite production in vitro and on building materials as well as in comparison with non‐indoor reference strains. On building materials, six different chaetoglobosins were detected in total concentrations of up to 950 mg/m² from Chaetomium globosum along with three different chaetoviridins/chaetomugilins in concentrations up to 200 mg/m². Indoor Chaetomium spp. preferred wood‐based materials over gypsum, both in terms of growth rate and metabolite production. Cochliodones were detected for the first time on all building materials infected by both C. globosum and Chaetomium elatum and are thus candidates as Chaetomium biomarkers. No sterigmatocystin was produced by Chaetomium spp. from indoor environment.     

Toxicity of cadmium, cobalt, uranium and zinc to Zoogloea ramigera

The toxic effects of cadmium, cobalt, uranium and zinc to the bacterium Zoogloea ramigera have been studied. This organism, which is abundant in sewage-treatment plants, responded to media supplemented with heavy metals by showing a prolonged lag phase and by decreasing its growth rate. The length of the lag phase was proportional to the metal concentration when Z. ramigera was exposed to cadmium, cobalt and zinc. When exposed to uranium (uranyl ions) the organism altered its growth behavior by showing an extended lag phase almost independent of the metal concentration. The order of toxicity of the metals to Z. ramigera was Cd²⁺ = Zn²⁺ > Co²⁺ > UO₂²⁺.     

A laboratory model for evaluating the behavior of heavy metals in an aquatic environment

A dynamic biological system capable of simultaneously distinguishing between bioaccumulation and biomagnification through successive trophic levels in an aquatic ecosystem is described. The organisms used in the system were algae, predominantly Scenedesmus sp., Daphnia magna, fresh water mussels (Ligumia sp. and Margaritifera sp.) and the fathead minnow, Pimephales promelas.Thiosulfate complexed mercury and silver were each studied at two concentrations. The water and organisms were analyzed for the metals periodically during the 10-week tests. Both mercury and silver can be bioaccumulated by fish. The concentration factors for mercury are greater than for silver. Further, mercury is biomagnified by fish whereas silver is not. Fresh water mussels were found to be poor indicator species for metal contamination.     

Metal sorption on blast-furnace slag

The removal of Cu, Ni and Zn-ions from water solution by ungranulated blast-furnace slag has been studied depending on contact time, initial ion concentration, pH and solution temperature. The polymineral composition and the slag specific properties determine its high sorption activity in metal salts solutions. In the range of the concentrations studied (10⁻⁴–10⁻³ M), the sorption data for Cu²⁺, Ni²⁺ and Zn²⁺ have been described using Freundlich's parabolic equation. The material's own alkalizing activity creates conditions for effective metal ions sorption in a wide pH range. With the temperature increase the hydrolysis of the sorption matrix intensifies which leads to the sorption improvement. On the basis of both literature data and the author's own data the mechanism of metal ions removed by blast-furnace slag has been discussed.