خيارات البحث
النتائج 691 - 700 من 1,506
Massive sedimentation of fine sediment with organic matter and enhanced benthic–pelagic coupling by an artificial dyke in semi-enclosed Chonsu Bay, Korea
2012
Lee, Jae-seong | Kim, Kee Hyun | Shim, JungHee | Han, Jeong Hee | Choi, Yang Ho | Khang, Bhum-Joo
To assess the impact of an artificial dyke in Chonsu Bay (CBD) on the organic carbon (Cₒᵣg) cycle, we measured excess ²¹⁰Pb activities, Cₒᵣg and nitrogen content in sediment cores. The Cₒᵣg oxidation rates (Cₒₓ) on the surface sediment and benthic nutrient fluxes were also quantified with an in situ benthic chamber. The higher excess ²¹⁰Pb inventory, Cₒᵣg and nitrogen in cores near the CBD indicated lateral transport and local, massive deposition of particulate matter due to tidal circulation altered by artificial dyke construction. The Cₒₓ in sediment near the CBD was about twice as high as that out of the bay, suggesting the importance of benthic remineralization of organic matter. The benthic fluxes of dissolved inorganic nitrogen and phosphate were four to six times higher than those outside the bay, corresponding to 141% and 131% respectively, of the requirements for primary production.
اظهر المزيد [+] اقل [-]The plant family Brassicaceae
2012
Anjum, Naser A.
Can pollution bias peatland palaeoclimate reconstruction?
2012
Payne, R.J. | Mitchell, E.A.D. | Hung Nguyen-Viet | Gilbert, D.
Peatland testate amoebae are widely used to reconstruct paleohydrological/climatic changes, but many species are also known to respond to pollutants. Peatlands around the world have been exposed to anthropogenic and intermittent natural pollution through the late Holocene. This raises the question: can pollution lead to changes in the testate amoeba paleoecological record that could be erroneously interpreted as a climatic change? To address this issue we applied testate amoeba transfer functions to the results of experiments adding pollutants (N, P, S, Pb, O3) to peatlands and similar ecosystems. We found a significant effect in only one case, an experiment in which N and P were added, suggesting that pollution-induced biases are limited. However, we caution researchers to be aware of this possibility when interpreting paleoecological records. Studies characterising the paleoecological response to pollution allow pollution impacts to be tracked and distinguished from climate change.
اظهر المزيد [+] اقل [-]Determination of agri-environmental risks on the 4 watersheds studied in the SUDOE area | Détermination des risques agro-environnementaux sur les 4 bassins versants étudiés dans la zone SUDOE
2012
Macary, Francis | Sánchez-Pérez, J.M.
L’identification des zones des bassins versants, potentiellement contributrices en contaminants d’origine agricole, est effectuée par une modélisation spatiale (méthode PIXAL) en croisant des indicateurs spatialisés de la vulnérabilité des eaux de surface avec ceux de la pression agricole. Ces indicateurs qui traduisent les facteurs de risque sont choisis d’abord suivant leur pertinence à l’égard des milieux sur les espaces géographiques considérés, mais aussi suivant la disponibilité des données nécessaires en ce qui concerne l’évaluation de la vulnérabilité des eaux de surface. Les pressions anthropiques d’origine agricole résultent du croisement entre l’occupation du sol et les pratiques agricoles pour une campagne donnée. L’occupation du sol est obtenue soit à partir d’images satellitales pour les grands bassins versants tels que Save, Flumen, soit à partir des données parcellaires du SIG-PAC pour les petits bassins tels qu’Alegria, Enxoe.
