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The Guidance Documents for setting reference conditions for rivers and lakes states that in the case of a small number of water bodies, mainly affected by human impact, reference condition should preferably be modeled. However, in the ECOSTAT activity and in the Italian legislation, the (discouraged) spatial approach was adopted. To verify if there are differences in the results given by those two approaches, in this report we used two general models of lake eutrophication to evaluate phosphorus reference conditions for all relevant Italian lakes. Furthermore, we used the relationships between phosphorus concentration and two quality index (chlorophyll concentration and PTI index) to estimate reference conditions for phytoplankton. The results of the exercise showed that the spatial approach was realistic, but one of the Italian phytoplankton indices (PTIspecies) is probably too stringent for the large deep lakes. For the Mediterranean shallow lakes, we also suggest a case-by-case evaluation of the reference conditions using specific models or paleolimnological tools, in order to avoid unrealistic restoration targets. Finally, the relationships between phosphorus concentration and the indices based on other biological quality elements (macrophytes, benthic invertebrates and fish fauna) were not strong enough to allow their prediction using these simple models, because these communities have complex response to multiple stressors, such as water quality, shore integrity and water level modifications. ; Le linee guida per la valutazione delle condizioni di riferimento dei corpi idrici indicano che quando vi sono pochi corpi idrici, per lo pi? impattati dall?attivit? umana, come nel caso dei laghi italiani, non ? opportuno utilizzare l?approccio spaziale per la stima delle condizioni di riferimento, ma ? preferibile un approccio modellistico. Tuttavia il gruppo di lavoro europeo ECOSTAT ha utilizzato l?approccio spaziale per la definizione delle condizioni di riferimento dei laghi, e tali valori sono stati recepiti dalla legislazione italiana. In questo rapporto abbiamo pertanto utilizzato due semplici modelli statistici per valutare il livello di riferimento di fosforo in tutti i laghi naturali italiani di rilevante importanza. Da questo, attraverso opportune equazioni di regressione, abbiamo poi calcolato le condizioni di riferimento per la concentrazione di clorofilla e per gli indici fitoplantonici. Questo esercizio ha mostrato che, almeno per il caso del fitoplancton, l?approccio spaziale utilizzato nel gruppo di lavoro ECOSTAT e nella stesura del D.M. 260/2010 pu? essere considerato corretto. Tuttavia, i nostri risultati consigliano di utilizzare l?indice PTIot per tutti i laghi italiani, scoraggiando l?uso dell?indice PTIspecies per i grandi laghi profondi. Inoltre nel caso dei laghi mediterranei poco profondi dei tipi ME-1 e ME-2 riteniamo opportuno verificare le condizioni di riferimento caso per caso, utilizzando modelli pi? complessi o tecniche paleolimnologiche, per evitare di porre obiettivi di risanamento troppo stringenti. Infine, per gli altri elementi di qualit? biologica, non essendovi una relazione semplice e diretta tra i valori degli indici e le concentrazioni di fosforo, non ? possibile utilizzare questi modelli per la validazione delle condizioni di riferimento.

