Using air quality modeling to study source–receptor relationships between nitrogen oxides emissions and ozone exposures over the United States

Human exposure to ambient ozone (O₃) has been linked to a variety of adverse health effects. The ozone level at a location is contributed by local production, regional transport, and background ozone. This study combines detailed emission inventory, air quality modeling, and census data to investigate the source–receptor relationships between nitrogen oxides (NO_x) emissions and population exposure to ambient O₃ in 48 states over the continental United States. By removing NO_x emissions from each state one at a time, we calculate the change in O₃ exposures by examining the difference between the base and the sensitivity simulations. Based on the 49 simulations, we construct state-level and census region-level source–receptor matrices describing the relationships among these states/regions. We find that, for 43 receptor states, cumulative NO_x emissions from upwind states contribute more to O₃ exposures than the state's own emissions. In-state emissions are responsible for less than 15% of O₃ exposures in 90% of U.S. states. A state's NO_x emissions can influence 2 to 40 downwind states by at least a 0.1 ppbv change in population-averaged O₃ exposure. The results suggest that the U.S. generally needs a regional strategy to effectively reduce O₃ exposures. But the current regional emission control program in the U.S. is a cap-and-trade program that assumes the marginal damage of every ton of NO_x is equal. In this study, the average O₃ exposures caused by one ton of NO_x emissions ranges from ? 2.0 to 2.3 ppm-people-hours depending on the state. The actual damage caused by one ton of NO_x emissions varies considerably over space.     

Anticipatory capacity in response to global change across an extreme elevation gradient in the Ica Basin,Peru

Regional Environmental Change - Mountainous areas with extreme elevation gradients and corresponding ranges of biophysical and socioeconomic conditions are highly vulnerable to global change. We...     

Mitigation and Adaptation Strategies for Global Change

Mitigation and Adaptation Strategies for Global Change -     

Activities of alkaline phosphatase in first trimester chorion biopsy tissue

We have determined the activity of alkaline phosphatase in chorionic villous tissue obtained in the first trimester of pregnancy, in order to obtain the normal range of values as a prerequisite for application to the prenatal diagnosis of the rare bone disease hypophosphatasia. The activities found were a combination of intestinal and liver/bone/kidney types; traces of placental type were present in only one sample.     

Prenatal exclusion of stickler syndrome

Stickler syndrome is an autosomal dominant disorder of the connective tissue which includes ocular and systemic manifestations. We report on a large kindred in which we were able to demonstrate very tight linkage between the disease and the type II collagen gene (COL2A1) (LOD score 3·91 at θ=0). In a family in which the father and one of his daughters were severely affected, DNA analysis from a chorionic villus sample demonstrated that the fetus possessed the normal allele of COL2A1. Thereafter a normal child was born.     

Why do <Emphasis Type="Italic">Manduca sexta</Emphasis> feed from white flowers? Innate and learnt colour preferences in a hawkmoth

Flower colour is an important signal used by flowering plants to attract pollinators. Many anthophilous insects have an innate colour preference that is displayed during their first foraging bouts and which could help them locate their first nectar reward. Nevertheless, learning capabilities allow insects to switch their colour preferences with experience and thus, to track variation in floral nectar availability. Manduca sexta, a crepuscular hawkmoth widely studied as a model system for sensory physiology and behaviour, visits mostly white, night-blooming flowers lacking UV reflectance throughout its range in the Americas. Nevertheless, the spectral sensitivity of the feeding behaviour of naïve moths shows a narrow peak around 450 nm wavelengths, suggesting an innate preference for the colour blue. Under more natural conditions (i.e. broader wavelength reflectance) than in previous studies, we used dual choice experiments with blue- and white-coloured feeders to investigate the innate preference of naïve moths and trained different groups to each colour to evaluate their learning capabilities. We confirmed the innate preference of M. sexta for blue and found that these moths were able to switch colour preferences after training experience. These results unequivocally demonstrate that M. sexta moths innately prefer blue when presented against white flower models and offer novel experimental evidence supporting the hypothesis that learning capabilities could be involved in their foraging preferences, including their widely observed attraction to white flowers in nature.