The Use of Subbottom Profiling in Refining Dredge Cuts for a Large‐Scale Sediment Remediation Project

A number of different techniques were employed to locate the target dredge grade on a large‐scale Canadian sediment remediation project. These techniques included various coring events, Seabed Terminal Impact Newton Gradiometer (STING) testing, and geotechnical borings. Despite these techniques, the data set for interpolation of the dredge grade was widely spaced, and some of the investigations were not specifically intended to be used for defining the dredge grade. In order to reduce the risk of extra expenses from contractor claims resulting from differing sediment conditions, more precise planning was required. Due to the size of the area and the desired accuracy, subbottom profiling was identified as a potential tool to provide high‐density coverage across the site. As with any geophysical tool, ground truth data were required to verify and aid in interpretation. This article describes how subbottom profiling was used to refine the dredge grade for the target layer, the associated challenges related to signal loss in some areas, and how they were overcome. ©2017 Wiley Periodicals, Inc.     

Multiscale satellite and spatial information and analysis framework in support of a large-area forest monitoring and inventory update

Many countries undertake a national forest inventory to enable statistically valid monitoring in support of national and international reporting of forest conditions and change. Canada’s National Forest Inventory (NFI) program is designed to operate on a 10-year remeasurement cycle, with an interim report produced at the 5-year mid-point. The NFI is a sample-based inventory, with approximately 18,850 2 ×2-km photo plots across the country, distributed on a 20×20-km grid of sample points; these photo plots are the primary data source for the NFI. Capacity to provide annual monitoring information is required to keep policy and decision makers apprised of current forest conditions. In this study, we implemented a multistage monitoring framework and used a Moderate Resolution Imaging Spectroradiometer (MODIS) change product to successfully identify 78% of the changes in forest cover area that were captured with a Landsat change detection approach. Of the NFI photo plots that were identified by both the Landsat and MODIS approaches as having changes in forest cover, the proportion of change area within the plots was similar (R ²?=?0.78). Approximately 70% of the Landsat-derived change events occupied less than 40% of a single MODIS pixel, and more than 90% of the change events of this size were successfully detected with the MODIS product. Finally, MODIS estimates of the proportion of forest cover change at the NFI photo plot level were comparable to change estimates for the ecoregions as a whole (R ²?=?0.95). High-temporal, low-spatial resolution imagery such as MODIS, in combination with other remotely sensed data sources, can provide information on disturbance events within a national forest inventory remeasurement cycle, thereby satisfying the interim information needs of policy and decision makers as well as the requirements of national and international reporting commitments.     

Evaluating regulatory issues and emission control equipment for air toxics applications

This article describes regulatory issues and emission control equipment for air toxics applications. A brief history of air quality legislation is provided, illustrating the difficulty government has had in implementing air quality statutes; this has contributed to the complexity of air quality regulations. Evaluation methodologies are described for three different emission control technologies: thermal oxidation, catalytic oxidation, and adsorption. Brief case histories are provided that describe the pitfalls and benefits associated with each technology. The benefits of integrating health risk assessment into an air quality program are also discussed.     

Effect of Cage Design on Growth of Transplanted Asian Clams: Implications for Assessing Bivalve Responses in Streams

This study was designed to determine whether survivorship and growth of Asian clams (Corbicula fluminea [Müller]) differed significantly between two types of field enclosures. Enclosures were either flexible mesh bags or rigid cages (hereto after referred as bioboxes) designed to homogenize substrate among study sites and accommodate Asian clam feeding mechanisms. For 96d, cages remained at 12 Clinch River (CR), Hurricane Fork (HF), and Dump's Creek (DC) sites upstream and downstream of a coal-fired power plant discharge, coal mining effluent, and coal combustion-related disposal facilities in Carbo, Virginia. Although survivorship was not significantly different between cage types, mean growth of clams in bioboxes was significantly greater overall (p = 0.0157). Despite the difference in growth between the two cage types, both confirmed significant reductions of survivorship and growth directly below the power plant discharge. Additionally, coefficient of variance values for biobox growth data were reduced at most study sites (averages of 16% for bioboxes versus 19% for mesh bags). Our results have implications toward strengthening weight-of-evidence approaches used to link impairment of transplanted bivalves to environmental contaminants. More importantly, these results suggest that ecotoxicological impairment of bivalves transplanted downstream of the coal-fired power plant discharge functioned independently of site-specific substrate provisions.     

