Report on Conference on Western Water Issues, 17-18 May 1979

Over the last few years several potential conflicts have emerged over the manner in which water is put to beneficial use in the western United States. These potential problems have been further heightened by the western drought of 1976-77 and by the recent upsurge of interest in developing western coal and oil-shale resources. The conference on Western Water Issues, held at the California Institute of Technology, 17-18 May 1979, provided a forum for representatives of industry, agriculture, government, environmental groups, research establishments and universities to exchange ideas on the subject. Most of the discussions centered on California and the Colorado River Basin. Specific items discussed included climatic fluctuations and predictability of the basic water supply; existing water law and needed changes; economics of water and the lack of real water markets; pending California state legislation (on the Peripheral Canal in the Sacramento-San Joaquin Delta area, and on limits to pumping overdrafted ground water basins); water availability for energy resources development; and competing needs by municipalities, industry, and agriculture. As a summary of the conference, this report should be regarded as a source book to clarify the issues and direct the reader to relevant individuals and references

Acquisition of acid vapor and aerosol concentration data for use in dry deposition studies in the South Coast Air Basin

An atmospheric monitoring network was operated throughout the South Coast Air Basin in the greater Los Angeles area during the year 1986. The primary objective of this study was to measure the spatial and temporal concentration distributions of atmospheric gas phase and particulate phase acids and bases in support of the California Air Resources Board's dry deposition research program. Gaseous pollutants measured include HNO_3, HCl, HF, HBr, formic acid, acetic acid and ammonia. The chemical composition of the airborne particulate matter complex was examined in three size ranges: fine particles (less than 2.2 μm aerodynamic diameter, AD), PM_(10) (less than 10 μm AD) and total particles (no size discrimination). Upwind of the air basin at San Nicolas Island, gas phase acids concentrations are very low: averaging 0.3 μg m^(-3) (0.1 ppb) for HNO_3, 0.8 μg m^(-3) for HCl, 0.13 μg m^(-3) for HF, and 2.6 μg m^(-3) for formic acid. Annual average HN03 concentrations ranged from 3.1 μg m^(-3) (1.2 ppb) near the Southern California coast to 6.9 μg m^(-3) (2.7 ppb) at an inland site in the San Gabriel Mountains. HCl concentrations within the South Coast Air Basin averaged from 0.8 μg m^(-3) to 1.8 μg m^(-3) during the year 1986. Long-term average HF concentrations within the air basin are very low, in the range from 0.14 to 0.22 μg m^(-3) between monitoring sites. Long-term average formic acid concentrations are lowest near the coastline (5.0 μg m^(-3) at Hawthorne), with the highest average concentrations (10.7 μg m^(-3)) observed inland at Upland. Ammonia concentrations at low elevation within the South Coast Air Basin average from 2.1 μg m^(-3) to 4.4 μg m^(-3) at all sites except Rubidoux. Rubidoux is located directly downwind of a large ammonia source created by dairy farming and other agricultural activities in the Chino area. Ammonia concentrations at Rubidoux average 30 μg m^(-3) during 1986, a factor of approximately 10 higher than elsewhere in the air basin. Annual average PM_(10) mass concentrations within the South Coast Air Basin ranged from 47.0 μg m^(-3) along the coast to 87.4 μg m^(-3) at Rubidoux, the farthest inland monitoring site. Five major aerosol components (carbonaceous material, NO_3^-, SO_4^-, NH_4^+ and soil-related material) accounted for greater than 80% of the annual average PM_(10) mass concentration at all on-land monitoring stations. A peak 24-h average PM_(10) mass concentration of 299 μg m^(-3) was observed at Rubidoux during 1986. That value is a factor of 2 higher than the federal 24-h average PM_(10) concentration standard, and a factor of 6 higher than the State of California PM_(10) standard. More than 40% of the PM_(10) aerosol mass measured at Rubidoux during that peak day event consisted of aerosol nitrates plus ammonium ion. Reaction of gaseous nitric acid to form aerosol nitrates was a major contributor to the high PM_(10) concentrations observed in the Rubidoux area near Riverside, California