Twelve Alpine lakes located in the Gran Paradiso National Park, in the western Italian Alps, were sampled during the ice free period in 2008 and analysed for the main morphological, chemical and physical variables in relation to the characteristics of their watershed, with the aim to create a reference database for present and future ecological studies and to support conservation politics with scientific data. The results highlighted that weathering process and direct precipitation input are the main factors determining the hydrochemistry of the studied lakes; moreover the morphological characteristics highly affects the physical properties of the lakes starting from stratification process. The acidification status, the atmospheric input of N compounds and the supply of nutrients were considered in detail. The studied lakes seem to be well preserved by acidification risk. Comparing data from Gran Paradiso National Park with data from European mountain regions ranging in N deposition rates, allows to consider long range anthropogenic impact: the detection of relative low Total Nitrogen (TN) concentration is not necessarily a synonym of a soft impact of long range pollutants, being the final nitrogen concentration dependent from retention process, closely related to catchment characteristics, besides N deposition rates; moreover the dominance of Inorganic Nitrogen (IN) on Organic Nitrogen (ON) highlights that the lakes are interested by N deposition and probably by long range transport of pollutants produced in the urbanized area surrounding the massif. However the Gran Paradiso National Park area is by far less affected by atmospheric pollutants than other Alpine regions, as the Central Alps. Total Phosphorus (TP) concentration in Gran Paradiso lakes (1-13 ?g L-1, mean level = 4 ?g L-1) is an index of oligotrophic and ultraoligotrophic conditions and according to Redfield's ratio phosphorus is mainly the phytoplankton growth limiting element, assuming a key role in biological processes and food-web dynamics; the high TN:TP ratio values detected in the studied lakes reflects the low N retention capacity of alpine sparse vegetation by comparison with prairies or forests.

Twelve Alpine lakes located in the Gran Paradiso National Park, in the western Italian Alps, were sampled during the ice free period in 2008 and analysed for the main morphological, chemical and physical variables in relation to the characteristics of their watershed, with the aim to create a reference database for present and future ecological studies and to support conservation politics with scientific data. The results highlighted that weathering process and direct precipitation input are the main factors determining the hydrochemistry of the studied lakes; moreover the morphological characteristics highly affects the physical properties of the lakes starting from stratification process. The acidification status, the atmospheric input of N compounds and the supply of nutrients were considered in detail. The studied lakes seem to be well preserved by acidification risk. Comparing data from Gran Paradiso National Park with data from European mountain regions ranging in N deposition rates, allows to consider long range anthropogenic impact: the detection of relative low Total Nitrogen (TN) concentration is not necessarily a synonym of a soft impact of long range pollutants, being the final nitrogen concentration dependent from retention process, closely related to catchment characteristics, besides N deposition rates; moreover the dominance of Inorganic Nitrogen (IN) on Organic Nitrogen (ON) highlights that the lakes are interested by N deposition and probably by long range transport of pollutants produced in the urbanized area surrounding the massif. However the Gran Paradiso National Park area is by far less affected by atmospheric pollutants than other Alpine regions, as the Central Alps. Total Phosphorus (TP) concentration in Gran Paradiso lakes (1-13 ?g L-1, mean level = 4 ?g L-1) is an index of oligotrophic and ultraoligotrophic conditions and according to Redfield's ratio phosphorus is mainly the phytoplankton growth limiting element, assuming a key role in biological processes and food-web dynamics; the high TN:TP ratio values detected in the studied lakes reflects the low N retention capacity of alpine sparse vegetation by comparison with prairies or forests.

Abstract
The effects of the COVID-19 lockdown on deposition and surface water chemistry were investigated in an area south of the Alps. Long-term data provided by the monitoring networks revealed that the deposition of sulfur and nitrogen compounds in this area has stabilized since around 2010; in 2020, however, both concentrations and deposition were significantly below the average values of the previous decade for SO4 and NO3. Less evident changes were observed for NH4 and base cation. The estimated decrease of deposition in 2020 with respect to the previous decade was on average − 54% and − 46% for SO4 and NO3, respectively. The lower deposition of SO4 and NO3 recorded in 2020 was caused by the sharp decrease of SO2 and particularly of NOx air concentrations mainly due to the mobility restrictions consequent to the COVID-19 lockdown. The limited effects on NH4 deposition can be explained by the fact that NH3 emission was not affected by the lockdown, being mainly related to agricultural activities. A widespread response to the decreased deposition of S and N compounds was observed in a group of pristine freshwater sites, with NO3 concentrations in 2020 clearly below the long-term average. The rapid chemical recovery observed at freshwater sites in response to the sharp decrease of deposition put in evidence the high resilience potential of freshwater ecosystems in pristine regions and demonstrated the great potential of emission reduction policy in producing further substantial ameliorations of the water quality at sensitive sites.

