Salt Lake City Region Research Articles

Impact of wildfire smoke on ozone concentrations using a Generalized Additive model in Salt Lake City, Utah, USA, 2006–2022

ABSTRACT We investigated the impact of wildfires on maximum daily 8-hr average ozone concentrations (MDA8 O3) at four sites in Salt Lake City (SLC), Utah for May to September for 2006–2022. Smoke days, which were identified by a combination of overhead satellite smoke detection and surface PM2.5 data and accounted for approximately 9% of the total number of days, exhibited O3 levels 6.8 to 8.9 ppb higher than no-smoke days and were predominantly characterized by high daily maximum temperatures and low relative humidity. A Generalized Additive Model (GAM) was developed to quantify the impact of wildfire contributions to O3. The GAM, which provides smooth functions that make the interpretation of relationships more intuitive, employed 17 predictors and demonstrated reliable performance in various evaluation metrics. The mean of the residuals for all sites was approximately zero for the training and cross-validation data and 5.1 ppb for smoke days. We developed three approaches to estimate the contribution of smoke to O3 from the model residuals. These generate a minimum and maximum contribution for each smoke day. The average of the minimum and maximum wildfire contributions to O3 for the SLC sites was 5.1 and 8.5 ppb, respectively. Between 2006 and 2022, an increasing trend in the wildfire contributions to O3 was observed in SLC. Moreover, trends of the fourth-highest MDA8 O3 before and after removing the wildfire contributions to O3 at the SLC Hawthorne site in 2006–2022 were quite different. Whereas the unadjusted data do not meet the current O3 standard, after removing the contributions from wildfires the SLC region is close to achieving levels that are consistent with meeting the O3 standard. We also found that the wildfire contribution during smoke days was particularly high under conditions of high temperature, high PM2.5 concentration, and low cloud fraction. Implications: In this study, we quantified the impact of wildfires on maximum daily 8-hr average ozone concentrations (MDA8 O3) in Salt Lake City, Utah, using a Generalized Additive Model (GAM). The GAM results demonstrate the importance of wildfires as contributors to O3 air pollution. Our results suggest that states could use the GAM approach to assist in quantifying the wildfire contribution to MDA8 O3 under the U.S. EPA exceptional events rule. These findings also highlight the need for strategies to manage wildfires and their subsequent impacts on air quality in an era of climate warming.

Mapping Green Infrastructure Based on Multifunctional Ecosystem Services: A Sustainable Planning Framework for Utah’s Wasatch Front

Most sustainable planning frameworks assess natural and social–economic landscape systems as separate entities, and our understanding of the interrelationships between them is incomplete. Landscape classification in urbanizing environments requires an integrated spatial planning approach to better address the United Nation’s sustainable development challenges. The objective of this research is to apply a multicriteria evaluation which ranked diverse ecosystem–service producing landscapes and synthesize the findings within a unique green infrastructure spatial planning framework. Local government stakeholder derived weighting and GIS classification were operated to map both the urban and natural landscapes of the Salt Lake City region of Utah, one of the most rapidly urbanizing areas in North America. Results were assimilated through five regional landscape typologies—Ecological, Hydrological, Recreational, Working Lands, and Community—and indicated those highest ranked landscape areas which provided multiple ecosystem services. These findings support collaborative decision making among diverse stakeholders with overlapping objectives and illustrates pathways to the development of ecosystem service criteria. This paper contributes to a better understanding of how to integrate data and visualize the strategic approaches required for sustainable planning and management, particularly in urban and urbanizing regions where complex socioecological landscapes predominate.

Stress Perturbations From Hydrological and Industrial Loads and Seismicity in the Salt Lake City Region

