Can bottom-up ocean CO2fluxes be reconciled with atmospheric13C observations?

The rare stable carbon isotope, 13C, has been used previously to partition CO2 fluxes into land and ocean components. Net ocean and land fluxes impose distinctive and predictable fractionation patterns upon the stable isotope ratio, making it an excellent tool for distinguishing between them. Historically, isotope constrained inverse methods for calculating CO2 surface fluxes&mdash;the &lsquo;double deconvolution&rsquo;&mdash;have disagreed with bottom-up ocean flux estimates. In this study, we use the double deconvolution framework, but add, as a constraint, independent estimates of time histories of ocean fluxes to the atmospheric observations of CO2 and 13CO2. We calculate timeseries of net land flux, total disequilibrium flux and terrestrial disequilibrium flux from 1991 to 2008 that are consistent with bottom-up net ocean fluxes.We investigate possible drivers of interannual variability in terrestrial disequilibrium flux, including terrestrial discrimination, and test the sensitivity of our results to those mechanisms. We find that C3 plant discrimination and shifts in the global composition of C3 and C4 vegetation are likely drivers of interannual variability in terrestrial disequilibrium flux, while contributions from heterotrophic respiration and disturbance anomalies are also possible. </div

Multi-Element Regulation of the Tropical Forest Carbon Cycle

Tropical ecosystems dominate the exchange of carbon dioxide between the atmosphere and terrestrial biosphere, yet our understanding of how nutrients control the tropical carbon (C) cycle remains far from complete. In part, this knowledge gap arises from the marked complexity of the tropical forest biome, in which nitrogen, phosphorus, and perhaps several other elements may play roles in determining rates of C gain and loss. As studies from other ecosystems show, failing to account for nutrient–C interactions can lead to substantial errors in predicting how ecosystems will respond to climate and other environmental changes. Thus, although resolving the complex nature of tropical forest nutrient limitation – and then incorporating such knowledge into predictive models – will be difficult, it is a challenge that the global change community must address

Água de baixa turbidez tratada com sementes de Moringa oleífera Lam.

Effective and affordable solutions are being researched to reduce the problems generated by water scarcity in rural communities. Moringa is a natural polymer composed of cationic proteins, which are highlighted as a coagulant in the treatment of water for human consumption. Thus, the objective was to find the best concentration values for the removal of color and turbidity and sedimentation time, thus evaluating the power of Moringa seeds in the removal of Escherichia coli (E. coli) and heterotrophic bacteria in waters of low turbidity, since it does not perform well. The dosages used were 500, 600, 800 and 1000 mg L-1 and the sedimentation times tested were between 18 and 90 minutes. The best values of color removal and turbidity were found with lower dosages, because it is low turbidity water, resulting in the ideal contraction of 500 mg L-1. The minimum sedimentation time for maximum clarification efficiency was 90 minutes. Finally, after the definition of the dosage and better sedimentation time, removals of up to 29% for E. coli and 66% for heterotrophic bacteria were obtained, being within the parameters of potability for water for human consumption.Soluções eficazes e acessíveis vêm sendo pesquisadas para diminuir os problemas gerados pela escassez dos recursos hídricos em comunidades rurais. A Moringa é um polímero natural constituído por proteínas catiônicas, que obtêm destaque como coagulante no tratamento de água para consumo humano. Assim, o objetivo foi encontrar os melhores valores de concentração para remoção de cor e turbidez e  tempo de sedimentação, com isso, avaliar o poder das sementes de Moringa na remoção de Escherichia coli (E. coli) e bactérias heterotróficas em águas de baixa turbidez, já que a mesma não apresenta bom desempenho. As dosagens utilizadas foram de 500, 600, 800 e 1000 mg L-1 e os tempos de sedimentação testados foram entre 18 e 90 minutos. Os melhores valores de remoção de cor e turbidez foram encontrados com menores dosagens, por se tratar de água de baixa turbidez, resultando na contração ideal de 500 mg L-1. O tempo de sedimentação mínimo para a máxima eficiência de clarificação foi aos 90 minutos. E, por fim, após a definição da dosagem e melhor tempo de sedimentação obtiveram-se remoções de até 29% para E. coli e 66% para bactérias heterotróficas, estando dentro dos parâmetros de potabilidade para água de consumo humano.

Methane leak detection and sizing over long distances using dual frequency comb laser spectroscopy and a bootstrap inversion technique

