Salt marshes are subject to an array of environmental changes that have the potential to alter community structure and function. Manipulative experiments often study environmental changes in isolation, although changes may interactively affect plant and ecosystem response. We report results of a factorial experiment examining the independent and interactive effects of atmospheric CO2, sea level rise (SLR), nitrogen availability, and warming on above- and belowground biomass allocation in two dominant salt marsh species in the northeastern US: Spartina alterniflora and Distichlis spicata. Growth rates of individual culms were tracked over time, and at the end of the experiment culms were separated into stem and leaf biomass. Computed tomography was used to quantify belowground productivity and characterize allocation to roots and rhizomes. The two species had distinct aboveground responses to environmental change; S. alterniflora allocated more biomass to stem tissue in response to SLR and nitrogen, whereas D. spicata allocation shifted stem-ward only when all stressors combined. However, D. spicata was more plastic in its specific mass, which declined in response to SLR and increased with N and CO2 enrichment. S. alterniflora net aboveground primary production (NAPP) was enhanced by SLR and N, with the response moderated by warming. D. spicata responded more positively to warming and showed evidence of a strong N amplification of the CO2 response. Belowground responses also varied by species. In the presence of SLR, S. alterniflora responded to N, CO2, and warming with increased surficial root and rhizome mass, but no net difference over the profile. D. spicata root and rhizome mass and volume declined with CO2 and combined N-CO2, but differences were moderated by sea level rise and warming. Complex, species-specific responses to environmental change have implications for carbon storage and other ecosystem-scale processes.
Reservoirs are a globally important source of methane (CH4) to the atmosphere, but measuring CH4 emission rates from reservoirs is difficult due to the spatial and temporal variability of the various emission pathways, including ebullition and diffusion. We used the eddy covariance method to measure fluxes of CH4 over a mid-sized (2.4 km2), eutrophic reservoir in southeast Ohio, US from winter thru fall of 2017. In addition to the eddy covariance
system, we deployed inverted funnels to monitor ebullitive fluxes, and a thermistor chain to relate underwater convective mixing to the air-water gas exchange.
Methane emissions increased from winter to summer, with average fluxes of 10.0 mg CH4 m-2 d-1 and 190 mg CH4 m-2 d-1 in February and June, respectively. While no clear diurnal pattern in emissions emerged from the eddy covariance results, “pulses” in CH4 emissions were observed that coincided with synoptic weather events and destratification of the water column. Details on the physical drivers of these pulse events and how they enhance CH4 emissions via the diffusive or ebullitive pathways will be discussed.
Federal Reserve Board and Federal Open Market Committee release economic projections from the December 12-13 FOMC meeting
Federal Reserve issues FOMC statement
Worldwide initiatives to screen for toxicity potential among the thousands of chemicals currently in use require inexpensive and high-throughput in vitro models to meet their goals. The devTOX quickPredict platform is an in vitro human pluripotent stem cell-based assay used to assess a wide range of chemicals (i.e., pharmaceutical, environmental and industrial compounds) for potential developmental toxicity affecting differing developmental lineages. The assay is being used by the United States Environmental Protection Agency (EPA) to screen the ToxCast chemical library in support of Tox21. A two tier testing strategy was employed to screen a total of 1066 chemicals in human pluripotent stem (hES) cells, guided by the AC50 (half-maximal activity concentration) across multiple cytotoxicity assays in ToxCast. To date, 347 chemicals were tested in an eight concentration dose-response in this assay. Spent media was collected to measure changes in biomarkers of developmental toxicity (ornithine and cystine) together with cell viability measurements. A preliminary analysis revealed a signal in 15-18% of all ToxCast chemicals tested based on a default threshold biomarker ratio (ORN/CYSS) <0.88. In most of these cases the concentration producing an effect in the biomarker ratio fell below the AC50 for cell viability. Model performance (28 compound training set) showed a balanced accuracy of 82% (sensitivity 0.71, specificity 1.0). The data presented here demonstrate the utility of the assay in screening and prioritizing compounds for further testing. (Disclaimer: this abstract does not reflect EPA policy).
The East Antarctic Ice Sheet locks away enough water to raise sea level an estimated 53 meters (174 feet), more than any other ice sheet on the planet. It’s also thought to be among the most stable, not gaining or losing mass even as ice sheets in West Antarctica and Greenland shrink.
But new research, led by The University of Texas at Austin and the University of South Florida (USF) and funded by the National Science Foundation (NSF), found that the East Antarctic Ice Sheet may not …
This is an NSF News item.
A 60-year-old mystery about the source of energetic, potentially damaging particles in Earth’s radiation belts has been solved using data from a shoebox-sized satellite built and operated by students. The satellite is called a CubeSat.
Imagine a fully instrumented satellite the size of a half-gallon milk carton. Then imagine that milk carton whirling in space, catching never-before-seen glimpses of atmospheric and geospace processes.
CubeSats, named for the roughly …
This is an NSF News item.
The National Science Foundation (NSF) is pleased to announce that James S. Ulvestad will serve as the agency’s first Chief Officer for Research Facilities (CORF), a position created in recognition of the critical role research infrastructure plays in science and engineering.
