Garon C. Smith

Amino Acid Concentrations in Extrafloral Nectar of Impatiens Sultani Increase after Simulated Herbivory

In many plants, extrafloral nectars attract ants that protect the plant from herbivory. Previous work indicates that both sugars and amino acids contribute to ant attraction and that herbivory may affect nectar production or composition. This study was designed to measure the effect of defoliation on sugar and amino acid concentrations in the extrafloral nectar of Impatiens sultan. Twenty-nine fall-raised plants and 45 spring- raised plants were subjected to varying degrees of defoliation in which 25, 50, or 75% of each leaf was removed. Extrafloral nectar was collected immediately before and 24 h after defoliation for the fall-raised plants; additionally, nectar was collected 24 h before and 48 and 72 h after defoliation in the spring-raised plants. Nectars were analyzed for sugar and amino acid content by means of high-pressure liquid chromatography (HPLC). Twenty- four hours after defoliation, amino acid content increased dramatically in plants subjected to all three levels of defoliation; amino acid concentrations of nectars 72 h after defoliation were indistinguishable from predefoliation levels. No change in sugar concentrations or nectar volumes was detected. Additional work is needed to determine if the increase in amino acids is adaptive and serves to attract more plant protectors.

Variation in nectar volume and composition of Impatiens capensis at the individual, plant, and population levels

Although the volume and chemical composition of nectars are known to vary among plant species and to affect pollinator response to plants, relatively little is known of the variation in volume, and sugar and amino acid composition within species. We collected nectar from Impatiens capensis in a nested design: three flowers from each of three plants from each of three populations. This design enabled us to quantify variation within individual plants, among plants within populations, and among populations. Using high performance liquid chromatography, we analyzed the sugar and amino composition of the 27 flowers. Analysis of variance showed that none of the parameters (volume, concentrations of three sugars and 24 amino compounds) varied within individuals. Variation in nectar volume was not significant among plants but was nearly significant among populations. Of the three sugars detected (sucrose, glucose, and fructose), the only significant variation was that of sucrose among populations. Concentrations of 12 amino compounds varied significantly at the plant level while 7 amino compounds varied among populations. The results indicate that: (1) pooling of nectar samples from flowers of individual plants can be an acceptable methodology for those seeking to understand within species variation; (2) amino compounds appear to vary more than either volumes or sugar concentrations; (3) future studies should assess how much of the observed variation is due to genetic versus environmental differences; (4) additional studies should examine the geographic variation in nectar parameters and pollinators of I. capensis in order to assess the role different pollinators play in shaping nectar composition.

ON THE INTERPRETATION OF SCHUBERT PLOT SLOPES FOR METAL-HUMATE SYSTEMS

In this paper we identify an error in the literature pertaining to the interpretation of nonintegral slopes in Schubert plots for metal-humate and metal-fulvate systems, and we derive equations that correctly describe the behavior of these systems.

The Missoula Valley semivolatile and volatile organic compound study: seasonal average concentrations.

Abstract The city of Missoula is located in a high mountain valley (elevation 3200 ft) in western Montana and contains one of the largest populations in the entire Rocky Mountain Region completely enclosed by mountains. During the 2000/2001 Missoula Valley Sampling Program, ambient levels of 61 semivolatile organic compounds (SVOCs) and 54 volatile organic compounds (VOCs) were originally quantified before refining the analytical program to 28 of the most prominent SVOCs and VOCs found in the Missoula Valley airshed. These compounds were measured over 24-hr periods at two locations throughout an entire year. This study provides the first, comprehensive appraisal of the levels of SVOCs and VOCs measured simultaneously throughout all four seasons at two locations in the Missoula Valley, including those levels measured during the 2000 Montana wildfire season. Generally, SVOC levels were comparable between both sides of the Missoula Valley. However, there were nearly double the amount of VOCs measured at the more urban Boyd Park site compared with the rural Frenchtown sampling site, a result of the greater number of automobiles on the eastern side of the Valley. SVOCs and VOCs were measured at their highest levels of the sampling program during the winter. Forest fire smoke samples collected during the summer of 2000 showed significant increases in SVOC phenolic compounds, including phenol, 2-methylphenol, 4-methylphenol, and 2,4-dimethylphenol. Although there were modest increases in some of the other SVOCs and VOCs measured during the fire season, none of the increases were as dramatic as the phenolics.

