Exploring Methane Emission Drivers in Wetlands: The Cases of Massaciuccoli and Porta Lakes (Northern Tuscany, Italy)

Wetlands are hotspots of CH4 emissions to the atmosphere, mainly sustained by microbial decomposition of organic matter in anoxic sediments. Several knowledge gaps exist on how environmental drivers shape CH4 emissions from these ecosystems, posing challenges in upscaling efforts to estimate global emissions from waterbodies. In this work, CH4 and CO2 diffusive fluxes, along with chemical and isotopic composition of dissolved ionic and gaseous species, were determined from two wetlands of Tuscany (Italy): (i) Porta Lake, a small wetland largely invaded by Phragmites australis reeds experiencing reed die-back syndrome, and (ii) Massaciuccoli Lake, a wide marsh area including open-water basins and channels affected by seawater intrusion and eutrophication. Both wetlands were recognized as net sources of CH4 to the atmosphere. Our data show that the magnitude of CH4 diffusive emission was controlled by CH4 production and consumption rates, being mostly governed by (i) water temperature and availability of labile carbon substrates and (ii) water column depth, wind exposure and dissolved O2 contents, respectively. This evidence suggests that the highest CH4 diffusive fluxes were sustained by reed beds, providing a large availability of organic matter supporting acetoclastic methanogenesis, with relevant implications for global carbon budget and future climate models.

Annual Dynamics of Phytoplankton in the Black Sea in Relation to Wind Exposure

Studies of the annual dynamics of phytoplankton in the NE Black Sea at two stations on the shelf and the continental slope were conducted in 2016, 2017, and 2019. The species composition of phytoplankton has not undergone significant changes compared to previous decades. The coccolithophore Emiliania huxleyi, small flagellates, and diatoms determined the abundance of phytoplankton; and diatoms, coccolithophores, and dinoflagellates determined the total biomass. The annual dynamics of the satellite-derived chlorophyll-a showed peaks in spring and autumn, and sometimes in summer. During the stratified water column period, strong winds in most cases led to a detectible increase in chlorophyll-a. The annual dynamics of phytoplankton followed the pattern: small diatoms (spring) → coccolithophores (late spring, early summer) → large diatoms (summer, autumn). Such a pattern was typical for the previous decades. Coccolithophores dominated in weak SE winds, diatoms in NE winds. The combined effect of sustained offshore wind and strong current can cause diatom blooms during stratified water, even if the wind velocity is moderate.

Cholesteatoma Causing a Horizontal Semicircular Canal Fistula

Horizontal canal fistulas are not uncommon in patients with cholesteatoma. Patients with canal wall down cavities and exposed horizontal canal fistulas develop significant dizziness with wind or suction exposure. Obliteration of mastoid cavities in patients with exposed fistulas can be challenging. We describe a patient with horizontal canal fistula and chronic dizziness from wind exposure who underwent successful mastoid cavity obliteration with preservation of hearing. Patients with horizontal canal fistulas in a canal wall down cavity can be managed with mastoid obliteration for relief of dizziness.

Storm surge and ponding explain mangrove dieback in southwest Florida following Hurricane Irma

Mangroves buffer inland ecosystems from hurricane winds and storm surge. However, their ability to withstand harsh cyclone conditions depends on plant resilience traits and geomorphology. Using airborne lidar and satellite imagery collected before and after Hurricane Irma, we estimated that 62% of mangroves in southwest Florida suffered canopy damage, with largest impacts in tall forests (>10 m). Mangroves on well-drained sites (83%) resprouted new leaves within one year after the storm. By contrast, in poorly-drained inland sites, we detected one of the largest mangrove diebacks on record (10,760 ha), triggered by Irma. We found evidence that the combination of low elevation (median = 9.4 cm asl), storm surge water levels (>1.4 m above the ground surface), and hydrologic isolation drove coastal forest vulnerability and were independent of tree height or wind exposure. Our results indicated that storm surge and ponding caused dieback, not wind. Tidal restoration and hydrologic management in these vulnerable, low-lying coastal areas can reduce mangrove mortality and improve resilience to future cyclones.

