Quantifying iridescent coloration in animals: a method for improving repeatability

Quantification of animal colors is important to a variety of fields of research, especially those dealing with visual communication and sexual selection. Most animal colors are easily measured using well-established spectrophotometric techniques. However, the unique characteristics of iridescent colors present particular challenges and opportunities to quantify novel color metrics. Due to the fine-scale angle dependence of iridescent coloration, color metrics, such as hue and brightness, must be measured using methods that allow for repeatable comparison across individuals (e.g., by carefully controlling and measuring viewing geometry). Here, we explain how the optical characteristics of iridescent colors should be considered when developing measurement techniques, describe the pitfalls of some commonly used techniques, and recommend improved methods and metrics (angular degree of color change and breadth of reflectance) for quantifying iridescent color. In particular, most studies of iridescent birds to date have used less than ideal procedures and have not provided repeatability estimates for their methods. For example, we demonstrate here that measuring coloration from overlapping patches of iridescent feathers may be problematic, and we argue against methods that do not carefully control viewing geometry. We recommend measuring iridescence at maximal reflectance angles using an apparatus that allows for sample rotation, and we compare this technique to some other commonly used methods using iridescent gorget and crown feathers from Anna’s hummingbirds (Calypte anna). Our apparatus allows for the quantification of angular color change, and we found that maximal reflectance measurements using single feathers are highly repeatable both within feather samples and among samples within an individual.     

Development of drinking water standards for perchlorate in the United States

Perchlorate, an anion that originates as a contaminant in ground and surface waters, is both naturally occurring and manmade. Because of its toxicity, there has been increased interest in setting drinking water safety standards and in health effects when perchlorate is present at low (parts per billion (ppb)) levels. In January 2009, the EPA issued a heath advisory to assist state and local officials in addressing local contamination of perchlorate in drinking water. The interim health advisory level of 15 micrograms per liter (μg/L), or ppb, is based on the reference dose recommended by the National Research Council (NRC) of the National Academy of Sciences (NAS). This paper describes scope and extent of contaminant issues and a legal process of setting standards for perchlorate concentration in drinking water in the United States of America.     

Stabilization of Heavy Metal Containing Hazardous Wastes with Byproducts from Advanced Clean Coal Technology Systems

ABSTRACT

The purpose of this investigation was to evaluate the success of residues from advanced Clean Coal Technology (CCT) systems as stabilization agents for heavy metal containing hazardous wastes. In the context examined here, stabilization refers to techniques that reduce the toxicity of a waste by converting the hazardous constituents to a less soluble, mobile, or toxic form.¹ Three advanced CCT byproducts were used: coal waste-fired circulating fluidized bed combustor residue, pressurized fluidized bed combustor residue, and spray drier residue. Seven metal-laden hazardous wastes were treated: three contaminated soils, two air pollution control dusts, wastewater treatment plant sludge, and sandblast waste. Each of the seven hazardous wastes was treated with each of the three CCT byproducts at dosages of 10, 30, and 50% by weight (byproduct:waste). The treatment effectiveness of each mixture was evaluated by the Toxicity Characteristic Leaching Procedure. Of the 63 mixtures evaluated, 21 produced non-hazardous residues. Treatment effectiveness can likely be attributed to mechanisms such as precipitation and encapsulation due to the formation of hydrated calcium silicates and calcium sulfo-alu-minates. Results indicate that these residues have potential beneficial uses to the hazardous waste treatment community, possibly substituting for costly treatment chemicals.     

