Bioturbator-stimulated loss of seagrass sediment carbon stocks

© 2018 Association for the Sciences of Limnology and Oceanography Seagrass ecosystems are highly productive, and are sites of significant carbon sequestration. Sediment-held carbon stocks can be many thousands of years old, and persist largely due to sediment anoxia and because microbial activity is decreasing with depth. However, the carbon sequestered in seagrass ecosystems may be susceptible to remineralization via the activity of bioturbating fauna. Microbial priming is a process whereby remineralization of sediment carbon (recalcitrant organic matter) is stimulated by disturbance, i.e., burial of a labile source of organic matter (seagrass). We investigated the hypothesis that bioturbation could mediate remineralization of sediment carbon stocks through burial of seagrass leaf detritus. We carried out a 2-month laboratory study to compare the remineralization (measured as CO 2 release) of buried seagrass leaves (Zostera muelleri) to the total rate of sediment organic matter remineralization in sediment with and without the common Australian bioturbating shrimp Trypaea australiensis (Decapoda: Axiidea). In control sediment containing seagrass but no bioturbators, we observed a negative microbial priming effect, whereby seagrass remineralization was favored over sediment remineralization (and thus preserving sediment stocks). Bioturbation treatments led to a two- to five-fold increase in total CO 2 release compared to controls. The estimated bioturbator-stimulated microbial priming effect was equivalent to 15% of the total daily sediment-derived CO 2 releases. We propose that these results indicate that bioturbation is a potential mechanism that converts these sediments from carbon sinks to sources through stimulation of priming-enhanced sediment carbon remineralization. We further hypothesized that significant changes to seagrass faunal communities may influence seagrass sediment carbon stocks

Can we manage coastal ecosystems to sequester more blue carbon?

© The Ecological Society of America To promote the sequestration of blue carbon, resource managers rely on best-management practices that have historically included protecting and restoring vegetated coastal habitats (seagrasses, tidal marshes, and mangroves), but are now beginning to incorporate catchment-level approaches. Drawing upon knowledge from a broad range of environmental variables that influence blue carbon sequestration, including warming, carbon dioxide levels, water depth, nutrients, runoff, bioturbation, physical disturbances, and tidal exchange, we discuss three potential management strategies that hold promise for optimizing coastal blue carbon sequestration: (1) reducing anthropogenic nutrient inputs, (2) reinstating top-down control of bioturbator populations, and (3) restoring hydrology. By means of case studies, we explore how these three strategies can minimize blue carbon losses and maximize gains. A key research priority is to more accurately quantify the impacts of these strategies on atmospheric greenhouse-gas emissions in different settings at landscape scales

Super-massive binary black holes and emission lines in active galactic nuclei

The broad emission spectral lines emitted from AGNs are our main probe of the geometry and physics of the broad line region (BLR) close to the SMBH. There is a group of AGNs that emits very broad and complex line profiles, showing two displaced peaks, one blueshifted and one redshifted from the systemic velocity defined by the narrow lines, or a single such peak. It has been proposed that such line shapes could indicate a supermassive binary black hole (SMB) system. We discuss here how the presence of an SMB will affect the BLRs of AGNs and what the observational consequences might be. We review previous claims of SMBs based on broad line profiles and find that they may have non-SMB explanations as a consequence of a complex BLR structure. Because of these effects it is very hard to put limits on the number of SMBs from broad line profiles. It is still possible, however, that unusual broad line profiles in combination with other observational effects (line ratios, quasi-periodical oscillations, spectropolarimetry, etc.) could be used for SMBs detection. Some narrow lines (e.g., [O\,III]) in some AGNs show a double-peaked profile. Such profiles can be caused by streams in the Narrow Line Region (NLR), but may also indicate the presence of a kilo-parsec scale mergers. A few objects indicated as double-peaked narrow line emitters are confirmed as kpc-scale margers, but double-peaked narrow line profiles are mostly caused by the complex NLR geometry. We briefly discuss the expected line profile of broad Fe K$\alpha$ that probably originated in the accretion disk(s) around SMBs. Finally we consider rare configurations where a SMB system might be gravitationally lensed by a foreground galaxy, and discuss the expected line profiles in these systems.Comment: The work was presented as an invited talk at special workshop "Spectral lines and super-massive black holes" held on June 10, 2011 as a part of activity within the frame of COST action 0905 "Black holes in a violent universe" and as a part of the 8th Serbian Conference on Spectral Line Shapes in Astrophysics.Sent to New Astronomy Review as a review pape