Wind Exposure Regulates Water Oxygenation in Densely Vegetated Shallow Lakes

The presence of dense macrophyte canopies in shallow lakes locally generates thermal stratification and the buildup of labile organic matter, which in turn stimulate the biological oxygen demand. The occurrence of hypoxic conditions may, however, be buffered by strong wind episodes, which favor water mixing and reoxygenation. The present study aims at explicitly linking the wind action and water oxygenation within dense hydrophytes stands in shallow lakes. For this purpose, seasonal 24 h-cycle campaigns were carried out for dissolved gases and inorganic compounds measurements in vegetated stands of an oligo-mesotrophic shallow lake. Further, seasonal campaigns were carried out in a eutrophic shallow lake, at wind-sheltered and -exposed sites. Overall results showed that dissolved oxygen (DO) daily and seasonal patterns were greatly affected by the degree of wind exposure. The occurrence of frequent wind episodes favored the near-bottom water mixing, and likely facilitated mechanical oxygen supply from the atmosphere or from the pelagic zone, even during the maximum standing crop of plants (i.e., summer and autumn). A simple model linking wind exposure (Keddy Index) and water oxygenation allowed us to produce an output management map, which geographically identified wind-sheltered sites as the most subjected to critical periods of hypoxia.

A Review of Architectural and Structural Design Typologies of Multi-Storey Timber Buildings in Europe

Numerous countries across the globe have witnessed the recent decades’ trend of multi-storey timber buildings on the rise, owing to advances in engineering sciences and timber construction technologies. Despite the growth and numerous advantages of timber construction, the global scale of multi-storey timber construction is still relatively low compared to reinforced concrete and steel construction. One of the reasons for a lower share of high-rise timber buildings lies in the complexity of their design, where the architectural design, the selection of a suitable structural system, and the energy efficiency concept strongly depend on the specific features of the location, particularly climate conditions, wind exposure, and seismic hazard. The aforementioned shows the need for a comprehensive study on existing multi-storey timber buildings, which correspond to the boundary conditions in a certain environment, to determine the suitability of such a construction in view of its adjustment to local contexts. Apart from exposing the problems and advantages of such construction, the current paper provides a brief overview of high-rise timber buildings in Europe. Moreover, it addresses the complexity of the design approach to multi-storey timber buildings in general. The second part of the paper highlights the importance of synthesising the architectural, energy, and structural solutions through a detailed analysis of three selected case studies. The findings of the paper provide an expanded view of knowledge of the design of tall timber buildings, which can significantly contribute to a greater and better exploitation of the potential of timber construction in Europe and elsewhere.

Probabilistic Assessment of Roof Snow Load and the Calibration of Shape Coefficients in the Eurocodes

In modern structural codes, the reference value of the snow load on roofs is commonly given as the product of the characteristic value of the ground snow load at the construction site multiplied by the shape coefficient. The shape coefficient is a conversion factor which depends on the roof geometry, its wind exposure, and its thermal properties. In the Eurocodes, the characteristic roof snow load is either defined as the value corresponding to an annual probability of exceedance of 0.02 or as a nominal value. In this paper, an improved methodology to evaluate the roof snow load characterized by a given probability of exceedance (e.g., p=0.02 in one year) is presented based on appropriate probability density functions for ground snow loads and shape coefficients, duly taking into account the influence of the roof’s geometry and its exposure to wind. In that context, the curves for the design values of the shape coefficients are provided as a function of the coefficient of variation (COVg) of the yearly maxima of the snow load on the ground expected at a given site, considering three relevant wind exposure conditions: sheltered or non-exposed, semi-sheltered or normal, and windswept or exposed. The design shape coefficients for flat and pitched roofs, obtained considering roof snow load measurements collected in Europe during the European Snow Load Research Project (ESLRP) and in Norway, are finally compared with the roof snow load provisions given in the relevant existing Eurocode EN1991-1-3:2003 and in the new version being developed (prEN1991-1-3:2020) for the “second generation” of the Eurocodes.

Colour Ageing in Acrylic Resin Plates and Natural Minerals on the Façade after 10 Years of Sun Exposure in the Marine Environment

The synthetic material developed by Dupont in 1963 for solid surfaces has been used since its origin for numerous applications. One of the most popular ones in the last decade is as a finishing layer on façades. The first references that contemplated this use on the outside were the Seeko’o hotel in Bordeaux executed in 2007 and the refurbishment of the 7700 m2 shell of the Hôtel Ivoire congress centre in Abidjan (Ivory Coast) in 2009. In Spain, the first example of the installation of this material is the rehabilitation of the main building of the La Rotonda de la Playa de San Juan urbanisation in Alicante, designed in 1965 by the architect Juan Guardiola Gaya and rehabilitated in 2010 by Miguel Salvador Landmann. Ten years later, our research is focused on the study of the colour ageing of the acrylic resin and natural mineral sheets on each of its façades, with different orientations and exposure to sea and wind. To this end, it has been studied the solar radiation of the surfaces, the wind exposure of their façades and tests with a tele-spectroradiometer has been carried out. The study makes it possible to quantify the differences in colour in all of them and to state that the combination of wind and radiation is the main atmospheric agent causing the degradation.