Avoidance and toxicity responses of fish to intermittent chlorination

The ability of fish to actively avoid concentrations of chlorine in a steep, horizontal, laboratory-controlled gradient was found to be species-specific and dependent upon the acclimation temperature, water quality conditions, and the type of chlorine residual tested. Comparison of behavioral avoidances with the results from bioassays using some form of intermittent chlorination, as reported in the literature, indicated that LC₅₀ concentrations (levels that cause the mortality of half the test individuals in a designated time period) usually exceeded avoidance threshold concentrations.This chlorine avoidance study, which was carried out in a field laboratory that utilized New River water for holding and testing procedures, was located at the Glen Lyn power plant in southwestern Virginia. Two basic types of avoidance trials were employed, TRC (total residual chlorine) and chloramine (CRC) exposures. The TRC trials contained variable amounts of free (FRC) and combined residual chlorine (CRC) depending upon water quality, while in chloramine trials, the TRC exposure was mainly comprised of monochloramine with little or no FRC. The first significant avoidance in TRC trials for several fish species tested, varied from 0.05 mg/1 for coho salmon (Oncorhynchus kisutch) to 0.40 for channel catfish (Ictalurus punctatus). Low levels of hypochlorous acid (HOCl), which are considered to be a potentially toxic constituent of FRC, appeared to consistently influence the avoidance response. Initial avoidance concentrations to HOCl ranged from 0.01–0.02 mg/1 for coho salmon to 0.04–0.12 mg/1 for channel catfish, depending upon acclimation temperatures tested. The pH in river water was more influential than temperature in controlling the amount of HOCl present within the FRC at each TRC exposure. Avoidance responses by fish to CRC concentrations were either equal to or greater than TRC exposures and were dependent upon the ammonia-N content. Chloramine and FRC (specifically the HOCl fraction) have been reported to have different mechanisms of toxicity, which offered possible explanations for the differences observed in avoidance behavior. Chlorine residuals discharged from the Glen Lyn power plant in previous years have exceeded the LC₅₀ values reported for many species, although no major fish kills from chlorine have been documented. Behavioral avoidance responses by fish to potentially lethal chlorinated discharges in aquatic receiving systems may be a major mechanism of these populations in adapting to or interacting within these industrially influenced environments.     

Development of a rotorcraft dust-emission parameterization using a CFD model

Flights of rotorcraft over the desert floor can result in significant entrainment of particulate matter into the atmospheric boundary layer. Continuous or widespread operation can lead to local and regional impacts on visibility and air quality. To account for this pollutant source in air quality models, a parameterization scheme is needed that addresses the complex vertical distribution of dust ejected from the rotorcraft wake into the atmospheric surface layer. A method to parameterize the wind and turbulence fields and shear stress at the ground is proposed here utilizing computational fluid dynamics and a parameterized rotor model. Measurements taken from a full scale experiment of rotorcraft flight near the surface are compared to the simulation results in a qualitative manner. The simulation is shown to adequately predict the forward detachment length of the induced ground jet compared to the measured detachment lengths. However, the simulated ground vortex widths and vorticity deviate substantially from the measured values under a range of flight speeds. Results show that the method may be applicable for air quality modeling assuming slow airspeeds of the rotorcraft, with advance ratios of 0.005–0.02.     

Risk management is not enough: a conceptual model for resilience and adaptation-based vulnerability assessments

The US government has focused considerable attention on enhancing our society’s ability to protect critical systems and services from disruptive events. Over the past decade, federal agencies have bolstered their efforts to identify and minimize threats using traditional risk-based approaches such as continuity of operations and disaster risk reduction processes. However, these valuable risk identification and management tools are limited because they rely upon foreseeable factor analyses of steady-state systems with predictable hazard frequencies and severities. In assessing the capability of complex adaptive systems to cope with disruptions, an overemphasis upon engineering resilience through risk management and planning for what is predictable may cloud or detract from our efforts to better understand a system’s emergent capabilities to withstand disruptions that are unforeseeable. This article contends that augmenting traditional risk approaches through the incorporation of methodologies grounded in socio-ecological system (SES) resilience principles offers a potential avenue for improving our agencies’ abilities to assess and manage both known and unknown risks. We offer a notional rationale for broadening our examination of system vulnerabilities and present a conceptual model that combines engineering and SES resilience paradigms to facilitate the identification, assessment, and management of system vulnerabilities. The Military Installation Resilience Assessment model described herein applies risk and resilience principles to evaluate whole systems, focusing on interconnections and their functionality in facilitating response and adaptation.     

