Models to Estimate Volatile Organic Hazardous Air Pollutant Emissions from Municipal Sewer Systems

Abstract

Emissions from municipal sewers are usually omitted from hazardous air pollutant (HAP) emission inventories. This omission may result from a lack of appreciation for the potential emission impact and/or from inadequate emission estimation procedures. This paper presents an analysis and comparison of the models available to estimate volatile organic HAP (VOHAP) emissions from sewers. Comparisons were made between the different theoretical foundations of the models, as well as between the emissions predicted by the models for a single sewer component. Sewer gas concentrations predicted by the models were also compared to measured sewer gas concentrations reported in the literature. Two of the models were compared in their ability to estimate sewer VOHAP emissions for a large U. S. city using National Pollution Discharge Effluent System data for the influent wastewater to the city's municipal wastewater treatment facilities. This estimate showed that, regardless of the model used, sewer emissions are a potentially significant source of VOHAP emissions in the urban environment. The choice of model, however, is thought to be less critical to sewer emission estimates than the source of sewer wastewater VOHAP concentration data.     

Understanding the conflicting values associated with motorized recreation in protected areas

The International Union for the Conservation of Nature World Parks Congress in 2014 reported that the quality of management of protected areas is crucial in halting the loss of the world’s biodiversity and meeting global environmental challenges. However, increasingly high-impact activities, including motorized recreation are occurring in protected areas such as national parks, creating an ongoing clash of values and further compromising protected area management. This paper discusses the values of protected areas in the context of increasingly high-impact motorized usage, the impact of divergent values placed on green spaces such as national parks, and perceptions about these spaces. Given the changing global context of this millennium, and increasing populations requiring space for high-impact activities including motorized recreation, rethinking recreation in protected areas is needed. A protected area classification to accommodate high-impact activities away from vulnerable natural areas may assist in maintaining protected area quality.     

The removal of arsenate from water using iron-modified diatomite (D-Fe): isotherm and column experiments

Iron hydroxide supported onto porous diatomite (D-Fe) is a low-cost material with potential to remove arsenic from contaminated water due to its affinity for the arsenate ion. This affinity was tested under varying conditions of pH, contact time, iron content in D-Fe and the presence of competitive ions, silicate and phosphate. Batch and column experiments were conducted to derive adsorption isotherms and breakthrough behaviours (50 μg L^?1) for an initial concentration of 1,000 μg L^?1. Maximum capacity at pH 4 and 17 % iron was 18.12–40.82 mg of arsenic/g of D-Fe and at pH 4 and 10 % iron was 18.48–29.07 mg of arsenic/g of D-Fe. Adsorption decreased in the presence of phosphate and silicate ions. The difference in column adsorption behaviour between 10 % and 17 % iron was very pronounced, outweighing the impact of all other measured parameters. There was insufficient evidence of a correlation between iron content and arsenic content in isotherm experiments, suggesting that ion exchange is a negligible process occurring in arsenate adsorption using D-Fe nor is there co-precipitation of arsenate by rising iron content of the solute above saturation.     

Racial differences in promotion candidate performance and reactions to selection procedures: a field study in a diverse top‐management context

The present study examined African‐American and White promotion candidates' reactions to and performance on selection procedures that were completed within a police department where African Americans occupied the majority of top‐management positions. Reactions (perceived job relatedness and test‐taking motivation) of 187 candidates competing for promotion to the rank of sergeant were assessed after completing a written job knowledge test and a situational interview. Analyses showed that both the African‐American and White candidates judged the situational interview to be more job‐related than the pencil‐and‐paper job knowledge test. In addition, African Americans perceived both selection measures to be more job‐related and reported higher levels of test‐taking motivation than White candidates even though African Americans performed more poorly than White candidates on the paper‐and‐pencil test. These results challenge the contention that lower test‐taking motivation for African‐American candidates is related to racial differences in performance on pencil‐ and‐paper tests. Implications and directions for future research on reactions to selection procedures for promotion in racially diverse employment settings are discussed. Copyright © 2007 John Wiley & Sons, Ltd.     

Geochemical parameters influencing tungsten mobility in soils

The biogeochemistry of tungsten and its effects on mobility have recently gained attention due to the existence of human cancer clusters, such as in Fallon, NV. Tungsten exists in many environmental matrices as the soluble and mobile tungstate anion. However, tungsten can polymerize with itself and other anions, creating poly- and heteropoly-tungstates with variable geochemical and toxicological properties. In the present work, geochemical parameters are determined for tungstate species in a model soil that describe the potential for tungsten mobility. Soluble tungsten leached from a metallic tungsten-spiked soil after six to twelve months aging reached an equilibrium concentration >150 mg/L within 4 h of extraction with deionized water. Partition coefficients determined for various tungstate and polytungstate compounds in the model soil suggest a dynamic system in which speciation changes over time affect tungsten geochemical behavior. Partition coefficients for tungstate and some poly-species have been observed to increase by a factor of 3 to 6 over a four month period, indicating decreased mobility with soil aging.     

