Addressing the nitrogen challenge: Footprint tools and on-farm solutions

Nitrogen management presents a unique dilemma: We must use nitrogen to grow our food and sustain life on earth, but excess reactive nitrogen that accumulates in the environment contributes to a cascade of negative impacts to human and ecosystem health. Addressing this nitrogen challenge will require a suite of solutions. This dissertation presents and explores three nitrogen management strategies: 1) The first ever integrated carbon and nitrogen footprint tool for campus sustainability management; 2) Exporting compost to improve a farm’s nitrogen efficiency; and 3) Methods for reducing gas emissions from aerated static pile heat recovery composting. Nitrogen footprint tools connect our everyday choices with the associated nitrogen pollution to the environment. The campus-level nitrogen footprint tool has been particularly successful at both communicating the nitrogen story and encouraging real change with nitrogen footprint reduction goals. However, it is important to assess environmental impacts together to identify management strategies and avoid trade-offs. In this paper, the development and methodology behind the first ever integrated carbon and nitrogen footprint tool for campuses is presented. Comparisons of campus carbon and nitrogen footprints show that the footprints correlate strongly, and scenario analyses indicate benefits to both footprints from a range of management strategies. Integrating the carbon and nitrogen footprints into a single tool for campuses facilitates more comprehensive and integrated management of campus sustainability. Food production is a significant source of nitrogen pollution, and new and improved farm nitrogen management practices are necessary to reduce nitrogen losses. In this study, aerated static pile heat recovery composting is considered as a nitrogen management strategy. To assess its potential, the nitrogen budget of an organic dairy farm was first assessed, where it was found that organic practices led to the cycling of substantially more nitrogen on the farm property than was imported or exported. Some of the potential farm nitrogen loss pathways were characterized, including gas emissions from the compost facility (ammonia, carbon dioxide, methane), but future research should characterize other nitrogen loss pathways to assess the balance between storage and environmental loss. Management strategies for reducing greenhouse gas and ammonia emissions from the compost facility were identified. Scenario analysis found that exporting finished compost was a viable strategy for improving the farm’s nitrogen use efficiency as long as enough nitrogen is retained on-site to support crop production

Calculating the Campus Nitrogen Footprint

Many universities interested in sustainability have calculated their carbon footprint. The carbon footprint is well-established and understood: it tells us how much carbon dioxide and other greenhouse gases are emitted to the atmosphere as a result of university activities. While important, this calculation addresses just one part of a university’s environmental impact. Universities that want to expand their approach to sustainability can now also calculate their nitrogen footprint.Nitrogen footprints connect entities, such as individuals or universities, with the reactive nitrogen (all species of nitrogen except N2) lost to the environment as a result of their activities. While necessary to life, excess reactive nitrogen can be detrimental to ecosystem and human health, causing impacts such as smog, eutrophication, biodiversity loss, climate change, and more. The nitrogen footprint differs importantly from the carbon footprint in that its impact is not only global but also local, impacting local watersheds and ecosystems. Addressing nitrogen allows us to protect and enhance the communities and landscapes of which we are directly a part.Tools are now available to help individuals, universities, and other institutions calculate and reduce their nitrogen footprint. A nitrogen footprint analysis generally considers energy usage, food production and consumption, fertilizer usage, and—especially for a land grant institution—agricultural activities related to its educational and research missions. Universities are particularly well-situated to reduce their carbon emissions and nitrogen pollution because they can both educate a community and make management decisions to reduce their impacts on the environment. Carbon and nitrogen footprints also have significant overlap, especially in the energy sector. Because of this, almost any plan to reduce a university’s carbon footprint will also reduce their nitrogen footprint. Combining the existing university carbon and nitrogen footprint tools could help universities better understand and address a broader range of their environmental impacts.In this talk, we will first present the nitrogen challenge and how nitrogen footprints can be part of the solution. We will demonstrate the university-level nitrogen footprint tool and will share nitrogen footprint results for universities that are already calculating their footprint, including the University of Virginia—where this approach was piloted—and the University of New Hampshire. Finally, we will explain how the carbon and nitrogen footprint overlap and we will make a case for combining the UNHSI Campus Carbon Calculator and the University Nitrogen Footprint Tool into a single tool for universities

Mesenchymal Stem Cell Spheroids Retain Osteogenic Phenotype Through α2β1 Signaling.

