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Methanol-Based Chain Elongation with Acetate to n-Butyrate and Isobutyrate at Varying Selectivities Dependent on pH
Full text linkBiomass fermentation technologies offer alternative methods to produce platform chemicals that currently originate from fossil sources. This research showed that an enriched microbiome was capable to produce isobutyrate (i-C4) from acetate via methanol-based chain elongation. A long-term continuous reactor experiment showed that the selectivity for i-C4 and/or n-butyrate (n-C4) could be reversibly adjusted by changing the reactor pH. A reactor pH of 6.75 led to formation of (carbon per total carbon of products) 0.78 n-C4 and 0.024 i-C4, whereas a reactor pH of 5.2 led to a selectivity of 0.24 n-C4 and 0.65 i-C4. This shift in product spectrum was also represented by a shift in microbial composition. The results suggest that a Eubacterium genus is responsible for the formation of n-C4, whereas a Clostridium luticellarii strain is responsible for the formation of a mixture of i-C4 and n-C4. The formation of n-C4 and i-C4 at a low pH was observed to be coupled according to the thermodynamics of isomerization. At a reactor pH of 5.5 and 5.2, the product ratio of i-C4:n-C4 approached 0.69 i-C4:0.31 n-C4, which is the theoretical ratio that would be achieved when determined by the equilibrium of isomerization. Various batch experiments at pH 5.5 and 5.2 confirmed that addition of either n-C4 or i-C4 at the start of the batch would directly lead to the formation of the other butyrate component. Moreover, batch experiments performed at pH 6.5 produced mainly n-C4 and led to the development of a completely different microbiome. The imposed pH is a strong selection pressure that can facilitate changes in product selectivities for n-C4 and i-C4 during methanol-based chain elongation of acetate.</p
Linking sensory and proton transfer reaction–mass spectrometry analyses for the assessment of melon fruit (Cucumis melo L.) quality traits
No full textSixty-seven samples of ten melon types (Cucumis melo L.) were evaluated to determine the relationship between their quality traits: sensory attributes, pH, soluble solids, and volatile organic compounds. Fruits from the cantalupensis, conomon, dudaim, inodorus, and momordica cultivar groups were analyzed. The sensory profiles were assessed using ten attributes covering odor, flavor, and taste characteristics, whereas the volatile profiles were derived by proton transfer reaction–mass spectrometry. Fruits from the cantalupensis and inodorus cultivars showed an opposite pattern for several quality traits. Fruits from the dudaim cultivar were more related to the cantalupensis, whereas conomon and momordica showed an intermediate behavior between inodorus and cantalupensis. The attributes of odor and flavor intensity, ripe fruit odor, fermentative odor, and fermentative flavor correlated positively to C3–C9 esters (r = 0.43–0.73; p ≤ 0.01). Positive correlations were also observed for several alcohols (r = 0.36–0.82; p ≤ 0.05), including methanol, ethanol, and diol alcohols, as well as for several aldehydes (r = 0.43–0.85; p ≤ 0.01), such as acetaldehyde, butanal, methyl butanal, heptanal, and decanal. The attributes mentioned above were negatively correlated with two C9 aldehydes, 2,6-nonadienal and nonenal (r = − 0.45 to − 0.62; p ≤ 0.01), whereas sweetness was negatively correlated with two C6 green leaf volatiles, hexenal and 3-hexenol (r = − 0.50; − 0.67; p ≤ 0.001). The melon fruits presented distinct differences in the quality traits evaluated. These results provide information for the development of new cultivars with characteristic taste combinations without compromising other desirable fruit quality traits.</p
What happens in Europe stays in Europe : apparent evolution by an invader does not help at home
No full textSome invasive plant species rapidly evolve greater size and/or competitive ability in their nonnative ranges. However, it is not well known whether these traits transfer back to the native range, or instead represent genotype-by-environment interactions where traits are context specific to communities in the new range where the evolution occurred. Insight into transferability vs. context specificity can be tested using experiments performed with individuals from populations from the native and nonnative ranges of exotic invasive species. Using a widespread invasive plant species in Europe, Solidago gigantea, we established reciprocal common garden experiments in the native range (Montana, North America; n = 4) and the nonnative range (Hungary, Europe; n = 4) to assess differences in size, vegetative shoot number, and herbivory between populations from the native and nonnative ranges. In a greenhouse experiment, we also tested whether the inherent competitive ability of genotypes from 15 native and 15 invasive populations differed when pitted against 11 common native North American competitors. In common gardens, plants from both ranges considered together produced five times more biomass, grew four times taller, and developed five times more rhizomes in the nonnative range garden compared to the native range garden. The interaction between plant origin and the common garden location was highly significant, with plants from Hungary performing better than plants from Montana when grown in Hungary, and plants from Montana performing better than plants from Hungary when grown in Montana. In the greenhouse, there were no differences in the competitive effects and responses of S. gigantea plants from the two ranges when grown with North American natives. Our results suggest that S. gigantea might have undergone rapid evolution for greater performance abroad, but if so, this response does not translate to greater performance at home.</p
