Jennifer L. Bouldin

Distribution and concentrations of petroleum hydrocarbons associated with the BP/Deepwater Horizon Oil Spill, Gulf of Mexico

We examined the geographic extent of petroleum hydrocarbon contamination in sediment, seawater, biota, and seafood during/after the BP/Deepwater Horizon Oil Spill (April 20-July 15, 2010; 28.736667°N, -88.386944°W). TPH, PAHs, and 12 compound classes were examined, particularly C1-benzo(a)anthracenes/chrysenes, C-2-/C-4-phenanthrenes/anthracenes, and C3-naphthalenes. Sediment TPH, PAHs, and all classes peaked near Pensacola, Florida, and Galveston, Texas. Seawater TPH peaked off Pensacola; all of the above classes peaked off the Mississippi River, Louisiana and Galveston. Biota TPH and PAHs peaked near the Mississippi River; C-3 napthalenes peaked near the spill site. Seafood TPH peaked near the spill site, with PAHs and all classes peaking near Pensacola. We recommend that oil concentrations continued to be monitored in these media well after the spill has ceased to assist in defining re-opening dates for fisheries; closures should be maintained until hydrocarbon levels are deemed within appropriate limits.

Aqueous toxicity and food chain transfer of Quantum DOTs in freshwater algae and Ceriodaphnia dubia.

Innovative research and diagnostic techniques for biological testing have advanced during recent years because of the development of semiconductor nanocrystals. Although these commercially available, fluorescent nanocrystals have a protective organic coating, the inner core contains cadmium and selenium. Because these metals have the potential for detrimental environmental effects, concerns have been raised over our lack of understanding about the environmental fate of these products. U.S. Environmental Protection Agency test protocol and fluorescence microscopy were used to determine the fate and effect of quantum dots (QDs; Qdot 545 ITK Carboxyl Quantum Dots [Fisher Scientific, Fisher part Q21391MP; Invitrogen Molecular Probes, Eugene, OR, USA]) using standard aquatic test organisms. No lethality was measured following 48-h exposure of Ceriodaphnia dubia to QD suspensions as high as 110 ppb, but the 96-h median lethal concentration to Pseudokirchneriella subcapitata was measured at 37.1 ppb. Transfer of QDs from dosed algae to C. dubia was verified with fluorescence microscopy. These results indicate that coatings present on nanocrystals provide protection from metal toxicity during laboratory exposures but that the transfer of core metals from intact nanocrystals may occur at levels well above toxic threshold values, indicating the potential exposure of higher trophic levels. Studies regarding the fate and effects of nanoparticles can be incorporated into models for predictive toxicology of these emerging contaminants.

Current and emerging technologies for rapid detection and characterization of Salmonella in poultry and poultry products

Salmonella is the leading cause of foodborne illnesses in the United States, and one of the main contributors to salmonellosis is the consumption of contaminated poultry and poultry products. Since deleterious effects of Salmonella on public health and the economy continue to occur, there is an ongoing need to develop more advanced detection methods that can identify Salmonella accurately and rapidly in foods before they reach consumers. Rapid detection and identification methods for Salmonella are considered to be an important component of strategies designed to prevent poultry and poultry product-associated illnesses. In the past three decades, there have been increasing efforts towards developing and improving rapid pathogen detection and characterization methodologies for application to poultry and poultry products. In this review, we discuss molecular methods for detection, identification and genetic characterization of Salmonella associated with poultry and poultry products. In addition, the advantages and disadvantages of the established and emerging rapid detection and characterization methods are addressed for Salmonella in poultry and poultry products. The methods with potential application to the industry are highlighted in this review.

Absorption of Semiconductor Nanocrystals by the Aquatic Invertebrate Ceriodaphnia dubia

When incubated with nanomolar concentrations of fluorescent semiconductor nanocrystals in moderately hard water the fluorescence of living Ceriodaphnia dubia increased. Average pixel intensity of exposed animals was greater than that of unexposed animals and increased in a dose and exposure time-dependent-manner. Internal structures were clearly visible in exposed and unexposed animals but fluorescence was most intense in the region of the abdominal appendages of exposed animals. Since these nanoparticles contain significant quantities of the toxic metals cadmium and selenium, their accumulation from aquatic environments by this standard test organism has significant implications about their potential environmental toxicity.

Effects of Exposure to Semiconductor Nanoparticles on Aquatic Organisms

Because of their unique physical, optical, and mechanical properties, nanomaterials hold great promise in improving on a wide variety of current technologies. Consequently, their use in research and consumer products is increasing rapidly, and contamination of the environment with various nanomaterials seems inevitable. Because surface waters receive pollutants and contaminants from many sources including nanoparticles and act as reservoirs and conduits for many environmental contaminants, understanding the potential impacts of nanoparticles on the organisms within these environments is critical to evaluating their potential toxicity. While there is much to be learned about interactions between nanomaterials and aquatic systems, there have been a number of recent reports of interactions of quantum dots (QDs) with aquatic environments and aquatic organisms. This review is focused on providing a summary of recent work investigating the impacts of quantum dots on aquatic organisms.

Evaluation of a Polyacrylamide Soil Additive to Reduce Agricultural-Associated Contamination

Polyacrylamide is an effective water treatment product used to reduce suspended sediment and associated contaminants. An anionic polyacrylamide-containing product was tested for sediment and associated contaminant reduction and potential toxicity in agricultural irrigation and rainfall runoff. The product effectively reduced turbidity, total suspended solids, and phosphate concentrations in the field when compared to the untreated runoff waters. Acute survival of Ceriodaphnia dubia and Pimephales promelas was not decreased compared to laboratory controls. No significant increases in toxicity were measured in 10-d sediment toxicity tests with Chironomus dilutus. Product applications were effective in controlling sediment and nutrient contamination without increasing measured toxicity.

Measurement of Accumulation of Semiconductor Nanocrystal Quantum Dots by Pimephales Promelas

As the production and use of nanomaterials increases, it is important to understand their environmental and biological fate. Because their unmatched chemical, physical, and optical properties make them useful in a wide variety of applications including biomedical imaging, photo-voltaics, and light emitting diodes, the use of semiconductor nanocrystals such as quantum dots (QDs) is increasing rapidly. Although QDs hold great potential in a wide variety of industrial and consumer applications, the environmental implications of these particles is largely unexplored. The nanocrystal core of many types of QDs contains the toxic metal cadmium (Cd), so possible release of Cd from the QD core is cause for concern. Because many types of QDs are miscible in water, QD interactions with aquatic organisms and their environment require more attention. In the present study we used fluorometry to measure time and dose dependent uptake, accumulation, and post-exposure clearance of accumulated QDs in the gut tract by the aquatic vertebrate Pimephales promelas. By using fluorometry, we were able to measure accumulated QD concentrations. To our knowledge, this is the first reported attempt to quantify accumulated QDs in an organism and is an important step in understanding the interactions among QDs in aquatic organisms and environments.

Mass Mortality of Wood Frogs (Rana sylvatica) in the Ozark National Forest: Is it Acid Rain?

We describe observations of a continuing mass mortality event primarily involving wood frogs, but involving other amphibians to a lesser degree. The investigation took place from Spring 2000 through Spring 2004. No definitive correlations between environmental variables and mortality could be identified. Forensic analysis could not isolate causal pathogens. Although mortality fluctuated during the study, it may have spread to other species. Our report identifies population level problems in the eastern part of the Ozark National Forest but is unable to identify a cause. Future studies that more thoroughly address contaminants, pathogens/parasites, and other potential environmental problems in the Ozark National Forest are warranted.