Comparison of field olfactometers in a controlled chamber using hydrogen sulfide as the test odorant.

A standard method for measuring and quantifying odour in the ambient air utilizes a portable odour detecting and measuring device known as a field olfactometer (US Public Health Service Project Grant A-58-541). The field olfactometer dynamically dilutes the ambient air with carbon-filtered air in distinct ratios known as "Dilutions-to-Threshold" dilution factors (D/Ts), i.e. 2, 4, 7, 15, etc. Thirteen US states and several cities in North America currently utilize field olfactometry as a key component of determining compliance to odour regulations and ordinances. A controlled environmental chamber was utilized, with hydrogen sulfide as the known test odorant. A hydrogen sulfide environment was created in this controlled chamber using an Advanced Calibration Designs, Inc. Cal2000 Hydrogen Sulfide Generator. The hydrogen sulfide concentration inside the chamber was monitored using an Arizona Instruments, Inc. Jerome Model 631 H2S Analyzer. When the environmental chamber reached a desired test concentration, test operators entered the chamber. The dilution-to-threshold odour concentration was measured using a Nasal Ranger Field Olfactometer (St Croix Sensory, Inc.) and a Barnebey Sutcliffe Corp. Scentometer. The actual hydrogen sulfide concentration was also measured at the location in the room where the operators were standing while using the two types of field olfactometers. This paper presents a correlation between dilution-to-threshold values (D/T) and hydrogen sulfide ambient concentration. For example, a D/T of 7 corresponds to ambient H2S concentrations of 5.7-15.6 microg/m3 (4-11 ppbv). During this study, no significant difference was found between results obtained using the Scentometer or the Nasal Ranger (r = 0.82). Also, no significant difference was found between results of multiple Nasal Ranger users (p = 0.309). The field olfactometers yielded hydrogen sulfide thresholds of 0.7-3.0 microg/m3 (0.5-2.0 ppbv). Laboratory olfactometry yielded comparable thresholds of 0.64-1.3 microg/m3 (0.45-0.9 ppbv). These thresholds are consistent with published values.

Ambient odour testing of concentrated animal feeding operations using field and laboratory olfactometers.

The Missouri Air Conservation Commission regulations include regulations that limit the amount of acceptable odor from confined animal feeding operations (CAFOs). The regulations concerning odor designate the use of a scentometer as a screening tool. The rules dictate that if an odor is detectable by an investigator at a dilution ratio of 5.4 using a scentometer then an air sample should be collected and sent to an olfactometry laboratory for an odor panel to determine the detection threshold and the intensity of the odor sample. The detection thresholds are determined following ASTM E679-91 and EN13725. The intensity is determined following ASTM E544-99. If the olfactometry laboratory determined the detection threshold of the sample to be above seven, then the CAFO would be in violation. If the olfactometry laboratory determined the intensity level to be above a level equivalent to 225 ppm of n-butanol, then the source of odor would be in violation. The CAFO odor rules came under scrutiny by representatives of the largest hog producer in the State of Missouri. Specifically, they argued that the detection threshold limit of seven in the CAFO portion of the rule was too low for the rule to realistically identify a violation. This paper presents the results of a study to find the appropriate regulatory level of odor as determined by laboratory olfactometry. The study took place from November 2001 to October 2002. Samples were collected from field locations that exhibited odor produced by confined animal feeding operations and from areas exhibiting no apparent odor. The odors were categorized based upon the scentometer level at which the odors were detectable, and then samples were sent to an odor evaluation laboratory for analysis by olfactometry.

Clonal population structure and genetic variation in sand-shinnery oak,Quercus havardii (Fagaceae).

We investigated clonal population structure and genetic variation in Quercus havardii (sand-shinnery oak), a deciduous rhizomatous shrub that dominates vegetation by forming uninterrupted expanses of ground cover over sandy deposits on the plains of western Texas, western Oklahoma, and eastern New Mexico. Isozyme electrophoresis (15 loci coding 11 enzymes) was used to recognize and map clones arrayed in a 2000-m transect (50-m sample intervals) and a 200 × 190 m grid (10-m sample intervals). Ninety-four clones were discovered, 38 in the transect and 56 in the grid, resulting in an estimated density of ∼15 clones per hectare. Clones varied greatly in size (∼100-7000 m), shape, and degree of fragmentation. The larger clones possessed massive interiors free of intergrowth by other clones, while the smaller clones varied in degree of intergrowth. The population maintained substantial levels of genetic variation (P = 60%, A = 2.5, H(exp) = 0.289) comparable to values obtained for other Quercus spp. and for other long-lived perennials. The population was outcrossing as evidenced by conformance of most loci to Hardy-Weinberg expected genotype proportions, although exceptions indicated a limited degree of population substructuring. These data indicate that despite apparent reproduction primarily through vegetative means, Q. havardii possesses conventional attributes of a sexual population.

An innovative approach to orientation: faculty preceptors.

The Faculty Summer Preceptor Program was instituted in the summer of 1987 to assist with the orientation of more than 200 newly employed graduate nurses at Thomas Jefferson University Hospital in Philadelphia. Plans had to be made to assist the staff in assimilating this large number of orientees without disrupting patient care delivery. Preceptorships were used extensively in nursing services during the past 10 years. A major advantage of using faculty is that they are very familiar with new graduates' skills, anxieties, and needs, and the faculty role closely corresponds with the role of the preceptor. The faculty is a "ready made" resource for nursing staff orientation.