Although the Water Framework Directive specifies that macrophytes and phytobenthos should be used for the ecological assessment of lakes and rivers, practice varieswidely throughout the EU.Most countries have separate methods for macrophytes and phytobenthos in rivers; however, the situation is very different for lakes. Here, 16 countries do not have dedicated phytobenthos methods, some include filamentous algaewithin macrophyte survey methods whilst others use diatoms as proxies for phytobenthos. The most widely-cited justification for not having a dedicated phytobenthos method is redundancy, i.e. that macrophyte and phytoplankton assessments alone are sufficient to detect nutrient impacts. Evidence from those European Union Member States that have dedicated phytobenthos methods supports this for high level overviews of lake condition and classification; however, there are a number of situations where phytobenthos may contribute valuable information for the management of lakes.

Although the Water Framework Directive specifies that macrophytes and phytobenthos should be used for the ecological assessment of lakes and rivers, practice varies widely throughout the EU. Most countries have separate methods for macrophytes and phytobenthos in rivers; however, the situation is very different for lakes. Here, 16 countries do not have dedicated phytobenthos methods, some include filamentous algae within macrophyte survey methods whilst others use diatoms as proxies for phytobenthos. The most widely-cited justification for not having a dedicated phytobenthos method is redundancy, i.e. that macrophyte and phytoplankton assessments alone are sufficient to detect nutrient impacts. Evidence from those European Union Member States that have dedicated phytobenthos methods supports this for high level overviews of lake condition and classification; however, there are a number of situations where phytobenthos may contribute valuable information for the management of lakes.

The natural variability of the biotic components, in particular of those showing seasonal cycles, often leads to significant changes of biomass as well as specific composition. This means that the choice of sampling frequency and distribution during the year may be crucial when assessing the ecological quality of a waterbody, starting from the structure of biotic communities. Among the four biological quality elements used to classify the lakes, three of them (phytoplankton, macrophytes and macroinvertebrates) show a marked seasonality and/or a certain degree of spatial variability. This document has the aim to evaluate how the metrics used are sensitive to the natural variability, especially respect to their response to the pressure gradients. The analysis was carried out on data collected during the project and is limited to phytoplankton and macrophytes, because the examination of autumn samples of macroinvertebrates, is still in progress. Regarding phytoplankton, three metrics defined by Italian national legislation (composition indices, chlorophyll and biovolume) were analyzed, comparing the variability due to anthropogenic origin (expressed by the gradient of total phosphorus) with the natural one (seasonal variations on different time scales) and estimating the uncertainty in the classification using different sampling frequencies. In the case of macrophytes, monitoring methods and classification were analyzed respect to their accuracy in assessing if the variability between sites, explained by a different anthropogenic pressure, is actually greater than the variance within the individual lake. In addition, we want to determine if the sampling effort, as established by the monitoring protocols, is adequate to the needs of the classification. Our analysis showed that the variability of phytoplankton metrics reflects the trophic gradient and is more significant than that explained by seasonal fluctuations, demonstrating the robustness of the indicators used. Moreover, the phytoplankton assemblages reveal a high stability in interannual patterns of succession. Conversely, the general formulation of the macrophytic index may need to be redefined to better understand the differences in ecological quality between lakes. Furthermore, as concerns macrophytes, a significant reduction of the sampling effort does not seem to be possible without compromising the quality of classification, while, as regards phytoplankton, it would be acceptable to reduce the number of annual samples from 6 to 4 without compromising the result of the classification, while observing the seasonality, because our analysis suggests that phytoplankton samples concentrated in a single season lead to increased uncertainty in the classification. ; La variabilit? naturale delle componenti biotiche, in modo particolare di quelle che mostrano cicli su base stagionale, porta