Mass Loading Measurements in Amargosa Valley

This work will be conducted under Task DRI-FI-001, “Mass Loading Measurements in Amargosa Valley.” The objective of this task is to measure, with known accuracy, the levels of atmospheric mass loading (mass concentration of suspended particulates) accompanying soil surface disturbing activities in Amargosa Valley. Mass loading is used in the biosphere model to calculate inhalation exposure for the human receptor, the maximally reasonably exposed individual (RMEI). The mass loading currently used in the biosphere model is based on literature data from the analog sites rather than on site-specific conditions. This work is subject to the Nevada System of Higher Education (NSHE, previously UCCSN) QA program requirements

Cash for Coolers

This paper examines a large-scale appliance replacement program in Mexico that since 2009 has helped 1.5 million households replace their old refrigerators and air-conditioners with energy-efficient models. Using household-level electric billing records from the population of Mexican residential customers we find that refrigerator replacement reduces electricity consumption by an average of 11 kilowatt hours per month, about a 7% decrease. We find that air conditioning replacement, in contrast, increases electricity consumption by an average of 6 kilowatt hours per month, with larger increases during the summer. To put these results in context we present a simple conceptual framework in which energy-efficient durable goods cost less to operate, so households use them more. This behavioral response, sometimes called the “rebound” effect, is important for air-conditioners, but not important for refrigerators

Cash for Coolers

This paper examines a large-scale appliance replacement program in Mexico that since 2009 has helped 1.5 million households replace their old refrigerators and air-conditioners with energy-efficient models. Using household-level electric billing records from the population of Mexican residential customers we find that refrigerator replacement reduces electricity consumption by an average of 11 kilowatt hours per month, about a 7% decrease. We find that air conditioning replacement, in contrast, increases electricity consumption by an average of 6 kilowatt hours per month, with larger increases during the summer. To put these results in context we present a simple conceptual framework in which energy-efficient durable goods cost less to operate, so households use them more. This behavioral response, sometimes called the “rebound” effect, is important for air-conditioners, but not important for refrigerators

Local air pollutants threaten Lake Tahoe's clarity

Lake Tahoe is a high-altitude (6,227 feet) lake located in the northern Sierra Nevada at the California-Nevada border. During the second half of the 20th century, the decline in Lake Tahoe's water clarity and degradation of the basin's air quality became major concerns. The loading of gaseous and particulate nitrogen, phosphorus and fine soil via direct atmospheric deposition into the lake has been implicated in its eutrophication. Previous estimates suggest that atmospheric nitrogen deposition contributes half of the total nitrogen and a quarter of the total phosphorus loading to the lake, but the sources of the atmospheric pollutants remain unclear. In order to better understand the origins of atmospheric pollutants contributing to the decline in Lake Tahoe's water clarity, we reviewed a series of studies performed by research groups from the U.S. Department of Agriculture's Forest Service, UC Davis and the Desert Research Institute. Overall, the studies found that the pollutants most closely connected to the decline in Lake Tahoe's water quality originated largely from within the basin

Real-World Automotive Emissions-Summary of Studies in the Fort McHenry and Tuscarora Mountain Tunnels

Motor vehicle emission rates of CO, NO, NOx, and gas-phase speciated nonmethane hydrocarbons (NMHC) and carbonyl compounds were measured in 1992 in the Fort McHenry Tunnel under Baltimore Harbor and in the Tuscarora Mountain Tunnel of the Pennsylvania Turnpike, for comparison with emission-model predictions and for calculation of the reactivity of vehicle emissions with respect to O3 formation. Both tunnels represent a high-speed setting at relatively steady speed. The cars at both sites tended to be newer than elsewhere (median age was \u3c 4 yr), and much better maintained as judged by low CO/CO2 ratios and other emissions characteristics. The Tuscarora Mountain Tunnel is flat, making it advantageous for testing automotive emission models, while in the underwater Fort McHenry Tunnel the impact of roadway grade can be evaluated. MOBILE4.1 and MOBILES gave predictions within ± 50% of observation most of the time. There was a tendency to overpredict, especially with MOBILES and especially at Tuscarora. However, light-duty-vehicle CO, NMHC, and NOx, all were underpredicted by MOBILE4.1 at Fort McHenry. Light-duty-vehicle CO/NOx ratios and NMHC/NOx, ratios were generally a little higher than predicted. The comparability of the predictions to the observations contrasts with a 1987 experiment in an urban tunnel (Van Nuys) where CO and HC, as well as CO/NOx, and NMHC/NOx, ratios, were grossly underpredicted. The effect of roadway grade on gram per mile (g mi−1) emissions was substantial. Fuel-specific emissions (g gal−1), however, were almost independent of roadway grade, which suggests a potential virtue in emissions models based on fuel-specific emissions rather than g mi−1) emissions. Some 200 NMHC and carbonyl emissions species were quantified as to their light- and heavy-duty-vehicle emission rates. The heavy-duty-vehicle NMHC emissions were calculated to possess more reactivity, per vehicle-mile, with respect to O3 formation (g O3 per vehicle-mile) than did the light-duty-vehicle NMHC emissions. Per gallon of fuel consumed, the light-duty vehicles had the greater reactivity. Much of the NMHC, and much of their reactivity with respect to O3 formation, resided in compounds heavier than C10, mostly from heavy-duty diesel, implying that atmospheric NMHC sampling with canisters alone is inadequate in at least some situations since canisters were found not to be quantitative beyond ∼ C10 The contrasting lack of compounds heavier than C10 from light-duty vehicles suggests a way to separate light- and heavy-duty-vehicle contributions in receptor modeling source apportionment. The division between light-duty-vehicle tailpipe and nontailpipe NMHC emissions was ∼ 85% tailpipe and ∼ 15% nontailpipe (evaporative running losses, etc.). Measured CO/CO2 ratios agreed well with concurrent roadside infrared remote sensing measurements on light-duty vehicles, although remote sensing HC/CO2 ratio measurements were not successful at the low HC levels prevailing. Remote sensing measurements on heavy-duty diesels were obtained for the first time, and were roughly in agreement with the regular (bag sampling) tunnel measurements in both CO/CO2 and HC/CO2 ratios. A number of recommendations for further experiments, measurement methodology development, and emissions model development and evaluation are offered