Olive production systems on sloping land: prospects and scenarios

The ultimate objective of the EU Olivero project was to improve the quality of life of the rural population and to assure the sustainable use of the natural resources of land and water in the sloping and mountainous olive production systems (SMOPS) areas in Southern Europe. One specific objective was to develop, with end-users, alternative future scenarios for olive orchards in the five Olivero target areas. This paper discusses the development of these scenarios, and their socio-economic and environmental effects. After presenting the different production systems (SMOPS) and their strengths, weaknesses, opportunities and threats, a general overview is given of the medium- and long-term prospects. These have been validated by experts from the olive sector and foresee changes towards abandonment, intensification and organic production. On balance, the changes could lead to lower production of some target areas in future. An analysis of major external factors affecting the future development of SMOPS indicates there will be labour shortages and increased wage rates, reduced subsidies and constant or rising olive oil prices. On the basis of these assumptions, four future scenarios are developed for the five target areas, with the help of a Linear Programming simulation model. The results are presented for two target areas. For the Trás-os-Montes target area in Portugal, three of the four tested scenarios point to a high level of abandonment, while in the most positive scenario the areas under semi-intensive low input and organic SMOPS increase. In the Granada and Jaen target area in Spain, all scenarios hint at intensification, and only the orchards on the steepest slopes are likely to be abandoned. The direction and extent of environmental effects (erosion, fire risk, pollution, water use and biodiversity) differ per scenario, as do the extent of cross-compliance and agri-environmental measures.     

Identifying Linkages Between Land Use,Geomorphology, and Aquatic Habitat in a Mixed-Use Watershed

The potential impacts of land use on large woody debris (LWD) were examined in Sourdough Creek Watershed, a rapidly growing area encompassing Bozeman, Montana, USA. We identified six land classes within a 250 m buffer extending on either side of Sourdough Creek and assessed aquatic habitat and geomorphologic variables within each class. All LWD pieces were counted, and we examined 14 other variables, including undercut bank, sinuosity, and substrate composition. LWD numbers were generally low and ranged from 0 to 8.2 pieces per 50 m of stream. Linear regression showed that LWD increased with distance from headwaters, riparian forest width, and sinuosity in four of the six land classes. Statistically significant differences between land classes for many aquatic habitat and geomorphologic variables indicated the impacts of different land uses on stream structure. We also found that practices such as active wood removal played a key role in LWD abundance. This finding suggests that managers should prioritize public education and outreach concerning the importance of in-stream wood, especially in mixed-use watersheds where wood is removed for either aesthetic reasons or to prevent stream flooding.     

The impact of coastal flooding on conservation areas: A study of the Clyde Estuary, Scotland

This study examines the impact of flooding on land of high conservation value located along part of the southern shoreline of the River Clyde Estuary in western Scotland. This paper hypothesizes that, over the next 50 years, the frequency and extent of coastal flooding will increase due to the gradual effect of global warming and the consequent rise in sea-level and increase in storminess. It is argued that because of the great cost of constructing new flood defence systems it will not be possible to protect all land areas to an equal extent from flooding. A means of ranking different land use will be necessary so that society can make a rational judgement concerning which sections of coastline will be worth protecting. This study provides a methodology that combines an objective ranking of conservation areas using non-economic indicators with a GIS model of flood potential, and permits accurate forecasts of flood losses to conservation areas of different ecological value. The conservation case study used in this paper proposes the use of an ecological weighting value based on five ecological variables each of 10 categories. Tables and maps identify the sites that have been highlighted as consisting of the most ‘valuable’ conservation sites. The methodology makes extensive use of geographical information systems (GIS) to model the predicted areas of flooding and to calculate conservation weighting values of the land areas.     

Fish abundances in shoreline habitats and submerged aquatic vegetation in a tidal freshwater embayment of the Potomac River

Submerged aquatic vegetation (SAV) is considered an important habitat for juvenile and small forage fish species, but many long-term recruitment surveys do not effectively monitor fish communities in SAV. To better understand the impact of recent large increases of SAV on the fish community in tidal freshwater reaches of the Potomac River, we compared traditional seine sampling from shore with drop ring sampling of SAV beds (primarily Hydrilla) in a shallow water (depths, <1.5 m) embayment, Gunston Cove. To accomplish this, we developed species-specific catch efficiency values for the seine gear and calculated area-based density in both shoreline and SAV habitats in late summer of three different years (2007, 2008, and 2009). For the dominant species (Fundulus diaphanus, Lepomis macrochirus, Etheostoma olmstedi, Morone americana, Lepomis gibbosus, and Fundulus heteroclitus), density was nearly always higher in SAV, but overall, species richness was highest in shoreline habitats sampled with seines. Although historical monitoring of fish in Gunston Cove (and throughout Chesapeake Bay) is based upon seine sampling (and trawl sampling in deeper areas), the high densities of fish and larger areal extent of SAV indicated that complementary sampling of SAV habitats would produce more accurate trends in abundances of common species. Because drop ring samples cover much less area than seines and may miss rare species, a combination of methods that includes seine sampling is needed for biodiversity assessment. The resurgence of SAV in tidal freshwater signifies improving water quality, and methods we evaluated here support improved inferences about population trends and fish community structure as indicators of ecosystem condition.