• Energy Research

Climate change is already having significant effects on aquatic ecosystems with recent scenarios indicating greater change in the Alps. Climate models are predicting significant changes in precipitation patterns, with mid-altitude lakes particularly vulnerable. These lakes provide valuable ecosystem services such as irrigation, power, recreation and fishing. LTER site Lake Tovel, Italy (46.26137 N, 10.94934 E, 1178 m asl) is a small, Alpine lake located in the Adamello Brenta Natural Park. In addition to standard limnological parameters since 1995, stable isotopes of oxygen (δ18O) have been sampled monthly along a depth gradient since 2009. δ18O can be used to successfully investigate many aspects of lake hydrology; for example Lake Tovel δ18O values between -13 and -12 ‰ indicate that the aquifer feeding the lake originates at ca. 1000 m above the lake. Long term data show a reduction of N, in line with general trends in the Alps, an increase in surface water temperature coherent with other lakes in the region, but no significant change in total phosphorus. Isotope values reflect winter precipitation. Recharge of the aquifer with rain instead of snow may result in a less steady inflow with repercussions on the lake ecosystem and services provided. Isotopes can contribute to a better understanding of a changing hydroclimate.

Abstract The use of forest biomass for energy production is growing in Europe and biomass energy plants market is constantly increasing. However, there is the need to define the environmental sustainability issues dealing with the emerging renewable energy scenario. In particular, the polluting emissions (i.e. PMx, NOx and ozone) caused by the biomass combustion heavily impact on the air quality. In this context, the elemental characterization of the wood and the element allocation in the different tree organs, can provide important information about the quality of the derived wood fuels and give hints about the choice of the most appropriate combustion technique and/or the right wood fuel for a given combustion technique. Moreover, since elements have different concentrations in the different plant tissues, the preventive knowledge of the elements allocation can lead to the identification of the best harvesting strategy aimed at producing wood fuel with the lowest possible ash forming elements and environmental impact. This work focuses on the allocation in three tree compartments (foliage, branches and stem) of five important macroelements (K, Mg, Ca, N and P) in Norway spruce (Picea abies), and points out the possible effects of different harvesting strategies and tree age on the quality of the wood fuels. Results suggest that the Stem Only Harvesting is preferable to Whole Tree Harvesting system in terms of prevention of mineral content loss, as well as is preferable to avoid forest biomass from young trees because of the poorer fuel quality of the wood chips.

Microalgae present promising green economy applications in the energy and biorefinery sectors. The work concerns a pilot study on the integration of anaerobic digestion with microalgae cultivation for managing at the same time emissions and digestate from the dry anaerobic treatment of organic waste. Biogas produced was used to feed Solid Oxide Fuel Cell after a filtering step for removing toxic compounds. The exhausts and digestate were used for providing carbon and nutrients for microalgae growth. The experimental workflow includes the characterization of both for defining their suitability in the microalgal growth (Chlorella vulgaris) tests. The exhausts of Solid Oxide Fuel Cells showed relatively stable concentration of CH4 (4–7%) and CO2 (93–96%) and low concentrations (sub ppm(v)) of sulphur, carbonyl and carboxyl, and aromatic compounds and terpenes, making it particularly suited for algae growing as compared with internal combustion engines. The challenging growing conditions are a compromise between carbon recovery and use of digestate. A good microalgae growth has been obtained (22.31 mm3 mL−1 of biovolume corresponding to 151 dry mg L−1 day−1) exploiting ammonia and phosphate from dilute digestate (removal efficiency 94% and 30% respectively) as well as a good carbon recovering (310 mg CO2 L−1 day−1). Based on our data, the integration of microalgae growth and anaerobic digestion process seems a viable solution to achieve (i) reduced emissions due to carbon recovery; (ii) optimum integrated management of anaerobic digestion waste and (iii) biomass production by low-cost nutrients and carbon.

In the present context of climate warming, the influence of permafrost (soil remaining at ≤0°C for at least two consecutive years) to the Alpine hydrology is increasing, while glaciers and snowpack shrink. As observed in previous studies, water emerging from rock-glaciers (rocky landforms resulting from mountain permafrost) exhibit distinctive features (e.g. constantly cold and clear water, stable channels, high solute and trace elements concentrations) that determine characteristic habitat conditions and biotic communities. We investigated the physical and chemical conditions, and benthic diatoms assemblages during the vegetative period of two consecutive years in a set of kryal (glacier-fed), krenal (groundwater-fed) and rock-glacial (rockglacier-fed) headwaters of the Eastern Italian Alps. The three stream typologies showed distinct physical habitat, while differences in water chemistry were related to lithology, water origin and seasonality. The diatom abundance appeared inhibited by the glacial ablation in summer, and affected by increasing solute concentrations in autumn. We observed a general shift of the maximum annual abundance from autumn to spring/early summer. The progressive glacier retreat, and the consequent reduction of environmental harshness and habitat heterogeneity in Alpine catchments, may enhance diatoms abundance and α-diversity, and cause a decrease in β-diversity.

