Intra- and interannual variability in seagrass carbon and nitrogen stable isotopes from south Florida, a preliminary study

δ13C and δ15N values were determined for the seagrassThalassia testudinum at four permanent seagrass monitoring stations in southFlorida, USA, through a quarterly sampling program over 3-years (1996–1998). All sites are seagrass beds with water depths of less than 6 m. Two sites are located on the Florida Bay side of the Florida Keys, and the other two sites are on the Atlantic side. The data analyzed over the 3 year study period display unique patterns associated with seasonal changes in primary productivity and potentially changes in the N and C pools. The mean carbon and nitrogenisotope values of T. testudinum from all four stations vary from −7.2 to −10.4‰ and 1.1 to 2.2‰, respectively. However, certain stations displayed anomalously depleted nitrogenisotope values (as low as −1.2‰). These values may indicate that biogeochemical processes like N fixation, ammonification and denitrification cause temporal changes in the isotopic composition of the source DIN. Both δ13C and δ15N values displayed seasonal enrichment-depletion patterns, with maximum enrichment occurring during the summer to early fall. The intra-annual variations of δ13C values from the different stations ranged from about 1 to 3.5‰; whereas variations in δ15N ranged from about 1 to 4.9‰. Certain sites showed a positive relationship between isotope values and productivity. These data indicate δ13C values display a high degree of seasonal variability as related to changes in productivity. δ15N values show clear intra-annual variations, but the observed changes do not necessarily follow a distinct seasonal cycle, indicating that changes in DIN will need further investigation.

Biogeochemistry of Nitrogen Across the Everglades Landscape

Compared to phosphorus (P), nitrogen (N) has received little attention across the Everglades landscape. Despite this lack of attention, N plays important roles in many Everglades systems, including being a significant pollutant in Florida Bay and the Gulf of Mexico, the limiting nutrient in highly P-impacted areas, and an important substrate for microbial metabolism. Storage and transport of N throughout the Everglades is dominated by organic forms, including peat soils and dissolved organic N in the water column. In general, N sources are highest in the northern areas; however, atmospheric deposition and active N2 fixation by the periphyton components are a significant N source throughout most systems. Many of the processes involved in the wetland N cycle remain unmeasured for most of the Everglades systems. In particular, the lack of in situ rates for N2 fixation and denitrification prevent the construction of system-level budgets, especially for the Southern mangrove systems where N export into Florida Bay is critical. There is also the potential for several novel N processes (e.g., Anammox) with an as yet undetermined importance for nitrogen cycling and function of the Everglades ecosystem. Phosphorus loading alters the N cycle by stimulating organic N mineralization with resulting flux of ammonium and DON, and at elevated P concentrations, by increasing rates of N2 fixation and N assimilation. Restoration of hydrology has a potential for significantly impacting N cycling in the Everglades both in terms of affecting N transport, but also by altering aerobic-anaerobic transitions at the soil-water interface or in areas with seasonal drawdowns (e.g., marl prairies). Based on the authors’ understanding of N processes, much more research is necessary to adequately predict potential impacts from hydrologic restoration, as well as the function of Everglades systems as sinks, sources, and transformers of N in the South Florida landscape.

Method development for the analysis of smokeless powders and organic gunshot residue by ultra performance liquid chromatography with tandem mass spectrometry

The goal of this project was to develop a rapid separation and detection method for analyzing organic compounds in smokeless powders and then test its applicability on gunshot residue (GSR) samples. In this project, a total of 20 common smokeless powder additives and their decomposition products were separated by ultra performance liquid chromatography (UPLC) and confirmed by tandem mass spectrometry (MS/MS) using multiple reaction monitoring mode (MRM). Some of the targeted compounds included diphenylamines, centralites, nitrotoluenes, nitroglycerin, and various phthalates. The compounds were ionized in the MS source using simultaneous positive and negative electrospray ionization (ESI) with negative atmospheric pressure chemical ionization (APCI) in order to detect all compounds in a single analysis. The developed UPLC/MS/MS method was applied to commercially available smokeless powders and gunshot residue samples recovered from the hands of shooters, spent cartridges, and smokeless powder retrieved from unfired cartridges. Distinct compositions were identified for smokeless powders from different manufacturers and from separate manufacturing lots. The procedure also produced specific chemical profiles when tested on gunshot residues from different manufacturers. Overall, this thesis represents the development of a rapid and reproducible procedure capable of simultaneously detecting the widest possible range of components present in organic gunshot residue.^

Restaurant Industry Perspectives on Pro-social Rule Breaking: Intent versus Action

The resounding message extracted from the service literature is that employees serve pivotal functions in the overall guest experience. This is of course due to the simultaneous delivery of personalized service provision with resultant consumption of those services. This simultaneous delivery and consumption cycle is at times challenged by a perceived desire to accommodate guest request that may violate, to a greater or lesser degree, an organizational rule. This is important to note because increased interactions with customers enable frontline employees to have a better sense of what customers want from the company as well as from the company itself (Bitner, et al, 1994). With that platform established, then why are some employees willing to break organizational rules and risk disciplinary action to better service a customer? This study examines the employee personality, degree of autonomy, job meaning, and co-worker influence on an employee's decision to break organizational rules. The results of this study indicate that co-worker influence exerted a minimal influence on employee decision to break rules while the presence of societal consciousness exerted a much stronger influence. Women reported that they were less likely to engage in rule divergence, and significant correlations were present when filtered by years in current position, and years in the industry.

Restaurant Industry Perspectives on Pro-social Rule Breaking: Intent versus Action

The resounding message extracted from the service literature is that employees serve pivotal functions in the overall guest experience. This is of course due to the simultaneous delivery of personalized service provision with resultant consumption of those services. This simultaneous delivery and consumption cycle is at times challenged by a perceived desire to accommodate guest request that may violate, to a greater or lesser degree, an organizational rule. This is important to note because increased interactions with customers enable frontline employees to have a better sense of what customers want from the company as well as from the company itself (Bitner, et al, 1994). With that platform established, then why are some employees willing to break organizational rules and risk disciplinary action to better service a customer? This study examines the employee personality, degree of autonomy, job meaning, and co-worker influence on an employee's decision to break organizational rules. The results of this study indicate that co-worker influence exerted a minimal influence on employee decision to break rules while the presence of societal consciousness exerted a much stronger influence. Women reported that they were less likely to engage in rule divergence, and significant correlations were present when filtered by years in current position, and years in the industry.