Application of an advanced atmospheric mesoscale model to dispersion in the Rocky Flats, Colorado vicinity

Atmospheric Studies in Complex Terrain (ASCOT) program sponsored a field experiment in the winter of 1991 near Rocky Flats, Colorado. Both meteorological and tracer dispersion measurements were taken. These two data sets provided an opportunity to investigate the influence of terrain-generated, radiatively-driven flows on the dispersion of the tracer. We use the Regional Atmospheric Modeling System (RAMS), originally developed at Colorado State University, to simulate meteorological conditions and tracer dispersion on the case night of 4-5 February 1991. The simulations described herein reveal considerable information about the extent to which the Rocky Mountains influence the flow along the Front Range , the importance of diffusion when simulating drainage flows and the computing needs of simulations in complex terrain regions

Rapid Response and Restoration for Coral Reef Injuries in Southeast Florida: Guidelines and Recommendations

From the time an injury to coral reef resources is reported, a well-coordinated and implemented plan is critical to the success of response and restoration efforts. There are three major plan components, each of which is equally important: (1) the Initial Response period immediately following notification of the incident; (2) the Response period, during which the Responsible Party (RP) is identified, the Trustees and RP carry out their respective responsibilities, a Primary Restoration plan is developed, authorizations and contractors to conduct restoration activities are sought and obtained, and primary restoration activities are conducted; and (3) the Post-Response period, which is largely a monitoring, compensatory restoration/mitigation, and penalty assessment phase that takes place after primary restoration activities are carried out. The guidelines and recommendations presented in this docuemnt were developed to examine reef injury response processes and to facilitate a rapid response to, and the successful restoration of, southeast Florida reefs. The document was developed as part of a Local Action Strategy (LAS) of the Southeast Florida Coral Reef Initiative (SEFCRI) to develop guidelines and recommendations for a rapid response and restoration process for reef injuries in the SEFCRI region. In February 2006, a two day workshop was held in Fort Lauderdale, Florida, to compile information on existing emergency response processes, identify deficiencies and develop solutions for those processes, and compile information on existing technologies and procedures for triage and the restoration of reef injuries. The first day of the workshop focused on process and policy issues. The second day addressed response, injury and mitigation assessment, restoration and repair, and monitoring. Workshop panelists and attendees included respresentatives from local, state, and federal agencies with proprietary or regulatory authority or jurisdiction over sovereign submerged lands and reef resources located within Florida\u27s waters. Also in attendance were technical and academic experts in the fields of coral reef research, injury assessment, and restoration, as well as marine contractors, private and public attorneys, nongovernmental organizations, and other interested parties. These guidelines and recommendations incorporate information from the combined experience of the workshop attendees, workshop outcomes, published documents, and numerous state and federal regulations, policies, and procedures

The Impact of an Extreme Storm Event on the Barrier Beach of the Lefkada Lagoon, NE Ionian Sea (Greece)

The present investigation examines the characteristics of a high energy storm event, that took place on November 9-11, 2007 in the NE Ionian Sea (eastern Mediterranean), and its impact upon the barrier beach that separates the Lefkada lagoon from the open Ionian Sea. The storm event was caused by NW winds with speeds exceeding 20 m/s (40 knots), which have an annual frequency of occurrence less than 0.015%. This high energy event produced waves with >5 m significant offshore height and 9.5 s period; these waves developed on 10th November during the rapid rise of barometric pressure (~1.4 hPa/hr), which followed the barometric pressure drop from 1020.5 hPa at 06:00 (UTC) of 9th November to 1001.7 hPa at 06:00 h (UTC) of 10th November. Secondary breaking at the shoreline produced wave heights >1.5 m, associated with a surge of >0.4 m and a run-up capability of >2.4 m. The waves managed to overtop the barrier beach (elevations ~2.5 m), lowering the seaward side of the barrier beach by 10-30 cm and causing a coastline retreat of 0.9 to 2.2 m; these morphological changes correspond volumetrically to a sediment loss of approximately 8 m3/m of coastline length from the sub-aerial part of the beach. During the last three decades a significant change in the frequency of occurrence and direction (from S-SW-W to N-NW-NE) of severe storms with wind speeds exceeding 40 knots has been recorded, affecting the sediment transport pattern and contributing to the erosion of the north beaches of Lefkada