اظهر المزيد [+] اقل [-]Biosorption of Toxic Heavy Metal Ions from Water Environment Using Honeycomb Biomass—An Industrial Waste Material
2012
Reddy, Desireddy Harikishore Kumar | Lee, Seung-Mok | Seshaiah, Kalluru
This paper examined the ability of honeycomb biomass (HC), a by-product of the honey industry, to remove Pb(II), Cd(II), Cu(II), and Ni(II) ions from aqueous solutions. The equilibrium adsorptive quantity was determined as a function of the solution pH, amount of biomass, contact time, and initial metal ion concentration in a batch biosorption technique. Biosorbent was characterized by Fourier transform infrared (FTIR), scanning electron microscopy with energy-dispersive X-ray, and X-ray diffraction studies. FTIR spectral analysis confirmed the coordination of metals with hydroxyl, carbonyl, and carboxyl functional groups present in the HC. The metals uptake by HC was rapid, and the equilibrium time was 40 min at constant temperature and pH. Sorption kinetics followed a nonlinear pseudo-second-order model. Isotherm experimental data were fitted to Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin isotherm models in nonlinear forms. The mechanism of metal sorption by HC gave good fits for Langmuir model, and the affinity order of the biosorbent for four heavy metals was Pb(II)>Cd(II)>Cu(II)>Ni(II). The thermodynamic studies for the present biosorption process were performed by determining the values of ΔG°, ΔH°, and ΔS°, and it was observed that biosorption process is endothermic and spontaneous. This work provides an efficient and easily available environmental friendly honeycomb biomass as an attractive option for removing heavy metal ions from water and wastewater.
اظهر المزيد [+] اقل [-]Assessment of the Intrinsic Vulnerability of Agricultural Land to Water and Nitrogen Losses via Deterministic Approach and Regression Analysis
2012
Aschonitis, V. G. | Mastrocicco, M. | Colombani, N. | Salemi, E. | Kazakis, N. | Voudouris, K. | Castaldelli, G.
A set of indices was developed in order to classify the vulnerability of agricultural land to water and nitrogen losses (LOS), setting a basis for the integrated water resources management in agricultural systems. To calibrate the indices using multiple regression analysis, the simulation results of Groundwater Loading Effects of Agricultural Management Systems (GLEAMS) model for combinations of different soil properties, topography, and climatic conditions of a reference field crop were used as “observed values.” GLEAMS quantified (1) the annual losses of the percolated water beneath the root zone, (2) the annual losses of the surface runoff, (3) the annual losses of the nitrogen leaching beneath the root zone, and (4) the annual losses of nitrogen through the surface runoff, which were used to calibrate the following indices LOSW-P, LOSW-R, LOSN-PN, and LOSN-RN, respectively. All the simulations to gain the LOS indices were carried out for the same reference field crop, the same nitrogen fertilization, and the same irrigation practice, in order to obtain the intrinsic vulnerability of agricultural land to water and nitrogen losses. The LOS indices were also combined to derive nitrogen concentrations in the percolated and in the runoff water. Finally, the connection of LOS indices with the groundwater was performed using an additional equation, which determines the minimum transit time of the percolated water to reach the groundwater table.
اظهر المزيد [+] اقل [-]Interactive and Single Effects of Ectomycorrhiza Formation and Bacillus cereus on Metallothionein MT1 Expression and Phytoextraction of Cd and Zn by Willows
2012
Hrynkiewicz, Katarzyna | Dąbrowska, Grażyna | Baum, Christel | Niedojadlo, Katarzyna | Leinweber, Peter
Single and joint ectomycorrhizal (+ Hebeloma mesophaeum) and bacterial (+ Bacillus cereus) inoculations of willows (Salix viminalis) were investigated for their potential and mode of action in the promotion of cadmium (Cd) and zinc (Zn) phytoextraction. Dual fungal and bacterial inoculations promoted the biomass production of willows in contaminated soil. Single inoculations either had no effect on the plant growth or inhibited it. All inoculated willows showed increased concentrations of nutritional elements (N, P, K and Zn) and decreased concentrations of Cd in the shoots. The lowest biomass production and concentration of Cd in the willows (+ B. cereus) were combined with the strongest expression of metallothioneins. It seems that biotic stress from bacterial invasion increased the synthesis of these stress proteins, which responded in decreased Cd concentrations. Contents of Cd and Zn in the stems of willows were combination-specific, but were always increased in dual inoculated plants. In conclusion, single inoculations with former mycorrhiza-associated B. cereus strains decreased the phytoextraction efficiency of willows by causing biotic stress. However, their joint inoculation with an ectomycorrhizal fungus is a very promising method for promoting the phytoextraction of Cd and Zn through combined physiological effects on the plant.
