Phytoplankton size-distribution and community structure in relation to mucilage occurrence in the northern Adriatic Sea

The spatial and temporal variations of pico-, nano- and microphytoplankton abundance and composition were investigated over a 37 month period, focusing on the ecological role of different size classes of phytoplankton, and on the changes of the community structure that might occur during periods when large mucilage macroaggregates appear. Samples were collected monthly from June 1999 to July 2002 at 11 stations, along three transects covering the northern Adriatic basin. Highest abundances were observed in late-winter/spring for microphytoplankton (mainly diatoms), in spring-summer for nanophytoplankton, and in summer for picophytoplankton. The autotrophic component was more abundant in the summers of 2000 and 2002 (when large mucilage aggregates occurred) than in the summers of 1999 and 2001 (when a massive phenomenon was not observed). This increase was statistically significant for pico-, nano- and, among microphytoplankton, only for dinoflagellates. Blooms of picophytoplankton were often observed at the bottom layer during mucilage summers. The microphytoplankton community during mucilage phenomena was characterized by a species composition (Chaetoceros spp., Cerataulina pelagica, Pseudo-nitzschia delicatissima, P. pseudodelicatissima, Cylindrotheca closterium, Dactyliosolen fragilissimus) comparable to that observed in summers without extensive mucilage occurrence. However, some species appeared with significantly higher densities in the summers of 2000 and 2002: Ceratium furca, C. closterium, Oxytoxum spp., Hemiaulus hauckii and Gonyaulax fragilis. Microscopic observation of aggregates revealed that the microphytoplankton species composition inside the aggregates was comparable to that observed in the water column, with an enrichment of opportunistic species such as C. closterium and P. delicatissima. The presence of mucilage aggregates affects the phytoplankton populations in the water column, even when aggregates are at early stages. It seems that there is a mutual relationship between phytoplankton and aggregates, i.e., several diatom and dinoflagellate species may contribute to the aggregate formation and enlargement, but mucilage aggregates themselves may also affect the phytoplankton populations, allowing the development of a rich diatom community and in general enhancing nanophytoplankton growth.     

Acid-treated Bentonite as filler in the development of novel composite PVA hydrogels

In this study, novel eco-friendly hydrogel adsorbents were synthesized based on poly(vinyl alcohol) (PVA) and different contents of an acid-treated bentonite (1–5 wt %). The hydrogels were prepared by freezing–thawing, which is a simple and nontoxic method. The materials were morphologically and thermally characterized by means of swelling assays, X-ray diffraction, scanning electron microscopy, dynamic scanning calorimetry, and thermogravimetric analysis in order to evaluate the effect of acid-treated bentonite loading. The composite hydrogels showed very distinct porous structure and thermal features in comparison to neat PVA as a consequence of the addition of the clay. Moreover, the performance of the obtained composite hydrogels was tested toward the adsorption of cationic (methylene blue) and anionic dyes (methyl red and methyl orange) from aqueous media. The presence of acid bentonite seems to be beneficial for improving the removal capacity of PVA-based hydrogels. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47663.     

Quantifying the Impact on Stormwater Management of an Innovative Ceramic Permeable Pavement Solution

Stormwater management in cities has traditionally been based on centralized systems, evacuating runoff as quickly as possible through drainage networks that collect and convey the runoff to the final point of treatment or the receiving water body. In recent years, a different approach focused on the use of Sustainable Urban Drainage Systems (SUDS) represents a paradigm shift, promoting a decentralized management as close to the runoff source as possible. Among these techniques, permeable pavements represent an effective solution for reducing runoff and providing pollutant treatment. This contribution describes the results obtained from an innovative ceramic permeable pavement developed as part of the LIFE CERSUDS project in the city of Benicàssim (Spain). This pavement, composed by modules built from ceramic tiles in stock, allows water infiltration, runoff treatment and water reuse as part of a SUDS built in 2018 and monitored from September 2018 to September 2019. The purpose of the research was to demonstrate the hydraulic performance of the proposed solution through monitoring of runoff quantity and quality variables. Monitoring data analysis have shown positive results, reducing peak runoff rates and the volume of water which is conducted downstream. From the hydrological point of view, the system capacity shown a 100% runoff management for events up to 15–25 mm of precipitation. This is a very significant threshold since these values represent, respectively, the 81% and 91% percentiles for the study area. System performance was confirmed in terms of runoff management and water infiltration. This demonstration case study represents a reference example of urban retrofitting actions which integrate social, economic and environmental aspects.

     

Improvement in environmental accessibility via volunteered geographic information: a case study

Universal Access in the Information Society - Although geo-crowdsourcing approaches provide an opportunity to collect and share environmental accessibility information for people with disabilities,...