Real-world Automotive Emissions—Summary of Studies in the Fort McHenry and Tuscarora Mountain Tunnels

Motor vehicle emission rates of CO, NO, NOx, and gas-phase speciated nonmethane hydrocarbons (NMHC) and carbonyl compounds were measured in 1992 in the Fort McHenry Tunnel under Baltimore Harbor and in the Tuscarora Mountain Tunnel of the Pennsylvania Turnpike, for comparison with emission-model predictions and for calculation of the reactivity of vehicle emissions with respect to O3 formation. Both tunnels represent a high-speed setting at relatively steady speed. The cars at both sites tended to be newer than elsewhere (median age was \u3c 4 yr), and much better maintained as judged by low CO/CO2 ratios and other emissions characteristics. The Tuscarora Mountain Tunnel is flat, making it advantageous for testing automotive emission models, while in the underwater Fort McHenry Tunnel the impact of roadway grade can be evaluated. MOBILE4.1 and MOBILES gave predictions within ± 50% of observation most of the time. There was a tendency to overpredict, especially with MOBILES and especially at Tuscarora. However, light-duty-vehicle CO, NMHC, and NOx, all were underpredicted by MOBILE4.1 at Fort McHenry. Light-duty-vehicle CO/NOx ratios and NMHC/NOx, ratios were generally a little higher than predicted. The comparability of the predictions to the observations contrasts with a 1987 experiment in an urban tunnel (Van Nuys) where CO and HC, as well as CO/NOx, and NMHC/NOx, ratios, were grossly underpredicted. The effect of roadway grade on gram per mile (g mi−1) emissions was substantial. Fuel-specific emissions (g gal−1), however, were almost independent of roadway grade, which suggests a potential virtue in emissions models based on fuel-specific emissions rather than g mi−1) emissions. Some 200 NMHC and carbonyl emissions species were quantified as to their light- and heavy-duty-vehicle emission rates. The heavy-duty-vehicle NMHC emissions were calculated to possess more reactivity, per vehicle-mile, with respect to O3 formation (g O3 per vehicle-mile) than did the light-duty-vehicle NMHC emissions. Per gallon of fuel consumed, the light-duty vehicles had the greater reactivity. Much of the NMHC, and much of their reactivity with respect to O3 formation, resided in compounds heavier than C10, mostly from heavy-duty diesel, implying that atmospheric NMHC sampling with canisters alone is inadequate in at least some situations since canisters were found not to be quantitative beyond ∼ C10 The contrasting lack of compounds heavier than C10 from light-duty vehicles suggests a way to separate light- and heavy-duty-vehicle contributions in receptor modeling source apportionment. The division between light-duty-vehicle tailpipe and nontailpipe NMHC emissions was ∼ 85% tailpipe and ∼ 15% nontailpipe (evaporative running losses, etc.). Measured CO/CO2 ratios agreed well with concurrent roadside infrared remote sensing measurements on light-duty vehicles, although remote sensing HC/CO2 ratio measurements were not successful at the low HC levels prevailing. Remote sensing measurements on heavy-duty diesels were obtained for the first time, and were roughly in agreement with the regular (bag sampling) tunnel measurements in both CO/CO2 and HC/CO2 ratios. A number of recommendations for further experiments, measurement methodology development, and emissions model development and evaluation are offered