Green roofs as a biotechnological solution to increase water retention in urban areas

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Extensive green roofs: different time approaches to runoff coefficient determination

Stormwater runoff in green roofs (GRs) is represented by the runoff coefficient, which is fundamental to assess their hydraulic performance and to design the drainage systems downstream. Runoff coefficient values in newly installed GR systems should be estimated by models that must be feasible and reproduce the retention behavior as realistically as possible, being thus adjusted to each season and climate region. In this study, the suitability of a previously developed model for runoff coefficient determination is assessed using experimental data, and registered over a 1 year period. Results showed that the previously developed model does not quite fit the experimental data obtained in the present study, which was developed in a distinct year with different climate conditions, revealing the need to develop a new model with a better adjustment, and taking into consideration other variables besides temperature and precipitation (e.g., early-stage moisture conditions of the GR matrix and climate of the study area). Runoff coefficient values were also determined with different time periods (monthly, weekly, and per rain event) to assess the most adequate approach, considering the practical uses of this coefficient. The monthly determination approach resulted in lower runoff coefficient values (0–0.46) than the weekly or per rain event (0.017–0.764) determination. When applied to a long-term performance analysis, this study showed no significant differences when using the monthly, weekly, or per rain event runoff, resulting on a variation of only 0.9 m3 of annual runoff. This indicates that the use of monthly values for runoff coefficient, although not suitable for sizing drainage systems, might be used to estimate their long-term performance. Overall, this pilot extensive GR of 0.4 m2 presented an annual retention volume of 469.3 L, corresponding to a retention rate of 89.6%, in a year with a total precipitation of 1089 mm. The assessment of different time scales for runoff coefficient determination is a major contribution for future GR performance assessments, and a fundamental decision support tool.info:eu-repo/semantics/publishedVersio

Epifluorescence microscope methods for bacterial enumeration in a 4-chlorophenol degrading consortium

Epifluorescence microscope methods, namely BacLight, direct epifluorescence filter technique and Rhodamine 123, consistently underestimated plate bacterial counts in a 4-chlorophenol degrading consortium. Cells capable of passing through 0.2 mgrm filters, referred as `ultramicrocells', were found. Although cell counts were higher when traditional methods were used, BacLight and direct epifluorescence filter technique were convenient techniques for the systematic monitoring of bacteria involved in biodegradation processes, as results were consistent and available within a short time

Selection and acclimatization of strains of edible mycorrhizal fungi for improved field persistence

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The effect of phosphate-solubilizing rhizobacteria on Zea mays growth on P-deficient soils

P-deficiency in soils is a limiting factor for plant growth. Several phosphate-solubilizing rhizobacteria (PSB) were used to enhance growth of Zea maysgrowing in a P-deficient soil. Strains were screened for their ability to solubilize P and to produce plant growth promoting (PGP) substances. The best-P solubilizing strains Rhodococcus sp. EC35, Pseudomonas sp. EAV and Arthrobacter nicotinovoransEAPAA were inoculated in maize growing in P-deficient soils without P fertilization and amended with soluble (KH2PO4) and insoluble P (Ca3(PO4)2). Results showed that PSB significantly enhanced Z. mays biomass production in all Ptreatments. Without P fertilization, bacterial inoculation increased plant dry biomass by ca. 20%, while under soluble P conditions the enhancement was higher. Pseudomonas sp. EAV was the strain that better performed improving rootand shoot biomass by 104% and 60%, respectively. In soils amended with insoluble P, plant biomass was also positive influenced by bacterial inoculation. Plant growth enhancement seems to be related not only to Psolubilization but also to other PGP traits, such as IAA and ACC-deaminase. This work shows that PSB may be used as bioinoculants and consequently constitute an attractive alternative to the phosphatic fertilizers amendments used to improve crop production

Plant growth promoting potential of rhizobacteria isolated from a contaminated area

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The mycorrhizal status of Phragmites australis in several polluted soils and sediments of an industrialised region of Northern Portugal

Roots of Phragmites australis from three polluted soils and sediments (a periodically flooded stream bank containing organic pollutants, a high-pH drying sedimentation pond and an acidic, periodically flooded sand polluted by industrial effluents) were sampled over a 1-year cycle of plant growth to assess the degree of colonisation by arbuscular mycorrhizal fungi (AMF). At the dry sedimentation pond, root samples of Juncus effusus and Salix atrocinerea were also taken to assess the presence of AMF throughout the year. Root colonisation was low (<5% root length colonised) but arbuscule presence peaked in P. australis during the spring and autumn prior to flowering. These changes in arbuscule abundance were also seen in a parallel greenhouse trial using seed taken from one of the sites. Roots of J. effusus contained mainly vesicular colonisation but arbuscule activity peaked during the winter months (December–March). S. atrocinerea roots were found to be ectomycorrhizal throughout the year but the fine feeder roots were colonised by AMF. The results confirm that semi-aquatics, like P. australis, can become arbuscular mycorrhizal but that this status changes during the year depending on soil moisture content and plant phenology. The influence of AMF in these polluted soils is uncertain but the potential exists to establish a more diverse plant ecosystem during the landscaping of these areas (phytostabilisation) by management of adapted plant and AMF ecotypes

Wild flowers in urban spaces

Research into wild flowers with a view to their use in urban spaces has not been undertaken in Portugal, considering their importance in ecological design. The Mediterranean climate involves the seasonally of air temperature and precipitation, which leads to a hot drought period in summer and wet period in winter. The reintroduction of native plants reduces the cost of establishing and maintaining as the sustainability green spaces. So, the aim of this work focuses on the behaviour of the native meadow in a young olive orchard, evaluating the floristic composition and its variation along the study. Three years of field experiment were performed comprising two treatments: the mobilized, in which the management of the plants was controlled through the mobilization, and the native meadowland covering until the beginning of the dry period. After that, the plants were cut off by a rotary mower. The observation of the development of the land covering was made with the help of floristical survey during the spring. The results observed in green cover, show a tendency to the increase of monocotyledonae in relation to dicotyledons