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AbstractAimThe aim was to decipher Europe‐wide spatio‐temporal patterns of forest growth dynamics and their associations with carbon isotope fractionation processes inferred from tree rings as modulated by climate warming.LocationEurope and North Africa (30‒70° N, 10° W‒35° E).Time period1901‒2003.Major taxa studiedTemperate and Euro‐Siberian trees.MethodsWe characterize changes in the relationship between tree growth and carbon isotope fractionation over the 20th century using a European network consisting of 20 site chronologies. Using indexed tree‐ring widths (TRWi), we assess shifts in the temporal coherence of radial growth across sites (synchrony) for five forest ecosystems (Atlantic, boreal, cold continental, Mediterranean and temperate). We also examine whether TRWi shows variable coupling with leaf‐level gas exchange, inferred from indexed carbon isotope discrimination of tree‐ring cellulose (Δ13Ci).ResultsWe find spatial autocorrelation for TRWi and Δ13Ci extending over a maximum of 1,000 km among forest stands. However, growth synchrony is not uniform across Europe, but increases along a latitudinal gradient concurrent with decreasing temperature and evapotranspiration. Latitudinal relationships between TRWi and Δ13Ci (changing from negative to positive southwards) point to drought impairing carbon uptake via stomatal regulation for water saving occurring at forests below 60° N in continental Europe. An increase in forest growth synchrony over the 20th century together with increasingly positive relationships between TRWi and Δ13Ci indicate intensifying impacts of drought on tree performance. These effects are noticeable in drought‐prone biomes (Mediterranean, temperate and cold continental).Main conclusionsAt the turn of this century, convergence in growth synchrony across European forest ecosystems is coupled with coordinated warming‐induced effects of drought on leaf physiology and tree growth spreading northwards. Such a tendency towards exacerbated moisture‐sensitive growth and physiology could override positive effects of enhanced leaf intercellular CO2 concentrations, possibly resulting in Europe‐wide declines of forest carbon gain in the coming decades.

Aquaculture has become an important sector of animal food production thanks to a fast and continuous growth over the last few decades. Both marine and fresh water fish can be reared in fish farms, and there are species that are mainly produced by aquaculture rather than capture. As most of the reared fish species are sensible to water temperature and its fluctuations, having the control of this parameter in fish farms becomes an important issue that has to be taken into account. In this paper, three different fish farms are studied by simulating the water temperature when a thermal energy storage (TES) system using phase change materials (PCMs) is implemented. The effect and the estimated amounts of PCM required in each particular case are also analyzed. The results show that appreciable effects can be obtained, especially when the TES unit is used in combination with auxiliary sources of energy, such as solar collectors.

The purpose of the present article is the evaluation, by means of life cycle assessment, of a system which consists of vacuum-tube solar thermal collectors. The system is appropriate for building integration and it has been developed in France. The methods ReCiPe and USEtox have been adopted. Regarding life-cycle results, according to the scenario "without recycling" and for 30-year system lifespan, ReCiPe payback time was calculated to be 18.14 years based on France's electricity mix whereas by using Spain's electricity mix (hypothetical scenario) it was found to be 4.03 years. Recycling offers a ReCiPe-payback time reduction of 2.66 years based on France's electricity mix and 0.59 years based on Spain's electricity mix. All the studied cases show ReCiPe payback times much lower than an assumed system-lifespan of 30 years. On the basis of ReCiPe midpoint and by considering material manufacturing of the 16 collectors and the additional elements of the system (scenario "without recycling"), among glass-, aluminium-, copper- and steel-based components, the copper-based ones present the highest impact in 15 of the 18 impact categories. For instance, for Freshwater eutrophication, the copper-based elements have a score that is around 30 times higher comparing to that of the aluminium-based ones. The USEtox findings, for the material manufacturing of the 16 collectors and the supplementary elements of the system and for the scenario "without recycling", reveal that the material with the highest total score in terms of: i) human toxicity/cancer is copper (6.7E-09 CTUh), ii) human toxicity non-cancer is propylene glycol (4.0E-08 CTUh), iii) ecotoxicity is copper (2.06 CTUe). Recycling of the metals, according to USEtox, offers an impact reduction of 20-95%. A discussion about factors that influence the environmental profile of building-integrated solar systems is also provided.

Thermal energy storage (TES) using phase change materials (PCM) can be used for load shaving or peak load shifting when coupled to a heating, ventilation, and air-conditioning (HVAC) system such as heat pump. In these systems the PCM is embedded in packages or used in bulk, so the compatibility of the encapsulation materials and the PCM is a key factor to ensure long operational life of the system. Although corrosion caused by salts is known from the chemical industry, when these salts are used as PCM no corrosion data is available, since the salts are used without being in water solution. Producing new corrosion data is essential for PCM utilisation in new applications. In this study the corrosion rate of two metals and two metal alloys when they are in contact with different salt hydrate PCM is evaluated; in total eleven PCM, being four of them commercial PCM, are tested. Since they are PCM to be used for heating and cooling applications they are classified in two different groups to present the corrosion study. Results present the recommendation of using each PCM with the different metals and metal alloys according to the obtained corrosion rate and visual observation of the samples.

Nanoparticles with different morphologies were added to water to study if the morphology of the nanoparticles affects the main parameters of water used as phase change material (PCM). Considered morphologies were spherical, tubes and sheets in the form of spherical carbon black nanoparticles (CB), multiwalled carbon nanotubes (MWCNT), and graphene oxide nanosheets (GO). Results demonstrate that effectively the morphology of nanoparticles affect the thermophysical properties of the nano-enhanced PCM (NePCM). Depending on the morphology of the added nanoparticle, the final NePCM will have different subcooling and thermal conductivity, whereas its phase change enthalpy is not affected and, therefore, is the same for all produced NePCM.