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Districts have a significant role in achieving the principles of sustainability. Within the past decades, a great variety of assessment tools and methodologies has been developed in an effort to ‘translate’ the sustainability criteria into applied cases. There is an increasing interest in this contribution scaled up the assessment to larger territorial analysis and urban agglomerations. Notwithstanding, developing an assessment tool with sustainable standards requires strategic approaches to incorporate the theoretical framework to their implementation of city districts by measuring their performance in a consistent manner in respect of multiple criteria. Among these issues, energy efficiency and the zero energy objectives are significant for European policies. This study aims to provide an overview of the existing assessment tools and methods comparing their criteria and key parameters. As a second step, it introduces a simplified methodological assessment theoretical tool (U-ZED) by focusing on the commitment towards the zero energy targets in a future district. In a more general perspective, the study deals with the challenge of the development of a tool from building to district with the main concern to define the context of sustainable and long-term districts dealing with the challenges of 2050 horizon.

Moss-associated N2 fixation by epiphytic microbes is a key biogeochemical process in nutrient-limited high-latitude ecosystems. Abiotic drivers, such as temperature and moisture, and the identity of host mosses are critical sources of variation in N2 fixation rates. An understanding of the potential interaction between these factors is essential for predicting N inputs as moss communities change with the climate. To further understand the drivers and results of N2 fixation rate variation, we obtained natural abundance values of C and N isotopes and an associated rate of N2 fixation with 15N2 gas incubations in 34 moss species collected in three regions across Alaska, USA. We hypothesized that δ15N values would increase toward 0‰ with higher N2 fixation to reflect the increasing contribution of fixed N2 in moss biomass. Second, we hypothesized that δ13C and N2 fixation would be positively related, as enriched δ13C signatures reflect abiotic conditions favorable to N2 fixation. We expected that the magnitude of these relationships would vary among types of host mosses, reflecting differences in anatomy and habitat. We found little support for our first hypothesis, with only a modest positive relationship between N2 fixation rates and δ15N in a structural equation model. We found a significant positive relationship between δ13C and N2 fixation only in Hypnales, where the probability of N2 fixation activity reached 95% when δ13C values exceeded - 30.4‰. We conclude that moisture and temperature interact strongly with host moss identity in determining the extent to which abiotic conditions impact associated N2 fixation rates.

Climate change is increasing overall temporal variability in precipitation resulting in a seasonal water availability, both increasing periods of flooding and water scarcity. During low water availability periods, the concentration of leachates from riparian vegetation increases, subsequently increasing dissolved organic matter (DOM). Moreover, shifts in riparian vegetation by land use changes impact the quantity and quality of DOM. Our objective was to test effects of increasing DOM concentrations from Eucalyptus grandis (one of the most cultivated tree species in the world) leachates on the metabolism (respiration, R; gross primary productivity, GPP) and extracellular enzyme activities (EEAs) of freshwater biofilms. To test effects of DOM concentrations on freshwater biofilm functions, we incubated commercial cellulose sponges in a freshwater pond to allow biofilm colonization, and then exposed biofilms to five different concentrations of leaf-litter leachates of E. grandis for five days. To test if responses to DOM concentrations varied with colonization stage of biofilms, we measured treatment effects on biofilms colonizing standard substrates after one, two, three and four weeks of colonization. Increases in leachates concentrations enhanced biofilm heterotrophy, increasing R rates and decreasing GPP. Leachate concentrations did not affect biofilm EEAs, and changes in biofilm metabolism were not explained by treatment-induced changes in biofilm biomass or stoichiometry. We detected the lowest production:respiration ratios, i.e. more heterotrophic assemblages, with the most concentrated leachate solution and the most advanced biofilm colonization stages. Shifts in quantity of dissolved organic matter in freshwaters may further influence ecosystem metabolism and carbon processing.

