Fant 9758 publikasjoner. Viser side 330 av 391:
1999
2014
2015
Atmospheric turbulence and in particular its effect on tracer dispersion may be measured by cameras sensitive to the absorption of ultraviolet (UV) sunlight by sulfur dioxide (SO2), a gas that can be considered a passive tracer over short transport distances. We present a method to simulate UV camera measurements of SO2 with a 3D Monte Carlo radiative transfer model which takes input from a large eddy simulation (LES) of a SO2 plume released from a point source. From the simulated images the apparent absorbance and various plume density statistics (centre-line position, meandering, absolute and relative dispersion, and skewness) were calculated. These were compared with corresponding quantities obtained directly from the LES. Mean differences of centre-line position, absolute and relative dispersions, and skewness between the simulated images and the LES were generally found to be smaller than or about the voxel resolution of the LES. Furthermore, sensitivity studies were made to quantify how changes in solar azimuth and zenith angles, aerosol loading (background and in plume), and surface albedo impact the UV camera image plume statistics. Changing the values of these parameters within realistic limits has negligible effects on the centre-line position, meandering, absolute and relative dispersions, and skewness of the SO2 plume. Thus, we demonstrate that UV camera images of SO2 plumes may be used to derive plume statistics of relevance for the study of atmospheric turbulent dispersion.
2020
2012
2002
Can plastic related chemicals be indicators of plastic ingestion in an Arctic seabird?
For decades, the northern fulmar (Fulmarus glacialis) has been found to ingest and accumulate high loads of plastic due to its feeding ecology and digestive tract morphology. Plastic ingestion can lead to both physical and toxicological effects as ingested plastics can be a pathway for hazardous chemicals into seabirds' tissues. Many of these contaminants are ubiquitous in the environment and the contribution of plastic ingestion to the uptake of those contaminants in seabirds’ tissues is poorly known. In this study we aimed at quantifying several plastic-related chemicals (PRCs) -PBDE209, several dechloranes and several phthalate metabolites- and assessing their relationship with plastic burdens (both mass and number) to further investigate their potential use as proxies for plastic ingestion. Blood samples from fulmar fledglings and liver samples from both fledgling and non-fledgling fulmars were collected for PRC quantification. PBDE209 and dechloranes were quantified in 39 and 33 livers, respectively while phthalates were quantified in plasma. Plastic ingestion in these birds has been investigated previously and showed a higher prevalence in fledglings. PBDE209 was detected in 28.2 % of the liver samples. Dechlorane 602 was detected in all samples while Dechloranes 601 and 604 were not detected in any sample. Dechlorane 603 was detected in 11 individuals (33%). Phthalates were detected in one third of the analysed blood samples. Overall, no significant positive correlation was found between plastic burdens and PRC concentrations. However, a significant positive relationship between PBDE209 and plastic number was found in fledglings, although likely driven by one outlier. Our study shows the complexity of PRC exposure, the timeline of plastic ingestion and subsequent uptake of PRCs into the tissues in birds, the additional exposure of these chemicals via their prey, even in a species ingesting high loads of plastic.
Elsevier
2024
2017
2019
2014
2011
2017
2012