Airborne Particles in Museums

Presents one in a series of research activities aimed at a better understanding of the origin and fate of air pollution within the built environment

Spatial and Temporal Distribution of Atmospheric Nitric Acid and Particulate Nitrate Concentrations in the Los Angeles Area

A 1-year atmospheric measurement program was conducted throughout the South Coast Air Basin in the greater Los Angeles area during 1986 to determine the long-term average concentration patterns of gaseous HNO_3, and aerosol nitrates. Upwind of the air basin at San Nicolas Island, HNO_3, levels are very low, averaging 0.3 µg m^(-3) (0.1 ppb) over the year 1986. Annual average HNO_3 concentrations ranged from 3.1 µg m^(-3) (1.2 ppb) near the Southern California coast to 6.9 µg m^(-3) (2.7 ppb) at an inland site in the San Gabriel Mountains. At most monitoring stations, a majority of the inorganic nitrate (HNO_3 plus its reaction product, aerosol nitrate) was in the aerosol phase. Conversion of HNO_3 to aerosol nitrates was most pronounced at Rubidoux, near Riverside, CA, where on the average 94% of the inorganic nitrate was found in the aerosol phase, and where fine particle nitrate concentrations exceeded 109 pg µg^(-3), during the peak 24-h period examined

Spatial and Temporal Distribution of Atmospheric Nitric Acid and Particulate Nitrate Concentrations in the Los Angeles Area

A 1-year atmospheric measurement program was conducted throughout the South Coast Air Basin in the greater Los Angeles area during 1986 to determine the long-term average concentration patterns of gaseous HNO_3, and aerosol nitrates. Upwind of the air basin at San Nicolas Island, HNO_3, levels are very low, averaging 0.3 µg m^(-3) (0.1 ppb) over the year 1986. Annual average HNO_3 concentrations ranged from 3.1 µg m^(-3) (1.2 ppb) near the Southern California coast to 6.9 µg m^(-3) (2.7 ppb) at an inland site in the San Gabriel Mountains. At most monitoring stations, a majority of the inorganic nitrate (HNO_3 plus its reaction product, aerosol nitrate) was in the aerosol phase. Conversion of HNO_3 to aerosol nitrates was most pronounced at Rubidoux, near Riverside, CA, where on the average 94% of the inorganic nitrate was found in the aerosol phase, and where fine particle nitrate concentrations exceeded 109 pg µg^(-3), during the peak 24-h period examined

Basinwide nitric acid and related species concentrations observed during the Claremont nitrogen species comparison study

In conjunction with the Claremont Nitrogen Species Comparison Study, tandem filter units designed to collect HNO_3/total aerosol (TA) NO_3− and NH_3/TA NH+_4 were operated at seven locations throughout the Los Angeles area, including Claremont. The sampling methods used were related to the comparison study via intensive short-term and long-term measurements made at Claremont by both the tandem filter method and the denuder difference method. Between methods, 4-h and 6-h duration HNO_3 samples taken by the tandem filter method were higher (~ 20%) than the HNO_3 results obtained by the denuder difference method. As sampling duration increased to 22 h, the tandem filter method HNO_3 and NH_3 concentration measurements increased, while the 22-h denuder difference method HNO_3 values remained indistinguishable from the average of simultaneous short-term 4- and 6-h average samples. Analysis of the basinwide data showed that Claremont experienced the highest measured HNO_3 concentrations in the Los Angeles area during the period of the comparison study, confirming that Claremont was a wise choice for the main site of the study. In contrast, an alternative site near Riverside experienced the lowest HNO_3 levels in the air basin, accompanied by high aerosol nitrate and very high NH_3 concentrations

Hydrochloric acid: A regional perspective on concentrations and formation in the atmosphere of Southern California