Particle emission characteristics of a gas turbine with a double annular combustor

The total climate, air quality and health impact of aircraft black carbon (BC) emissions depends on quantity (mass and number concentration), as well as morphology (fractal dimension and surface area) of emitted BC aggregates. This study examines multiple BC emission metrics from a gas turbine with a double annular combustor, CFM56-5B4-2P. As a part of the SAMPLE III.2 campaign, concurrent measurements of particle mobility, particle mass, particle number concentration and mass concentration, as well as collection of transmission electron microscopy (TEM) samples, allowed for characterization of the BC emissions. Mass- and number-based emission indices were strongly influenced by thrust setting during pilot combustion and ranged from <1 to 208 mg/kg-fuel and 3×1012 to 3×1016 particles/kg-fuel, respectively. Mobility measurements indicated that mean diameters ranged from 7-44 nm with a strong dependence on thrust during pilot-only combustion. Using aggregation and sintering theory with empirical effective density relationships, a power law relationship between primary particle diameter and mobility diameter is presented. Mean primary particle diameter ranged from 6-19 nm, however, laser induced incandescence (LII) and mass-mobility calculated primary particle diameters demonstrated opposite trends with thrust setting. Similarly, mass-mobility-calculated aggregate mass specific surface area and LII-measured surface area were not in agreement, indicating both methods need further development and validation before use as quantitative indicators of primary particle diameter and mass-specific surface area.The authors express their gratitude to a number of people and organizations in helping to plan, conduct, finance and provide instruments for this measurement campaign. The 537 European Aviation Safety Agency (EASA) funded the SAMPLE III SC02 campaign (EASA.2010.FC.10, Specific Contract No: SC02). The Federal Office of Civil Aviation, Switzerland (FOCA) was critical in for providing additional financial support and arranging facilities which made this study possible. We also thank the SR Technics test bed staff, including Frithjof Siegerist, for operating the engines and enabling access to the test facility. We thank AVL, Cambustion, Grimm & TSI supplying both instruments and expertise.This is the author accepted manuscript. The final version is available from Taylor & Francis via http://dx.doi.org/10.1080/02786826.2015.107845

Smoking, respiratory symptoms and likely asthma in young people: evidence from postal questionnaire surveys in the Wythenshawe Community Asthma Project (WYCAP)

BACKGROUND: Although it is recognised that smoking is a major risk factor for subjects with chronic obstructive pulmonary disease and is associated with respiratory symptoms, there is less agreement concerning the relationship between asthma and smoking. This study aims to examine the relationship between cigarette smoking and asthma prevalence. METHOD: Data were used from two postal questionnaire surveys (1999 and 2001) in two general practice populations, using a respiratory questionnaire based on the ECRHQ and a generic quality of life questionnaire (EQ-5D). Only subjects less than 45 years old were included in the survey. An empirical definition of likely asthma was used based on respiratory questionnaire responses. Smoking was examined according to three categories, current smoker, ex smoker and never smoker. RESULTS: Almost 3500 subjects were included in the analyses. Current smokers had a higher prevalence of likely asthma compared to never smokers, odds ratio (OR) 1.59 (95% confidence interval (CI) 1.24 to 2.04). and also compared to ex smokers OR 1.79 (CI 1.25 to 2.56), but there was no difference between ex smokers and never smokers (OR 1.00 (0.75–1.35)). Current smoking was also positively associated with all symptoms but not with a history of hayfever/eczema. CONCLUSION: Although the positive association found between current smoking and obstructive airways disease is likely to be due to the effect of cigarettes on asthma, it could reflect an association with early COPD (GOLD stages 0 or 1). Smoking cessation has a beneficial effect on the prevalence of respiratory symptoms and is therefore of paramount importance among these young adults