A GIS Model of Subsurface Water Potential for Aquatic Resource Inventory,Assessment, and Environmental Management

Biological, chemical, and physical attributes of aquatic ecosystems are often strongly influenced by groundwater sources. Nonetheless, widespread access to predictions of subsurface contributions to rivers, lakes, and wetlands at a scale useful to environmental managers is generally lacking. In this paper, we describe a neighborhood analysis approach for estimating topographic constraints on spatial patterns of recharge and discharge and discuss how this index has proven useful in research, management, and conservation contexts. The Michigan Rivers Inventory subsurface flux model (MRI-DARCY) used digital elevation and hydraulic conductivity inferred from mapped surficial geology to estimate spatial patterns of hydraulic potential. Model predictions were calculated in units of specific discharge (meters per day) for a 30-m²-cell raster map and interpreted as an index of potential subsurface water flux (shallow groundwater and event through-flow). The model was evaluated by comparison with measurements of groundwater-related attributes at watershed, stream segment, and local spatial scales throughout Lower Michigan (USA). Map-based predictions using MRI-DARCY accounted for 85% of the observed variation in base flow from 128 USGS gauges, 69% of the observed variation in discharge accrual from 48 river segments, and 29% of the residual variation in local groundwater flux from 33 locations as measured by hyporheic temperature profiles after factoring out the effects of climate. Although it does not incorporate any information about the actual water table surface, by quantifying spatial variation of key constraints on groundwater-related attributes, the model provides strata for more intensive study, as well as a useful spatial tool for regional and local conservation planning, fisheries management, wetland characterization, and stream assessment.     

Cost-effectiveness Analysis of Reducing the Emission of Nitrogen Oxides in Asia

The purpose of this study is to evaluate cost-effective reduction strategies for nitrogen oxides (NO _x ) in the Asian region. The source-receptor relationships of the Lagrangian “puff” model of long-range transportation, ATMOS-N, were used to calculate the wet/dry deposition of the nitrogen (N) in Asia. Critical loads of N deposition in Asia were calculated from the relationships between the critical load of sulfur (S) and balance of N in and out using the data of S critical load of RAINS-ASIA. The cost functions of N reduction of Asian countries were derived by the regression analysis with the data of cost functions of European countries used in RAINS. In order to assess the environmental impact, the gaps between N deposition and critical load of N were calculated. The emission of NO _x was reduced in some cases of this model, and the changes of gaps between N deposition and critical load were observed as well as the changes of the reduction cost. It is shown that a uniform reduction of NO _x emissions by countries in Asia is not cost-effective strategy.     

Pilot‐scale evaluation using bioaugmentation to enhance PCE dissolution at dover AFB national test site

An Interstate Technology and Regulatory Council (ITRC) forum was recently held that focused on six case studies in which bioremediation of dense nonaqueous‐phase liquids (DNAPLs) was performed; the objective was to demonstrate that there is credible evidence for bioremediation as a viable environmental remediation technology. The first two case studies from the forum have been previously published; this third case study involves a pilot‐scale demonstration that investigated the effects of biological activity on enhancing dissolution of an emplaced tetrachloroethene (PCE) DNAPL source. It used a controlled‐release test cell with PCE as the primary DNAPL in a porous media groundwater system. Both laboratory tests and a field‐scale pilot test demonstrated that bioaugmentation can stimulate complete dechlorination to a nontoxic end product and that the mass flux from a source zone increases when biological dehalorespiration activity is enhanced through nutrient (electron donor) addition and bioaugmentation. All project goals were met. Important achievements include demonstrating the ability to degrade a PCE DNAPL source to ethene and obtaining significant information on the impacts to the microbial populations and corresponding isotope enrichments during biodegradation of a source area. © 2007 Wiley Periodicals, Inc.     