Vapor-phase and fine particulate matter concentrations of polycyclic aromatic hydrocarbons measured during the winter months in a Northern Rocky Mountain urban airshed

Abstract A fine particulate matter (PM2.5) sampling program was conducted in Missoula, MT, to investigate both the particle and vapor phases of PM2.5-associated polycyclic aromatic hydrocarbons (PAHs) found in a northern Rocky Mountain urban airshed. Twenty-four-hour samples were collected during the cold winter months of January through April 2002, when many of the more volatile organic components of PM2.5 were expected to be found in the condensed particle form. To meet analytical detection limits, each of the 12 individual sample days were aggregated into four total filter and polyurethane foam (PUF) samples, respectively, with each aggregate containing 3 sample days. Quartz filter (particle-phase PAHs) and PUF (vapor-phase PAHs) aggregates were analyzed separately for 18 individual PAHs and phenolics by gas chromatography/mass spectrometry. Results showed that 87% of the PM2.5-associated phenolics and PAHs measured in this study were found in the vapor phase. PM2.5-associated gas/particle partition coefficients (Kp,2.5) ranged from 0 for the lighter phenolics and PAHs to ~0.1 for some of the heavier PAHs, such as fluoranthene and pyrene. Calculating Kp,2.5 for the heaviest measured PAHs was not feasible because of low or undetectable concentrations in the vapor phases of these compounds. Phenolics and two-ringed and three-ringed PAHs were found almost exclusively in the vapor phase. Four-ringed PAHs were distributed between the particle and vapor phases, with more mass measured in the vapor phase. Very little five-ringed and higher PAHs were measured from either the filter or PUF sampling medium. These results provide information on both the concentrations and different phases of PM2.5-associated PAHs measured during the winter months in a northern Rocky Mountain urban airshed, when concentrations of PM2.5 are generally at their highest compared with the rest of the year.

High-Volume PUF versus Low-Volume PUF Sampling Comparison for Collecting Gas Plus Particulate Polycyclic Aromatic Hydrocarbons

A yearlong sampling program for PM2.5and semivolatile organic compounds (SVOCs) was conducted in 2000/2001 in Missoula, Montana by The University of Montana, Department of Chemistry. One aspect of this program was to investigate the SVOC fraction of the Missoula Valley PM2.5by evaluating a Federal Reference Method (FRM) PM2.5sampler modified with Polyurethane Foam (PUF) sorbent (PM2.5PUF). In addition, a method of comparison was made between sampling for SVOCs using this modified PM2.5PUF sampler and in using a high-volume PUF sampler (Hi-vol PUF) following EPA protocol. For this comparison, the quartz filter and PUF plugs were extracted together in the analysis of the PM2.5PUF and Hi-vol PUF samples, respectively. Results of this program showed that a trade off between Hi-vol PUF sampling and PM2.5PUF sampling was revealed. During the same sampling periods, the PM2.5PUF measured more of the lighter (smaller molecular weight) SVOCs in a side-by-side comparison with the Hi-vol PUF sampler, with much less volume of sample collected due to a lower flow rate. However, each 24 h Hi-vol PUF sample run provided enough material on which to conduct an SVOC analysis, avoiding the need to aggregate samples (or longer sampling periods) to meet analytical detection limits. In addition, the results presented here also raise important questions about the efficiency of existing PUF samplers (when using quartz filters and PUF sorbent media) in the accurate measurement of lower molecular weight particle and gas-phase SVOCs.