Field studies on the ammonia odor threshold based on ambient air-sampling following accidental releases

Ammonia is one of the most widely produced and utilized chemicals in the U.S., and while numerous lab studies have been undertaken, there is no consensus on the odor threshold. In contrast to controlled lab conditions used to determine odor thresholds, the field conditions following unintentional chemical releases are uncontrolled and highly variable due to many factors. A critical component in managing the response to these chemical spills involves understanding how lab data could be applied to uncontrolled field conditions in and around the affected community. It was postulated that analysis of field data collected following accidental releases of ammonia might augment and verify data collected in lab experiments. The widespread transport and use of ammonia has resulted in a number of unintentional releases of ammonia into the environment as a result of train derailments, tanker spills, and plant accidents. In the field studies reported here, air monitoring data were collected following a variety of accidental ammonia releases. Of 6539 readings between 0 and 1 ppm, odor was detected only in 208 samples (3.2%). Of 65 readings between 1.1 and 1.5 ppm, odor was detected in 51 samples (78.5%). These data are consistent with an ammonia odor threshold within a concentration range of 1.1–1.5 ppm. This level is consistent with the recently published odor threshold data for ammonia, but is significantly lower than frequently cited historical data. Furthermore, a review of the ammonia literature demonstrates that the ammonia odor threshold is significantly lower than levels that produce eye, nose, or throat irritation.     

Aggregation and dispersal based on social cues as a nest-site selection strategy in a resource-defence polygynandry mating system

Many animals must choose a nest site in order to reproduce. However, it is unclear how nest-site selection strategies vary across different mating systems. We must therefore explore nest-site selection strategies in a range of mating systems, including the interaction between resource-defence polygyny and polyandry (i.e. polygynandry). In this study, we imposed a re-settlement event in the terrestrial toadlet Pseudophryne bibronii and measured the influence of the spatial position of each male’s nest site with respect to rival males on the likelihood that it would be abandoned or receive eggs. We captured every calling male in a population, measured their breeding success and released them back into the breeding area. We then recorded the establishment and abandonment of nest sites by males over 26 consecutive nights. Spatial positioning did not have any significant effects on male-breeding success, supporting claims that females show less discrimination between nest sites when they are polyandrous and spread their eggs amongst multiple male nests. However, we found that males consistently selected nest sites according to a site’s spatial position, which suggests that fitness benefits unrelated to male breeding success (e.g. reduced mortality risk) might influence male nesting decisions. Overall, our study provides new evidence that the mating system adopted by a population can influence the cues that individuals respond to when selecting nest sites.     

The relevance of environmental conditions for departure decision changes en route in migrating geese

The timing of life-cycle events crucially influences fitness, particularly in migratory birds, which visit chains of sites with varying seasonality. Here, we used a proportional hazards model to identify local environmental factors, which a long-distance migrant, the Pink-footed Goose (Anser brachyrhynchus), uses for departure decisions on multiple sites along its spring flyway from Denmark via Norway to Svalbard. Our results not only identified day length, local accumulated temperature, and their interaction as likely candidates, but also (more importantly) showed for the first time that their relevance changes en route. The results suggest that the birds switch on a "migratory program" in their wintering grounds, with day length providing general information on time of the year and integrated temperatures providing information on larger scale climate trends. Thereafter, on the stopover sites, local accumulated temperatures allow the geese to infer information on the advancement of spring, which is then used to adjust the speed of progressing northward.     

Dendrochemical analysis of lead and calcium in southern Appalachian American beech

The health of the northern hardwood forest in the southern Appalachian Mountains of Tennessee, North Carolina, and Virginia has gained attention from the media and environmental stakeholders due to a purported decline in forest health at higher elevations. This project examined lead (Pb) and calcium (Ca) concentrations in growth rings of an important northern hardwood species, American beech (Fagus grandifolia Ehrh.) at Mount Rogers and Whitetop Mountain, Virginia and attempted to examine concentration relationships with stem growth patterns. Dominant and codominant trees were sampled from 16 research plots at two elevations. Tree cores were crossdated, divided into sections of 10-yr periods, and analyzed using atomic absorption spectroscopy. Lead concentrations correlated negatively with ring width. Elevation and aspect were significantly associated with the Pb concentration, while Ca concentrations were only associated with aspect. Tree core samples taken from higher elevation plots contained higher Pb concentrations than samples collected from lower elevation plots, while the northwest and southwest aspects contained significantly higher amounts of Pb and Ca. Both Pb and Ca concentrations increased during the 1860s and again during the mid-1900s.     

