1,720,973 research outputs found
Improved arsenic phytoextraction by combined use of mobilizing chemicals and autochthonous soil bacteria
No full textProper plant selection and application of suitable strategies are key factors to ensure the effectiveness of a reclamation via phytoremediation approach. In this study, micro- and meso-cosm scale experimentation has been realized to address a persistent contamination by arsenic on a disused industrial site through an assisted phytoremediation intervention. Three crop species, namely Brassica juncea, Helianthus annuus and Zea mays, have been considered and the addition of K2HPO4, a common mobilizing agent for As, or (NH4)S2O3, a promising additive for As mobilization in case of mercury co-presence, evaluated. The use of these additives significantly enhanced the bioavailability of the target contaminant and therefore its phytoextraction up to 80%. Furthermore, in order to maximize the extraction efficiency of the plants, the influence of five indigenous Plant Growth Promoting Bacteria (PGPB), in combination with the mobilizing agents, was measured. The addition of the microbial consortium led to a further increase in the total uptake of arsenic, especially in B. juncea (up to 140%). The combined strategy supports and enhances the arsenic phytoextraction together with an improvement of the soil quality, as shown by phytotoxicity tests
Dealing with complex contamination: A novel approach with a combined bio-phytoremediation strategy and effective analytical techniques
No full textPhytoremediation is a sustainable technology capable of efficiently removing low or moderate contamination. However, complex pollution conditions can drastically reduce efficiency, as plants can show themselves sensitive to organic contaminants, growing slowly and thus impairing metals' absorption. In cases where the action of indigenous bacteria degrading hydrocarbons and promoting plant growth is not sufficient, more sophisticated strategies are necessary.
This investigation aims to evaluate the effectiveness of a train of technologies that sees advanced phytoremediation in combination with other biological approaches to remediate soil from a disused industrial area contaminated by N-containing compounds, alkyl aromatic hydrocarbons, copper, and nickel. In particular, a stepwise procedure was used with a pre-treatment (landfarming and bioaugmentation), significantly affecting the soil's fertility, increasing germinability up to 85%, and allowing the plants to extract the metals adequately. Furthermore, with EDTA as a mobilizing agent, nickel absorption has increased up to 36% in Helianthus annuus and up to 88% in Zea mays. For copper, an increase of up to 262% in Helianthus annuus and up to 202% in Zea Mays was obtained. Analysis through Fourier-Transform Ion Cyclotron Resonance Mass Spectrometry highlighted the biodegradation of some of the N-containing compounds recording, after phytoremediation, a decrease of up to almost 90%. Metagenomic analysis of the soil showed a typical microbial population of oxidizing hydrocarbon strains with a prevalence of the Nocardiaceae family (43%). The results obtained appear to confirm the usefulness of the approach developed, and the employed cutting-edge analytical techniques allowed a top-notch characterization of the remediation scenario
Low-impact Management of Produced Water: Assessing Phytodepuration with Halocnemun Strobilaceum and Suaeda fruticosa
Full text linkOil-produced waters are the most abundant wastewater stream in oil exploration and production, and their treatment is one of the most expensive processes in the petroleum industry. Since one of the peculiar characteristics of oil-produced waters is the presence of high salinity, developing an effective phytoremediation system for this type of wastewater first requires the selection of salt-tolerant plants. In this contribution, Halocnemum strobilaceum (Pallas) M. Bieb. and Suaeda fruticosa (L.) Forsk. were tested in experiments with mesocosms trials at different saline concentrations and hydrocarbons to study the plants tolerance and the hydrocarbon degradation capacity. The experimental campaign showed species-specific results: Halocnemum showed better tolerance to salt and hydrocarbons, and Suaeda showed better performance as hydrocarbon degradation.
The metagenomic analysis carried out on the roots of the plants at the end of the test highlighted a significant speciation of the microbial communities, especially evident at the family level. The differences detected were found both in the comparison between the different treatments and between the two plant species. In general, the Pseudomonadaceae family was predominant in mesocosms with Suaeda, whereas the Halomonadaceae family was dominant in those with Halocnemum.
