Chemical Warfare Materiel: Unique Regulatory Issues

In those states that have not included CWM as hazardous materials in their RCRA programs, the RCRA requirements for management of hazardous waste would not strictly apply to any of the CWM. The Army has historically implemented procedures requiring that chemical warfare agents be managed as RCRA hazardous waste regardless of the concentration, physical form, or configuration of the agent. Such application of strict hazardous waste requirements to management of potentially nonhazardous CWM can result in remedial costs well out of proportion to potential human health and environmental benefits. Recent development of chronic toxicity values for the CWM has opened the door for development of cleanup and waste management standards for waste streams or media containing small residual amounts of CWM. Implementation of this health-based approach to management of CWM remediation wastes may, in part, help to reduce potentially unnecessary hazardous waste management costs for the nonhazardous CWM.     

Superfund cleanup: Designing containment remedies for recreational reuse

In July, 1999, EPA announced its Superfund Redevelopment Initiative, the Agency's effort to help communities bring Superfund sites back into productive use in a manner that is protective of human health and the environment. As part of the Superfund Redevelopment Initiative, the Agency is developing reuse design guides that provide technical information related to the design of remedies that safely support reuse. The design guides focus on the reuse of containment sites, and address such topics as settlement, gas control, irrigation, drainage, and operation and maintenance. Case studies of redeveloped sites are also presented in the guides. EPA is currently developing design guides that address the reuse of Superfund sites for commercial purposes, wildlife areas, parking lots, recreational sports fields, and golf courses. This article provides information on the first guide in the series‐the reuse of Superfund sites for recreational purposes.     

Organochlorine pesticide contamination of ground water in the city of Hyderabad

Organochlorine pesticides are ubiquitous and persistent organic pollutants used widely throughout the world. Due to the extensive use in agriculture, organic environmental contaminants such as HCH, DDT along with other organochlorine pesticides are distributed globally by transport through air and water. The main aim of present study is to determine contamination levels of organochlorine pesticides in the ground water of Hyderabad City. Water samples were collected from 28 domestic well supplies of the city. For this study, random sampling technique was applied, all the samples were collected in high purity glass bottles and refrigerated at 4 degrees C until analysis. Solid Phase Extraction (SPE) is used for the extraction of organochlorine pesticide residues in water sample. The collected water samples were pre-filtered through a 0.45 microg glass fiber filter (Wattman GF/F) to remove particulate matter and were acidified with hydrochloric acid (6N) to pH 2.5. Methanol modifier (BDH, for pesticide residue analysis, 10 mL) was added to water sample for better extraction. SPE using pre-packed reversed phase octadecyl (C-18 bonded silica) contained in cartridges was used for sample preparation. Prior to the extraction, the C-18 bonded phase, which contains 500 mg of bonded phase, was washed with 20 mL methanol. The sample was mixed well and allowed to percolate through the cartridges with flow rate of 10-15 mL/min under vacuum. After sample extraction, suction continued for 15 min to dry the packing material and pesticides trapped in the C-18 bonded phases were eluted by passing 10 mL hexane and fraction was evaporated in a gentle steam of Nitrogen. In all samples pesticide residues were analyzed by GC (Chemito-8510) with Ni63 ECD detector. Helium was used as carrier gas and nitrogen was used as make up gas. The injection technique was split/split less. All the samples analyzed were found to be contaminated with four pesticides i.e. DDT, beta-Endosulfan, alpha-Endosulfan and Lindane. DDT was found to range between 0.15 and 0.19 microg L(-1), beta-Endosulfan ranges between 0.21 and 0.87 microg L(-1), alpha-Endosulfan ranges between 1.34 and 2.14 microg L(-1) and Lindane ranges between 0.68 and 1.38 microg L(-1) respectively. These concentrations of pesticides in the water samples were found to be above their respective Acceptable Daily Intake (ADI) values for Humans.     

Relative costs of conserving threatened species across taxonomic groups

Bias toward legally protecting and prioritizing charismatic taxonomic groups, such as mammals and birds, and against others, such as insects and plants, is well documented. However, the relative costs of conserving various taxonomic groups and the potential of these costs to interact with existing biases have been much less explored. We analyzed conservation programs across more than 2,000 species in 3 countries to investigate the costs of conserving species within taxonomic groups and how these costs might affect conservation planning. For each data set, we tested for differences in mean annual cost among taxonomic groups. For the data set from the United States, recovery plans differed in duration, so we also tested for differences in total costs among taxonomic groups. Although the costs for individual species varied widely, there were strong international consistencies. For example, mammals cost 8–26 times more on average to conserve than plants and 13–19 times more to conserve than aquatic invertebrates. On average, bird species cost 5–30 times more to conserve than plants and 6–14 times more to conserve than aquatic invertebrates. These cost differences could exacerbate unequal resource allocation among taxonomic groups such that more charismatic groups both receive more attention and require more resources, leading to neglect of other taxonomic groups.     