A Comparison of Bayesian Methods for Uncertainty Analysis in Hydraulic and Hydrodynamic Modeling

We evaluate and compare the performance of Bayesian Monte Carlo (BMC), Markov chain Monte Carlo (MCMC), and the Generalized Likelihood Uncertainty Estimation (GLUE) for uncertainty analysis in hydraulic and hydrodynamic modeling (HHM) studies. The methods are evaluated in a synthetic 1D wave routing exercise based on the diffusion wave model, and in a multidimensional hydrodynamic study based on the Environmental Fluid Dynamics Code to simulate estuarine circulation processes in Weeks Bay, Alabama. Results show that BMC and MCMC provide similar estimates of uncertainty. The posterior parameter densities computed by both methods are highly consistent, as well as the calibrated parameter estimates and uncertainty bounds. Although some studies suggest that MCMC is more efficient than BMC, our results did not show a clear difference between the performance of the two methods. This seems to be due to the low number of model parameters typically involved in HHM studies, and the use of the same likelihood function. In fact, for these studies, the implementation of BMC results simpler and provides similar results to MCMC. The results of GLUE are, on the other hand, less consistent to the results of BMC and MCMC in both applications. The posterior probability densities tend to be flat and similar to the uniform priors, which can result in calibrated parameter estimates centered in the parametric space.     

Intervention of pentoxifylline on silica-induced inflammatory reaction and apoptosis

Pentoxifylline (PTX) is a clinically used drug mainly for peripheral circulation improvement. This drug also possesses potent anti-inflammatory effects and was found to inhibit acute lung injury induced by chemical agents in animal models. Since it is also a potential apoptosis enhancer, this study was designed to examine the influence of PTX on silica-induced lung inflammation and pulmonary leucocyte apoptosis. Male Wistar rats were intratracheally instilled with either silica dust suspension or saline and intraperitoneally injected with saline or PTX. These treatments continued for six weeks and all rats were then sacrificed to obtain bronchoalveolar lavage cells and lavage fluid. Data demonstrated that PTX attenuated silica-induced lung injury in the rat model and this attenuation may possibly be attributed to its role in the enhancement of pulmonary apoptosis. As a known clinically safe drug, PTX may thus have potential use in the treatment of human silicosis.     

Climate change adaptation,mitigation and livelihood benefits in coffee production: where are the synergies?

There are worldwide approximately 4.3 million coffee (Coffea arabica) producing smallholders generating a large share of tropical developing countries’ gross domestic product, notably in Central America. Their livelihoods and coffee production are facing major challenges due to projected climate change, requiring adaptation decisions that may range from changes in management practices to changes in crops or migration. Since management practices such as shade use and reforestation influence both climate vulnerability and carbon stocks in coffee, there may be synergies between climate change adaptation and mitigation that could make it advantageous to jointly pursue both objectives. In some cases, carbon accounting for mitigation actions might even be used to incentivize and subsidize adaptation actions. To assess potential synergies between climate change mitigation and adaptation in smallholder coffee production systems, we quantified (i) the potential of changes in coffee production and processing practices as well as other livelihood activities to reduce net greenhouse gas emissions, (ii) coffee farmers’ climate change vulnerability and need for adaptation, including the possibility of carbon markets subsidizing adaptation. We worked with smallholder organic coffee farmers in Northern Nicaragua, using workshops, interviews, farm visits and the Cool Farm Tool software to calculate greenhouse gas balances of coffee farms. From the 12 activities found to be relevant for adaptation, two showed strong and five showed modest synergies with mitigation. Afforestation of degraded areas with coffee agroforestry systems and boundary tree plantings resulted in the highest synergies between adaptation and mitigation. Financing possibilities for joint adaptation-mitigation activities could arise through carbon offsetting, carbon insetting, and carbon footprint reductions. Non-monetary benefits such as technical assistance and capacity building could be effective in promoting such synergies at low transaction costs.     

Insight into the growth dynamics and systematic affinities of the Late Cretaceous Gargantuavis from bone microstructure

Enigmatic avialan remains of Gargantuavis philoinos from the Ibero-Armorican island of the Late Cretaceous European archipelago (Southern France) led to a debate concerning its taxonomic affinities. Here, we show that the bone microstructure of Gargantuavis resembles that of Apteryx, the extinct emeids and Megalapteryx from New Zealand, and indicates that like these slow-growing terrestrial birds, it took several years to attain skeletal maturity. Our findings suggest that the protracted cyclical growth in these ornithurines may have been in response to insular evolution.     

Understanding the sources and composition of the incremental excess of fine particles across multiple sampling locations in one air shed

Well-designed health studies and the development of effective regulatory policies need to rely on an understanding of the incremental differences in particulate matter concentrations and their sources. Although only a limited number of studies have been conducted to examine spatial differences in sources to particulate matter within an air shed, routine monitoring data can be used to better understand these differences. Measurements from the US EPA Chemical Speciation Network （CSN） collected between 2002-2008 were analyzed to demonstrate the utility of regulatory data across three sites located within 100 km of each other. Trends in concentrations, source contribution, and incremental excesses across three sites were investigated using the Positive Matrix Factorization model. Similar yearly trends in chemical composition were observed across all sites, however, excesses of organic matter and elemental carbon were observed in the urban center that originated from local emissions of mobile sources and biomass buming. Secondary sulfate and secondary nitrate constituted over half of the PM2.5 with no spatial differences observed across sites. For these components, the excess of emissions from industrial sources could be directly quantified. This study demonstrates that CSN data from multiple sites can be successfully used to derive consistent source profiles and source contributions for regional pollution, and that CSN data can be used to quantify incremental differences in source contributions of across these sites. The analysis strategy can be used in other regions of the world to take advantage of existing ambient particulate matter monitoring data to better the understanding of spatial differences in source contributions within a given air shed.