Unlabelled: The induction of mesenchymal stem cells (MSCs) toward the osteoblastic lineage using osteogenic supplements prior to implantation is one approach under examination to enhance their bone-forming potential. MSCs rapidly lose their induced phenotype upon removal of the soluble stimuli; however, their bone-forming potential can be sustained when provided with continued instruction via extracellular matrix (ECM) cues. In comparison with dissociated cells, MSC spheroids exhibit improved survival and secretion of trophic factors while maintaining their osteogenic potential. We hypothesized that entrapment of MSC spheroids formed from osteogenically induced cells would exhibit better preservation of their bone-forming potential than would dissociated cells from monolayer culture. Spheroids exhibited comparable osteogenic potential and increased proangiogenic potential with or without osteogenic preconditioning versus monolayer-cultured MSCs. Spheroids were then entrapped in collagen hydrogels, and the osteogenic stimulus was removed. In comparison with entrapped dissociated MSCs, spheroids exhibited significantly increased markers of osteogenic differentiation. The capacity of MSC spheroids to retain their osteogenic phenotype upon withdrawal of inductive cues was mediated by α2β1 integrin binding to cell-secreted ECM. These results demonstrate the capacity of spheroidal culture to sustain the mineral-producing phenotype of MSCs, thus enhancing their contribution toward bone formation and repair.SignificanceDespite the promise of mesenchymal stem cells (MSCs) for cell-based therapies for tissue repair and regeneration, there is little evidence that transplanted MSCs directly contribute to new bone formation, suggesting that induced cells rapidly lose their osteogenic phenotype or undergo apoptosis. In comparison with dissociated cells, MSC spheroids exhibit increased trophic factor secretion and improved cell survival. The loss of phenotype represents a significant clinical challenge for cell therapies, yet there is no evidence for whether MSC spheroids retain their osteogenic phenotype upon entrapment in a clinically relevant biomaterial. These findings demonstrate that MSC spheroids retain their osteogenic phenotype better than do dissociated MSCs, and this is due to integrin engagement with the cell-secreted extracellular matrix. These data provide evidence for a novel approach for potentiating the use of MSCs in bone repair

State anxiety and cortisol reactivity to skydiving in novice versus experienced skydivers

Previous studies have suggested that skydiving, a naturalistic stressor, is associated with increases in self-reported stress, anxiety and cortisol levels. However, it has not been established whether this stress reactivity is altered as a function of repeated exposure to skydiving. This is of interest due to previous observations that cortisol reactivity becomes habituated with repeated exposure to laboratory stressors, however, few studies have investigated such habituation to naturalistic stressors. State anxiety and cortisol reactivity to skydiving were measured in 11 first-time skydivers and 13 experienced skydivers (≥ 30 jumps, mean jumps = 397.6), who were to complete a solo skydive. The novice skydivers reported significantly greater levels of state anxiety prior to the jump; however, there were no differences in pre-jump levels of salivary cortisol. Both groups exhibited significantly elevated salivary cortisol levels immediately post-jump, relative to i) pre-jump and ii) recovery. However, the two groups were indistinguishable with regard to their cortisol reactivity to the skydive. These findings support previous research demonstrating that skydiving elicits acute cortisol activation. Further, they suggest that i) cortisol reactivity does not habituate in experienced jumpers, and ii) that there is lack of concordance between self-reported levels of anxiety and biological stress reactivity in experienced skydivers

The Performance and Calibration of the CRAFT Fly's Eye Fast Radio Burst Survey

Since January 2017, the Commensal Real-time ASKAP Fast Transients survey (CRAFT) has been utilising commissioning antennas of the Australian SKA Pathfinder (ASKAP) to survey for fast radio bursts (FRBs) in fly's eye mode. This is the first extensive astronomical survey using phased array feeds (PAFs), and a total of 20 FRBs have been reported. Here we present a calculation of the sensitivity and total exposure of this survey, using the pulsars B1641-45 (J1644-4559) and B0833-45 (J0835-4510, i.e.\ Vela) as calibrators. The design of the survey allows us to benchmark effects due to PAF beamshape, antenna-dependent system noise, radio-frequency interference, and fluctuations during commissioning on timescales from one hour to a year. Observation time, solid-angle, and search efficiency are calculated as a function of FRB fluence threshold. Using this metric, effective survey exposures and sensitivities are calculated as a function of the source counts distribution. The implied FRB rate is significantly lower than the $37$\,sky$^{-1}$\,day$^{-1}$ calculated using nominal exposures and sensitivities for this same sample by \citet{craft_nature}. At the Euclidean power-law index of $-1.5$, the rate is $10.7_{-1.8}^{+2.7}\,{\rm (sys)} \, \pm \, 3\,{\rm (stat)}$\,sky$^{-1}$\,day$^{-1}$ above a threshold of $57\pm6\,{\rm (sys)}$\,Jy\,ms, while for the best-fit index for this sample of $-2.1$, it is $16.6_{-1.5}^{+1.9} \,{\rm (sys)}\, \pm 4.7\,{\rm (stat)}$\,sky$^{-1}$\,day$^{-1}$ above a threshold of $41.6\pm1.5\,{\rm (sys)}$\,Jy\,ms. This strongly suggests that these calculations be performed for other FRB-hunting experiments, allowing meaningful comparisons to be made between them.Comment: 21 pages, 15 figures, 2 tables, accepted for publication in PAS