اظهر المزيد [+] اقل [-]The Influence of Cadmium Stress on the Content of Mineral Nutrients and Metal-Binding Proteins in Arabidopsis halleri
2012
Przedpełska-Wąsowicz, Ewa | Polatajko, Aleksandra | Wierzbicka, Małgorzata
We investigated the influence of cadmium stress on zinc hyperaccumulation, mineral nutrient uptake, and the content of metal-binding proteins in Arabidopsis halleri. The experiments were carried out using plants subjected to long-term cadmium exposure (40 days) in the concentrations of 45 and 225 μM Cd²⁺. Inductively coupled plasma-mass spectrometry, size exclusion chromatography coupled with plasma-mass spectrometry, and laser ablation inductively coupled plasma-mass spectrometry used for ablation of polyacylamide gels were employed to assess the content of investigated elements in plants as well as to identify metal-binding proteins. We found that A. halleri is able to translocate cadmium to the aerial parts in high amounts (translocation index >1). We showed that Zn content in plants decreased significantly with the increase of cadmium content in the growth medium. Different positive and negative correlations between Cd content and mineral nutrients were evidenced by our study. We identified more than ten low-molecular-weight (<100 kDa) Cd-binding proteins in Cd-treated plants. These proteins are unlikely to be phytochelatins or metallothioneins. We hypothesize that low-molecular-weight Cd-binding proteins can be involved in cadmium resistance in A. halleri.
اظهر المزيد [+] اقل [-]Use of Biosolids for Phytocapping of Landfill Soil
2012
Lamb, Dane T. | Heading, Stephen | Bolan, Nanthi | Naidu, R.
Conventional clay capping for post-closure management of landfill commonly cracks and deteriorates over time. As a consequence, water ingress into waste increases as a function of time, potentially causing a range of environmental issues. An alternative approach is known as phytocapping, which utilizes select plant species to control cap stability and moisture percolation. In this study, growth of Arundo donax L. (giant reed), Brassica juncea (L.) Czern. (Indian mustard), and Helianthus annuus L. (sunflower) on a landfill site was studied with different biosolid amendment rates (0, 25, and 50 Mg ha−1). Cultivation of the landfill cap and amendment with biosolids significantly improved the characteristics of the soil. Growth of each plant species increased due to biosolid addition. Giant reed produced the largest biomass in the 50 Mg ha−1 biosolid amendment rate (38 Mg ha−1 dry weight). The high pH and clay content of landfill cap soil, and the low metal concentrations of the biosolid resulted in low heavy metal (copper, zinc, cadmium, and lead) accumulation in leaves of most treatments. The improvement in growth and limited uptake of metal contaminants to plant shoots indicated that biosolid application to landfill clay caps improves the application of phytocapping of old landfill sites.
اظهر المزيد [+] اقل [-]Twenty-Year Road Traffic Emissions Trend in Greece
2012
Progiou, Athena | Ziomas, Ioannis
Air pollutants emissions from traffic are very closely connected to urban air quality, in a local scale, as well as to global problems like climate change, in a large scale. Road transport air pollutants emissions represent, in most cases, a critical parameter for a comprehensive and successful understanding of the mechanisms governing the air pollutants concentrations. Hence, reliable estimations and comprehension of road transport emissions are indispensable in order to set reliable strategies in the direction of air pollution abatement and management of air pollutants and greenhouse gases emissions. In this framework, in the present work, the emissions of air pollutants from road transport in Greece will be presented for the whole period 1990–2009 as it was found that a detailed, accurate and reliable emissions inventory was missing. The whole period emissions variation has clarified the impact of the change in the vehicle fleet, the engine technologies and the fuel quality. The calculated results have revealed that the age of the vehicles and the corresponding engine technology are the critical parameters determining the amount of the pollutants emitted. This was mainly observed in both passenger cars and heavy duty vehicles demonstrating the importance of a renewal programme of the old circulating vehicles in order to set an effective air pollution abatement strategy. Passenger cars were found to be responsible for the major part of most air pollutants emissions except from nitrogen oxides and particulates emissions. Heavy duty vehicles contribute more than 66% to nitrogen oxides and particulates emissions. For the whole time period, all calculated pollutants present a decreasing trend, with the exception of carbon dioxide and nitrous oxide which increase constantly, ranging from −96% for sulphur dioxide to −1% for PM10.
اظهر المزيد [+] اقل [-]