AbstractThe interconnection between anthropogenic and natural surface loads and seismicity continues to be poorly understood. The metropolitan Salt Lake City in Utah hosts various industrial, hydrological, and tectonic processes, including the Bingham Canyon mine and its associated tailings facility, precipitation and water storage at the surface and in aquifers, as well as the seismically active Wasatch Fault Zone. The March 18, 2020 M5.7 Magna earthquake occurred east of a mine tailings impoundment that receives ∼60 million tons/yr of ore waste products since the early 1900s. Here we investigate the spatiotemporal elastic stress changes due to anthropogenic mass transfer and natural hydrological loading and unloading. Two local earthquake clusters host persistent microseismicity and the 2020 M5.7 Magna earthquake sequence. The amplitude and sign of the computed Coulomb stress changes at seismogenic depths strongly vary with the receiver fault geometry, the frictional coefficient, and the location, and can reach tens of kPa and ∼1 kPa/yr due to the tailings loads, a substantial fraction of background tectonic loading. The long‐term and seasonal stress changes from regional hydrological processes are only up to a few kPa. A lack of statistically significant seasonality in seismicity across Utah suggests a weak control by cyclic hydrological loads. Explicit knowledge of the fault architecture is essential to allow for seismic hazard assessment considering external stress loading.

Seismic Analysis of the 2020 Magna, Utah, Earthquake Sequence: Evidence for a Listric Wasatch Fault

AbstractThe 18 March 2020 Mw 5.7 Magna earthquake near Salt Lake City, Utah, offers a rare glimpse into the subsurface geometry of the Wasatch fault system—one of the world's longest active normal faults and a major source of seismic hazard in northern Utah. We analyze the Magna earthquake sequence and resolve oblique‐normal slip on a shallow (30–35°) west‐dipping fault at ~9‐ to 12‐km depth. Combined with near‐surface geological observations of steep dip (~70°), our results support a curved, or listric, fault shape. High‐precision aftershock locations show the activation of multiple, low‐angle (<30–35°) structures, indicating the existence of a complicated fault system. Our observations constrain the deep structure of the Wasatch fault system and suggest that ground shaking in the Salt Lake City region in future Wasatch fault earthquakes may be higher than previously estimated.

High-intensity endurance training is associated with left atrial fibrosis

Endurance athletes are at higher risk for developing atrial fibrillation as compared to the general population. The exact mechanism to explain this observation is incompletely understood. Our study aimed to determine whether degree of left atrial fibrosis detected by late gadolinium-enhancement magnetic resonance imaging (LGE-MRI) differed between Masters athletes and non-athlete controls. We recruited 20 endurance healthy Masters athletes and 20 healthy control subjects who underwent cardiac MRI. Healthy controls were recruited during screening colonoscopies and Masters athletes were recruited through word of mouth and at competitions. The two groups were age and gender matched. None of the participants were known to have an arrhythmia. Fibrosis, as measured by late gadolinium-enhancement, was measured in each participant by blinded readers. The degree of left atrial fibrosis was compared between the two groups. All participants were recruited from the Salt Lake City region and scanned at the University of Utah healthcare complex. Left ventricular function was normal in all study participants. Left atrial volumes were significantly larger in the athletes (74.2 ml ± 14.4) as compared to the healthy control subjects (60.8 mL ± 21.4) (P = .02). Mean left atrial fibrosis score, reported as a percentage of the LA, was 15.5% ± 5.9 in the athlete cohort compared to 9.6% ± 4.9 in the controls (P = .002). To our knowledge this is the first study that describes, characterizes and specifically quantifies fibrotic changes within the left atrium of highly trained endurance athletes. Increased atrial fibrosis seen in this population may be an early indicator for endurance athletes at risk of developing atrial arrhythmias.

Comparative case studies: trip and parking generation at Orenco Station TOD, Portland Region and Station Park TAD, Salt Lake City Region

The subjects of this comparative case study are Orenco Station, a transit-oriented development (TOD) in the Portland region, and Station Park, a transit-adjacent development (TAD) in Salt Lake City region. The peak parking demand at Orenco Station is less than one half the Institute of Transportation Engineers (ITE) suburban parking supply guideline. Also, vehicle trip generation rates are about half what is suggested in the ITE guidelines. Vehicle trip generation rates at Station Park show a smaller reduction but still substantial due to the mixed-use nature of Station Park. Parking generation rates are also lower than the ITE guidelines. In terms of metrics often associated with transportation performance, the large-scale TOD dramatically outperforms the large-scale TAD. The adjacent rail station appears to have little effect on the performance of the TAD, but a substantial effect on the performance of the TOD.

Near-Death Experience Patterns From Research in the Salt Lake City Region

Article examining interviews of 100 subjects in the Salt Lake City, Utah, region who claimed to have had a near-death experience (NDE) or analogous spiritual event.