a cambiamenti spesso significativi della composizione specifica e della biomassa. Questo significa che la scelta della frequenza di campionamento e la distribuzione dei prelievi nel corso dell'anno possono rappresentare dei fattori critici quando si tratta di valutare la qualit? ecologica a partire dalla struttura delle comunit? biotiche. Delle quattro componenti biologiche usate per classificare i laghi, tre (fitoplancton, macrofite e macroinvertebrati) mostrano una spiccata stagionalit? e/o una certa variabilit? spaziale. Il presente documento ? stato redatto con lo scopo di valutare quanto le metriche utilizzate siano sensibili alla variabilit? di origine naturale, soprattutto in relazione alla loro risposta rispetto ai gradienti di pressione. L?analisi ? stata condotta sui dati raccolti nel corso del progetto ed ? limitata al fitoplancton ed alle macrofite, poich? l?esame dei campioni autunnali dei macroinvertebrati ? tuttora in corso. Per quanto riguarda il fitoplancton sono state analizzate tre metriche indicate dalla normativa nazionale (indici di composizione, clorofilla e biovolume), confrontandone la variabilit? di origine antropica (espressa dal gradiente di fosforo totale) con quella naturale (stagionalit? su diverse scale temporali) e stimando l?incertezza nella classificazione con frequenze di prelievo diverse. Nel caso delle macrofite, i metodi di monitoraggio e di classificazione sono stati analizzati rispetto alla loro accuratezza nel valutare se la variabilit? tra ambienti, dovuta alla diversa pressione antropica, sia effettivamente maggiore rispetto alla varianza all?interno del singolo lago. Inoltre, si vuole valutare se lo sforzo di campionamento, previsto dai protocolli di monitoraggio, sia adeguato alle esigenze della classificazione. La nostra analisi ha messo in evidenza che la variabilit? delle metriche fitoplanctoniche rispecchia il gradiente trofico ed ? pi? significativa rispetto a quella spiegata dalle fluttuazioni stagionali, dimostrando la robustezza degli indicatori utilizzati e che le associazioni fitoplanctoniche rilevano un grande stabilit? negli schemi di successione interannuali. Viceversa, la formulazione generale dell?indice macrofitico potrebbe necessitare di una ridefinizione per meglio cogliere le differenze di qualit? ecologica tra i laghi. Inoltre, nel caso delle macrofite, una riduzione significativa dello sforzo di campionamento non pare possibile senza compromettere la qualit? della classificazione, mentre, per quanto riguarda il fitoplancton, sarebbe accettabile ridurre il numero dei prelievi annuali da 6 a 4 senza compromettere il risultato della classificazione, rispettando comunque la stagionalit?, poich? prelievi di fitoplancton concentrati in una sola stagione determinano una maggiore incertezza nella classificazione.

Across the 28 EU member states there were nearly half a million premature deaths in 2015 as a result of exposure to PM2.5, O3 and NO2. To set the target for air quality levels and avoid negative impacts for human and ecosystems health, the National Emission Ceilings Directive (NECD, 2016/2284/EU) sets objectives for emission reduction for SO2, NOx, NMVOCs, NH3 and PM2.5 for each Member State as percentages of reduction to be reached in 2020 and 2030 compared to the emission levels into 2005. One of the innovations of NECD is Article 9, that mentions the issue of "monitoring air pollution impacts" on ecosystems. We provide a clear picture of what is available in term of monitoring network for air pollution impacts on Italian ecosystems, summarizing what has been done to control air pollution and its effects on different ecosystems in Italy. We provide an overview of the impacts of air pollution on health of the Italian population and evaluate opportunities and implementation of Article 9 in the Italian context, as a case study beneficial for all Member States. The results showed that SO42− deposition strongly decreased in all monitoring sites in Italy over the period 1999–2017, while NO3− and NH4+ decreased more slightly. As a consequence, most of the acid-sensitive sites which underwent acidification in the 1980s partially recovered. The O3 concentration at forest sites showed a decreasing trend. Consequently, AOT40 (the metric identified to protect vegetation from ozone pollution) showed a decrease, even if values were still above the limit for forest protection (5000 ppb h−1), while PODy (flux-based metric under discussion as new European legislative standard for forest protection) showed an increase. National scale studies pointed out that PM10 and NO2 induced about 58,000 premature deaths (year 2005), due to cardiovascular and respiratory diseases. The network identified for Italy contains a good number of monitoring sites (6 for terrestrial ecosystem monitoring, 4 for water bodies monitoring and 11 for ...

