Monitoring Polycyclic Aromatic Hydrocarbon Concentrations in Austin, TX, After the Coal-Tar Sealant Ban

Polycyclic Aromatic Hydrocarbons (PAH) are a group of chemicals consisting of three or more fused benzene rings. Many of this group of compounds are considered Toxic Pollutants and listed as Priority Pollutants by the EPA. In 2006, the City of Austin enacted a ban on coal-tar sealant to remove a source of PAH contamination to Austin creeks. Sediment samples collected in approximately 50 of Austin’s largest watersheds from 1996 until 2010 were analyzed. The total PAH concentration of these samples was calculated as the sum of the 16 compounds found within the first EPA Priority Pollutant list. Kruskal-Wallis analysis and regression analysis were used to determine any temporal trends in Austin as a whole and at individual sites. 3-ringed PAH were significantly higher in 1996-1999 compared to 2003-2005, 2006-2008, and 2009-2010; and 4-ringed PAH were significantly higher in 1996-1999 compared to 2006-2008. Total PAH significantly decreased at Barton Creek above Barton Springs Pool from 1996 to 2010. While PAH concentrations at the majority of Austin locations were less than the Probable Effect Concentration (above which adverse effects on aquatic organisms are expected to occur), there were several sites where PAH concentrations were above urban background levels found in the literature. These sites require additional investigation to isolate and potentially remediate sources of PAH.Waller Creek Working Grou

Linking Biologic Metrics to Hydrologic Characteristics in Austin, Texas Streams

This report compiles various hydrological information from several Austin creeks (including Waller) to study their impact on aquatic life.Urbanization can alter the hydrology of creeks as land use changes as represented by increases in impervious cover. Flow regime change is modeled directly on the basis of impervious cover in the City of Austin; however, it would be helpful for planning purposes if other aspects of the environmental integrity of urban creeks could be modeled on the same basis. Benthic macroinvertebrates and diatoms are used as biological indicators of creek health, but an adequate direct relationship between the impervious cover and these biological metrics has not been found. Relationships between flow and biological health were investigated in order to form an indirect link so that changes in biological health could be predicted by changes to impervious cover. Pearson correlations and step-wise regression was performed on 35 hydrologic metrics and 25 biological metrics using sub-daily and daily flow data from the US Geologic Survey in 14 creeks in Austin, Texas. Data were grouped by impervious cover period or water year. The sub-daily flow data grouped by impervious cover period created the best model using mean--area (avg neg flowrate changes/watershed area),FHn (avg times mean flow > 75%-tile), and TQmean (fraction of time daily mean flow > mean for period) as the predictive hydrologic metrics to describe biological health of the creeks. Correlations were strongest between hydrology and the sensitive taxa biologic metrics. As the hydrology becomes flashy, one result of an increase in impervious cover, the sensitive taxa decrease at a site thereby decreasing the overall biological health of a site. It is recommended that this indirect link be used in water quality improvement projects to predict how the biological health of a creek in Austin will be affected by changes in land use.Waller Creek Working Grou

Riparian Functional Assessment Phase Two Summary

This report contains data regarding the drainage area, restoration strategy and banks sampled of three Waller Creek locations.In an effort to assess the response of degraded riparian buffers to the cessation of the main disturbance regime (mowing) and the facilitated succession approach to riparian restoration, the City of Austin implemented phase 2 of the Riparian Functional Assessment (RFA) which consisted of sampling degraded buffers after 1 year with no disturbance. Only degraded sites were included in this phase and their functional scores were compared with those of reference sites from the initial sample year representing healthy riparian function. A total of 9 degraded sites were added to the initial 16 degraded sites from phase 1 for this assessment. Results suggest that degraded buffers lacked the necessary time to show a response in riparian function after only one year of recovery. Sampling design changes are recommended to better assess the growing number of buffer site locations tracked in this project, including reinstituting reference site sampling and shifting to a biannual sampling regime. Based on analysis of phase 2 data, changes to the assessment tool include the following: substitute organic soil carbon for direct soil moisture measurements, coalesce the hardwood demography and recruitment parameters into woody community dynamics, and upgrade soil compaction instruments for higher accuracy and reliability.Waller Creek Working Grou

Environmental Integrity Index Phase I & II (2011-2012) Watershed Summary Report

Waller Creek Working Grou

Monitoring DDT and PAHs in Barton Springs Sediment

This report discusses the concentration of known hazardous chemicals in Waller Creek, and compares them to accepted levels.Barton Springs is an environmentally-sensitive area which provides habitat for two endangered aquatic salamander species, supplies water to Barton Springs pool, and represents the primary discharge point for the Barton Springs segment of the Edwards Aquifer, a sole-source aquifer for the Austin area. DDT, DDD, DDE, and a list of polycyclic aromatic hydrocarbons (PAH) are toxic pollutants that have been monitored in the sediment at Barton Springs for at least 15 years. Trends of these pollutants over time were analyzed at Barton Springs and current concentrations of the pollutants present within the springs were compared to concentrations of the pollutants in sediment samples collected throughout Austin in 2013 and 2014. DDT, DDD, and DDE were not pollutants of concern for Barton Springs; however, PAH including benzo(a)anthracene, benzo(a)pyrene, benzo(e)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(g,h,i)perylene, chrysene, fluoranthene, indeno(1,2,3-cd)pyrene, phenanthrene, and pyrene have risen in concentration beginning in approximately 2006. While many samples at Barton Springs have not contained samples above probable effect concentration levels, investigation is warranted to determine why the PAH concentrations increased. The initial concern of this report was to address sediment pollution at Barton Springs but additional sites of concern were identified upon comparison of pollutant concentrations at Barton Springs to concentrations throughout Austin in 2013 and 2014. Most notably, sediment samples collected within the Harper’s Branch watershed indicate chronically toxic sediments and an investigation for a source should be conductedWaller Creek Working Grou

