Case Study and Retrospective: Aerobic Fixed Film Biological Treatment Process for 1,4‐Dioxane at the Lowry Landfill Superfund Site

An aerobic fixed film biological treatment system has been successfully treating recovered groundwater/landfill leachate containing 1,4‐dioxane, tetrahydrofuran (THF), and other constituents since 2003. The most likely mode of 1,4‐dioxane biotransformation is via a cometabolic pathway in the presence of THF. Pilot studies conducted during the process development phase established a design basis process loading factor of 0.6 g 1,4‐dioxane and THF (as chemical oxygen demand [COD])/g total solids per day and proved the efficacy of the process. Full‐scale design includes the use of three parallel moving bed bioreactors with effluent recycle capability. Removal efficiencies in excess of 98 percent have been documented for 1,4‐dioxane. Evolving operational challenges are associated with recent trends in 1,4‐dioxane pretreatment discharge limitations in combination with ongoing process optimization and increased influent flow rate conditions associated with seasonal precipitation patterns. ©2016 Wiley Periodicals, Inc.     

PAH and soot emissions from burning components of medical waste: examination/surgical gloves and cotton pads

This is a laboratory investigation on the emissions from batch combustion of representative infectious ("red bag") medical waste components, such as medical examination latex gloves and sterile cotton pads. Plastics and cloth account for the majority of the red bag wastes by mass and, certainly, by volume. An electrically heated, horizontal muffle furnace was used for batch combustion of small quantities of shredded fuels (0.5-1.5 g) at a gas temperature of approximately 1000 degrees C. The residence time of the post-combustion gases in the furnace was approximately 1 s. At the exit of the furnace, the following emissions were measured: CO, CO2, NOx, particulates and polynuclear aromatic compounds (PACs). The first three gaseous emissions were measured with continuous gas analyzers. Soot and PAC emissions were simultaneously measured by passing the furnace effluent through a filter (to collect condensed-phase PACs) and a bed of XAD-4 adsorbent (to capture gaseous-phase PACs). Analysis involved soxhlet extraction, followed by gas chromatography-mass spectrometry (GC-MS). Results were contrasted with previously measured emissions from batch combustion of pulverized coal and tire-derived fuel (TDF) under similar conditions. Results showed that the particulate soot) and cumulative PAC emissions from batch combustion of latex gloves were more than an order of magnitude higher than those from cotton pads. The following values are indicative of the relative trends (but not necessarily absolute values) in emission yields: 26% of the mass of the latex was converted to soot, 11% of which was condensed PAC. Only 2% of the mass of cotton pads was converted to soot, and only 3% of the weight of that soot was condensed PAC. The PAC yields from latex were comparable to those from TDF. The PAC yields from cotton were higher than those from coal. A notable exception to this trend was that the three-ring gas-phase PAC yields from cotton were more significant than those from latex. Emission yields of CO and CO2 from batch combustion of cotton were, respectively, comparable and higher than those from latex, despite the fact that the carbon content of cotton was half that of latex. This is indicative of the more effective combustion of cotton. Nearly all of the mass of carbon of cotton gasified to CO and CO2 while only small fractions of the carbon in latex were converted to CO2 and CO (20% and 10%, respectively). Yields of NOx from batch combustions of latex and cotton accounted for 15% and 12%, respectively, of the mass of fuel nitrogen indicating that more fuel nitrogen was converted to NOx in the former case, possibly due to higher flame temperatures. No SO2 emissions were detected, indicating that during the fuel-rich combustion of latex, its sulfur content was converted to other compounds (such as H2S) or remained in the soot.     

Ten years of varying lake level and selection on size-at-maturity in sockeye salmon

Despite the ubiquity of studies quantifying the strength and form of selection in nature, rarely is the ecological context for contemporary selection understood. Here we report a case where lake level is a selective factor acting on sockeye salmon body size-at-maturity because low lake levels cause large salmon to strand and die rather than reach the breeding grounds. As a result of a semelparous life history, death for salmon at this stage results in a lifetime fitness of zero. We combined information on the level of Lake Aleknagik (southwestern Alaska, USA) from 1952 through 2006 with a detailed comparison of the body size of mature salmon that died at the mouth of Hansen Creek vs. individuals that successfully ascended to the spawning grounds over 10 breeding seasons (1997-2006). The percentage of salmon stranding at the mouth varied among years: 2-42% in males and < 1-26% in females. Formal selection analyses indicated that the largest individuals were most susceptible to stranding mortality, especially in years when many salmon stranded, and these were years with low lake levels. Taken together, these results suggest that lake level was a strong and consistent selective force acting on this salmon population, acting synergistically with size-selective predation by bears. Salmon breeding in Hansen Creek tend to be smaller, younger, and more streamlined than conspecifics from neighboring populations, suggesting that selection against large individuals could be driving these patterns.     