This report summarizes the finding of the InHabit project on the importance of atmospheric nitrogen deposition in affecting the chemical composition of lake water and in eventually altering the biological communities living in them. Previous deliverables (I2d5, Id26 and I2d7) have shown that; 1. in both regions studied in the InHabit project (Piedmont and Sardinia), atmospheric deposition of nitrogen compounds is relevant; 2. the flux of nitrogen from the atmosphere to the ecosystem is markedly larger in Piedmont than in Sardinia; 3. models of the dynamic behavior of nitrogen in forested catchments indicates that Piedmon soils are mainly N-saturated, so that nitrogen carried by atmospheric deposition can be released form forest soil to the surface water; 4. in Sardinia, soil are less saturated, but a part of the deposited nitrogen is still carried to surface water; 5. trend analysis of deposition and stream water revealed that nitrogen deposition is stable or slightly decreasing in recent years, both in atmospheric deposition and in stream water; 6. the importance relative importance of N deposition is relevant for sites in or close to reference conditions; 7. the relationships between environmental variables and organisms belonging to the four biotic communities used to define the lake's ecological quality, according to provisions of the Italian legislation (D.Lgs. 260, November 2010) and the European Water Framework 2000/60 differ depending on the biological quality element considered; 8. phytoplankton community shows the clearer responses: according to the result of multivariate analysis, total nitrogen and ammonium nitrogen are among the most significant factors explaining the relationships among phytoplankton orders, species and environmental variables. In particular, cyanobacteria increased considerably with increasing availability of ammonium nitrogen. Conversely, high concentrations of this compound suppress the development of diatoms. On the basis of those results, which are summarized in this deliverable, we focused on the effect of different levels of nitrogen in lakes with low phosphorus concentration, slightly affected by direct trophic pressure and close to the reference conditions. The comparison between two lakes in Piedmont with low P concentration and high N concentration with two reservoirs in Sardinia with low levels of both nutrients shows that the formers are dominated by diatoms and the latter by dynophytes. Two reservoirs in Piedmont with high N levels are also dominated by diatoms. In spite of the small number of lakes studied, it seems that dynophytes are more fitted to low N lakes, probably because of their ability to use an heterotrophic metabolism, while lakes in reference conditions are generally considered to be dominated by oligotrophic diatoms, Our findings call for deeper studies on reference conditions in the Mediterranean ecoregion, because they suggest that lakes not affected by direct trophic pressure, i.e. reference lakes, may host different diatom communities depending on the amount of nitrogen deposition they receive.

