Bird feathers are potential biomonitors for airborne elemental carbon

Birds can serve as effective biomonitors of air pollution, yet few studies have quantified external particulate matter accumulation on bird feathers. Biomonitoring of airborne elemental carbon (EC) is of critical significance because EC is a component of particulate matter with adverse effects on air quality and human health. To assess their effectiveness for use in EC monitoring, we compared EC accumulation on bird feathers at two sites that differed in vehicular traffic volume in an urban environment within the Dallas-Fort Worth Metropolitan Area, USA. Moulted flight feathers from domestic chickens were experimentally exposed to ambient EC pollution for 5 days in two urban microenvironments 1.5 km distant from each other that differed in traffic volume--adjacent to an interstate highway and a university campus bus stop. Feathers near the highway accumulated approximately eight times more EC (307 ± 34 μg m^-2 day^-1), on average, than feathers near the bus stop (40 ± 9 μg m^-2 day^-1). These findings indicate that EC accumulation on feathers varies over short distances within urban areas and that bird feathers potentially can be used for biomonitoring airborne EC.

Exogenous 13C glucose oxidation during exercise: North American vs Western European studies

The purpose of this study was to test the hypothesis that the well-documented changes in background 13C enrichment of expired CO2 observed in response to exercise and carbohydrate ingestion, in subjects living on a North American diet, are not present in subjects living on a Western European diet. The experimental protocol used by Pirnay et al. in 1977 and by Krzentowski et al. in 1984 in subjects living on a Western European diet (4 h of exercise on a treadmill at approximately 50% VO2max with ingestion of 100 g of glucose in 400 ml of water) was duplicated as closely as possible in six subjects living on a North American diet. The actual amounts of exogenous glucose oxidized, computed with a high artificial 13C enrichment of glucose (+189.7/1000 delta 13C PDB-1) which allows one to neglect the 1-2/1000 delta changes in 13C background, were [mean (SEM)] 54.7 (5.4) and 84.2 (3.4) g over 2 h and 4 h of exercise, respectively. These values compare well with data computed by Pirnay et al. [56.6 (13.1) and 94.9 (4.2) g] and by Krzentowski et al. [55.0 (6.2) and 88.0 (4.5) g] using a natural enrichment of glucose (-11.21 and -10.63/1000 delta 13C PDB-1, respectively) assuming no change in 13C background in their Western European subjects. Under the same assumption and using a natural enrichment of glucose (-11.30/1000 delta 13C PDB-1) the oxidation of exogenous glucose was overestimated by 30-40% in our North American subjects.(ABSTRACT TRUNCATED AT 250 WORDS)