Risk aversion in hand-reared bananaquits

Summary To study risk aversion in hand-reared bananaquits (Coereba flaveola) we placed individuals in a cage with a 1 m² floral board having a random array of 85 yellow and 85 red artificial flowers. Flowers of one color were filled with the same quantity of nectar (constant flowers), whereas flowers of the other color were filled with variable quantities of nectar (variable flowers). The constant and variable flowers had identical mean contents, only their variances differed. After three presentations, the constant flowers were made variable and vice versa to control for color preferences. Naive foragers tended to avoid variable flowers. The degree of risk aversion was influenced by previous experience, the relative variability of the variable flowers, and flower color. Variable flowers having similar coefficients of variation, but different reward variables (volume or concentration) resulted in similar levels of risk aversion. Within single foraging episodes the following was observed: sequences of constant flowers increased while sequences of variable flowers remained similar to random foraging; the probability of revisiting a constant flower was higher than revisiting a variable flower; the average amount of nectar consumed from constant and variable flowers was similar within the assessment periods (prior to favoring constant flowers); the proportion of visits falling below the mean expected reward during the assessment period or its inverse (the proportion visited with at least the equivalent of the mean) may be a cue used for risk aversion; risk aversion persisted through long foraging bouts despite changed nectar distributions suggesting that the bananaquits did not track resource distributions well within foraging bouts.     

Future Trends of Land-Use Emissions of Major Greenhouse Gases

Land-use emissions of greenhouse gases make up over one-third of current total anthropogenic emissions of greenhouse gases and about three-quarters of the total anthropogenic emissions of CH4 and N2O. Considering their contribution to global emissions, it is important to understand their future trends in order to anticipate and mitigate climate change. This paper reviews published scenarios of major categories of these emissions with the aim to provide background information for the development of new scenarios. These categories include CO2 from deforestation, CH4 from rice cultivation, CH4 from enteric fermentation of cattle, and N2O from fertilizer application. Base year estimates of all these categories varied greatly from reference to reference, and hence emissions of all scenarios were normalized relative to their 1990 value before being compared to one another. The range of published scenarios of CO2 emissions from deforestation is widest around the middle of the 21st century and then all scenarios converge to low values towards 2100. By contrast, the different scenarios of CH4 and N2O diverge with time, showing their widest range in 2100. Global emissions of CH4 from rice cultivation vary by a factor of three in 2100 and N2O from fertilized soils by a factor of 2.3. Emissions of CH4 from enteric fermentation of animals have the smallest range (factor of 2.0). The typical long-range trends of land-use emission scenarios vary greatly from region to region - they stabilize in industrialized regions after a few decades, but tend to stabilize later in developing regions or continue to grow throughout the 21st century. To improve the realism of the estimates of future trends of land-use emissions, it is especially important to improve the estimation of the future extent of agricultural land and the rate of deforestation, while taking into account significant driving forces such as the demand for agricultural commodities and crop yields.     

Smart Characterization—An Integrated Approach for Evaluating a Complex 1,4‐Dioxane Site

Smart characterization approaches apply the latest high‐resolution site characterization methods to find the contaminant mass flux, by integrating relative permeability mapping, classical hydrostratigraphy interpretation, and high‐density groundwater and saturated soil sampling. The key factor that makes Smart characterization different is the application of quantitative saturated soil sampling in less permeable slow advection and storage zones to diagnose plume maturity and understand its implications for remedy selection and performance. Because direct sensing tools like the membrane interface probe are capable of providing screening‐level assessments for hydrocarbons and chlorinated solvents in storage zones, but not 1,4‐dioxane, the recommended Smart approach involves application of specialized high‐capacity mobile laboratories or rapid turn‐around using fixed commercial labs. In addition to the benefit of rapidly characterizing sites, Smart characterization facilitates a flux‐based conceptual site model, which allows stakeholders to focus remedies on the mobile portion of the contaminant mass or, in effect, the mass that matters. Through systematic planning and implementation, predesign characterization can be completed to optimize source and plume remedy strategies, balancing investment in Smart characterization with reductions in total life‐cycle costs to ensure that an appropriate return on investigation is obtained.  © 2016 Wiley Periodicals, Inc.     

