Phytoextraction of cadmium by rice (Oryza sativa L.), soybean (Glycine max (L.) Merr.), and maize (Zea mays L.)

Selecting a phytoextraction plant with high Cd-accumulating ability based on the plant's compatibility with mechanized cultivation techniques may yield more immediately practical results than selection based on high tolerance to Cd. Rice (Oryza sativa L., cv. Nipponbare and Milyang 23), soybean (Glycine max [L.] Merr., cv. Enrei and Suzuyutaka), and maize (Zea mays L., cv. Gold Dent) were grown on one Andosol and two Fluvisols with low concentration of Cd contamination ranging from 0.83 to 4.29 mg Cd kg(-1), during 60 days in pots (550 mL) placed in a greenhouse. Shoot Cd uptake was as follows: Gold Dent相似文献   

Lead induced changes in antioxidant metabolism of horsegram (Macrotyloma uniflorum (Lam.) Verdc.) and bengalgram (Cicer arietinum L.)

One-month old horsegram (Macrotyloma uniflorum (Lam.) Verdc. cv VZM1) and bengalgram (Cicer arietinum L. cv Annogiri) were exposed to different regimes of lead stress as Pb(NO3)2 at 0, 200, 500 and 800 ppm concentrations. The extent of oxidative damage as the rate of lipid peroxidation, antioxidative response and the accumulation of lead in roots and shoots of both plants were evaluated after 12 days of lead stress. Lead (Pb) treated plants showed increased levels of lipid peroxidation as evidenced from the increased malondialdehyde content coupled with the increase in the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione reductase (GR), glutathione S-transferase (GST) compared to control (untreated) plants. Lead stress caused significant changes in the activity of antioxidative enzymes. The effect of lead was found to be concentration dependent. Higher concentration of lead (800 ppm) resulted 2- to 3-fold increase in SOD, catalase and peroxidase activities, 3- to 5-fold increase in GR activity and 3- to 4-fold increase in GST activity in roots and leaves of both horsegram and bengalgram plants. Lead stress caused a significant increase in the rate of peroxidation as showed in the levels of malondialdehyde content in roots and leaves of both plant species. Horsegram registered lower Pb accumulation than bengalgram, however localization of Pb was greater in roots than leaves in both plants. In general, lipid peroxide levels and antioxidative enzyme activities were higher in horsegram than bengalgram and also more in roots than leaves which best concordance with the lead contents of both the plants and organs. These results suggest that Pb toxicity causes oxidative stress in plants and the antioxidative enzymes SOD, CAT, POD, GR, GST could play a pivotal role against oxidative injury.     

Accumulation of heavy metals in Typha angustifolia (L.) and Potamogeton pectinatus (L.) living in Sultan Marsh (Kayseri, Turkey)

Concentrations of heavy metals (Cd, Pb, Cr, Ni, Zn and Cu) were measured in bottom sediments, water and Typha angustifolia and Potamogeton pectinatus in Sultan Marsh. Sultan Marsh is one of the largest and most important wetlands in Turkey, Middle East and Europe, embodying saline and fresh water ecosystems and providing a shelter for 426 bird species. The organs of T. angustifolia have a larger quantity of the measured elements than the P. pectinatus. Considerably higher contents of Cd were found rather than in helophytes (P. pectinatus) in submerged plant (= emergent, T. angustifolia) species. The percentage of Cd in plant tissues points to a certain degree of water pollution in Sultan Mash. Analyses of water, bottom sediments and plant samples indicated that the Marsh were polluted with Pb, Cd, and partly with Cu and Zn. All sampling sites in the study area basin are generally more or less polluted when compared with the control values. Strong positive correlation was found between concentrations of Pb in water and in plants. Ni and Pb were accumulated by plants at a higher rate from bottom sediments than from water. Leaves of T. angustifolia accumulated less heavy metal than the corresponding roots. There was a significant relationship between Cd concentration in samples of plants and water pH value. It has been found that the tissues of T. angustifolia accumulate more heavy metals than the tissues of P. pectinatus. Therefore, all plants can be used as a biological indicator while determining environmental pressures; however, T. angustifolia is proved more appropriate for such studies.     