Atmospheric gaseous hydrochloric acid (HCl) concentrations and water-soluble species in the aerosol phase were measured at nine sites in Southern California throughout the year 1986. Annual average HCl concentrations measured by the denuder difference method ranged from 0.39 ppb at an offshore island to 1.25 ppb onshore at Hawthorne, California. An ion balance on the aerosol shows that coarse particle chloride begins as sea salt over the ocean and is depleted relative to aerosol sodium with transport inland. Total chloride and sodium balances show that chloride depletion from the aerosol is matched by a comparable increase in gaseous HCl concentrations, consistent with the proposition that acid gas reactions with sea salt are the principal source of gaseous HCl in the Southern California atmosphere. Fine aerosol chloride exceeds fine particle sodium on a number of occasions, particularly at one inland site known for extraordinarily high NH_3 levels. There is evidence that coarse aerosol chloride from sea salt is being processed by atmospheric reactions through HCl to form fine aerosol, possibly NH_4Cl

Hydrochloric acid: A regional perspective on concentrations and formation in the atmosphere of Southern California

Atmospheric gaseous hydrochloric acid (HCl) concentrations and water-soluble species in the aerosol phase were measured at nine sites in Southern California throughout the year 1986. Annual average HCl concentrations measured by the denuder difference method ranged from 0.39 ppb at an offshore island to 1.25 ppb onshore at Hawthorne, California. An ion balance on the aerosol shows that coarse particle chloride begins as sea salt over the ocean and is depleted relative to aerosol sodium with transport inland. Total chloride and sodium balances show that chloride depletion from the aerosol is matched by a comparable increase in gaseous HCl concentrations, consistent with the proposition that acid gas reactions with sea salt are the principal source of gaseous HCl in the Southern California atmosphere. Fine aerosol chloride exceeds fine particle sodium on a number of occasions, particularly at one inland site known for extraordinarily high NH_3 levels. There is evidence that coarse aerosol chloride from sea salt is being processed by atmospheric reactions through HCl to form fine aerosol, possibly NH_4Cl

Hydrofluoric Acid in the Southern California Atmosphere

Atmospheric hydrofluoric acid concentrations were measured at nine sites in Southern California during an 8-month period. Long-term average HF concentrations measured by the tandem filter method ranged from 0.13 μg m^(-3) (0.15 ppb) at San Nicolas Island to 0.22 μg m^(-3) (0.25 ppb) onshore at Rubidoux, CA. The ambient concentration of HF shows little change throughout the year, with the notable exception of an occasional spike which approaches or exceeds 1 μg m^(-3) (1.12 ppb) over a 24-h averaging time. Due to the wide-ranging uses of HF in industry, and lacking natural sources to account for such spikes, it is possible that these spikes are due to accidental emissions from industrial sources, although no direct evidence of accidents on the dates involved was found

Seasonal and Spatial Characteristics of Formic and Acetic Acids Concentrations in the Southern California Atmosphere

Formic and acetic acids measurements made during the year 1986 are reported for eight sites in the Los Angeles basin and one remote offshore site. Formic and acetic acids concentrations measured in marine air upwind of the Los Angeles area over an 8-month period average 1.4 and 0.6 ppb, respectively, while concentrations within the Los Angeles urban area average 2.7−5.8 ppb formic acid and 2.9−4.2 ppb acetic acid. Average formic and acetic acids concentrations exceed average HNO_3 and HCl concentra tions, making them the most abundant gas phase acids in the southern California atmosphere throughout the year. Formic and acetic acids concentrations near the coast change in proportion to changes in atmospheric dilution potential, as would be expected if formic and acetic acids were emitted directly from widespread area sources such as motor vehicle traffic. Downwind of Los Angeles, formic and acetic acids concentrations peak during the summer photochemi cal smog season, and concentration changes track both changes in atmospheric oxidant concentrations and markers for heterogeneous conversion within clouds or fog. Formic and acetic acids concentrations thus appear to arise both from direct emissions and from atmospheric chemical production, with the relative importance of these pathways varying spatially over the area surveyed