Abstract Power-to-gas (PtG), as a promising technology proposed to store surplus renewable energy (RE), can hardly be commercialized for its low profitability. In this paper, three approaches are proposed in this paper to enhance the profitability of the PtG. Firstly, a cooperative union containing PtG is proposed and its sustainability analysis is undertaken based on Shapley Value method. Secondly, the PtG reaction heat, as an essential by-product of PtG which is valuable and therefore requires further study, is fully exploited for district heating in the operation of regional integrated energy system, which is solved by an improved SOCP method. Thirdly, a symbiosis cooperation mode is designed for wind power and PtG to enhance the benefit of PtG through optimization-based trading strategy, which is a MINLP model and solved by Big-M method. The results show that the daily profit of PtG is significantly increased with the cooperative union as the symbiosis cooperation mode can produce a 15.1% profit lift, meanwhile, exploitation of reaction heat can produce an 8.6% profit lift. Finally, our study reveals the conflict of interest between wind power and the cogeneration. A sensitivity study on the proportion of reaction heat used for district heating is performed to verify the mutually beneficial relation between PtG and the cogeneration. The findings of this paper can guide the commercialization of PtG.

Abstract Risks posed by composting of municipal solid waste (MSW) depend on the assessment approach used. Occupational risks at present are not overtly serious— only nausea, eye irritation, etc. are reported from inhalation, the chief exposure pathway—but details are lacking on outcomes of pathogenic, chemical and physical threats, including potential secondary problems with organisms developed in compost, their endotoxins, and metabolic products such as aflatoxin. Potential risk pathways of public exposure to MSW compost are dominated by children's lead ingestion, but “dioxins” and other persistent organic carcinogens are also of dietary concern. Risks to the “most exposed individual” (MET) may differ substantially from those based on the Alternative Pollutant Limit (APL) approach. Neither deals adequately with uncertainty or multiple pathway/chemical threats to public and environmental health. Additional issues include (a) incremental vs. total risk, (b) required nutrient intake vs. proscribed toxicant exposure (for the same element) and (c) long-term matters of “no net degradation,” and composting in recycling.

Abstract Variations in 13 C natural abundance and distribution of total C among five size and density fractions of soil organic matter, water soluble organic C (WSOC) and microbial biomass C (MBC) were investigated in the upper layer (0–20 cm) of a continuous grassland soil (CG, C 3 vegetation), a C 3 ‐humus soil converted to continuous maize cultivation (CM, C 4 vegetation) and a C 3 ‐humus soil converted to a rotation of maize cultivation and grassland (R). The amounts of WSOC and MBC were both significantly larger in the CG than in the CM and the R. In the three soils, WSOC was depleted while MBC was enriched in 13 C as compared with whole soil C. The relative contributions to the total C content of C stored in the macro‐organic matter and in the size fraction 50–150 µm decreased with decreasing total C contents in the order CG > R > CM, while the relative contribution of C associated with the clay‐ and silt‐sized fraction <50 µm increased. This reflects a greater stability and physical protection against microbial degradation associated with soil disruption (tillage) of the clay‐ and silt‐associated organic C, in relation to the organic C in larger size fractions. The size and density fractions from the CG soil showed significant differences in 13 C enrichment, indicating different degrees of microbial degradation and stability of soil organic C associated with physically different soil organic matter (SOM) fractions. δ 13 C analysis of the size and density fractions from CM and R soils reflected a decreasing turnover rate of soil organic C with increasing density among the macro‐organic matter fractions and with decreasing particle size. Copyright © 2002 John Wiley & Sons, Ltd.