Investigation of arsenic accumulation and tolerance potential of Sesuvium portulacastrum (L.) L

Sesuvium portulacastrum (L.) L., a facultative halophyte, is considered a suitable candidate for the phytoremediation of metals. An investigation of As accumulation and tolerance was conducted in Sesuvium plants upon exposure to As(V) (100-1000 μM) for 30 d. Plants demonstrated a good growth even after prolonged exposure (30 d) to high As(V) concentrations (1000 μM) and a significant As accumulation (155 μg g⁻¹ dry weight) with a bioaccumulation factor of more than ten at each concentration. The results of shoot and root dry weight, malondialdehyde accumulation, photosynthetic pigments, and total soluble proteins demonstrated that plants did not experience significant toxicity even at 1000 μM As(V) after 30 d. However, metabolites (total non-protein thiols and cysteine) and enzymes (serine acetyltransferase, cysteine synthase and γ-glutamylcysteine synthetase) of thiol metabolism, in general, remained either unaffected or showed slight decline. Hence, plants tolerated high As(V) concentrations without an involvement of thiol metabolism as a major component. Taken together, the results indicate that plants are potential As accumulator and may find application in the re-vegetation of As contaminated sites.     

Efficacy of Si fertilization to modulate the heavy metals absorption by barley (Hordeum vulgare L.) and pea (Pisum sativum L.)

Silicon-based fertilizers and soil amendments can have direct and indirect positive influences on cultivated plants. The solid forms of Si-based substances, the most widespread in use, are efficient only at high application rates due to their low level of solubility. Several types of Si-based substances such as fumed silica, slags from the iron and steel industry, modified slags, and a Si-rich product were tested using barley and pea as silicon accumulative and non-accumulative plants, respectively, at two application rates. The plants were grown under toxic concentrations of heavy metals in a greenhouse. Si-rich materials high in water-soluble Si had a positive effect at both the low and high application rates, and for both plant species. This type of substance can be regarded as Si fertilizer, demonstrating greater efficiency at a low application rate and lessened efficiency at a high application rate for protection of the cultivated plants against accumulation of the heavy metals.

     

Metabolic enzymes activity and histomorphology in the liver of whitefish (Coregonus lavaretus L.) and pike (Esox lucius L.) inhabiting a mineral contaminated lake

The effects of wastewater from a mining and ore-dressing mill on fish in Lake Kostomukshskoe, which is used as a cesspool of circulating water and for storage of industrial wastes produced by the Kostomuksha mining and ore-dressing mill in northwest Russia, were studied. The lake is characterized by heavy mineralization, high pH, elevated levels of K⁺, Li⁺, SO₄ ^2?, NO^2?, Cl^?, Li, Mn, and Ni, and the presence of a fine-dispersed mechanical suspension. To assess the impact of contamination on fish and determine the mechanisms of their adaptation, we investigated the biochemical indices and histology of the liver of whitefish (Coregonus lavaretus L.) and pike (Esox lucius L.) inhabiting Lake Kostomukshskoe, downstream Lake Koyvas (64° 47′ 30° 59′), and Lake Kamennoe, which is located in a nature preserve and has not been affected by anthropogenic activity (64° 28′ 30° 13′). Changes were detected in the activity of metabolic enzymes (cytochrome c oxidase (COX), lactate dehydrogenase, and glucose-6-phosphate dehydrogenase) in the liver. Specifically, the COX activity in the liver of both fish species from the contaminated lake decreased, indicating a low level of aerobic metabolism. Lipid infiltration was the most visible and widespread change observed in the liver of both fish species; therefore, it can be considered a marker of such long-term contamination. Lesions in pike liver demonstrated a wider range of severity than in those of whitefish. In summary, metabolic enzyme activity and histomorphology of the liver of whitefish and pike differed among lakes in a species-specific manner. The changes in enzyme activity and histomorphological alterations in fish that were observed can be applied for evaluation of freshwater systems that may be subjected to mineral pollution.     