Soil management intensity shifts microbial catabolic profiles across a range of European long-term field experiments
Full text linkAssessing soil microbial functionality has the potential to reveal meaningful effects of soil management on soil processes influencing soil quality. We used MicroResp™ to assess microbial respiration upon the addition of six carbon substrates (glucose, alanine, aminobutyric acid, N-acetyl glucosamine, alpha-ketoglutaric acid, and lignin). From this, we calculated the multiple substrate induced respiration (MSIR), the microbial catabolic profile expressed as absolute and relative utilization rate, and the Shannon microbial functional diversity index (H′). We tested the effect of tillage (reduced vs. conventional) and organic matter addition (high vs. low) on these microbial parameters in soil from 10 European long-term field experiments (LTEs), and investigated their relationships with labile organic carbon fractions and various soil parameters linked to soil functions. Reduced tillage and high organic matter input increased MSIR compared to conventional tillage and low organic matter input. In addition, reduced tillage resulted in a small but significant increase in functional diversity compared to conventional tillage. An increase in soil management intensity (CT-Low > CT-High > RT-Low > RT-High) was associated with lower utilization of all the substrates expressed as absolute utilization rate, and a proportionately higher utilization of alpha-ketoglutaric acid compared to the other substrates. More intensive management systems also showed lower soil quality as measured by various soil parameters, in particular total and labile organic carbon, basal respiration, and microbial biomass nitrogen. The present work shows for the first time the key role of labile organic carbon, as affected by soil management, in determining microbial functional diversity. Aggregating results from 10 European arable LTEs, making use of a comprehensive dataset, MicroResp™ showed that reduced tillage and increased organic matter addition created a more favourable habitat for the microbial community to utilize different carbon substrates and, thereby, the potential for nutrient cycling.</p
Inferring Changes in Summertime Surface Ozone-NO<sub>x</sub>-VOC Chemistry over U.S. Urban Areas from Two Decades of Satellite and Ground-Based Observations
No full textUrban ozone (O3) formation can be limited by NOx, VOCs, or both, complicating the design of effective O3 abatement plans. A satellite-retrieved ratio of formaldehyde to NO2 (HCHO/NO2), developed from theory and modeling, has previously been used to indicate O3 formation chemistry. Here, we connect this space-based indicator to spatiotemporal variations in O3 recorded by on-the-ground monitors over major U.S. cities. High-O3 events vary nonlinearly with OMI HCHO and NO2, and the transition from VOC-limited to NOx-limited O3 formation regimes occurs at higher HCHO/NO2 value (3 to 4) than previously determined from models, with slight intercity variations. To extend satellite records back to 1996, we develop an approach to harmonize observations from GOME and SCIAMACHY that accounts for differences in spatial resolution and overpass time. Two-decade (1996-2016) multisatellite HCHO/NO2 captures the timing and location of the transition from VOC-limited to NOx-limited O3 production regimes in major U.S. cities, which aligns with the observed long-term changes in urban-rural gradient of O3 and the reversal of O3 weekend effect. Our findings suggest promise for applying space-based HCHO/NO2 to interpret local O3 chemistry, particularly with the new-generation satellite instruments that offer finer spatial and temporal resolution.</p
Niet alles kan overal : Eindadvies over structurele aanpak op lange termijn
Full text linkHet Adviescollege Stikstofproblematiek heeft de opdracht gekregen de minister van Landbouw, Natuur en Voedselkwaliteit te adviseren over hoe om te gaan met de stikstofproblematiek in Nederland. Na het uitbrengen van het eerste advies ‘Niet alles kan’, het tussentijdse advies over ‘Bemesten en beweiden in 2020’ en het ‘Advies Luchtvaartsector’ is het Adviescollege van start gegaan met de tweede fase van de opdracht. Opdracht voor deze tweede fase betreft het adviseren over een structurele aanpak van de stikstofproblematiek op de lange termijn. Dit advies is verwoord in deze eindrapportage
A schematic sampling protocol for contaminant monitoring in raptors