“For almost seven decades, NSF has helped build the research infrastructure that allows the United States to be a world leader in innovation. Investment at that scale requires high-level oversight and …
This is an NSF News item.
There has been a long standing argument that ecosystems have intrinsic value and therefore there is no need to put a price tag on Mother Nature. The concept of intrinsic value reflects the perspective that nature has value in its own right, independent of human uses. Intrinsic value is viewed from an ecocentric or biocentric standpoint. Conversely, the economic concepts of use and non-use values are viewed from an anthropocentric perspective. Non-use values describe the worth, typically in monetary terms, that people ascribe to ecosystem services that they do not directly or indirectly use yet view as affecting their well-being. Yet intrinsic and economic valuation need not be mutually exclusive. The challenge is to develop scientifically rigorous approaches that include both intrinsic and economic value in the calculus of environmental decision making.
This image from NASA’s Mars Reconnaissance Orbiter (MRO) of northern Meridiani Planum shows faults that have disrupted layered deposits.
Original release date: December 13, 2017
CERT Coordination Center (CERT/CC) has released information on a Transport Layer Security (TLS) vulnerability. Exploitation of this vulnerability could allow an attacker to access sensitive information.
The TLS vulnerability is also known as Return of Bleichenbacher’s Oracle Threat (ROBOT). ROBOT allows an attacker to obtain the RSA key necessary to decrypt TLS traffic under certain conditions. Mitigations include installing updates to affected products as they become available. US-CERT encourages users and administrators to review CERT/CC Vulnerability Note VU #144389.
By: Edward M. Cox, M.D., M.P.H. When a patient has an infection, healthcare providers often order a test to help them select a drug that is likely to work against that infection. This testing is performed by laboratories and is … Continue reading →
Abstract: Coronal jets are frequent magnetically channeled narrow eruptions. All coronal jets observed in EUV and X-ray images show a bright spire with a base brightening, also known as jet bright point (JBP). Recent studies of jets show that coronal jets are driven by small-scale filament eruptions (e.g. Hong et al. 2011, Shen et al. 2012, Adams et al. 2014, Sterling et al. 2015). We recently investigated the triggering mechanism of ten on-disk quiet-region coronal jet eruptions and found that magneti…
Abstract: NASA’s decadal survey determined that simultaneous measurements from a 3D volume of space are advantageous for a variety of studies in space physics and Earth science. Therefore, swarm concepts with multiple spacecraft in close proximity are a growing topic of interest in the small satellite community. Among the capabilities needed for swarm missions is a means to maintain operator-specified geometry, alignment, or separation. Swarm stationkeeping poses a planning challenge due to the limited…
Abstract: Aeolus is a small satellite mission to observe surface and atmospheric forcing and general circulation of Mars, by measuring surface energy balance, atmospheric temperatures, aerosols and clouds, and winds. Critically, Aeolus will make these measurements at all local times of day, providing information on both seasonal and diurnal variability. To date, direct measurements of Martian wind speeds have only been possible at the surface, only during daylight hours, and over small areas limited by…
Abstract: Coronal heating generally increases with increasing magnetic field strength: the EUV/X-ray corona in active regions is 10–100 times more luminous and 2–4 times hotter than that in quiet regions and coronal holes, which are heated to only about 1.5 MK, and have fields that are 10–100 times weaker than that in active regions. From a comparison of a nonlinear force-free model of the three-dimensional active region coronal field to observed extreme-ultraviolet loops, we find that (1) umbra-to-…
Abstract: No abstract available
Abstract: The Assurance Case approach is being adopted in a number of safety-mission-critical application domains in the U.S., e.g., medical devices, defense aviation, automotive systems, and, lately, civil aviation. This paradigm refocuses traditional, process-based approaches to assurance on demonstrating explicitly stated assurance goals, emphasizing the use of structured rationale, and concrete product-based evidence as the means for providing justified confidence that systems and software are fit …
In August 2013, EPA released the draft literature searches and associated search strategies, evidence tables, and exposure response arrays for TBA to obtain input from stakeholders and the public prior to developing the draft IRIS assessment. Specifically, EPA was interested in comments on the following:
- Draft literature search strategies
- The approach for identifying studies
- The screening process for selecting pertinent studies
- The resulting list of pertinent studies
- Preliminary evidence tables
- The process for selecting studies to include in evidence tables
- The quality of the studies in the evidence tables
The literature search strategy, which describes the processes for identifying scientific literature, contains the studies that EPA considered and selected to include in the evidence tables. The preliminary evidence tables and exposure-response arrays present the key study data in a standardized format. The evidence tables summarize the available critical scientific literature. The exposure-response figures provide a graphical representation of the responses at different levels of exposure for each study in the evidence table.
Abstract: With the ever-growing desire for mankind to reach destinations whose distances had been deemed impossible to transit, the largest rocket known to man was designed and is being developed. The Space Launch System (SLS), National Aeronautics and Space Administrationâ€™s (NASA) solution for deep space travel, will begin its missions with the launch of Exploration Mission 1 (EM-1) and Exploration Mission 2 (EM-2). In order to accommodate the larger rocket, Kennedy Space Center made crucial upgrade…