This research project focuses on using a multiproxy approach to discriminate between overwash and non-hurricane marsh sediments within the bed of a coastal lake. 3 marsh cores were collected in an area of McFaddin National Wildlife Refuge just south of Clam Lake that are known to contain 4 hurricane overwash deposits, Ike, Rita, Carla, and Audrey. LOI and XRF analysis were used to determine the signature of the hurricane overwash layers. 3 more cores were collected from Clam Lake where there are no visible sand layers. The elemental signature of the overwash layers found in the marsh cores was used to run a hierarchical cluster analysis on the lake cores. This was able to determine the effectiveness of XRF's ability to distinguish between hurricane overwash and marsh sediments. The combination of cluster analysis, LOI, and XRF can tentatively identify hurricane overwash deposits in a coastal lake, however, it is more successful in the marsh cores. Results in the lake cores are somewhat inconsistent and uncertain, possibly because there may have not been enough overwash deposits to identity or that the XRF analysis needs more distinct sand layers to distinguish between overwash and marsh.

This research investigates particulate matter (PM) deposition to rock pigeons (Columba livia) in urban environments within Denton County, Texas. Pigeon habitat was characterized within a 2-km radius at eight locations using the 2016 National Land Cover Database (NLCD). In summer 2020, feathers were sampled from 10 rock pigeons at two locations (n = 20) differing in degree of urban development. Birds were captured using walk-in funnel traps baited with bird seed. Based on molt pattern and appearance, four old flight feathers were identified and sampled from each bird. New primary feathers were obtained from each population as reference samples. Feathers were washed three times with double deionized water and acetone, and the solution vacuum filtered through a glass microfiber filter to collect all particles >1.5 µm in diameter. Particulate matter mass was determined by gravimetric analysis and calculated per unit feather surface area. Relative PM accumulation rates were significantly different between the populations. Characteristics of urban land cover, proximity to and types of emissions sources, wind exposure, and building density were drivers of variability in PM deposition to feather surfaces. The results from this study should be useful for subsequent research to help identify best practices for using feathers collected …

From 2011 to 2014, one of the most severe and intense droughts in Texas recorded history led to widespread wildfires across the state, with unknown effects on atmospheric nutrient and pollutant deposition. The objectives of this research were to: (1) characterize the frequency, magnitude, and spatiotemporal distribution of Texas wildfires (2011-2014); (2) identify smoke occurrence and source regions at eight Texas National Atmospheric Deposition Program (NADP) National Trends Network (NTN) sites (2011); and (3) quantify the influence of wildfire on weekly rainwater chemistry and deposition in 2011 at three NADP sites (Sonora, LBJ Grasslands, Attwater Prairie NWR). Data on large wildfires, smoke occurrence, and rainfall chemistry and deposition were coupled with principal component and back-trajectory analysis to address these objectives. Between 2011-2014, 72% of all wildfires occurred in 2011, accounting for 90% of the total area burned. In total, there were 17 extreme wildfires (i.e., in the 95th percentile of hectares burned), of which 11 occurred in 2011. Wildfire activity was concentrated in West Texas ecoregions and consumed primarily shrub/scrub and grassland/herbaceous land cover. Although West Texas experienced the most wildfires, smoke at the NADP locations in 2011, the "high-fire year," was more frequent in East Texas due to regional …