The nitrogen footprint of Ukraine: why personal consumption matters

Unintended reactive nitrogen (N) losses from agriculture, energy and transportation pose significant environmental hazards, including eutrophication, acidification, water and air pollution, biodiversity loss, human health risks and climate change. The concept of a Nitrogen Footprint (NF) emerges as a pivotal metric, reflecting potential N losses in the entire production-consumption chain of goods and services used by an individual within a defined timeframe. In a pioneering assessment of per capita NF in Ukraine, key factors, such as the food production chain, consumption patterns, connection to wastewater treatment (WWT) system and the efficacy of WWT facilities, were identified as critical components. Addressing specific challenges, such as data availability, soil N depletion and manure waste, was found to be particularly complex. The apparent high nitrogen use efficiency (NUE) in Ukrainian cropping systems was highlighted to be actually reflected in the elevated N mineralization rate in Ukrainian soils characterized by high organic matter content. The individual Ukraine NF (22.1 kg N cap-1 yr-1 as of 2017) was found to be much lower than that of the US and Australia being comparable to Western European countries. Even so, significant opportunities for reduction remain through a wide range of options towards healthier and more sustainable dietary choices. Potential reductions, ranging from 22% to 69%, were shown for omnivore, reduced red meat, no red meat, half meat products, vegetarian and vegan diets. In the absence of proper manure management in Ukraine, even greater reductions of an ‘actual’ NF can be achieved if wasted N manure is considered. The war's impact is assumed to result in a slight increase or no changes in individual food consumption NFs and an increase in food production NFs for local products, while reductions in individual transport and energy NFs were likely across Ukraine. Nonetheless, refugees massively displaced to less affected regions overload a largely outdated civilian infrastructure, leading to higher N losses. Looking ahead, sustained support, capital investments, legislative enhancements and regulatory frameworks, especially upon post-war renovation of Ukraine, are imperative for reducing the individual NF. This involves enhancing nitrogen use efficiency in agriculture, establishing efficient manure management, upgrading WWT facilities, promoting renewable energy adoption, bolstering requisite infrastructure and raising public awareness on environmental sustainability

Intentional versus unintentional nitrogen use in the United States : trends, efficiency and implications

© The Author(s), 2012. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biogeochemistry 114 (2013): 11-23, doi:10.1007/s10533-012-9801-5.Human actions have both intentionally and unintentionally altered the global economy of nitrogen (N), with both positive and negative consequences for human health and welfare, the environment and climate change. Here we examine long-term trends in reactive N (Nr) creation and efficiencies of Nr use within the continental US. We estimate that human actions in the US have increased Nr inputs by at least ~5 times compared to pre-industrial conditions. Whereas N2 fixation as a by-product of fossil fuel combustion accounted for ~1/4 of Nr inputs from the 1970s to 2000 (or ~7 Tg N year−1), this value has dropped substantially since then (to <5 Tg N year−1), owing to Clean Air Act amendments. As of 2007, national N use efficiency (NUE) of all combined N inputs was equal to ~40 %. This value increases to 55 % when considering intentional N inputs alone, with food, industrial goods, fuel and fiber production accounting for the largest Nr sinks, respectively. We estimate that 66 % of the N lost during the production of goods and services enters the air (as NO x , NH3, N2O and N2), with the remaining 34 % lost to various waterways. These Nr losses contribute to smog formation, acid rain, eutrophication, biodiversity declines and climate change. Hence we argue that an improved national NUE would: (i) benefit the US economy on the production side; (ii) reduce social damage costs; and (iii) help avoid some major climate change risks in the future.This work resulted from a workshop supported by NSF Research Coordination Network Awards DEB-0443439 and DEB-1049744 and by the David and Lucille Packard Foundation

New reductive rearrangement of N-Arylindoles triggered by the Grubbs-Stoltz reagent Et3SiH/KOtBu

N-Arylindoles are transformed into dihydroacridines in a new type of rearrangement, through heating with triethylsilane and potassium tert-butoxide. Studies indicate that the pathway involves (i) the formation of indole radical anions followed by fragmentation of the indole C2-N bond, and (ii) a ring-closing reaction that follows a potassium-ion dependent hydrogen atom transfer step. Unexpected behaviors of ‘radical-trap’ substrates prove very helpful in framing the proposed mechanis