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The global emission of ammonia (NH $ ) is about 54 Mt N. The major global sources are excreta from domestic animals and fertilizers, but oceans, biomass burning and crops are also important. About 60 % of the global NH $ emission is estimated to come from anthropogenic sources. NH $ -N emissions are of the same order as the NO x -N emissions on both global and European scales. Emitted NH $ returns to the surface mainly in the form of dry deposition of NH $ and wet deposition of ammonium (NH % + ). In countries with high NH $ emission densities, dry deposition of NH $ from local sources and wet deposition of NH % + from remote sources dominate the deposition. In countries with low NH $ emission densities only wet deposition of NH % + from remote sources dominates the deposition. Surface exchange of NH $ is essentially bi-directional, depending on the NH $ compensation point concentration of the vegetation and the airborne concentration. In general, the compensation point is larger for agricultural than semi-natural plants, and varies with plant growth stage. According to basic thermodynamics the leaf tissue or stomatal compensation point of NH $ doubles for each increase of 5 mC. However, exchange of NH $ does not only occur through the stomata, but it can also be deposited to leaf surfaces, as well as emitted back to the atmosphere from drying leaf surfaces. Atmospheric transport and deposition models can be used to interpolate NH $ concentrations and depositions in space and time, to calculate import\export balances and to estimate past or future situations. Adverse effects on sensitive ecosystems caused by high N deposition can be reduced by lowering the emissions and, to a limited extent, also by removing sources close to the ecosystem to be protected.

The most widespread dietary problem in the world is mineral deficiency. We used the nicotianamine synthase (NAS) gene to increase mineral contents in rice grains. Nicotianamine (NA) is a chelator of metals and a key component of metal homeostasis. We isolated activation-tagged mutant lines in which expression of a rice NAS gene, OsNAS3, was increased by introducing 35S enhancer elements. Shoots and roots of the OsNAS3 activationtagged plants (OsNAS3-D1) accumulated more Fe and Zn. Seeds from our OsNAS3-D1 plants grown on a paddy field contained elevated amounts of Fe (2.9-fold), Zn (2.2-fold), and Cu (1.7-fold). The NA level was increased 9.6-fold in OsNAS3-D1 seeds. Analysis by size exclusion chromatography coupled with inductively coupled plasma mass spectroscopy showed that WT and Os-NAS3-D1 seeds contained equal amounts of Fe bound to IP6, whereas OsNAS3-D1 had 7-fold more Fe bound to a low molecular mass, which was likely NA. Furthermore, this activation led to increased tolerance to Fe and Zn deficiencies and to excess metal (Zn, Cu, and Ni) toxicities. In contrast, disruption of OsNAS3 caused an opposite phenotype. To test the bioavailability of Fe, we fed anemic mice with either engineered or WT seeds for 4 weeks and measured their concentrations of hemoglobin and hematocrit. Mice fed with engineered seeds recovered to normal levels of hemoglobin and hematocrit within 2 weeks, whereas those that ate WT seeds remained anemic. Our results suggest that an increase in bioavailable mineral content in rice grains can be achieved by enhancing NAS expression. activation tagging ͉ bioavailability ͉ hemoglobin ͉ metal homeostasis

With more than 60% of the land farmed, with vulnerable freshwater and marine environments, and with one of the most intensive, export-oriented livestock sectors in the world, the nitrogen (N) pollution pressure from Danish agriculture is severe. Consequently, a series of policy action plans have been implemented since the mid 1980s with significant effects on the surplus, efficiency and environmental loadings of N. This paper reviews the policies and actions taken and their ability to mitigate effects of reactive N (N r ) while maintaining agricultural production. In summary, the average N-surplus has been reduced from approximately 170 kg N ha −1 yr −1 to below 100 kg N ha −1 yr −1 during the past 30 yrs, while the overall N-efficiency for the agricultural sector (crop + livestock farming) has increased from around 20-30% to 40-45%, the N-leaching from the field root zone has been halved, and N losses to the aquatic and atmospheric environment have been significantly reduced. This has been achieved through a combination of approaches and measures (ranging from command and control legislation, over market-based regulation and governmental expenditure to information and voluntary action), with specific measures addressing the whole N cascade, in order to improve the quality of ground-and surface waters, and to reduce the deposition to terrestrial natural ecosystems. However, there is still a major challenge in complying with the EU Water Framework and Habitats Directives, calling for Environmental Research Letters Environ.

Abstract:The aim of the current paper is to discuss the sustainability aspect of biorefinery systems with focus on: biomass supply chains, processing of biomass feedstocks in biorefinery platforms and sustainability assessment methodologies. From the stand point of sustainability, it is important to optimize the agricultural production system and minimize the related environmental impacts at the farming system level. These impacts are primarily related to agri-chemical inputs and the related undesired environmental emissions and to the repercussions from biomass production. At the same time, the biorefineries needs a year-round supply of biomass and about 40-60% of the total operating cost of a typical biorefinery is related to the feedstocks chosen, and thus highlights on the careful prioritization of feedstocks mainly based on their economic and environmental loadings. Regarding the processing in biorefinery platforms, chemical composition of biomasses is important. Biomasses with higher concentrations of cellulose and hemicelluloses compared to lignin are preferred for bioethanol production in the lignocellulosic biorefinery, since the biodegradability of cellulose is higher than lignin. A green biorefinery platform enables the extraction of protein from grasses, producing an important alternative to importing protein sources for food products and animal feed, while also allowing processing of residues to deliver bioethanol. Currently, there are several approaches to integrate biorefinery platforms, which are aimed to enhance their economic and environmental sustainability. Regarding sustainability assessment, the complexities related to the material flows in a biorefinery and the delivery of alternative biobased products means dealing with multiple indicators in the decision-making process to enable comparisons of alternatives. Life Cycle Assessment is regarded as one of the most relevant tools to assess the environmental hotspots in the biomass supply chains, at processing stages and also to support in the prioritization of any specific biobased products and the alternatives delivered from biorefineries.Keywords: biorefinery, biomass feedstock, sustainability, biobased product, environmental performances, economic performances, Life Cycle Assessment 2 IntroductionThe societal need of energy and materials is predicted to reach a crisis point in the near future [1]. This is because of the coupling between escalating demand and cost of fossil fuels upon which the production of chemicals, materials and energy conversions still depend. The high energy intensity in material production has sustainability impacts on the energy sector, environment and economy [2]. Currently fossil fuels contribute about 80% of the global energy demand, and even if the current political commitments and strategies to tackle the issues of climate change and energy insecurity, as envisioned by different countries are in place, the global energy demand in 2035 is still projected to rise by 40% with fossil fuels contributing 75% [3]. The ...