Riparian reference condition: Using regional plant composition to guide functional improvements in the City of Austin

This technical report focuses on ways to restore riparian habitat within specific Austin creeks. This study is designed to serve as a template for restoration efforts with other urbanized creeks (Waller).As a result of an expanding and rapidly urbanizing metropolitan area, the riparian vegetation communities of Austin-area streams continue to diverge further from their natural state. In an effort to maintain the ecological function and the natural character of Austin watersheds, the City of Austin Watershed Protection Department has identified a need to characterize an archetype, or background condition of Edwards Plateau and Blackland Prairie riparian communities for use as a template for both benchmarking and target for stream restoration projects. Species composition, spatial arrangement and physical attributes of vegetation communities for 12 sites located in both smaller and larger watersheds were characterized using multiple belt-transects. Multivariate analyses including detrended correspondence analysis (DCA), analysis of similarity (ANOSIM), and similarity percentage (SIMPER) were performed by Community Analysis Package software (Seaby and Henderson 2007). Results show that there was a significant difference in plant community composition in all compared drainage areas and ecoregions for both ground cover and overstory communities (p<0.05). The analysis of similarity showed that the samples should be grouped by ecoregion and location within the watershed for overstory and ground cover communities. Recommended vegetation templates are presented as a guide for comparison to other riparian communities in the Austin area, and also a reference point for restoration of degraded systems. These quantitative species distribution lists are an important resource for riparian ecologists in this region.Waller Creek Working Grou

Adaptable Classroom and Workspace Table

Mr. Michael Brennan, entrepreneur and founder of Co-Act Furniture, presented the problem of a classroom and workspace table that can be quickly, easily, and safely reconfigured to accommodate different types of collaboration and learning within a limited space. Current classroom and workspace furniture lacks modularity, which limits the usability of the space. Different groups use the same room to learn in different ways; adjustable furniture would benefit their learning and productivity. Mr. Brennan has developed several prototype tables with varying features, including adjustable angle, height, and tabletop surface area. Our team, composed of three mechanical engineering students, has a project goal to design and build an adaptable table that meets our sponsor’s requirements and improves the modularity of classroom and work spaces. This document includes background research, establishes project objectives, illustrates the design process, and explains the manufacturing steps and project implementation

magnetoARPES: Angle Resolved Photoemission Spectroscopy with Magnetic Field Control

Angle-Resolved Photoemission Spectroscopy (ARPES) is a premier technique for understanding the electronic excitations in conductive, crystalline matter, in which the induced photocurrent is collected and dispersed in energy and angle of emission to reveal the energy- and momentum-dependent single particle spectral function $A(\mathbf{k},\omega)$. So far, ARPES in a magnetic field has been precluded due to the need to preserve the electron paths between the sample and detector. In this paper we report progress towards "magnetoARPES", a variant of ARPES that can be conducted in a magnetic field. It is achieved by applying a microscopic probe beam ($\lesssim$ 10 $\mu$m ) to a thinned sample mounted upon a special sample holder that generates magnetic field confined to a thin layer near the sample surface. In this geometry we could produce ARPES in magnetic fields up to around $\pm$ 100 mT. The magnetic fields can be varied from purely in-plane to nearly purely out-of-plane, by scanning the probe beam across different parts of the device. We present experimental and simulated data for graphene to explore the aberrations induced by the magnetic field. These results demonstrate the viability of the magnetoARPES technique for exploring symmetry breaking effects in weak magnetic fields.Comment: 21 pages, 6 figure

SO2 Emissions and Lifetimes: Estimates from Inverse Modeling Using In Situ and Global, Space-Based (SCIAMACHY and OMI) Observations

Top-down constraints on global sulfur dioxide (SO2) emissions are inferred through inverse modeling using SO2 column observations from two satellite instruments (SCIAMACHY and OMI). We first evaluated the S02 column observations with surface SO2 measurements by applying local scaling factors from a global chemical transport model (GEOS-Chem) to SO2 columns retrieved from the satellite instruments. The resulting annual mean surface SO2 mixing ratios for 2006 exhibit a significant spatial correlation (r=0.86, slope=0.91 for SCIAMACHY and r=0.80, slope = 0.79 for OMI) with coincident in situ measurements from monitoring networks throughout the United States and Canada. We evaluate the GEOS-Chem simulation of the SO2 lifetime with that inferred from in situ measurements to verity the applicability of GEOS-Chem for inversion of SO2 columns to emissions. The seasonal mean SO2 lifetime calculated with the GEOS-Chem model over the eastern United States is 13 h in summer and 48 h in winter, compared to lifetimes inferred from in situ measurements of 19 +/- 7 h in summer and 58 +/- 20 h in winter. We apply SO2 columns from SCIAMACHY and OMI to derive a top-down anthropogenic SO2 emission inventory over land by using the local GEOS-Chem relationship between SO2 columns and emissions. There is little seasonal variation in the top-down emissions (<15%) over most major industrial regions providing some confidence in the method. Our global estimate for annual land surface anthropogenic SO2 emissions (52.4 Tg S/yr from SCIAMACHY and 49.9 Tg S / yr from OMI) closely agrees with the bottom-up emissions (54.6 Tg S/yr) in the GEOS-Chem model and exhibits consistency in global distributions with the bottom-up emissions (r = 0.78 for SCIAMACHY, and r = 0.77 for OMI). However, there are significant regional differences