Next generation guided wave health monitoring for long range inspection of pipes

Shown in this paper are recent accomplishments of robust leading edge technologies in the guided wave technique and the technology transfer to the Gas and Petrochemical Industries. Focusing of guided wave beams is a key for success, compared to conventional axisymmetric excitation. Guided wave scanning and significant sensitivity enhancement are established via the newly implemented focusing scheme. In addition, using both longitudinal and torsional modes is essential to improve sensitivity and reliability in data analysis over the conventional technique based on only longitudinal or torsional. The related theoretical studies and experimental data are also presented along with field test results for confirmation.     

Turbulent kinetic energy budgets in a model canopy: comparisons between LES and wind-tunnel experiments

A comparative study of turbulence in a wind-tunnel model canopy is performed, using Large eddy simulation (LES) and experimental data from PIV and hot-wire anemometry measurements. The model canopy is composed of thin cylindrical stalks. In the LES, these are represented using a plant-scale approach, while the scale-dependent Lagrangian dynamic model is used as subgrid-scale model. LES predictions of turbulence statistics and energy spectra are found to be in good agreement with the experimental data. Turbulent kinetic energy (TKE) budgets from the LES simulation are analyzed to provide more information absent in the measurements. Results confirm that sloshing motions at the low levels of the canopy are mainly driven by pressure fluctuations. A difference between the energy flux obtained from the energy spectrum and the SGS dissipation rate is observed, consistent with a spectral bypass mechanism in which the real spectral flux due to cascade is smaller than that implied by the energy-spectrum level, due to direct drain by the canopy.     

Quantifying sources of climate uncertainty to inform risk analysis for climate change decision-making

Quantitative estimates of future climate change and its various impacts are often based on complex climate models which incorporate a number of physical processes. As these models continue to become more sophisticated, it is commonly assumed that the latest generation of climate models will provide us with better estimates of climate change. Here, we quantify the uncertainty in future climate change projections using two multi-model ensembles of climate model simulations and divide it into different components: internal, scenario and model. The contributions of these sources of uncertainty changes as a function of variable, temporal and spatial scale and especially lead time in the future. In the new models, uncertainty intervals for each of the components have increased. For temperature, importance of scenario uncertainty is the largest over low latitudes and increases nonlinearly after the mid-century. It has a small importance for precipitation simulations on all time scales, which hampers estimating the effect which any mitigation efforts might have. In line with current state-of-the-art adaptation approaches, we argue that despite these uncertainties climate models can provide useful information to support adaptation decision-making. Moreover, adaptation decisions should not be postponed in the hope that future improved scientific understanding will result in more accurate predictions of future climate change. Such simulations might not become available. On the contrary, while planning adaptation initiatives, a rational framework for decision-making under uncertainty should be employed. We suggest that there is an urgent need for continued development and use of improved risk analysis methods for climate change adaptation.     

Evaluating the Eco‐Geomorphological Condition of Restored Streams Using Visual Assessment and Macroinvertebrate Metrics

The Stream Performance Assessment (SPA), a new rapid assessment method, was applied to 93 restored, 21 impaired, 29 reference, and 13 reference streams with some incision throughout North Carolina. Principal component analysis (PCA) indicated restored streams align more closely with reference streams rather than impaired streams. Further, PCA‐based factor analysis revealed restored streams were similar to reference streams in terms of morphologic condition, but exhibited a greater range of scores relative to aquatic habitat and bedform. Macroinvertebrate sampling and GIS watershed analyses were conducted on 84 restored streams. SPA and watershed data were compared to Ephemeroptera, Plecoptera, and Trichoptera (EPT) taxa to determine which factors indicate stream health. SPA and watershed factors were used in least squares, ridge, and principal component regression (PCR) to develop a prediction model for EPT taxa. All three methods produced reasonable predictions for EPT taxa. Cross‐validation indicated ridge regression resulted in the lowest prediction error. The ridge model was then used to predict EPT taxa numbers for 21 impaired and 25 reference streams in addition to the 84 restored streams. Statistical comparisons of the predicted scores indicated urban streams (>10% impervious watershed cover) have lower expected numbers of EPT taxa. Rural restored streams have macroinvertebrate metric scores similar to those predicted for rural reference streams.     

Turbulence suppression by suspended sediment within a geophysical flow

Experiments are performed in a mixing box to evaluate the effect of suspended sediment on turbulence generated by an oscillating grid. Quartz-density sand of varying sizes and concentrations is used, and particle image velocimetry is employed to quantify only the fluid phase. Results show that (1) while a relatively large secondary flow field is present in the box, turbulence is a maximum near the grid and it decreases systematically toward the water surface; (2) relatively high concentrations of fine sediment can markedly alter this secondary flow field and significantly decrease both the time-mean and turbulent kinetic energy within the flow, yet these same sediment concentrations have little effect on the integral time and length scales derived for each velocity component; and (3) the overall turbulence suppression observed can be related to the transfer of energy from the fluid to the sediment and the maintenance of a suspended sediment load rather than commonly employed turbulence modulation criteria. These experimental data demonstrate unequivocally that the presence of a suspended sediment load can significantly reduce overall turbulent kinetic energy, and these results should be applicable to a range of sediment-laden geophysical flows.