Climate drives fire synchrony but local factors control fire regime change in northern Mexico

The occurrence of wildfire is influenced by a suite of factors ranging from “top-down” influences (e.g., climate) to “bottom-up” localized influences (e.g., ignitions, fuels, and land use). We carried out the first broad-scale assessment of wildland fire patterns in northern Mexico to assess the relative influence of top-down and bottom-up drivers of fire in a region where frequent fire regimes continued well into the 20th century. Using a network of 67 sites, we assessed (1) fire synchrony and the scales at which synchrony is evident, (2) climate drivers of fire, and (3) asynchrony in fire regime changes. We found high fire synchrony across northern Mexico between 1750 and 2008, with synchrony highest at distances oscillations, especially El Niño-Southern Oscillation, were important drivers of fire synchrony. However, bottom-up factors modified fire occurrence at smaller spatial scales, with variable local influence on the timing of abrupt, unusually long fire-free periods starting between 1887 and 1979 CE. Thirty sites lacked these fire-free periods. In contrast to the neighboring southwestern United States, many ecosystems in northern Mexico maintain frequent fire regimes and intact fire–climate relationships that are useful in understanding climate influences on disturbance across scales of space and time

The effects of nitroxyl (HNO) on soluble guanylate cyclase activity: interactions at ferrous heme and cysteine thiols

It has been previously proposed that nitric oxide (NO) is the only biologically relevant nitrogen oxide capable of activating the enzyme soluble guanylate cyclase (sGC). However, recent reports implicate HNO as another possible activator of sGC. Herein, we examine the affect of HNO donors on the activity of purified bovine lung sGC and find that, indeed, HNO is capable of activating this enzyme. Like NO, HNO activation appears to occur via interaction with the regulatory ferrous heme on sGC. Somewhat unexpectedly, HNO does not activate the ferric form of the enzyme. Finally, HNO-mediated cysteine thiol modification appears to also affect enzyme activity leading to inhibition. Thus, sGC activity can be regulated by HNO via interactions at both the regulatory heme and cysteine thiols

Oxygen Activation and Radical Transformations in Heme Proteins and Metalloporphyrins

As a result of the adaptation of life to an aerobic environment, nature has evolved a panoply of metalloproteins for oxidative metabolism and protection against reactive oxygen species. Despite the diverse structures and functions of these proteins, they share common mechanistic grounds. An open-shell transition metal like iron or copper is employed to interact with O_2 and its derived intermediates such as hydrogen peroxide to afford a variety of metal–oxygen intermediates. These reactive intermediates, including metal-superoxo, -(hydro)peroxo, and high-valent metal–oxo species, are the basis for the various biological functions of O_2-utilizing metalloproteins. Collectively, these processes are called oxygen activation. Much of our understanding of the reactivity of these reactive intermediates has come from the study of heme-containing proteins and related metalloporphyrin compounds. These studies not only have deepened our understanding of various functions of heme proteins, such as O2 storage and transport, degradation of reactive oxygen species, redox signaling, and biological oxygenation, etc., but also have driven the development of bioinorganic chemistry and biomimetic catalysis. In this review, we survey the range of O_2 activation processes mediated by heme proteins and model compounds with a focus on recent progress in the characterization and reactivity of important iron–oxygen intermediates. Representative reactions initiated by these reactive intermediates as well as some context from prior decades will also be presented. We will discuss the fundamental mechanistic features of these transformations and delineate the underlying structural and electronic factors that contribute to the spectrum of reactivities that has been observed in nature as well as those that have been invented using these paradigms. Given the recent developments in biocatalysis for non-natural chemistries and the renaissance of radical chemistry in organic synthesis, we envision that new enzymatic and synthetic transformations will emerge based on the radical processes mediated by metalloproteins and their synthetic analogs