This report presents an analysis of the relationships between environmental variables and organisms belonging to the four biotic communities used to define the lake's ecological quality, according to provisions of the Italian legislation (D.Lgs. 260, November 2010) and the European Water Framework 2000/6. The data analyzed were collected during the sampling surveys carried out within InHabit Project in 13 water bodies, 7 in Piedmont and 6 in Sardinia respectively. In particular, the aim of the study was to evaluate the possible effects of nitrogen on biotic communities. Phytoplankton community shown the clearer responses: according to the result of multivariate analysis, total nitrogen and ammonium nitrogen are among the most significant factors explaining the relationships among phytoplankton orders, species and environmental variables. In particular, cyanobacteria increased considerably with increasing availability of ammonium nitrogen. Conversely, high concentrations of this compound suppress the development of diatoms. Other algal groups show a nonlinear response with respect to nitrogen, with a possible limitation under low levels of nitrogen and an inhibition at higher levels. A comparative analysis, carried out to evaluate the response to the gradient of total phosphorus, shows that this nutrient is not as selective as nitrogen in controlling the structure of the algal assemblage in different environmental conditions. Other biotic communities did not show a clear relationship with nitrogen, but they rather responded to the trophic gradient as a whole: responses by macroinvertebrates seem, especially in the analysis of functional groups, complex and difficult to discriminate, highlighting a possible shifting of the food web towards the presence of large carnivores at high trophic status. Regarding the fish, the results show that nitrogen alone does not seem to be an important controlling factor for the fish communities. However together with the phosphorus, is one of the main elements controlling both biomass and size of the fish fauna, as well as the presence of tolerant, omnivorous or benthofagous species. In conclusion, the results of our analysis highlight the need for a greater emphasis on nitrogen inputs, which, especially in cases of nitrogen carried by atmospheric deposition, may even affect lake ecosystems relatively distant from direct impacts of human activities, thus altering the structure of biotic communities. ; A partire dai dati raccolti con le campagne di campionamento effettuate nell?ambito del progetto InHabit, questo documento presenta un?analisi delle relazioni tra le variabili ambientali e gli organismi appartenenti alle quattro comunit? biotiche utilizzate per la definizione della qualit? ecologica degli ambienti lacustri, secondo quanto previsto dal D.Lgs. 260 del novembre 2010, che recepisce la Direttiva Europea sulle Acque 2000/60. I campionamenti sono stati condotti in 13 ambienti lacustri, 7 in Piemonte e 6 in Sardegna. In particolare, lo scopo del lavoro ? stato valutare i possibili effetti sulla comunit? biotiche di concentrazioni variabili dei composti azotati inclusi tra le variabili considerate. La comunit? che mostra le risposte pi? chiare ? quella fitoplanctonica: come risulta dall?analisi multivariata, sia azoto ammoniacale che azoto totale compaiono tra le variabili significative per spiegare l?ordinamento di ordini e specie fitoplanctoniche. Tra questi, sono soprattutto i cianobatteri che aumentano sensibilmente all?aumentare della disponibilit? di azoto ammonicale. Al contrario, elevate concentrazioni di questo composto deprimono lo sviluppo delle diatomee. Altri gruppi algali mostrano una risposta non lineare rispetto ai composti azotati, con una possibile limitazione a bassi livelli di azoto ed una inibizione a livelli troppo elevati. L?analisi della risposta rispetto al gradiente di fosforo totale, mostra che questo nutriente non ? selettivo come l?azoto nel controllare la struttura delle associazioni algali in diverse condizioni ambientali. Le altre comunit? non hanno mostrato una relazione evidente con i composti azotati, ma, piuttosto, con il gradiente trofico complessivo: le risposte evidenziate dalla fauna macroinvertebrata, sembrano, soprattutto nell?analisi dei gruppi funzionali, complesse e difficili da discriminare, evidenziando un possibile spostamento degli equilibri della rete trofica verso i carnivori in presenza di elevati livelli trofici. Relativamente alla fauna ittica, i risultati mostrano che da solo l?azoto non sembra essere un fattore di controllo importante per la comunit? ittiche. Tuttavia insieme al fosforo, ? uno degli elementi principali a cui si associano positivamente la biomassa e le dimensioni della fauna ittica, nonch? la presenza di specie tolleranti, onnivore o bentofaghe. In conclusione, i risultati della nostra analisi, sottolineano ulteriormente la necessit? di porre una maggiore attenzione agli apporti di azoto, che, soprattutto nei casi di azoto veicolato da deposizioni atmosferiche, potrebbero interessare anche ecosistemi lacustri relativamente distanti da impatti diretti delle attivit? antropiche, alterandone la struttura delle comunit? biotiche.