Trail erosion patterns in Great Smoky Mountains National Park

All the maintained trails in Great Smoky Mountains National Park were surveyed for width, depth, and a variety of types of erosion. Trail erosion is related to a number of environmental variables, including vegetation type, elevation, trail slope, and section of the park. Open grass balds and spruce-fir forest are the most erosion-sensitive plant communities, and the xeric oak and pine types are the least sensitive. Trails in virgin or mature forest tend to be in poorer condition than those in successional areas. The most important physical factor is the slope of the trail.Trails in the Tennessee district are in slightly poorer condition, on the average, than those in the North Carolina district, but the Appalachian Trail is more eroded than either. A poor section of the park may have ten times the erosion of a good section. On an allpark basis, water erosion is the most important problem, with 15% of the trail surface affected.A comparison of visitation patterns with trail condition indicates that redistribution of use would help to mitigate some erosion problems. Because trail condition is correlated to physical environmental factors, however, some sites will require intensive maintenance, even if visitation is low.The data from this survey have already been used in environmental analysis of proposed developments within the park and can be applied to long-range planning for the park trail system as a whole.     

Rapid measurement of emissions from military aircraft turbine engines by downstream extractive sampling of aircraft on the ground: Results for C-130 and F-15 aircraft

Aircraft emissions affect air quality on scales from local to global. More than 20% of the jet fuel used in the U.S. is consumed by military aircraft, and emissions from this source are facing increasingly stringent environmental regulations, so improved methods for quickly and accurately determining emissions from existing and new engines are needed. This paper reports results of a study to advance the methods used for detailed characterization of military aircraft emissions, and provides emission factors for two aircraft: the F-15 fighter and the C-130 cargo plane. The measurements involved outdoor ground-level sampling downstream behind operational military aircraft. This permits rapid change-out of the aircraft so that engines can be tested quickly on operational aircraft. Measurements were made at throttle settings from idle to afterburner using a simple extractive probe in the dilute exhaust. Emission factors determined using this approach agree very well with those from the traditional method of extractive sampling at the exhaust exit. Emission factors are reported for CO₂, CO, NO, NO_x, and more than 60 hazardous and/or reactive organic gases. Particle size, mass and composition also were measured and are being reported separately. Comparison of the emissions of nine hazardous air pollutants from these two engines with emissions from nine other aircraft engines is discussed.     

Ban on landfilling of wooden pallets in North Carolina: an assessment of recycling and industry capacity

Pallets literally move the world and an estimated 2 billion of them are in use in the U.S. every day. However, pallets have a short life span and thus consume vast quantities of resources. They are also responsible for 2–3% of all waste landfilled in the United States. This is despite the fact that technologies and markets exist that allow pallets to be reused, recycled, converted into other products or turned into mulch, boiler fuels or alcohols (ethanol). The State of North Carolina's legislature debated a ban on landfilling pallets for several years and has now enacted legislation to ban this practice beginning in 2009. This study provided information used to help reach that decision.North Carolina had 103 known pallet recycling operations that were surveyed in 2003–2004. Using 34 responses, the total pallet recycling capacity in North Carolina was close to 60 million units per year, while 34 million pallets were actually recycled in 2003. The average operation employed nearly 34 persons and recycled about 326,000 pallets per year. On average, 20% of the pallets received by a recycling operation were reused, 45% were refurbished, 19% were recycled, and 15% were ground. The industry generally thought that a ban on landfilling pallets was a good idea (56%) with 18% indicating it was a bad idea. Another 18% of respondents did not care and 9% had different ideas.