Full text linkBirds of prey, owls and falcons are widely used as sentinel species in raptor biomonitoring programmes. A major current challenge is to facilitate large-scale biomonitoring by coordinating contaminant monitoring activities and by building capacity across countries. This requires sharing, dissemination and adoption of best practices addressed by the Networking Programme Research and Monitoring for and with Raptors in Europe (EURAPMON) and now being advanced by the ongoing international COST Action European Raptor Biomonitoring Facility. The present perspective introduces a schematic sampling protocol for contaminant monitoring in raptors. We provide guidance on sample collection with a view to increasing sampling capacity across countries, ensuring appropriate quality of samples and facilitating harmonization of procedures to maximize the reliability, comparability and interoperability of data. The here presented protocol can be used by professionals and volunteers as a standard guide to ensure harmonised sampling methods for contaminant monitoring in raptors.</p
Assessing the capacity of European regional seas to supply ecosystem services using marine status assessments
No full textIn this paper we describe work that progresses the understanding of socio-ecological systems from the perspective of exploring how the supply of ecosystem services might vary with changes in the state of ecosystem components. We developed and tested a new assessment approach (concept, framework and methodology) to assess the capacity of marine ecosystems to supply services, which could be carried out using available policy-reported assessment information on marine biodiversity and ecosystem status. The starting point was an assessment that drew on an understanding of ecosystem state-service relationships, and that was extended to incorporate operational, policy-relevant ecosystem assessment information at European regional sea scales in response to the requirements of the EU Biodiversity Strategy to 2020. The assessment consists of three key steps: (1) identifying all the instances where a marine ecosystem component can potentially contribute to the supply of a marine ecosystem service; (2) developing a critical pathway analysis to identify the major ecosystem component(s) contributing to the supply of a given service; (3) interpreting available information on the state and trends of these major contributing components with knowledge of the ecosystem state-service relationship, to assess the ecosystem's capacity for service supply and its direction of change. The assessment provides a common approach that can be applied across marine regions, and in data rich or data poor situations. This approach captures the sustainability of ecosystem service supply capacity through retaining the connection with the state of the ecosystem and can help to inform management decisions and track the effectiveness of environmental policies.</p
Skill of large-scale seasonal drought impact forecasts
Full text linkForecasting of drought impacts is still lacking in drought early-warning systems (DEWSs), which presently do not go beyond hazard forecasting. Therefore, we developed drought impact functions using machine learning approaches (logistic regression and random forest) to predict drought impacts with lead times up to 7 months ahead. The observed and forecasted hydrometeorological drought hazards – such as the standardized precipitation index (SPI), standardized precipitation evaporation index (SPEI), and standardized runoff index (SRI) – were obtained from the The EU-funded Enhancing Emergency Management and Response to Extreme Weather and Climate Events (ANYWHERE) DEWS. Reported drought impact data, taken from the European Drought Impact Report Inventory (EDII), were used to develop and validate drought impact functions. The skill of the drought impact functions in forecasting drought impacts was evaluated using the Brier skill score and relative operating characteristic metrics for five cases representing different spatial aggregation and lumping of impacted sectors. Results show that hydrological drought hazard represented by SRI has higher skill than meteorological drought represented by SPI and SPEI. For German regions, impact functions developed using random forests indicate a higher discriminative ability to forecast drought impacts than logistic regression. Moreover, skill is higher for cases with higher spatial resolution and less lumped impacted sectors (cases 4 and 5), with considerable skill up to 3–4 months ahead. The forecasting skill of drought impacts using machine learning greatly depends on the availability of impact data. This study demonstrates that the drought impact functions could not be developed for certain regions and impacted sectors, owing to the lack of reported impacts
Financial schemes for resilient flood recovery
No full textOptions for the increase of flood resilience during the recovery phase is, to a large extent, overlooked. The special issue Financial Schemes for Resilient Flood Recovery investigates how the implementation of financial schemes (government relief subsidies, insurance schemes, buy-outs, etc.) might increase flood resilience. Five papers address following questions: Shall government relief subsidies exist when there is flood insurance in place, and, if so, how might they both be coordinated? Where (or how) to decide about build back better incentives and where to go for planned relocation programs? What is the distributional equity of financial schemes for flood recovery, and has it been sufficiently treated?.</p