Il macrosito “IT08 Laghi Sudalpini” comprende un gruppo di laghi localizzato al margine meridionale della catena alpina. Le tipologie lacustri sono rappresentate da laghi estesi e profondi (Orta, Garda, Maggiore, Como e Iseo) e da un lago di minori dimensioni e bassa profondità (Candia). Le tematiche comuni a tutti i siti di ricerca comprendono: composizione, struttura e dinamica delle comunità biologiche (plancton, necton e comunità litorali) e loro risposte all’eutrofizzazione e ai cambiamenti climatici; le reti trofiche; la paleolimnologia; l’ecotossicologia; la qualità ecologica; il telerilevamento. Le attività di ricerca sono supportate da una ricca disponibilità di laboratori localizzati nelle differenti sedi e da un’ampia dotazione di apparecchiature tecnologiche. Queste infrastrutture, finanziate nell’ambito dei singoli istituti coinvolti nella ricerca, hanno permesso non solo di mantenere, ma anche di aggiornare i classici approcci utilizzati nel monitoraggio scientifico, aprendo, nel contempo, nuovi indirizzi di ricerca: ne sono esempi gli sviluppi nel campo dell’ecologia molecolare e microbica, il profiling metabolomico, la ricerca di geni di resistenza agli antibiotici, la sperimentazione di sistemi di monitoraggio ad alta frequenza mediante l’utilizzo di sensori. Nel corso dell’ultimo decennio, la regolarità nelle attività di ricerca nei laghi di maggiori dimensioni è stata favorita dalla disponibilità di finanziamenti esterni (progetti competitivi o previsti nell’ambito di cooperazioni transfrontaliere) e ordinari (progetti definiti nei singoli istituti o attività istituzionali nel caso delle ARPA). La varietà delle attività di ricerca svolte nei laghi sudalpini è testimoniata dalla pubblicazione di numerosi articoli scientifici e divulgativi, dai contributi presentati in congressi nazionali e internazionali, dall’organizzazione di convegni, seminari e attività e di formazione e divulgazione, oltre che dalla presenza nei media giornalistici. La collaborazione tra i siti di ricerca appartenenti al macrosito Laghi Sudalpini vanta una lunga tradizione. Seppur regolate nell’ambito di progetti e accordi informali, numerose forme di collaborazione tra tutti gli attuali siti di ricerca erano infatti già attive ancor prima dell’istituzione della rete LTER-Italia. Nell’ambito di queste collaborazioni va inserito anche il Lago di Lugano che, pur non incluso nell’attuale network, rimane largamente coinvolto nelle attività di collaborazione scientifica con il supporto attivo della Scuola Universitaria Professionale della Svizzera italiana (SUPSI, Canobbio). Le collaborazioni riguardano attività di supporto logistico reciproco (raccolta di campioni e analisi di laboratorio, intercalibrazioni), campagne di indagine focalizzate su argomenti specifici (tra cui ricerca di specie tossigeniche, zooplancton, reti trofiche, ecologia microbica, evoluzione a lungo termine dello stato trofico e dinamiche di mescolamento in relazione alle fluttuazioni climatiche, telerilevamento, microplastiche). I numerosi risultati ottenuti nell’ambito delle collaborazioni hanno permesso di produrre un elevato numero di articoli scientifici e contributi sinottici a livello congressuale e seminariale. In particolare, numerosi lavori di carattere sinottico sono stati recentemente pubblicati in un numero speciale della rivista Hydrobiologia dedicato ai grandi laghi perialpini (2018, volume 824, Issue 1). Riassumendo, l’elemento chiave delle ricerche LTER nei laghi a sud delle Alpi è il loro approccio a lungo termine, su scale temporali che vanno ben oltre la durata tipica dei progetti di ricerca. Il monitoraggio scientifico costituisce un elemento centrale delle ricerche LTER, comprendendo non solo la raccolta di dati (monitoraggio di base), ma anche la loro interpretazione, modellizzazione e manipolazione sperimentale, con particolare attenzione a gruppi chiave di variabili selezionate al fine di individuare gli stressori ambientali più significativi e il grado di cambiamento a livello di ecosistema, comunità, specie e popolazioni. Tale approccio richiede necessariamente di essere implementato in un contesto di ricerca scientifica in grado di mantenere un elevato livello di qualità sia nei dati raccolti sia nella loro elaborazione, interpretazione, diffusione e valorizzazione, non solo a livello di singolo lago o macrosito, ma anche in più ampi contesti nazionali ed internazionali. The Macrosite "IT08 Subalpine Lakes" includes a group of lakes located at the southern border of the Alps. The lake typologies are represented by large and deep lakes (Orta, Garda, Maggiore, Como and Iseo) and by a lake of smaller size and shallow depth (Candia). Topics common to all the research sites include the impact of eutrophication and climate change, the composition, structure and dynamics of biological communities (plankton, necton and littoral communities), trophic webs, paleolimnology, ecotoxicology, ecological status and remote sensing. Scientific investigations are supported by a wide availability of technological infrastructures and laboratories located in the reference institutions, and by a wide range of technological equipment for fieldwork. These facilities, funded within the individual institutes involved in the research, have allowed not only to maintain, but also to update the classical approaches used in scientific monitoring, while opening up new research fields (especially molecular ecology, microbial ecology, metabolomic profiling, antibiotic resistance genes, high frequency monitoring by sensor technology). Over the last decade, the continuity and regularity of investigations have been facilitated by the availability of both external and ordinary funds. The variety of research activities carried out on the IT08 macrosite is evidenced by the publication of numerous scientific papers, as well as contributions (oral or poster) presented at national and international conferences, and by the presence in the mass media. In this context, the scientific monitoring is a key element of LTER research, including not only data collection (basic monitoring), but also data interpretation, modeling, and experimental manipulation, with particular attention to key groups of selected variables in order to identify the most significant environmental stressors and the degree of change at the level of ecosystems, communities, species and populations.