Advances in natural gas extraction technology have led to increased activity in the production and transport sectors in the United States, and, as a consequence, an increased need for reliable monitoring of methane leaks to the atmosphere. We present a statistical methodology in combination with an observing system for the detection and attribution of fugitive emissions of methane from distributed potential source location landscapes such as natural gas production sites. We measure long (&gt;500 m), integrated open path concentrations of atmospheric methane using a dual frequency comb spectrometer and combine measurements with an atmospheric transport model to infer leak locations and strengths using a novel statistical method, the non-zero minimum bootstrap (NZMB). The new statistical method allows us to determine whether the empirical distribution of possible source strengths for a given location excludes zero. Using this information, we identify leaking source locations (i.e., natural gas wells) through rejection of the null hypothesis that the source is not leaking. The method is tested with a series of synthetic data inversions with varying measurement density and varying levels of model-data mismatch. It is also tested with field observations of 1) a non-leaking source location and 2) a source location where a controlled emission of 2.1 E-5 kg s-1 of methane gas is released over a period of several hours. This series of synthetic data tests and outdoor field observations using a controlled methane release demonstrate the viability of the approach for the detection and sizing of very small (&lt;2 g m-1 ) leaks of methane across large distances (4+ km2 in synthetic tests). The field tests demonstrate the ability to attribute small atmospheric enhancements of 18 ppb to the emitting source location against a background of combined atmospheric (e.g., background methane variability) and measurement uncertainty of 6 ppb (1-sigma), when measurements are averaged over 2 minutes. The results of the synthetic and field data testing show that the new observing system and statistical approach greatly decreases the incidence of false alarms (that is, wrongly identifying a well site to be leaking) compared with the same tests that don&rsquo;t use the NZMB approach, and therefore offers increased leak detection and sizing capabilities.</p

Evaluating consistency between total column CO2 retrievals from OCO-2 and the in situ network over North America: implications for carbon flux estimation

The requested paper has a corresponding corrigendum published. Please read the corrigendum first before downloading the article. &nbsp; Feedbacks between the climate system and the carbon cycle represent a key source of uncertainty in model projections of Earth's climate, in part due to our inability to directly measure large-scale biosphere&ndash;atmosphere carbon fluxes. In situ measurements of the CO2 mole fraction from surface flasks, towers, and aircraft are used in inverse models to infer fluxes, but measurement networks remain sparse, with limited or no coverage over large parts of the planet. Satellite retrievals of total column CO2 (XCO2), such as those from NASA's Orbiting Carbon Observatory-2 (OCO-2), can potentially provide unprecedented global information about CO2 spatiotemporal variability. However, for use in inverse modeling, data need to be extremely stable, highly precise, and unbiased to distinguish abundance changes emanating from surface fluxes from those associated with variability in weather. Systematic errors in XCO2 have been identified and, while bias correction algorithms are applied globally, inconsistencies persist at regional and smaller scales that may complicate or confound flux estimation. To evaluate XCO2 retrievals and assess potential biases, we compare OCO-2&nbsp;v10 retrievals with in situ data-constrained XCO2 simulations over North America estimated using surface fluxes and boundary conditions optimized with observations that are rigorously calibrated relative to the World Meteorological Organization X2007 CO2 scale. Systematic errors in simulated atmospheric transport are independently evaluated using unassimilated aircraft and AirCore profiles. We find that the global OCO-2&nbsp;v10 bias correction shifts the distribution of retrievals closer to the simulated XCO2, as intended. Comparisons between bias-corrected and simulated XCO2 reveal differences that vary seasonally. Importantly, the difference between simulations and retrievals is of the same magnitude as the imprint of recent surface flux in the total column. This work demonstrates that systematic errors in OCO-2&nbsp;v10 retrievals of XCO2 over land can be large enough to confound reliable surface flux estimation and that further improvements in retrieval and bias correction techniques are essential. Finally, we show that independent observations, especially vertical profile data, such as those from the National Oceanic and Atmospheric Administration aircraft and AirCore programs are critical for evaluating errors in both satellite retrievals and carbon cycle models.</p

Mastering the Hard Stuff: The History of College Concrete-Canoe Races and the Growth of Engineering Competition Culture

This article details the history of college engineering competitions, originating with student concrete-canoe racing in the 1970s, through today’s multi-million-dollar international multiplicity of challenges. Despite initial differences between engineering educators and industry supporters over the ultimate purpose of undergraduate competitions, these events thrived because they evolved to suit many needs of students, professors, schools, corporations, professional associations, and the engineering profession itself. The twenty-first-century proliferation of university-level competitions in turn encouraged a trickling-down of technical contests to elementary-age children and high schools, fostering the institutionalization of what might be called a competition culture in engineering

Embodying compassion: A virtual reality paradigm for overcoming excessive self-criticism

Virtual reality has been successfully used to study and treat psychological disorders such as phobias and posttraumatic stress disorder but has rarely been applied to clinically-relevant emotions other than fear and anxiety. Self-criticism is a ubiquitous feature of psychopathology and can be treated by increasing levels of self-compassion. We exploited the known effects of identification with a virtual body to arrange for healthy female volunteers high in self-criticism to experience self-compassion from an embodied first-person perspective within immersive virtual reality. Whereas observation and practice of compassionate responses reduced self-criticism, the additional experience of embodiment also increased self-compassion and feelings of being safe. The results suggest potential new uses for immersive virtual reality in a range of clinical conditions.N/

Long-term collapse in fruit availability threatens Central African forest megafauna

Afrotropical forests host many of the world’s remaining megafauna, but even here they are confined to areas where direct human influences are low. We use a rare long-term dataset of tree reproduction and a photographic database of forest elephants to assess food availability and body condition of an emblematic megafauna species at Lopé National Park, Gabon. We show an 81% decline in fruiting over a 32-year period (1986-2018) and an 11% decline in body condition of fruit-dependent forest elephants from 2008-2018. Fruit famine in one of the last strongholds for African forest elephants should raise concern for the ability of this species and other fruit-dependent megafauna to persist in the long-term, with consequences for broader ecosystem and biosphere functioning