IGC Field Trip T181: Engineering geology of western United States urban centers

1989 ◽  
pp. 1-4
Author(s):  
Jeffrey R. Keaton ◽  
Richard N. Morris
Keyword(s):  
United States ◽  
Engineering Geology ◽  
Field Trip ◽  
Western United States ◽  
Urban Centers

Wet and dry plastic deposition in the western United States

2021 ◽  
Author(s):  
Janice Brahney ◽  
Margaret Hallerud ◽  
Eric Heim ◽  
Maura Hahnenberger ◽  
Suja Sukumaran
Keyword(s):  
United States ◽  
High Resolution ◽  
Wet Deposition ◽  
Life Histories ◽  
Western United States ◽  
Temporal Data ◽  
Urban Centers ◽  
Conservation Areas ◽  
Deposition Rates ◽  
Global Transport

<p>Eleven billion tons of plastic are projected to accumulate in the environment by 2025. Because plastics are persistent, they fragment into pieces that are susceptible to wind entrainment. Using high resolution spatial and temporal data we tested whether plastics deposited wet versus dry have unique atmospheric life histories. Further, we report on the rates and sources of deposition to remote U.S. conservation areas. We show that urban centers and resuspension from soils or water are important sources for wet deposition. In contrast, plastics deposited dry were smaller in size and rates were related to indices that suggest longer range or global transport. Deposition rates averaged 132 plastics m<sup>-2</sup> day<sup>-1</sup> amounting to > 1000 tons of plastic deposition to western U.S. protected lands annually.</p>

scholarly journals Model evaluation of NO<sub>3</sub> secondary organic aerosol (SOA) source and heterogeneous organic aerosol (OA) sink in the Western United States

2012 ◽  
Vol 12 (2) ◽  
pp. 5189-5223 ◽  
Author(s):  
J. L. Fry ◽  
K. Sackinger
Keyword(s):  
United States ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Chemical Mechanism ◽  
Western United States ◽  
Urban Centers ◽  
Aerosol Composition ◽  
Organic Gases ◽  
Source And Sink ◽  
Loss Rates

Abstract. The relative importance of NO3-initiated source and heterogeneous sink of organic aerosol in the Western United States is investigated using the WRF/Chem regional weather and chemistry model. The model is run for the four individual months, representing the four seasons, of January, May, August, and October, to produce hourly spatial maps of surface concentrations of NO3, organic aerosol (OA), and reactive organic gases (ROG, a sum of alkene species tracked in the lumped chemical mechanism employed). These "baseline" simulations are used in conjunction with literature data on secondary organic aerosol (SOA) mass yields, average organic aerosol composition, and reactive uptake coefficients for NO3 on organic surfaces to predict SOA source and OA heterogeneous loss rates due to reactions initiated by NO3. We find both source and sink rates maximized downwind of urban centers, therefore with a varying location that depends on wind direction. Both source and sink terms are maximum in summer, and SOA source dominates over OA loss by approximately three orders of magnitude, with large day-to-day variability. The NO3 source of SOA is found to be atmospherically significant (peak production rates of 0.4–3.0 μg kg−1 h−1), while the heterogeneous sink of OA via NO3 surface reactions (peak loss rates of 0.11–2.3 × 10−3 μg kg−1 h−1) is likely too small to significantly impact the atmospheric lifetime of either organic aerosol or oxidized nitrogen (NOy).

scholarly journals Model investigation of NO<sub>3</sub> secondary organic aerosol (SOA) source and heterogeneous organic aerosol (OA) sink in the western United States

2012 ◽  
Vol 12 (18) ◽  
pp. 8797-8811 ◽  
Author(s):  
J. L. Fry ◽  
K. Sackinger
Keyword(s):  
United States ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Chemical Mechanism ◽  
Western United States ◽  
Urban Centers ◽  
Aerosol Composition ◽  
Organic Gases ◽  
Source And Sink ◽  
Loss Rates

Abstract. The relative importance of NO3-initiated source and heterogeneous sink of organic aerosol in the western United States is investigated using the WRF/Chem regional weather and chemistry model. The model is run for the four individual months, representing the four seasons, of January, May, August, and October, to produce hourly spatial maps of surface concentrations of NO3, organic aerosol (OA), and reactive organic gases (ROG, a sum of alkene species tracked in the lumped chemical mechanism employed). These "baseline" simulations are used in conjunction with literature data on secondary organic aerosol (SOA) mass yields, average organic aerosol composition, and reactive uptake coefficients for NO3 on organic surfaces to predict SOA source and OA heterogeneous loss rates due to reactions initiated by NO3. We find both source and sink rates maximized downwind of urban centers, therefore with a varying location that depends on wind direction. Both source and sink terms are maximum in summer, and SOA source dominates over OA loss by approximately three orders of magnitude, with large day-to-day variability. The NO3 source of SOA (peak production rates of 0.4–3.0 μg kg−1 h−1) is found to be significantly larger than the heterogeneous sink of OA via NO3 surface reactions (peak loss rates of 0.5–8 × 10−4 μg kg−1 h−1).

Writing Time in Metaphors

2018 ◽  
Author(s):  
Jennifer J. Smith
Keyword(s):  
United States ◽  
The United States ◽  
Western United States ◽  
Entire System ◽  
Language And Culture ◽  
Space Race ◽  
Do So

Coherence of place often exists alongside irregularities in time in cycles, and chapter three turns to cycles linked by temporal markers. Ray Bradbury’s The Martian Chronicles (1950) follows a linear chronology and describes the exploration, conquest, and repopulation of Mars by humans. Conversely, Louise Erdrich’s Love Medicine (1984) jumps back and forth across time to narrate the lives of interconnected families in the western United States. Bradbury’s cycle invokes a confluence of historical forces—time as value-laden, work as a calling, and travel as necessitating standardized time—and contextualizes them in relation to anxieties about the space race. Erdrich’s cycle invokes broader, oppositional conceptions of time—as recursive and arbitrary and as causal and meaningful—to depict time as implicated in an entire system of measurement that made possible the destruction and exploitation of the Chippewa people. Both volumes understand the United States to be preoccupied with imperialist impulses. Even as they critique such projects, they also point to the tenacity with which individuals encounter these systems, and they do so by creating “interstitial temporalities,” which allow them to navigate time at the crossroads of language and culture.

Sign in / Sign up

Export Citation Format

Share Document