Avoidance of toxic mixing zones by Atlantic salmon (Salmo salar L.) and brown trout (Salmo trutta L.) in the limed River Audna, southern Norway

Chlorophyll a (chl a) fluorescence was used to determine the effects of treatments with gaseous HF or aqueous solutions of NaF on the photosynthetic apparatus of spinach prior to the appearance of visible injury. Placing the petioles in 2 mM NaF for 3 h resulted in the accumulation of 240 ppm F in leaf blades. The second oldest leaves of spinach plants accumulated similar concentrations (270 ppm F) when the plants were exposed to gaseous HF at 5 microg F m(-3) for 6 days. These NaF and HF treatments did not result in visible injury nor did they affect Fo, Fm or Fv/Fm. However, during the slow (>2 s) induction kinetics, fluorescence quenching in fluoride-treated leaves increased during the P to S phase and the M peak was no longer resolved. This was due, in part, to increased photochemical quenching. The results are consistent with a reduced ability to develop or maintain a trans-thylakoid proton gradient in chloroplasts containing elevated concentrations of F.     

Uptake of oxytetracycline and its phytotoxicity to alfalfa (Medicago sativa L.)

A series of experiments were conducted in a hydroponic system to investigate the uptake of oxytetracycline (OTC) and its toxicity to alfalfa (Medicago sativa L.). OTC inhibited alfalfa shoot and root growth by up to 61% and 85%, respectively. The kinetics of OTC uptake could be well described by Michaelis-Menten equation with Vmax of 2.25 micromol g-1 fresh weight h-1, and Km of 0.036 mM. The uptake of OTC by alfalfa was strongly inhibited by the metabolic inhibitor, 2,4-DNP (2,4-dinitrophenol), at pH 3.5 and 6.0, but not by the aquaporin competitors, glycerol and Ag+. OTC uptake, however, was significantly inhibited by Hg2+, suggesting that the inhibition of influx was due to general cellular stress rather than the specific action of Hg2+ on aquaporins. Results from the present study suggested that OTC uptake into alfalfa is an energy-dependent process.     

Photodegradation of PCDD/Fs adsorbed on spruce (Picea abies (L.) Karst.) needles under sunlight irradiation

Spruce (Picea abies (L.) Karst.) needles were exposed to exhaust gas containing polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) generated by combustion of polyvinyl chloride, wood, high-density polyethylene, and styrene. Photodegradation of PCDD/Fs adsorbed on spruce needles under sunlight irradiation was studied. The photodegradation of PCDD/Fs follows pseudo-first-order reaction kinetics, with photolysis half-lives ranging between 40 and 100 h. The photolysis rates of PCDF congeners are higher than PCDD congeners with the same chlorinated substitutions. Higher chlorinated PCDD/Fs tend to photolyze slowly. The wax components in spruce needles may act as proton donors and accelerate the photolysis rate. C-Cl cleavage through the addition of protons to PCDD/F molecules may be an important route for PCDD/Fs photodegradation.     

Residual behaviour and risk assessment of flubendiamide on chickpea (Cicer arietinum L.)

The study was undertaken to determine the disappearance trends of flubendiamide residues on chickpea under field conditions and thereby, ensure consumer safety. Average initial deposits of flubendiamide on chickpea pods were found to be 0.68 and 1.17 mg kg⁻¹, respectively, following three applications of flubendiamide 480SC @ 48 and 96 g a.i. ha⁻¹ at 7 d intervals. Half-life of flubendiamide on chickpea pods was observed to be 1.39 and 1.44 d, respectively, at single and double dosages whereas with respect to chickpea leaves, these values were found to be 0.77 and 0.86 d. Desiodo flubendiamide was not detected at 0.05 mg kg⁻¹ level on chickpea samples collected at different intervals. Theoretical maximum residue contribution (TMRC) for flubendiamide was calculated and found to be well below the maximum permissible intake (MPI) on chickpea pods and leaves at 0-day (1 h after spraying) for the both dosages. Thus, the application of flubendiamide at the recommended dose on chickpea presents no human health risks and is safe to the consumers.     

