Projections for future radiocarbon content in dissolved inorganic carbon in hardwater lakes: a retrospective approach

Inland water bodies contain significant amounts of carbon in the form of dissolved inorganic carbon (DIC) derived from a mixture of modern atmospheric and pre-aged sources, which needs to be considered in radiocarbon-based dating and natural isotope tracer studies. While reservoir effects in hardwater lakes are generally considered to be constant through time, a comparison of recent and historical DI14C data from 2013 and 1969 for Lake Constance reveals that this is not a valid assumption. We hypothesize that changes in atmospheric carbon contributions to lake water DIC have taken place due to anthropogenically forced eutrophication in the 20th century. A return to more oligotrophic conditions in the lake led to reoxygenation and enhanced terrigenous organic matter remineralization, contributing to lake water DIC. Such comparisons using DI14C measurements from different points in time enable nonlinear changes in lake water DIC source and signature to be disentangled from concurrent anthropogenically induced changes in atmospheric 14C. In the future, coeval changes in lake dynamics due to climate change are expected to further perturb these balances. Depending on the scenario, Lake Constance DI14C is projected to decrease from the 2013 measured value of 0.856 Fm to 0.54–0.62 Fm by the end of the century

Fully anharmonic infrared cascade spectra of polycyclic aromatic hydrocarbons

The infrared (IR) emission of polycyclic aromatic hydrocarbons (PAHs) permeates our universe; astronomers have detected the IR signatures of PAHs around many interstellar objects. The IR emission of interstellar PAHs differs from their emission as seen under conditions on Earth, as they emit through a collisionless cascade down through their excited vibrational states from high internal energies. The difficulty in reproducing interstellar conditions in the laboratory results in a reliance on theoretical techniques. However, the size and complexity of PAHs requires careful consideration when producing the theoretical spectra. In this work we outline the theoretical methods necessary to lead to a fully theoretical IR cascade spectra of PAHs including: an anharmonic second order vibrational perturbation theory (VPT2) treatment; the inclusion of Fermi resonances through polyads; and the calculation of anharmonic temperature band shifts and broadenings (including resonances) through a Wang--Landau approach. We also suggest a simplified scheme to calculate vibrational emission spectra that retains the essential characteristics of the full IR cascade treatment and can directly transform low temperature absorption spectra in IR cascade spectra. Additionally we show that past astronomical models were in error in assuming a 15 cm$^{-1}$ correction was needed to account for anharmonic emission effects

Petrogenic organic carbon retention in terrestrial basins: a case study from perialpine Lake Constance

Inland waters play a major role in the global carbon cycle, with particulate organic carbon (POC) burial in terrestrial wetlands surpassing that in ocean sediments. Lake Constance, the second largest lake at the periphery of the European Alps, receives POC sourced from both aquatic and terrestrial productivity as well as petrogenic OC (OCpetro) from bedrock erosion. Distinguishing POC inputs to lake sediments is key to assessing carbon flux and fate as reworked OCpetro represents neither a net sink of atmospheric CO2 nor source of O2. New stable and radiocarbon isotopic data indicate that 11 (9–12) Gg/yr of OCpetro is buried in Lake Constance with underlying sediments on average containing 0.3 (0.25–0.33) wt% OCpetro. Extrapolation of these results suggests that 27 TgOCpetro/yr (12–54 TgOC/yr) could be subject to temporary geological storage in lakes globally, which is comparable to estimates of 43−25+61 TgOCpetro/yr delivered to the ocean by rivers (Galy et al., 2015). More studies are needed to quantify OCpetro burial in inland sedimentary reservoirs in order to accurately account for atmospheric carbon sequestration in terrestrial basins

The GALEX Arecibo SDSS Survey. VIII. Final Data Release -- The Effect of Group Environment on the Gas Content of Massive Galaxies

We present the final data release from the GALEX Arecibo SDSS Survey (GASS), a large Arecibo program that measured the HI properties for an unbiased sample of ~800 galaxies with stellar masses greater than 10^10 Msun and redshifts 0.025<z<0.05. This release includes new Arecibo observations for 250 galaxies. We use the full GASS sample to investigate environmental effects on the cold gas content of massive galaxies at fixed stellar mass. The environment is characterized in terms of dark matter halo mass, obtained by cross-matching our sample with the SDSS group catalog of Yang et al. Our analysis provides, for the first time, clear statistical evidence that massive galaxies located in halos with masses of 10^13-10^14 Msun have at least 0.4 dex less HI than objects in lower density environments. The process responsible for the suppression of gas in group galaxies most likely drives the observed quenching of the star formation in these systems. Our findings strongly support the importance of the group environment for galaxy evolution, and have profound implications for semi-analytic models of galaxy formation, which currently do not allow for stripping of the cold interstellar medium in galaxy groups.Comment: 36 pages, 16 figures. Accepted for publication in MNRAS. Version with supplementary material available at http://www.mpa-garching.mpg.de/GASS/pubs.php . GASS released data can be found at http://www.mpa-garching.mpg.de/GASS/data.ph

What on Earth have we been burning? Deciphering sedimentary records of pyrogenic carbon