Mountain glacier shrinkage represents a major effect of the current global warming and 80-100% of the Alpine glaciers are predicted to vanish within the next few decades. As the thawing rate of mountain permafrost ice is much lower than for glacier ice, a shift from glacial to periglacial dynamics is predicted for Alpine landscapes during the 21st century. Despite the growing literature on the impacts of deglaciation on Alpine hydrology and ecosystems, chemical and biological features of waters emerging from Alpine rock glaciers (i.e. permafrost landforms composed by a mixture of ice and debris) have been poorly investigated so far, and knowledge on microbial biodiversity of headwaters is still sparse. A set of glacier-, rock glacier- and groundwater/precipitation-fed streams was investigated in the Italian Central Alps in late summer 2016, aiming at exploring bacterial community composition and diversity in epilithic and surface sediment biofilm and at verifying the hypothesis that rock glacier-fed headwaters represent peculiar ecosystems from both a chemical and biological point of view. Rock glacier-fed waters showed high values of electrical conductivity and trace elements related to their bedrock lithology, and their highly diverse bacterial assemblages significantly differed from those detected in glacier-fed streams. Bacterial taxonomic composition appeared to be mainly related to water and substrate type, as well as to water chemistry, the latter including concentrations of nutrients and trace metals. The results of this study confirm the chemical and biological peculiarity of rock glacier-fed waters compared to glacial waters, and suggest a potential driving role of thawing permafrost in modulating future ecological traits of Alpine headwaters within the context of progressing deglaciation.

AbstractRock glaciers are increasingly influencing the hydrology and water chemistry of Alpine catchments. During three consecutive summers (2017–2019), we monitored by recording probes and fortnightly/monthly field campaigns the physical and chemical conditions of two rock glacier springs (ZRG, SRG) in the Zay and Solda/Sulden catchments (Eastern Italian Alps). The springs have contrasting hydrological conditions with ZRG emerging with evident ponding (pond‐like), and SRG being a typical high‐elevation seep (stream‐like). Water temperature was constantly low (mean 1.2°C, standard deviation 0.1°C) at both springs. Concentrations of major ions (dominated by SO42−, HCO3−, Ca2+ and Mg2+) and trace elements (As, Sr, Ba, U, Rb) increased, and water became more enriched in heavy stable isotopes (δ18O, δ2H) towards autumn. This solute and isotopic enrichment had an asymptotic trend at SRG, and a unimodal pattern at ZRG, where peaks occurred 60–80 days after the snowmelt end. Wavelet analysis of electrical conductivity (EC) and water temperature records revealed daily cycles only at SRG, and significant weekly/biweekly fluctuations at both springs attributable to oscillations of meteorological conditions. Several rainfall events triggered a transient (0.5–2 h) EC drop (of 5–240 μS cm−1) and water temperature rise (of 0.2–1.4°C) at SRG (dilution and warming), whereas only intense rainfall events occasionally increased EC (by 15–85 μS cm−1) at ZRG (solute enrichment and thermal buffering), with a long‐lasting effect (6–48 h). Building on previous research, we suggest that rock glacier springs with differing flow conditions, that is, stream‐like and pond‐like, have contrasting fluctuations of water parameters at different timescales. Thus, for pond‐like springs, peaks of EC/solute concentrations might indicate a seasonal window of major permafrost thaw. Our quantitative description of the hydrochemical seasonality in rock glacier outflows and the physical and chemical response to precipitation events provides relevant information for water management in mountain areas under climate change.