Effect of altitude on brain intracellular pH and inorganic phosphate levels

Normal brain activity is associated with task-related pH changes. Although central nervous system syndromes associated with significant acidosis and alkalosis are well understood, the effects of less dramatic and chronic changes in brain pH are uncertain. One environmental factor known to alter brain pH is the extreme, acute change in altitude encountered by mountaineers. However, the effect of long-term exposure to moderate altitude has not been studied. The aim of this two-site study was to measure brain intracellular pH and phosphate-bearing metabolite levels at two altitudes in healthy volunteers, using phosphorus-31 magnetic resonance spectroscopy (31P-MRS). Increased brain pH and reduced inorganic phosphate (Pi) levels were found in healthy subjects who were long-term residents of Salt Lake City, UT (4720ft/1438m), compared with residents of Belmont, MA (20ft/6m). Brain intracellular pH at the altitude of 4720ft was more alkaline than that observed near sea level. In addition, the ratio of inorganic phosphate to total phosphate signal also shifted toward lower values in the Salt Lake City region compared with the Belmont area. These results suggest that long-term residence at moderate altitude is associated with brain chemical changes.

Group A streptococcal puerperal sepsis: initial characterization of virulence factors in association with clinical parameters

Group A beta-hemolytic streptococcus (GAS) is an uncommon but potentially fatal source of postpartum infection. Pathogenesis in invasive GAS infections has been linked to bacterial virulence factors. In this study, we sought to provide an initial description of potential virulence factors in association with puerperal morbidity by virtue of specific M-protein type antigens. Women with confirmed GAS puerperal infection in the Salt Lake City region were prospectively identified over a 6-year interval (1991-1997). From this cohort, GAS isolates were analyzed with respect to M-serotype and presence of genes encoding the Streptococcal Pyogenic Exotoxins A and B (SPE-A and SPE-B). Bacterial isolates from 18 subjects with GAS puerperal infection underwent M-serotyping and PCR-based genotyping for the speA and speB genes. Among these, 8/18 subjects manifest criteria of severe disease. All 18 isolate strains expressed speB; 6/18 isolates expressed speA. Of the M-serotypes, 8/8 severe disease isolates expressed M-types 1 (N=3) or 28 (N=5). Pulse-field gel electrophoresis did not indicate an outbreak strain among similar isolates. We conclude that in this initial characterization, morbidity among women with GAS puerperal infection is associated with M-types 1 and 28, but not speB genotype.

High altitude medicine

Normal brain activity is associated with task-related pH changes. Although central nervous system syndromes associated with significant acidosis and alkalosis are well understood, the effects of less dramatic and chronic changes in brain pH are uncertain. One environmental factor known to alter brain pH is the extreme, acute change in altitude encountered by mountaineers. However, the effect of long-term exposure to moderate altitude has not been studied. The aim of this two-site study was to measure brain intracellular pH and phosphate-bearing metabolite levels at two altitudes in healthy volunteers, using phosphorus-31 magnetic resonance spectroscopy (31P-MRS). Increased brain pH and reduced inorganic phosphate (Pi) levels were found in healthy subjects who were long-term residents of Salt Lake City, UT (4720 ft/1438 m), compared with residents of Belmont, MA (20 ft/6 m). Brain intracellular pH at the altitude of 4720 ft was more alkaline than that observed near sea level. In addition, the ratio of inorganic phosphate to total phosphate signal also shifted toward lower values in the Salt Lake City region compared with the Belmont area. These results suggest that long-term residence at moderate altitude is associated with brain chemical changes.