Practical access to planar chiral 1,2-(α-Ketotetramethylene)- ferrocene by non-enzymatic kinetic resolution and conclusive confirmation of its absolute configuration

The asymmetric transfer hydrogenation (ATH) of racemic 1,2-(α-ketotetramethylene)ferrocene using the [N-(tosyl)-1,2-diphenylethylendiamine]ruthenium(II) complex [TsDPEN-Ru(II)] as catalyst takes place with a high level of kinetic resolution to deliver the ketone in up to 99% ee. The X-ray crystallographic structure of a derivative of the alcohol co-product serves to confirm conclusively both the absolute configuration of 1,2-(α-ketotetramethylene)ferrocene and the endo-reduction selectivity

Enhancing the Scientific Value of Industry Remotely Operated Vehicles (ROVs) in Our Oceans

© Copyright © 2020 McLean, Parsons, Gates, Benfield, Bond, Booth, Bunce, Fowler, Harvey, Macreadie, Pattiaratchi, Rouse, Partridge, Thomson, Todd and Jones. Remotely operated vehicles (ROVs) are used extensively by the offshore oil and gas and renewables industries for inspection, maintenance, and repair of their infrastructure. With thousands of subsea structures monitored across the world’s oceans from the shallows to depths greater than 1,000 m, there is a great and underutilized opportunity for their scientific use. Through slight modifications of ROV operations, and by augmenting industry workclass ROVs with a range of scientific equipment, industry can fuel scientific discoveries, contribute to an understanding of the impact of artificial structures in our oceans, and collect biotic and abiotic data to support our understanding of how oceans and marine life are changing. Here, we identify and describe operationally feasible methods to adjust the way in which industry ROVs are operated to enhance the scientific value of data that they collect, without significantly impacting scheduling or adding to deployment costs. These include: rapid marine life survey protocols, imaging improvements, the addition of a range of scientific sensors, and collection of biological samples. By partnering with qualified and experienced research scientists, industry can improve the quality of their ROV-derived data, allowing the data to be analyzed robustly. Small changes by industry now could provide substantial benefits to scientific research in the long-term and improve the quality of scientific data in existence once the structures require decommissioning. Such changes also have the potential to enhance industry’s environmental stewardship by improving their environmental management and facilitating more informed engagement with a range of external stakeholders, including regulators and the public

Conditional meta-analysis stratifying on detailed HLA genotypes identifies a novel type 1 diabetes locus around TCF19 in the MHC

The human leukocyte antigen (HLA) class II genes HLA-DRB1, -DQA1 and -DQB1 are the strongest genetic factors for type 1 diabetes (T1D). Additional loci in the major histocompatibility complex (MHC) are difficult to identify due to the region’s high gene density and complex linkage disequilibrium (LD). To facilitate the association analysis, two novel algorithms were implemented in this study: one for phasing the multi-allelic HLA genotypes in trio families, and one for partitioning the HLA strata in conditional testing. Screening and replication were performed on two large and independent datasets: the Wellcome Trust Case–Control Consortium (WTCCC) dataset of 2,000 cases and 1,504 controls, and the T1D Genetics Consortium (T1DGC) dataset of 2,300 nuclear families. After imputation, the two datasets have 1,941 common SNPs in the MHC, of which 22 were successfully tested and replicated based on the statistical testing stratifying on the detailed DRB1 and DQB1 genotypes. Further conditional tests using the combined dataset confirmed eight novel SNP associations around 31.3 Mb on chromosome 6 (rs3094663, p = 1.66 × 10−11 and rs2523619, p = 2.77 × 10−10 conditional on the DR/DQ genotypes). A subsequent LD analysis established TCF19, POU5F1, CCHCR1 and PSORS1C1 as potential causal genes for the observed association