Response of antibiotics and resistance genes to high-intensity and low-intensity manure management

The purpose of this study was to determine the response of antibiotics and antibiotic resistance genes (ARG) to manure management. A pilot field study was conducted using horse manure containing no antibiotics, into which chlortetracycline (CTC), tylosin (TYL), and monensin (MON) were spiked and compared to unspiked controls. Subsequently, a large-scale field study was conducted comparing manure from a dairy with minimal use of antibiotics and a feedlot with regular subtherapeutic use of antibiotics. The manures were subjected to high-intensity management (HIM) (amending, watering, and turning) and low-intensity management (LIM) (no amending, watering, or turning) and were monitored for antibiotic concentrations and levels of tetracycline ARG [tet(W) and tet(O)] using quantitative real-time polymerase chain reaction. All three antibiotics in the pilot study dissipated more rapidly in HIM manure, with half-lives ranging from 4 to 15 d, compared to LIM manure, with half-lives ranging from 8 to 30 d. Levels of tet(W) were significantly higher after 141 d of treatment, but levels of tet(O) were significantly lower in all treatments. In the large-scale study, the feedlot manure had higher initial concentrations than the dairy manure of tetracycline (TC), oxytetracycline (OTC), and CTC as well as tet(W) and tet(O). Tetracycline and OTC dissipated more rapidly in HIM manure, with half-lives ranging from 6 to 15 d, compared to LIM manure, with half-lives ranging from 7 to 31 d. After 6 mo of treatment, tet(W) and tet(O) decreased significantly in feedlot manure, whereas dairy manure required only 4 mo of treatment for similar results.     

Monitoring Parks Through Remote Sensing: Studies in Nepal and Honduras

The effectiveness of parks as management regimes is hotly contested. Much of the current discussion centered around comparisons of management regimes can be traced to a dearth of cross-site quantitative evaluations. Remote sensing provides a particularly effective tool for this purpose, yet analysis of remotely sensed data requires fieldwork to interpret human activities and the socioeconomic and political contexts that relate to land cover change. This paper examines the effect of establishment of the Celaque National Park, Honduras, and the Royal Chitwan National Park buffer zone, Nepal, on limiting deforestation. In Celaque, the park itself has been largely successful in maintaining forest cover. However, recent changes in land use patterns have led to increasing pressure on the park boundaries, exacerbated by the lack of involvement of local residents. In the Royal Chitwan National Park, in contrast, participatory approaches towards co-management have been implemented over the past decade in the park buffer zone. With significant incomes derived from ecotourism, complete protection of the buffer zone forest has been adopted, leading to significant regrowth of tree cover. However, local decision-making power is limited, and buffer zone management has largely proven successful due to the investment and support provided by international donor agencies. These two case studies demonstrate the utility of remote sensing and Geographical Information Systems analysis in providing a spatiotemporal perspective for assessing management policies. They also demonstrate the importance of fieldwork to provide a nuanced understanding of the socioeconomic and institutional conditions affecting the outcomes of forest management regimes.     

Multivariate Analysis of the Ecoregion Delineation for Aquatic Systems

The ecoregion concept is a popular method of understanding the spatial distribution of the environment', however, it has yet to be adequately demonstrated that the environment is distributed in accordance with these bounded units. In this paper, we generated a testable hypothesis based on the current usage of ecoregions: the ecoregion classification will allow for discrimination between lakes of different water quality. The ecoregion classification should also be more effective better than a comparably scaled classification based on political boundaries, land-use class, or random grouping. To test this hypothesis we used the Environmental Monitoring and Assessment Program (EMAP) lake water chemistry data from the northeast United States. The water chemistry data were reduced to four components using principal component analysis. For comparison to an optimal grouping of these data we used K-means cluster analysis to define the extent at which these lakes could be segregated into distinct classes. Jackknifed discriminant analysis was used to determine the classification rate of ecoregions, the three alternative spatial classification methods, and the clustering algorithm. The classification based on ecoregions was successful for 35% of the lakes included in this study, in comparison to the clustered groups accuracy of 98%. These results suggest that the large scale spatial distribution of ecosystem types is more complicated than that suggested by the present ecoregion boundaries. Further tests of ecoregion delineations are needed and alternative large-scale management strategies should be investigated.     

DUAL URBAN AND RURAL HYDROGRAPH SIGNALS IN THREE SMALL WATERSHEDS1

ABSTRACT: Many studies can be found in the literature pertaining to the effects of urbanization on surface runoff in small watersheds and the hydrologic response of undeveloped watersheds. However, an extensive literature review yielded few published studies that illustrate differing hydrologic responses from multiple source areas within a watershed. The concepts discussed here are not new, but the methods used provide a unique, basic procedure for investigating stormwater hydrology in topographically diverse basins. Six storm hydrographs from three small central Pennsylvania watersheds were analyzed for this paper; five are presented. Two important conclusions are deduced from this investigation. First, in all cases we found two distinct peaks in stream discharge, each representing different contributing areas to direct discharge with greatly differing curve numbers and lags representative of urban and rural source regions. Second, the direct discharge represents only a small fraction of the total drainage area with the urban peak becoming increasingly important with respect to the rural peak with the amount of urbanization and as the magnitude of the rain event decreases.