Nitrogen oxide fluxes between corn (Zea mays L.) leaves and the atmosphere

In the United States, fertilized corn fields, which make up approximately 5% of the total land area, account for approximately 45% of total soil NO_x emissions. Leaf chamber measurements were conducted of NO and NO₂ fluxes between individual corn leaves and the atmosphere in (1) field-grown plants near Champaign, IL (USA) in order to assess the potential role of corn canopies in mitigating soil–NO_x emissions to the atmosphere, and (2) greenhouse-grown plants in order to study the influence of various environmental variables and physiological factors on the dynamics of NO₂ flux. In field-grown plants, fluxes of NO were small and inconsistent from plant to plant. At ambient NO concentrations between 0.1 and 0.3 ppbv, average fluxes were zero. At ambient NO concentrations above 1 ppbv, NO uptake occurred, but fluxes were so small (14.3±0.0 pmol m⁻² s⁻¹) as to be insignificant in the NO_x inventory for this site. In field-grown plants, NO₂ was emitted to the atmosphere at ambient NO₂ concentrations below 0.9 ppbv (the NO₂ compensation point), with the highest rate of emission being 50 pmol m⁻² s⁻¹ at 0.2 ppbv. NO₂ was assimilated by corn leaves at ambient NO₂ concentrations above 0.9 ppbv, with the maximum observed uptake rate being 643 pmol m⁻² s⁻¹ at 6 ppbv. When fluxes above 0.9 ppbv are standardized for ambient NO₂ concentration, the resultant deposition velocity was 1.2±0.1 mm s⁻¹. When scaled to the entire corn canopy, NO₂ uptake rates can be estimated to be as much as 27% of the soil-emitted NO_x. In greenhouse-grown and field-grown leaves, NO₂ deposition velocity was dependent on incident photosynthetic photon flux density (PPFD; 400–700 nm), whether measured above or below the NO₂ compensation point. The shape of the PPFD dependence, and its response to ambient humidity in an experiment with greenhouse-grown plants, led to the conclusion that stomatal conductance is a primary determinant of the PPFD response. However, in field-grown leaves, measured NO₂ deposition velocities were always lower than those predicted by a model solely dependent on stomatal conductance. It is concluded that NO₂ uptake rate is highest when N availability is highest, not when the leaf deficit for N is highest. It is also concluded that the primary limitations to leaf-level NO₂ uptake concern both stomatal and mesophyll components.     

Vanishing seagrass (Zostera marina, L.) in Swedish coastal waters

Along the Swedish Skagerrak coast eelgrass (Zostera marina) is a dominant phanerogam on shallow soft bottoms. Eelgrass meadows are important biotopes for many crustacean and fish species being either migratory or stationary. During the 1980s, inventories of the shallow coastal areas with eelgrass have been carried out along the Swedish west coast as a basis for coastal zone management. In the present study we revisited 2000 ha of eelgrass meadows in 5 coastal regions along 200 km of the Skagerrak coast. The inventory was made with the same methods (aquascope) as during the 1980s, but increasing the mapping accuracy by using a Global Positioning System (GPS). The results from this study show that the areal extension of Zostera marina has decreased 58% in 10-15 years with great regional variations. The decline was mainly restricted to the shallow parts of the meadow. The causes and ecological consequences are discussed.     

Alteration of physiological parameters in needles of cloned spruce trees (Picea abies (L.) Karst.) by ozone and acid mist

Three-year-old clonal spruce trees, kept in growth chambers, were treated with ozone and acid mist during a period of 14 months. One half of the trees were grown on an acidic sandy soil, the other half on a calcareous soil rich in carbonate. At the end of the fumigation period, carbohydrates (glucose, fructose, sucrose, raffinose, starch, glucose-1-phosphate and fructose-6-phosphate) and parameters of the energy status (ATP-, AdN-(ATP + ADP + AMP)- levels, ATP/ADP-ratios and adenylate-energy-charge-(AEC)-values) were determined in the current-year's needles. The results indicate that the metabolic status of a plant tissue is not only influenced by the nature of the air pollutants. Soil factors play an important role in metabolic changes within the plant and are thus of relevance in the manifestation of damage symptoms.     