Assessing the extent and nature of wildlife trade on the dark web

Use of the internet as a trade platform has resulted in a shift in the illegal wildlife trade. Increased scrutiny of illegal wildlife trade has led to concerns that online trade of wildlife will move onto the dark web. To provide a baseline of illegal wildlife trade on the dark web, we downloaded and archived 9852 items (individual posts) from the dark web, then searched these based on a list of 121 keywords associated with illegal online wildlife trade, including 30 keywords associated with illegally traded elephant ivory on the surface web. Results were compared with items known to be illegally traded on the dark web, specifically cannabis, cocaine, and heroin, to compare the extent of the trade. Of these 121 keywords, 4 resulted in hits, of which only one was potentially linked to illegal wildlife trade. This sole case was the sale and discussion of Echinopsis pachanoi (San Pedro cactus), which has hallucinogenic properties. This negligible level of activity related to the illegal trade of wildlife on the dark web relative to the open and increasing trade on the surface web may indicate a lack of successful enforcement against illegal wildlife trade on the surface web.     

Isothermal Oxidation of White Phosphorus Dispersed in Water in a Stirred-Tank Reactor

ABSTRACT

A global, first-order kinetic model was found to fit the data for the isothermal wet oxidation of elemental white phosphorus (P₄) in a batch, stirred-tank reactor. The initial concentration of white phosphorus solids was held constant at 1 g/L and an air flow of 2.0 standard liters per minute was used to supply the oxygen for the reaction. A CD6-like turbine and an A2 impeller were evaluated at speeds from 1000-2250 rpm. For the CD6-like turbine, mass transfer effects were assumed to be eliminated above 2000 rpm. Thus, the CD6-like turbine with a speed of 2250 rpm was selected for the isothermal studies. Particle size and temperature were varied. For the isothermal conditions, the first order kinetic constant varied from 0.022 min^-1 at 46 °C to 0.078 min^-1 at 80 °C. The apparent activation energy was 6.78 kcal/mol. Oxygen reacted with the suspended P₄ particles forming oxides of phosphorus, primarily phosphorus pentoxide (P₄0₁₀ or P₂ O₅). Some of the P₂O₅ reacted with the water to form PO₄ ^3- as the primary product of white phosphorus oxidation. The amount of phosphorus pentoxide absorbed in the water increased with temperature. The rate of phosphate formation followed zero order kinetics and was independent of particle size. As the temperature increased, the ratio of PO₄/ PO₃ increased. This observation and the apparently low activation energy suggest that diffusion effects may not have been eliminated completely.     

A comparative evaluation of the performance of full-scale high-rate methane biofilter (HMBF) systems and flow-through laboratory columns

Methane biofilter (MBF) technology, a cost effective method to control atmospheric emission of CH₄, is usually developed as a passively aerated system to control low-volume point-source emissions such as those from landfills with gas collection systems. Actively aerated high-rate methane biofilter (HMBF) systems are designed to overcome the shortcomings of passively aerated systems by ensuring the entire filter bed is utilized for CH₄ oxidation. Flow-through column experiments point to the fact that CH₄ oxidation rates of actively aerated systems could be several times higher than that of passively aerated systems. However, reports of the performance of field HMBF systems are not available in literature. Furthermore, there are no studies that demonstrate the possibility of using laboratory data in the design and operation of field systems. The current study was conducted to fill this research gap and involve a comparative study of the performance of laboratory columns to field performance of a HMBF system using solution gas produced at an oil battery site as the CH₄ source. The actively aerated column studies confirmed past results with high CH₄ oxidation rates; one column received air at two injection points and achieved an oxidation rate of 1417 g/m³/d, which is the highest reported value to date for compost-filled columns. Subsequent studies at a specially designed field HMBF filled with compost showed a higher oxidation rate of 1919 g/m³/d, indicating the possibility of exceeding the high CH₄ oxidation rates observed in the laboratory. The achievement of observed field oxidation rates being higher than those in the laboratory is attributed to the capability of maintaining higher temperatures in field HMBFs. Furthermore, results show that field HMBFs could operate at lower than stoichiometric air to CH₄ ratios, and lower retention times than that of laboratory columns. Results indicated that laboratory columns may not truly represent field behavior, and said results could only be used in the preliminary design of field HMBFs.