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Formation of phosphorus monoxide through the P ( 4 S ) + O 2 ( 3 Σ − ) → O ( 3 P ) + P O ( 2 Π ) reaction
Phosphorus is a key and vital element for a diverse set of important biological molecules, being indispensable for life as we know. A deeper comprehension of its role in astrochemistry and atmospheric chemistry may aid in finding answers to how this element became available on Earth. The PO molecule is one of the main reservoirs of phosphorus in the interstellar medium (ISM), and a better understanding of the mechanisms and rate coefficients for its formation in the ISM is important for modelling its abundances. In this work, we perform multireference configuration interaction calculations on the formation of PO via the
reaction, analyzing its potential energy surface and rate coefficients for the global reaction on both doublet and quartet states. We also perform DFT (M06-2X) and CCSD(T) calculations, in order to compare the results. We found that the OPO system possesses a high multiconfigurational character, making DFT and CCSD methodologies not suitable for its potential energy landscape calculation. The rate coefficients have been calculated using the master equation system solver (MESS) package, and the results compared to recent experimental data. It is shown that the quartet state contributes for temperatures higher than 700K. The computed rate coefficient can be described by a modified Arrhenius equation [
] with
,
and
K.
Journal Article
The devil's element : phosphorus and a world out of balance
The story of phosphorus spans the globe and vast tracts of human history. The race to mine phosphorus took people from the battlefields of Waterloo, which were looted for the bones of fallen soldiers, to the fabled guano islands off Peru, the Bone Valley of Florida, and the sand dunes of the Western Sahara. Over the past century, phosphorus has made farming vastly more productive, feeding the enormous increase in the human population. Yet, as the author harrowingly reports, our overreliance on this vital crop nutrient is causing toxic algae blooms and \"dead zones\" in waterways from the coasts of Florida to the Mississippi River basin to the Great Lakes and beyond. This book also explores the alarming reality that diminishing access to phosphorus poses a threat to the food system worldwide--which risks rising conflict and even war. -- Adapted from publisher's description.
Book
Utilizing soil organic phosphorus for sustainable crop production: insights into the rhizosphere
Background
We are facing the challenge of sustainable phosphorus (P) use due to high P inputs in farmland and low P-use efficiency of crops, which leads to critical soil P imbalances and accelerates consumption of limited P resources. Organic P is an essential component of the soil P cycle, and if managed properly, may compensate partly for decreased usage of P fertilizers. However, organic P dynamics in the rhizosphere has received little attention even though it is important for P availability to plants.
Scope
We review biological turnover of organic P in soils, focusing on the processes driven by roots and microbial communities and their interactions in the rhizosphere. We also consider recent progress in understanding of organic P acquisition strategies that integrate soil carbon (C) cycling. We address several perspectives to achieve more sustainable P use in agriculture via rhizosphere management aimed at recycling and re-using soil organic P.
Conclusions
Organic P mineralization by microorganisms may be limited by low P and/or C availability. In these processes, plants interact with microorganisms to alter stoichiometric ratios of C to P in the rhizosphere soils or microbial community, thus impacting on turnover of organic P into inorganic P for plant absorption, which is manifested in plant-microbial facilitation/competition in the rhizosphere. We highlight future research in improving rhizosphere management of agroecosystems by optimizing nutrient inputs and enhancing rhizosphere interactions to manipulate P and C dynamics towards sustainable organic P use.
Journal Article
Phosphorus in soils and plants – facing phosphorus scarcity
Introduction : Phosphorus is a fundamental nutrient for primary productivity of ecosystems and agricultural production, but its misuse impacts agricultural sustainability and has important environmental consequences. Access to global reserves of phosphate rock is politically sensitive and economically challenging. Phosphorus accumulates in agricultural soils, representing a financial loss to farmers and increasing the risk of loss to water. The challenges facing phosphorus sustainability are varied, but many solutions are to be found in the plant–soil system. Scope : This special issue arises from the 5th International Symposium on Phosphorus in Soils and Plants (PSP5), held in Montpellier, France. Articles highlighted here discuss ways to tackle food security, improve phosphorus sustainability by understanding the imbalanced phosphorus cycle, use technology to reduce phosphorus demand and recycle phosphorus in waste products, and consider how efforts to increase phosphorus efficiency interact with other sustainability challenges. Conclusions : The challenges associated with P sustainability are tackled from many different directions, including plant genetics, soil microbiology, novel imaging and modelling techniques, the development of new technologies, and an improved understanding of how these technologies interact with agronomic management. Integration of the various approaches will be necessary to deliver a truly effective solution to the challenge of attaining phosphorus sustainability.
Journal Article
Phosphorus facilitation and covariation of root traits in steppe species
• Different phosphorus (P)-acquisition strategies may be relevant for species coexistence and plant performance in terrestrial communities on P-deficient soils. However, how interspecific P facilitation functions in natural systems is largely unknown.
• We investigated the root physiological activities for P mobilization across 19 coexisting plant species in steppe vegetation, and then grew plants with various abilities to mobilize sorbed P in a microcosm in a glasshouse.
• We show that P facilitation mediated by rhizosphere processes of P-mobilizing species promoted growth and increased P content of neighbors in a species-specific manner. When roots interacted with a facilitating neighbor, Cleistogenes squarrosa and Bromus inermis tended to show greater plasticity of root proliferation or rhizosheath acid phosphatase activity compared with other non-P-mobilizing species. Greater variation in these root traits was strongly correlated with increased performance in the presence of a facilitator. The results also show, for the first time, that P facilitation was an important mechanism underlying a positive complementarity effect.
• Our study highlights that interspecific P-acquisition facilitation requires that facilitated neighbors exhibit a better match of root traits with a facilitating species. It provides a better understanding of species coexistence in P-limited communities.
Journal Article
Uncovering the Ediacaran phosphorus cycle
Phosphorus is a limiting nutrient that is thought to control oceanic oxygen levels to a large extent
1
–
3
. A possible increase in marine phosphorus concentrations during the Ediacaran Period (about 635–539 million years ago) has been proposed as a driver for increasing oxygen levels
4
–
6
. However, little is known about the nature and evolution of phosphorus cycling during this time
4
. Here we use carbonate-associated phosphate (CAP) from six globally distributed sections to reconstruct oceanic phosphorus concentrations during a large negative carbon-isotope excursion—the Shuram excursion (SE)—which co-occurred with global oceanic oxygenation
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–
9
. Our data suggest pulsed increases in oceanic phosphorus concentrations during the falling and rising limbs of the SE. Using a quantitative biogeochemical model, we propose that this observation could be explained by carbon dioxide and phosphorus release from marine organic-matter oxidation primarily by sulfate, with further phosphorus release from carbon-dioxide-driven weathering on land. Collectively, this may have resulted in elevated organic-pyrite burial and ocean oxygenation. Our CAP data also seem to suggest equivalent oceanic phosphorus concentrations under maximum and minimum extents of ocean anoxia across the SE. This observation may reflect decoupled phosphorus and ocean anoxia cycles, as opposed to their coupled nature in the modern ocean. Our findings point to external stimuli such as sulfate weathering rather than internal oceanic phosphorus–oxygen cycling alone as a possible control on oceanic oxygenation in the Ediacaran. In turn, this may help explain the prolonged rise of atmospheric oxygen levels.
Reconstruction of oceanic phosphorus concentrations during a large negative carbon-isotope excursion co-occurring with global oceanic oxygenation and evolution of some of Earth’s earliest animals suggests that decoupled phosphorus and ocean anoxia cycles during the Ediacaran may have prolonged the rise of atmospheric oxygen.
Journal Article