Uptake and biotransformation of arsenate in the lichen Hypogymnia physodes (L.) Nyl

The uptake and metabolism of arsenate, As(V), as a function of time and concentration were examined in the lichen Hypogymnia physodes (L.) Nyl. Lichen thalli were exposed to As(V) in the form of a solution. Exponential uptake of As(V) from 4 microg mL(-1) As(V) solution was accompanied by constant arsenite, As(III), excretion back into the solution. Arsenate taken up into the lichens from 0, 0.1, 1, 10 microg mL(-1) As(V) solutions was partially transformed into As(III), dimethylarsinic acid (DMA) and (mono)methylarsonic acid (MA). 48 h after exposure, the main arsenic compound in the lichens was DMA in 0.1, As(III) in 1 and As(V) in 10 microg mL(-1) treatment. The proportion of methylated arsenic compounds decreased with increasing arsenate concentration in the exposure solution. These results suggest that at least two types of As(V) detoxification exist in lichens; arsenite excretion and methylation.     

Effects of low-level long-term ozone fumigation and acid mist on photosynthesis and stomata of clonal Norway spruce (Picea abies (L.) Karst.)

Four clones of 3-year-old Norway spruce (Picea abies (L.) Karst.), grown on two soils, were from July 1986 to September 1987 exposed to ozone fumigation (50 microg m(-3) as a control, 100 microg m(-3) plus peaks between 130 and 360 microg m(-3) as treatment) and acid mist of pH 3.0 (versus mist pH 5.6 in the control). Climatic conditions, identical for both control and treatment, followed a diurnal and seasonal pattern characteristic of medium high altitudes of the Bavarian Forest, an area affected by the new-type forest decline. Gas-exchange measurements were carried out on the plants from December 1986 until the end of the 14-month's exposure using a series of climate-controlled minicuvettes. ANOVA of the four clones investigated towards the end of the experiment gave hints of a treatment-related depression of the photosynthetic capacity of the previous year's needles (age-class 1986). Within this age-class only one of the clones (11) showed a significant treatment effect, indicating an age-class dependence and a genetic influence of the treatment-related depression of the photosynthetic capacity. The current year's flush was not impaired through the ozone and acid mist exposure. Analysis also revealed clear effects of soil, clone and needle age on photosynthetic parameters.     

Evaluation of kapok (Ceiba pentandra (L.) Gaertn.) as a natural hollow hydrophobic-oleophilic fibrous sorbent for oil spill cleanup

Oil sorption capacity and hydrophobic-oleophilic characteristics of an agricultural product, kapok (Ceiba pentandra), was thoroughly examined. The kapok fiber has a hollow structure with large lumen. Its performance was compared with that of a polypropylene (PP), a widely used commercial oil sorbent for oil spill cleanup. The oils investigated were diesel, hydraulic oil (AWS46), and engine oil (HD40). Reusability of the kapok after application to various oils was also evaluated. Both loose (at its natural state) and densely packed kapok assemblies were examined. Sorption capacities of the packed kapok assemblies were very much dependent on their packing densities. At 0.02gcm(-3), its oil sorption capacities were 36, 43 and 45gg(-1) for diesel, ASW46 and HD40, respectively. The values decreased to 7.9, 8.1 and 8.6gg(-1) at 0.09gcm(-3). Its sorption capacities for the three oils were significantly higher than those of PP. When the oil-saturated kapok assemblies were allowed to drain, they exhibited high oil retention ability, with less than 8% of the absorbed diesel and HD40, and 12% of the absorbed AWS46 lost even after 1h of dripping. When applied on oil-over-water baths, the kapok exhibited high selectivity for the oils over the water; almost all oils spilled could be removed with the kapok, leaving an invisible oil slick on water. After the 4th cycle of reuse, the reused kapok assembly only lost 30% of its virgin sorption capacity if packed at 0.02gcm(-3), and the loss in sorption capacity was much less at higher packing densities. The hydrophobic-oleophilic characteristics of the kapok fiber could be attributed to its waxy surface, while its large lumen contributed to its excellent oil absorbency and retention capacity.     

Zinc compartmentation in Halimione portulacoides (L.) Aellen and some effects on leaf ultrastructure

Introduction

The halophyte Halimione portulacoides collected in a polluted area of the river Sado estuary (Portugal) and obtained from hydroponic cultures was used to evaluate the compartmentation of Zn and its preferential binding sites. In parallel, we tried to assess if the minimum available Zn concentration found in marsh soil induces changes at the ultrastructural level.