In parallel, some strains showing good potential for promoting plant growth were isolated. In conclusion, the experimentation allowed to identify the operating conditions for which the technology could be exploited as a sustainable alternative to consolidated technologies
Overcoming limitation of “recalcitrant areas” to phytoextraction process: The synergistic effects of exogenous cytokinins and nitrogen treatments
No full textThe aim of the present work was to test the efficiency of the phytoextraction process involving the use of exogenous phytohormone (cytokinins, CKs) and fertilizer (nitrogen, N) treatments in phytotechnologies to address risk management in “recalcitrant areas”. The CKs and N treatments, alone or combined (CKs + N) in a Modulated Application (MA), were tested on the crop plant Helianthus annuus, common to Mediterranean area, fast growing and with high biomass production. Plants were grown on boron (B) contaminated sediments (collected from a geothermal area located in Tuscany (Italy). Plant growth, B uptake, together with plant stress parameters were investigated. Boron is easily taken up and translocated by some crop plants, but the high phytotoxicity can dramatically impact the plant growth and consequently the applicability and efficiency of the phytoextraction process. As indicators of plant stress, oxidative balance and photosynthetic parameters were investigated to give a deeper insight of phytotoxic mechanisms. Results showed that while each treatment (CKs and N alone) had significantly positive effects on plant health, the MA treatment provided a synergistic effect on morphological parameters and biomass production as a whole. After MA treatment, plants showed antioxidant activity comparable to that of the control (unpolluted sediments) and showed an increase of net photosynthesis. Moreover, our data showed very high values of B uptake and translocation (about 800 mg kg−1 in shoots), without any alteration triggered by the treatments (CKs and N alone or combined in MA). B phytoextraction resulted increased about fivefold with the MA treatments, while each treatment alone increased only two or three folds when treated with either CKs or N. The MA treatment is not “contaminant specific”, so it could be applied in other “recalcitrant areas” where different types of contaminations occur, in order to overcome limitations of plant growth
Enhanced Lead Phytoextraction by Endophytes from Indigenous Plants
No full textLead (Pb) is one of the most common metal pollutants in soil, and phytoextraction is a sustainable and cost-effective way to remove it. The purpose of this work was to develop a phytoextraction strategy able to efficiently remove Pb from the soil of a decommissioned fuel depot located in Italy by the combined use of EDTA and endophytic bacteria isolated from indigenous plants. A total of 12 endophytic strains from three native species (Lotus cornicolatus, Sonchus tenerrimus, Bromus sterilis) were isolated and selected to prepare a microbial consortium used to inoculate microcosms of Brassica juncea and Helianthus annuus. As for B. juncea, experimental data showed that treatment with microbial inoculum alone was the most effective in improving Pb phytoextraction in shoots (up to 25 times more than the control). In H. annuus, on the other hand, the most effective treatment was the combined treatment (EDTA and inoculum) with up to three times more Pb uptake values. These results, also validated by the metagenomic analysis, confirm that plant-microbe interaction is a crucial key point in phytoremediation
Soil Remediation: Towards a Resilient and Adaptive Approach to Deal with the Ever-Changing Environmental Challenges
No full textPollution from numerous contaminants due to many anthropogenic activities affects soils quality. Industrialized countries have many contaminated sites; their remediation is a priority in environmental legislation. The aim of this overview is to consider the evolution of soil remediation from consolidated invasive technologies to environmentally friendly green strategies. The selection of technology is no longer exclusively based on eliminating the source of pollution but aims at remediation, which includes the recovery of soil quality. “Green remediation” appears to be the key to addressing the issue of remediation of contaminated sites as it focuses on environmental quality, including the preservation of the environment. Further developments in green remediation reflect the aim of promoting clean-up strategies that also address the effects of climate change. Sustainable and resilient remediation faces the environmental challenge of achieving targets while reducing the environmental damage caused by clean-up interventions and must involve an awareness that social systems and environmental systems are closely connected
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Genotoxic effects of Boron contaminated sediments from Cecina basin (Tuscany) on Vicia faba L
No full textIn this work a Boron contaminated sediment from the Cecina basin in Tuscany (Italy) was considered for its possible genotoxic effects on plants. The greatest part of Cecina basin is located in the geothermal zone of Larderello, where for about a hundred years the mine activities in this area and more recently the geothermoelectric industry spilled in the Possera and Pavone creeks (tributaries of Cecina river) until about 1975. However, contamination is still present in certain areas of the basin with high level of B
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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