Woody plant encroachment has been long observed in the southern Great Plains (SGP) of the United States. However, our understanding of its spatiotemporal variability, which is the basis for informed and targeted management strategy, is still poor. This study investigates the encroachment of evergreen forest, which is the most important encroachment component in the SGP. A validated evergreen forest map of the SGP (30 m resolution, for the time period 2015 to 2017) from our previous study was utilized (referred to as evergreen_base). Sample plots of evergreen forest (as of 2017) were collected across the study area, based on which a threshold of winter season (January and February) mean normalized difference vegetation index (NDVIwinter) was derived for each of the 5 sub-regions, using Landsat 7 surface reflectance data from 2015 to 2017. Then a NDVIwinter layer was created for each year within the four time periods of 1985-1989, 1995-1999, 2005-2009, and 2015-2017, with winter season surface reflectance data from Landsat 4, 5, and 7. By applying the sub-region specific NDVIwinter thresholds to the annual NDVIwinter layers and the evergreen_base, a SGP evergreen forest map was generated for each of those years. The annual evergreen forest maps within each time period were composited into one. According to the resulting four composite evergreen forest maps, mean annual encroachment rate (km2/year) was calculated at sub-region and ecoregion scales, over each of the three temporal stages 1990-1999, 2000-2009, and 2010-2017, respectively. To understand the spatiotemporal variability of the encroachment, the encroachment rate at each temporal stage was related to the corresponding initial evergreen forest area, mean annual precipitation (MAP), and mean annual burned area (MABA) through linear regression and pairwise comparison. Results suggest that most of the ecoregions have seen a slowing trend of evergreen forest encroachment since 1990. The temporal trend of encroachment rate tends to be consistent with that of MAP, but opposite to that of MABA. The spatial variability of the encroachment rate among ecoregions can be largely (>68%) explained by initial evergreen forest area but shows no significant relationship with MAP or MABA. These findings provide pertinent guidance for the combat of woody plant encroachment in the SGP under the context of climate change.

• Premise of the study: Climate‐induced forest retreat has profound ecological and biogeochemical impacts, but the physiological mechanisms underlying past tree mortality are poorly understood, limiting prediction of vegetation shifts with climate variation. Climate, drought, fire, and grazing represent agents of tree mortality during the late Cenozoic, but the interaction between drought and declining atmospheric carbon dioxide ([CO2]a) from high to near‐starvation levels ∼34 million years (Ma) ago has been overlooked. Here, this interaction frames our investigation of sapling mortality through the interdependence of hydraulic function, carbon limitation, and defense metabolism.• Methods: We recreated a changing Cenozoic [CO2]a regime by growing Sequoia sempervirens trees within climate‐controlled growth chambers at 1500, 500, or 200 ppm [CO2]a, capturing the decline toward minimum concentrations from 34 Ma. After 7 months, we imposed drought conditions and measured key physiological components linking carbon utilization, hydraulics, and defense metabolism as hypothesized interdependent mechanisms of tree mortality.• Key results: Catastrophic failure of hydraulic conductivity, carbohydrate starvation, and tree death occurred at 200 ppm, but not 500 or 1500 ppm [CO2]a. Furthermore, declining [CO2]a reduced investment in carbon‐rich foliar defense compounds that would diminish resistance to biotic attack, likely exacerbating mortality.• Conclusions: Low‐[CO2]a‐driven tree mortality under drought is consistent with Pleistocene pollen records charting repeated Californian Sequoia forest contraction during glacial periods (180–200 ppm [CO2]a) and may even have contributed to forest retreat as grasslands expanded on multiple continents under low [CO2]a over the past 10 Ma. In this way, geologic intervals of low [CO2]a coupled with drought could impose a demographic bottleneck in tree recruitment, driving vegetation shifts through forest mortality.

Regional and local decision-makers still require relevant information and training in order to establish long-term strategies and to contribute to national and supranational energy and climate targets. As an example, a widespread participation of local authorities to comply with the Italian long-term building renovation strategy has not occurred so far. Thus, the overall target, annual 1% floor area of new or deeply renovated buildings to the nearly zero-energy building (nZEB) standard by 2020 (PanZEB 2015), proves to have been disregarded to date. Evidence-based, data-enabled assessment of the building stock and of its relationship with the energy system as a whole at a capillary level is crucial to this extent. In Italy, various building databases are already being used with the ultimate purpose of EPBD implementation and to track and record incentives for public and private building renovation. These datasets have an untapped potential for local energy planning that could be released from wider integration, also including energy consumption data and smart-metering data. Moreover, the regulatory landscape is changing toward an interaction of the building with the user, the energy grid and other buildings in a dynamic and functional way. Within this context, the paper will investigate how integrated data could unlock the value of a more evidence-based planning starting from the DIPENDE integrated dataset, a REQUEST2ACTION (IEE 2014–2017) pilot project combining data from energy performance certificates (EPCs) with bottom-up information on building renovation, and other data in order to support decision making at different territorial scales.