Beyond the 16 EPA priority pollutant PAHs : environmental characterizations of oxygenated PAHs and dibenzopyrene isomers

Polycyclic aromatic hydrocarbons (PAHs) with a molecular weight (MW) of 302 and oxygenated-PAHs (OPAHs) have demonstrated toxicity beyond that of frequently monitored and known carcinogenic PAHs. Airborne particulate matter (PM) was characterized for MW 302 isomers to evaluate risk and air quality indices and OPAHs in order to fill data gaps concerning sources and distribution of OPAHs. Additionally, standard reference materials of numerous environmental media were analyzed for OPAH occurrence. Air samples were collected from two locations: the remote atmosphere of Mt. Bachelor, Oregon and the urban atmosphere of Beijing, China. Collection of size fractionated particles of PM 2.5 and PM 10 allowed evaluation of air quality indexes as well as OPAH distribution profiles for source identification. Standard reference materials (SRMs) possessing certified values of PAHs were purchased and methods of analysis were developed. Results demonstrate that MW 302 isomers are highly abundant in the urban atmosphere of Beijing, China. Although toxicity information is not available for all MW 302 isomers, for those with available carcinogenic potency, the combined potency of MW 302 isomers contributes to a significant portion of carcinogenic risk for PAHs in Beijing. Results further convey the dependency of air quality assessment outcomes on metrics used and monitored PAHs. OPAHs were measured in many of the SRM matrices for the first time and the abundance of OPAHs, with respect to PAHs, is a major finding. Results indicate that diesel exhaust could be a major source of OPAHs and that biota could be a sink. Measurement of OPAHs from ambient air confirmed that OPAHs are environmentally abundant. Particulate matter air samples from Mt. Bachelor show that while OPAHs are more concentrated than PAHs, the particle size distribution could not be used to determine origins of OPAH formation. Results did show that OPAHs are concentrated on the smallest, most respirable size fraction of particulate matter collected from both Mt. Bachelor and Beijing. We conclude that MW 302 isomers and OPAHs are environmentally relevant and concentrated PAHs requiring continued study

Experiment demonstrating skeletal muscle biomechanics.

Many students have limited opportunities to develop scientific expertise. This is caused, in part, by the scarcity of scientific educational materials and the expense of supplies and equipment. To address these concerns, we developed an inexpensive laboratory experience that introduces students to the scientific process. Our objective was to create an interactive experiment that requires minimal equipment. To this end, we created an exercise that examines muscle biomechanics. The students conduct a hands-on experiment as researchers and as subjects by investigating the physiological concepts of muscle biomechanics using only supplies that can be found at any school. Questions are interspersed throughout the text to highlight key principles and challenge student thinking on the important concepts. This exercise not only provides an opportunity for students to interact and discuss the important physiological principles but also provides a window through which students may see a future in science. </jats:p

Organochlorine and Metal Contaminants in the Blood Plasma of Green Sturgeon Caught in Washington Coastal Estuaries

Abstract Non-invasive monitoring was used to evaluate the concentrations of forty contaminants in the blood plasma of the North American Green Sturgeon Acipenser medirostris caught and released from three estuaries in Washington State. The highest contaminant loads were found in fish caught in the most urbanized sites. Few statistical differences were found when evaluating contaminant levels according to sex, maturation stage, or distinct population segments of Green Sturgeon. The results indicate that recent exposure to legacy contaminants was reflected in Green Sturgeon plasma. Aldrin, 4,4-DDE, a-BHC, copper, and selenium were the most frequently detected contaminants. This study also explored the challenges of assessing toxicity in threatened species using non-lethal approaches. There is currently a lack of environmental contaminant monitoring data in estuaries frequented by Green Sturgeon and limited plasma to tissue toxicity correlations.</jats:p