Predictability of Low-Level Winds by Mesoscale Meteorological Models

Abstract This study describes the verification of model-based, low-level wind forecasts for the area of the Salt Lake valley and surrounding mountains during the 2002 Salt Lake City, Utah, Winter Olympics. Standard verification statistics (such as bias and mean absolute error) for wind direction and speed were compared for four models: the Eta, Rapid Update Cycle (RUC-2), and Global Forecast System of the National Centers for Environmental Prediction, and the fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5). Even though these models had horizontal grid increments that ranged over almost two orders of magnitude, the highest-resolution MM5 with a 1.33-km grid increment exhibited a forecast performance similar to that of the other models in terms of grid-average, conventional verification metrics. This is in spite of the fact that the MM5 is the only model capable of reasonably representing the complex terrain of the Salt Lake City region that exerts a strong influence on the local circulation patterns. The purpose of this study is to investigate why the standard verification measures did not better discriminate among the models and to describe alternative measures that might better represent the ability of high-horizontal-resolution models to forecast locally forced mesogamma-scale circulations. The spatial variability of the strength of the diurnal forcing was quantified by spectrally transforming the time series of wind-component data for each observation location. The amount of spectral power in the band with approximately a diurnal period varied greatly from place to place, as did the amount of power in the bands with periods longer (superdiurnal) and shorter (subdiurnal) than the diurnal. It is reasonable that the superdiurnal power is largely in the synoptic-scale motions, and thus can be reasonably predicted by all the models. In contrast, the subdiurnal power is mainly in nondiurnally forced small-scale fluctuations that are generally unpredictable with any horizontal resolution because they are unobserved in three dimensions by the observation network. A strong positive relationship is demonstrated between the strength of the local forcing at each observation location, as measured by the spectral power in the diurnal band of the wind component time series, and forecast skill, as reflected by an alternative verification metric, a measure of anomaly correlation. However, the mean-absolute error showed no relationship to the power in the diurnal band. Two other measures of comparison among the low-level wind forecasts, the direction climatology and the spatial variance, showed a positive correlation between forecast quality and horizontal resolution.

Molecular analysis of group A Streptococcus type emm18 isolates temporally associated with acute rheumatic fever outbreaks in Salt Lake City, Utah.

Acute rheumatic fever (ARF) and subsequent rheumatic heart disease are rare but serious sequelae of group A Streptococcus (GAS) infections in most western countries. Salt Lake City (SLC), Utah, and the surrounding intermountain region experienced a resurgence of ARF in 1985 which has persisted. The largest numbers of cases were encountered in 1985-1986 and in 1997-1998. Organisms with a mucoid colony phenotype when grown on blood agar plates were temporally associated with the higher incidence of ARF. To develop an understanding of the molecular population genetic structure of GAS strains associated with ARF in the SLC region, 964 mucoid and nonmucoid pharyngeal isolates recovered in SLC from 1984 to 1999 were studied by sequencing the emm gene. Isolates with an emm18 allele were further characterized by sequencing the spa, covR, and covS genes. Peak periods of ARF were associated with GAS isolates possessing an emm18 allele encoding the protein found in serotype M18 isolates. Among the serotype M18 isolates, the difference in the number of C repeats produced three size variants. Variation was limited in spa, a gene that encodes a streptococcal protective antigen, and covR and covS, genes that encode a two-component regulatory system that, when inactivated, results in a mucoid phenotype and enhanced virulence in mouse infection models. Pulsed-field gel electrophoresis showed a single restriction profile for serotype M18 organisms isolated during both peak periods of ARF. In SLC, the incidence of ARF coresurged with the occurrence of GAS serotype M18 isolates that have very restricted genetic variation.

Near-death experience patterns from research in the Salt Lake City region.

Article examining interviews of 100 subjects in the Salt Lake City, Utah, region who claimed to have had a near-death experience (NDE) or analogous spiritual event.

Geology of Salt Lake City, Utah, United States of America

Geology of Salt Lake City, Utah, United States of America

Water Reuse Systems Analysis

Quantity-quality availabilities and requirements are part of the system description to be considered in the solution based upon an origin-destination matrix. When tertiary treatment and desalting plants and blending are included in the matrix, plant capacities can be obtained for any year of projected demand. Entries in the matrix must include the unit cost of delivering water having a specified quality from each origin to each destination; these costs include both transport and treatment costs. Least cost allocation solution is obtained by the transportation problem algorithm. The procedure was demonstrated by a cursory case study of the Salt Lake City region, an agro-urban-industrial area. Least cost results for 1965, 19890, 2000, and 2020 levels of demand showed a changing pattern of allocation. For 1965 demand levels surface and groundwater supplies were sent directly to municipal and agricultural uses, with effluents to system outflow. By 1980 tertiary treatment enters the picture and by 2020 desalting becomes important. For 2020 all surface and groundwater goes to blending to combine with output from tertiary treatment and desalting plants.