Materials and methods

A sequential extraction method was used to study the Zn compartmentation within the cell. Both dried plant samples and extracts/residues from compartmentation studies were digested by HNO₃?CHClO₄ (4:1) until dryness and analyzed by atomic absorption spectrophotometry. Segments of young leaves, previously exposed to Zn were fixed in glutaraldehyde and osmium tetroxide. Ultrathin sections were stained and examined by transmission electron microscopy at 80 kV.

Results and discussion

Proteins and carbohydrates of the cell walls constitute preferential binding sites of Zn, containing between 25% and 33% and between 30% and 40% of the total, respectively. Hydroponic plants accumulate Zn in their leaves up to (194 ??g g^?1) without visible damage or changes in the protein and chlorophyll concentrations, compared with the controls. Chlorenchyma chloroplasts of Zn-treated plants exhibited an unusual number of starch grains, which can be seen as an alert mechanism.

Conclusions and perspectives

Although so far the levels of Zn in the leaves within the studied area have not reached high values, monitoring them remains a priority. Also, issues related with starch synthesis and organic ligands must be evaluated. The understanding of the predictable behavior of this halophyte is our main goal, and the results here presented can contribute to this achievement.     

Inheritance of ambient ozone insensitivity in common bean (Phaseolus vulgaris L.)

The inheritance of ozone (O(3)) insensitivity in common bean (Phaseolus vulgaris L.) was evaluated using F(2) and F(3) populations under ambient conditions. This study was conducted over two growing seasons (1987, 1988) at Virginia State University, Randolph Research Farm, Petersburg, Virginia. Two populations were obtained by crossing insensitive plant introductions with sensitive commercial cultivars. Ratings on the scale of 1 to 5 (1 = 0 to 20% leaf injury, 2 = 21 to 40%, 3 = 41 to 60%, 4 = 61 to 80%, and 5 > 80%) were made on 160 F(2), F(3) progenies, and parental lines. Population mean injury ratings were recorded and estimates of genotypic, environmental, and phenotypic variances were computed. Estimates of heritability in the broadsense and of genetic advance were calculated for each population using F(2) and family component variance methods. Population means of the F(2) and F(3) progenies were not significantly different from their mid-parent values, suggesting that genetic variance was primarily additive. Broad-sense heritability estimates using F(2) variance method ranged from 51.4 to 70.5% and using family component variance method ranged from 62.1 to 75.6%. In this study, the computed genetic advance values closely parallel those of heritability estimated values. The high heritable nature of insensitivity would indicate that effective levels of insensitivity could be transferred to agronomically superior cultivars in a relatively short time.     

Interaction between cadmium and atrazine during uptake by rice seedlings (Oryza sativa L.)

The uptake of atrazine by rice seedlings (Oryza sativa L.) through plant roots from nutrient solution was investigated in the presence and absence of Cd2+ over an exposure period of four weeks. It was found that both atrazine and Cd2+ were toxic to rice seedlings. Both shoot and root biomasses decreased when the seedlings were exposed to increasing atrazine or Cd2+ concentrations in nutrient solutions. In the absence of Cd2+, a linear relationship was observed between atrazine concentrations in roots/shoots and in external solution, and more atrazine is concentrated in roots than in shoots. When atrazine and Cd2+ concentrations in solution were maintained at mole ratio of 1:1, the accumulation of atrazine by seedlings was less and the seedling biomass was greater than found with other ratios, such as 1:2 or 2:1. Therefore, the formation of the complex between atrazine and Cd2+ reduced the individual toxicities. Analyses of data with the quasi-equilibrium partition model indicated that the atrazine concentrations in rice seedlings and external water were close to equilibrium. In the presence of Cd2+, however, the measured bioconcentration factor (BCF) of atrazine with roots and shoots were considerably greater. The latter findings resulted presumably from the atrazine-Cd2+ complex formation that led to a large apparent BCF.     

Monitoring behavioural responses to metals inGammarus pulex (L.) (Crustacea) with impedance conversion

Environmental Science and Pollution Research - An impedance conversion technique was used to study the behaviour ofGammarus pulex (L.) exposed to acutely toxic concentrations of Pb (0.01, 0.05, 0.1...