Humans have interacted with fire for thousands of years, yet the utilization of fossil fuels marked the beginning of a new era. Ubiquitous in the environment, pyrogenic carbon (PyC) arises from incomplete combustion of biomass and fossil fuels, forming a continuum of condensed aromatic structures. Here we develop and evaluate 14C records for two complementary PyC molecular markers, benzene-polycarboxylic-acids (BPCAs) and polycyclic-aromatic-hydrocarbons (PAHs) preserved in aquatic sediments from a sub-urban and a remote catchment in the United States (U.S.) from mid-1700s to 1998. Results show that the majority of PyC stems from local sources and is transferred to aquatic sedimentary archives on sub-decadal to millennial time scales. Whereas a small portion stems from near-contemporaneous production and sedimentation, the majority of PyC (&lt;90%) experiences delayed transmission due to ‘pre-aging’ on millennial timescales in catchment soils prior to its ultimate deposition. BPCAs (soot) and PAHs (precursors of soot) trace fossil fuel-derived PyC. Both markers parallel historical records of the consumption of fossil fuels in U.S., yet never account for more than 19% total PyC. This study demonstrates that isotopic characterization of multiple tracers is necessary to constrain histories and inventories of PyC, and that sequestration of PyC can markedly lag its production

Treating and Preventing Influenza in Aged Care Facilities: A Cluster Randomised Controlled Trial

PMCID: PMC3474842This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Online 13C and 14C gas measurements by EA-IRMS–AMS at ETH Zürich

Studies using carbon isotopes to understand the global carbon cycle are critical to identify and quantify sources, sinks, and processes and how humans may impact them. 13C and 14C are routinely measured individually; however, there is a need to develop instrumentation that can perform concurrent online analyses that can generate rich data sets conveniently and efficiently. To satisfy these requirements, we coupled an elemental analyzer to a stable isotope mass spectrometer and an accelerator mass spectrometer system fitted with a gas ion source. We first tested the system with standard materials and then reanalyzed a sediment core from the Bay of Bengal that had been analyzed for 14C by conventional methods. The system was able to produce %C, 13C, and 14C data that were accurate and precise, and suitable for the purposes of our biogeochemistry group. The system was compact and convenient and is appropriate for use in a range of fields of research

Relationships between grain size and organic carbon 14C heterogeneity in continental margin sediments

Highlights • Continental margin-scale spatial variability in C values among grain size fractions is presented. • Two different hydrodynamic modes influencing in 14C heterogeneity are identified. • A new index (H14 index) is defined to describe overall 14C heterogeneity within marine surface sedimentary OC. Abstract The deposition and long-term burial of sedimentary organic matter (OM) on continental margins comprises a fundamental component of the global carbon cycle. A key unknown in interpretation of carbon isotope records of sedimentary OM is the extent to which OM accumulating in continental shelf and slope sediments is influenced by dispersal and redistribution processes. Here, we present results from an extensive survey of organic carbon (OC) characteristics of grain size fractions (ranging from <20 to 250 μm) retrieved from Chinese marginal sea surface sediments in order to assess the extent to which the abundance and isotope composition of OM in shallow shelf seas is influenced by hydrodynamic processes. Our findings show that contrasting relationships exist between 14C contents of OC and grain size in surface sediments associated with two different hydrodynamic modes, suggesting that transport pathways and mechanisms imparted by the different hydrodynamic conditions exert a strong influence on 14C contents of OM in continental shelf sediments. In deeper regions and erosional areas, we infer that bedload transport exerts the strongest influence on (decreases) OC 14C contents of the coarser fraction, while resuspension processes induce OC 14C depletion of intermediate grain size fractions in shallow inner-shelf settings. We use the inter-fraction spread in 14C values, defined here as 14H , to argue that the hydrodynamic processes amplify overall 14C heterogeneity within corresponding bulk sediment samples. The magnitude and footprint of this heterogeneity carries implications for our understanding of carbon cycling in shallow marginal seas

Implementing lean management/Six Sigma in hospitals: beyond empowerment or work intensification?

This article analyses a process improvement project based on Lean Six Sigma (LSS) techniques in the emergency department (ED) of a large Australian hospital. We consider perspectives of the clinical and managerial staff involved in the project implementation, its implications for empowerment and work intensification. We find that the project appeared to improve patient flow from the ED to the wards and to have positive implications for some staff. However, these achievements tended to be the result of senior staff using the project to leverage resources and create desirable outcomes, rather than the result of the use of LSS, in particular. We found some evidence of work intensification, but this was attributable to wider systemic issues and budget constraints, rather than being a direct consequence of the use of LSS. We argue that translating LSS from a manufacturing context into the politicised and professionalised context of healthcare changes the usual questions about empowerment or work intensification to questions about the influences of powerful stakeholders

A nonhuman primate model of inherited retinal disease.

Inherited retinal degenerations are a common cause of untreatable blindness worldwide, with retinitis pigmentosa and cone dystrophy affecting approximately 1 in 3500 and 1 in 10,000 individuals, respectively. A major limitation to the development of effective therapies is the lack of availability of animal models that fully replicate the human condition. Particularly for cone disorders, rodent, canine, and feline models with no true macula have substantive limitations. By contrast, the cone-rich macula of a nonhuman primate (NHP) closely mirrors that of the human retina. Consequently, well-defined NHP models of heritable retinal diseases, particularly cone disorders that are predictive of human conditions, are necessary to more efficiently advance new therapies for patients. We have identified 4 related NHPs at the California National Primate Research Center with visual impairment and findings from clinical ophthalmic examination, advanced retinal imaging, and electrophysiology consistent with achromatopsia. Genetic sequencing confirmed a homozygous R565Q missense mutation in the catalytic domain of PDE6C, a cone-specific phototransduction enzyme associated with achromatopsia in humans. Biochemical studies demonstrate that the mutant mRNA is translated into a stable protein that displays normal cellular localization but is unable to hydrolyze cyclic GMP (cGMP). This NHP model of a cone disorder will not only serve as a therapeutic testing ground for achromatopsia gene replacement, but also for optimization of gene editing in the macula and of cone cell replacement in general