1,721,012 research outputs found
Recent Developments in Stripping Analysis on Microelectrodes
No full textThis review surveys the main aspects of the combination of microelectrodes and stripping analysis, including recent developments in working microelectrodes, analytical methodologies, instrumentation, and applications in both synthetic and real matrices. Emphasis is given to papers published since 2000
Efficiency of nutrient and heavy metals removal by Phragmites australis and Bolboshoenus maritimus growing in a re-constructed wetland
No full textAccumulation of nutrients and heavy metals in Phragmites australis (Cav.) Trin. ex Steudel and Bolboschoenus maritimus (L.) Palla in a constructed wetland of the Venice lagoon watershed
No full textA recently constructed wetland, located in the Venice lagoon watershed, was monitored to investigate growth dynamics, nutrient and heavy metal shoot accumulation of the two dominating macrophytes: Phragmites australis and Bolboschoenus maritimus. Investigations were conducted over a vegetative season at three locations with different distance to the inlet point to assess effects on vegetation. The distance from the inlet did not affect either shoot biomass or nutrients (N, P, K and Na) and heavy metals (Cr, Ni, Cu and Zn) shoot content. With the exception of Na, nutrient and heavy metal concentrations were higher in shoots of P. australis than in B. maritimus. Heavy metal concentration in the incoming water and in the soil was not correlated to the plant content of either species. Shoot heavy metal concentrations were similar to those reported in the current literature, but accumulation generally increased towards the end of the growing season
Preparation and characterization of nation coated mercury micro electrodes. Effects of the coating film dimension and thickness on the ion pre concentration step
No full textEvaluation of plant efficiency in a constructed wetland receiving treated tannery wasterwater.
No full textA free water surface pilot-plant was constructed with the aim to reduce the high concentrations of sulfate, sodium, chloride and chromium in treated tannery wastewater. The CW was composed of two cells, one planted with Phragmites australis and the other with Carex ssp. Plants were sampled monthly to evaluate the effects of wastewater on growth and the accumulation of Cr, S, Na, Cl in different plant organs.
No effects of the wastewater quality on fresh and dry weight of plants and on leaf pigment content were observed. Accumulation of cromium, sulfur, sodium and chloride was higher in roots than in shoots of both plant species. Mean Cr and S contents were recorded to be higher in P.australis plants (74.3 μg g-1 d.w. for Cr, 16.9 mg g-1 d.w. for S).than in Carex ssp. plants (16.2 μg g-1 d.w. for Cr, 12.1 mg g-1 d.w. for S). Carex ssp. plants accumulated more Na (17.4 mg g-1 d.w.) and Cl (22.7 mg g-1 d.w.) than P.australis ,12.6 mg g-1 d.w. and 18.7 mg g-1 d.w., respectively.
P.australis plants seem to be more suitable for removal of pollutants from the tannery wastewater, due to the greater biomass produced
A steady state voltammetric procedure for the determination of hydrogen ions and total acid concentration in mixtures of a strong and a weak monoprotic acid
No full textA linear sweep voltammetric (LSV) method for the simultaneous determination of free hydrogen ions and total concentration of the acids forming aqueous mixtures of a weak and a strong acid is proposed. The method is based on recording LSVs in the solutions investigated by a platinum microelectrode, and on the mathematical analysis of the voltammetric responses. In particular, the first derivative of the waves allows establishing the steady-state limiting currents due to hydrogen ions. Using the latter values, the overall LSV currents and a theoretical equation, which is valid for weak acids having dissociation constants higher than about 10-6, both hydrogen ions and total acid concentration can be evaluated. The validity and degree of accuracy of the proposed procedure is preliminarily assessed by digital simulation for mixtures of a strong acid and acetic acid (HAc). In general, an agreement between expected and evaluated (by the proposed method) concentration values within 2% is found. The proposed method is then tested in synthetic mixtures made by HClO4 and HAc at different concentrations. An application to some vinegar samples is also presented to individuate if these matrices were adulterated by strong mineral acids. For these experimental cases, the concentrations values evaluated with the proposed method and those determined by the classical titration procedure agree within 4%
Osmotic and ionic effects of NaCl and Na2SO4 salinity on Phragmites australis
No full textOsmotic and ion-specific effects of NaCl and Na(2)SO(4) on Phragmites australis (Cav.) Trin ex. Steud. were investigated in a laboratory experiment by examining effects of iso-osmotic solutions of NaCl and Na(2)SO(4) on growth, osmolality of cell sap, proline content, elemental composition and gas exchange. Plants were supplied with a control standard nutrient solution (Psi = -0.09 MPa) or solutions of NaCl or Na(2)SO(4) at water potentials of -0.50, -1.09 or -1.74 MPa. Salt treatments increased root concentrations of Na and S or Cl, whereas P. australis had efficient mechanisms for exclusion of Na and S and partly Cl ions from the leaves. Incomplete exclusion of Cl from the leaves may affect aboveground biomass production, which was significantly more reduced by NaCl than Na(2)SO(4). Stomatal conductance was negatively influenced by decreasing water potentials caused by NaCl or Na(2)SO(4), implying that a non-significant photosynthetic depression observed in plants grown at -1.74 MPa was mainly due to osmotically induced stomatal closure. This was supported by decreasing internal CO(2) concentrations. Saline conditions increased the intrinsic water use efficiency and did not alter photosynthetic parameters derived from light response curves, supporting the assumption of a well-functioning CO(2) utilization in salt stressed plants. The leaf proline concentration increased equally in NaCl and Na(2)SO(4)-treated plants, and may play an important role as a compatible organic solute. P. australis possesses a range of mechanisms conferring tolerance to both NaCl and Na(2)SO(4) stress and except in terms of growth the phytotoxicity of NaCl and Na(2)SO(4) are comparable
Adattamento di phragmites australis alla carenza di azoto e zolfo
No full textPhragmites australis Trin. is one of the most commonly used plants in phytoremediation. Although the role of this species in removing nutrients from wastewater is well recognized, very little is known about the physiological mechanisms involved. In order to bridge this gap, plants of Phragmites australis were grown in the presence of either nitrate or ammonium, and in abscence of nitrogen or sulfur.
Ammonium net uptake was higher than that of nitrate, and the nitrogen source did not affect the sulphate influx rate, which was approximately 50% higher in S-deprived
plants. Changes in the chloroplast ultrastructure were observed using a transmission electron microscope in both S- and N-deprived plants. The thylakoid systems appeared
partially disorganized, with grana size reduced, and a higher accumulation of starch was visible
Nutrient and heavy mmetals removal by macrophytes in a re-constructed wetland of the Venice lagoon watershed
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