Assessment of particulate matter and ammonia emission concentrations and respective plume profiles from a commercial poultry house.

Poultry-emitted air pollutants, including particulate matter (PM) and ammonia, have raised concerns due to potential negative effects on human health and the environment. However, developing and optimizing remediation technologies requires a better understanding of air pollutant concentrations, the emission plumes, and the relationships between the pollutants. Therefore, we conducted ten field experiments to characterize PM (total suspended particulate [TSP], particulate matter less than 10 µm in aerodynamic diameter [PM10], and particulate matter less than 2.5 µm in aerodynamic diameter [PM2.5]) and ammonia emission-concentration profiles from a typical commercial poultry house. The emission factors of the poultry house, which were calculated using the concentrations and fan speed, were 0.66 (0.29-0.99) g NH3-N bird-1d-1 for ammonia, 52 (44-168) g d-1AU-1 (AU = animal unit = 500 kg) for TSP, 3.48 (1.16-9.03) g d-1AU-1 for PM10, and 0.07 (0.00-0.36) g d-1AU-1 for PM2.5. PM and ammonia emission concentrations decreased as distance from the fan increased. Although emission concentrations were similar in the daytime and nighttime, diurnal and nocturnal plume shapes were different due to the increased stability of the atmosphere at night. Particle size distribution analysis revealed that, at a given height, the percentage of PM10 and PM2.5 was consistent throughout the plume, indicating that the larger particles were not settling out of the airstream faster than the smaller particles. Overall, the direction of the measured air pollutant emission plumes was dominated by the tunnel fan ventilation airflow rate and direction instead of the ambient wind speed and direction. This is important because currently-available air dispersion models use ambient or modeled wind speed and direction as input parameters. Thus, results will be useful in evaluating dispersion models for ground-level, horizontally-released, point sources and in developing effective pollutant remediation strategies for emissions.

The transduction properties of intercostal muscle mechanoreceptors.

BACKGROUND: Intercostal muscles are richly innervated by mechanoreceptors. In vivo studies of cat intercostal muscle have shown that there are 3 populations of intercostal muscle mechanoreceptors: primary muscle spindles (1 degrees ), secondary muscle spindles (2 degrees ) and Golgi tendon organs (GTO). The purpose of this study was to determine the mechanical transduction properties of intercostal muscle mechanoreceptors in response to controlled length and velocity displacements of the intercostal space. Mechanoreceptors, recorded from dorsal root fibers, were localized within an isolated intercostal muscle space (ICS). Changes in ICS displacement and the velocity of ICS displacement were independently controlled with an electromagnetic motor. ICS velocity (0.5 - 100 microm/msec to a displacement of 2,000 microm) and displacement (50-2,000 microm at a constant velocity of 10 microm/msec) parameters encompassed the full range of rib motion. RESULTS: Both 1 degrees and 2 degrees muscle spindles were found evenly distributed within the ICS. GTOs were localized along the rib borders. The 1 degrees spindles had the greatest discharge frequency in response to displacement amplitude followed by the 2 degrees afferents and GTOs. The 1 degrees muscle spindles also possessed the greatest discharge frequency in response to graded velocity changes, 3.0 spikes x sec(-1)/microm x msec(-1). GTOs had a velocity response of 2.4 spikes x sec(-1)/microm x msec(-1) followed by 2 degrees muscle spindles at 0.6 spikes x sec(-1)/microm x msec(-1). CONCLUSION: The results of this study provide a systematic description of the mechanosenitivity of the 3 types of intercostal muscle mechanoreceptors. These mechanoreceptors have discharge properties that transduce the magnitude and velocity of intercostal muscle length.