Simulating the impacts of fire: A computer program

Recurrent fire has played a dominant role in the ecology of southwestern ponderosa pine forests. To assess the benefits or losses of fire in these forests, a computer simulation model, called BURN, considers vegetation (mortality, regeneration, and production of herbaceous vegetation), wildlife (populations and habitats), and hydrology (streamflow and water quality). In the formulation of the model, graphical representations (time-trend response curves) of increases or losses (compared to an unburned control) after the occurrence of fire are converted to fixedterm annual ratios, and then annuities for the simulation components. Annuity values higher than 1.0 indicate benefits, while annuity values lower than 1.0 indicate losses. Studies in southwestern ponderosa pine forests utilized in the development of BURN are described briefly.     

Mining during the next 25 years: issues and challenges

This article examines possible future trends in the mining industry in the light of past developments. After a preliminary discussion, the article considers various aspects of demand, supply, corporate structures, geographic distribution of investment, and social and environmental factors influencing the minerals industry. Scepticism is expressed about the smooth, exponential growth envisaged by many commentators. Some risks are elaborated, and a digression about gold is included.
The article argues that, while the minerals industry has concentrated on reducing cash costs through technical innovation and productivity improvement, new approaches may be needed in future that are not directly linked to economies of scale. Contracting out is an interesting trend with major implications.
The view that the mineral industry's corporate structure is becoming increasingly concentrated is challenged. Developments in consumer countries as well as historical precedents strongly suggest a more diverse structure.
The spread of minerals investment from North America and Australasia, and the resurgence of foreign direct investment in minerals projects, are placed in context and discussed from the viewpoints of both companies and host countries.
Although the appropriate responses to many of these issues can only properly be made by governments at all levels, the industry has to play its part.     

Phosphorus fractionation in manure from swine fed traditional and low-phytate corn diets

Traditional corn (Zea mays L.) (TC), the primary grain used in swine (Sus scrofa) diets, stores a majority of its P as phytate, which is largely unavailable for digestion by nonruminant animals. Low-phytate corn (LPC) contains similar amounts of total P but a smaller percentage of P as phytate. When fed to swine, LPC increases P utilization and reduces P content of manure. While differences in P content between manure from animals fed TC and LPC diets have been documented, solubility and lability of manure P have not been compared. Manure P was characterized in manure from swine fed either LPC or TC diets in 2000 and 2001. Total P was lower (20 vs. 34 g kg(-1)) and N to P ratio was higher (4.5 vs. 3.3) in LPC manure than in TC manure. Manures were sequentially extracted with deionized water, 0.5 M NaHCO3, 0.1 M NaOH, and 1.0 M HCl. Extracts were analyzed for inorganic and total P. Most P (approximately 80%) in the extracts was in the inorganic form. Concentration of P in the water-extractable fraction was lower for LPC manure (10.2 g kg(-1) in 2000 and 9.7 g kg(-1) in 2001) than for TC manure (13.6 g kg(-1) in 2000 and 17.0 g kg(-1) in 2001). Percentage of total P in each extract was in the order of: H2O (60%), HCl (22%), NaHCO3 (12%), NaOH (8%), and residue (<1%). Total P and distribution of P in extracts indicates swine are able to utilize more P contained in LPC feed but the composition of P excreted in LPC manure is similar to TC manure. Solubility, crop availability, and lability of P in LPC manure should be similar to that of TC manure.     

Delays in DUI blood testing: Impact on cannabis DUI assessments

Objective: This study examined the time from law enforcement dispatch to the first blood draw in cases of driving under the influence (DUI) vehicular homicide and a subset of DUI vehicular assault cases in Colorado in 2012. Laboratory toxicology results were also examined to understand the implications of delays in blood draws in cases of driving while under the influence of marijuana's delta-9-tetrahydrocannabinol (THC).

Methods: Colorado court records were reviewed and information regarding charges, presence of alcohol and/or drugs, time of law enforcement contact and blood draw, crash location, and other contextual factors were identified. The distributions of first blood draw times were studied by charge and by responding law enforcement agency. Toxicology data from a different cohort of DUI traffic arrests in Colorado and Washington were examined to determine the proportion of blood tests for THC that were above specified legal limits in those states.

Results: The average time from law enforcement dispatch to blood draw in cases of vehicular homicide and vehicular assault was 2.32 h (SD ± 1.31 h), with a range of 0.83 to 8.0 h and a median of 2.0 h. Data from DUI traffic arrests found that between 42 and 70% of all cannabinoid-positive traffic arrests tested below 5 ng/ml THC in blood, which is the legal limit in Colorado and Washington.

Conclusion: Given the current delays to blood testing in cases of arrests for vehicular homicide and vehicular assault in Colorado, many blood tests are unlikely to confirm that drivers who are impaired from smoking marijuana have THC levels above established legal limits.