Comparison of the SCAQS Tunnel Study with Other On Road Vehicle Emission Data

The Van Nuys Tunnel experiment conducted in 1987 by Ingalls et al. (see A&WMA Paper 89-137.3), to verify automotive emission inventories as part of the Southern California Air Quality Study (SCAQS), gave higher CO and HC emission-rate values than expected on the basis of automotive-emission models—by factors of approximately 3 and 4, respectively. The CO/NO_X and HC/NO_X emission-rate ratios moreover were higher than expected—by similar factors (NO_X emission rates were about as expected). The purpose of the present paper is to review the literature on dynamometer and on-road (in tunnels and along roadways) testing of in-use vehicles, and on urban-air CO/HC/NO_X concentration ratios, to see whether the Van Nuys Tunnel results are reasonable in terms of previous experience. The conclusions are that (1) on-road CO and HC emissions higher than expected have been reported before, (2) on-road CO and HC emissions consistent with the Van Nuys Tunnel results have been reported before, and (3) on-road CO/NO_X and HC/NO_X emission-rate ratios higher than expected have been reported before. The Van Nuys Tunnel NO_X results actually are lower than in other on-road experiments, and the CO/NO_X and HC/NO_X ratios consequently are higher. The higher-than-predicted CO/NO_X and HC/NO_X ratios at Van Nuys and other on-road sites suggest richer operation on-road than predicted or than observed in the inuse- vehicle dynamometer tests which serve as the model inputs. Support for these suggestions and conclusions is found in comparison of urban-air and emission-inventory HC/NO_X ratios.     

Integrated Measures of Anthropogenic Stress in the U.S. Great Lakes Basin

Integrated, quantitative expressions of anthropogenic stress over large geographic regions can be valuable tools in environmental research and management. Despite the fundamental appeal of a regional approach, development of regional stress measures remains one of the most important current challenges in environmental science. Using publicly available, pre-existing spatial datasets, we developed a geographic information system database of 86 variables related to five classes of anthropogenic stress in the U.S. Great Lakes basin: agriculture, atmospheric deposition, human population, land cover, and point source pollution. The original variables were quantified by a variety of data types over a broad range of spatial and classification resolutions. We summarized the original data for 762 watershed-based units that comprise the U.S. portion of the basin and then used principal components analysis to develop overall stress measures within each stress category. We developed a cumulative stress index by combining the first principal component from each of the five stress categories. Maps of the stress measures illustrate strong spatial patterns across the basin, with the greatest amount of stress occurring on the western shore of Lake Michigan, southwest Lake Erie, and southeastern Lake Ontario. We found strong relationships between the stress measures and characteristics of bird communities, fish communities, and water chemistry measurements from the coastal region. The stress measures are taken to represent the major threats to coastal ecosystems in the U.S. Great Lakes. Such regional-scale efforts are critical for understanding relationships between human disturbance and ecosystem response, and can be used to guide environmental decision-making at both regional and local scales.     

Nitrate retention in riparian ground water at natural and elevated nitrate levels in north central Minnesota

The relationship between local ground water flows and NO(3)(-) transport to the channel was examined in three well transects from a natural, wooded riparian zone adjacent to the Shingobee River, MN. The hillslope ground water originated as recharge from intermittently grazed pasture up slope of the site. In the hillslope transect perpendicular to the stream, ground water NO(3)(-) concentrations decreased from approximately 3 mg N L(-1) beneath the ridge (80 m from the channel) to 0.01 to 1.0 mg N L(-1) at wells 1 to 3 m from the channel. The Cl(-) concentrations and NO(3)/Cl ratios decreased toward the channel indicating NO(3)(-) dilution and biotic retention. In the bankside well transect parallel to the stream, two distinct ground water environments were observed: an alluvial environment upstream of a relict beaver dam influenced by stream water and a hillslope environment downstream of the relict beaver dam. Nitrate was elevated to levels representative of agricultural runoff in a third well transect located approximately 5 m from the stream to assess the effectiveness of the riparian zone as a NO(3)(-) sink. Subsurface NO(3)(-) injections revealed transport of up to 15 mg N L(-1) was nearly conservative in the alluvial riparian environment. Addition of glucose stimulated dissolved oxygen uptake and promoted NO(3)(-) retention under both background and elevated NO(3)(-) levels in summer and winter. Disappearance of added NO(3)(-) was followed by transient NO(2)(-) formation and, in the presence of C(2)H(2), by N(2)O formation, demonstrating potential denitrification. Under current land use, most NO(3)(-) associated with local ground water is biotically retained or diluted before reaching the channel. However, elevating NO(3)(-) levels through agricultural cultivation would likely result in increased NO(3)(-) transport to the channel.