Atmospheric Chemistry of Toxic Contaminants. 3. Unsaturated Aliphatics: Acrolein,Acrylonitrile, Maleic Anhydride

Detailed mechanisms are outlined for the chemical reactions that contribute to In-situ formation and atmospheric removal of the unsaturated aliphatic contaminants acrolein, acrylonitrile, and maleic anhydride. In-situ formation of small amounts of acrolein and maleic anhydride may Involve the reaction of OH (and O₃) with 1,3-dienes and the reaction of OH with aromatic hydrocarbons, respectively. There is no known pathway for In-situ formation of acrylonitrile. Rapid removal of acrolein (half-life = less than one day) and of maleic anhydride (half-life = several hours) is expected from their rapid reactions with OH (major), O₃, and NO₃. These reactions lead to formaldehyde and glyoxal from acrolein and to dicarbonyls from maleic anhydride. Acrylonitrile is removed at a slower rate (half-life = 2–7 days) by reaction with OH, leading to formaldehyde and formyl cyanide.     

Atmospheric Chemistry of Toxic Contaminants. 5. Unsaturated Halogenated Aliphatics: Allyl Chloride,Chloroprene, Hexachlorocyclopentadiene,Vinylidene Chloride

Detailed mechanisms are outlined for the chemical reactions involved In the atmospheric removal of four unsaturated chlorinated aliphatic contaminants, allyl chloride, chloroprene, hexachlorocyclopentadiene and vlnylldene chloride. Rate constants estimated from structure-reactivity relationships Indicate rapid removal for all four compounds by reactions with OH (major), ozone, and NO₃, with half-lives of 2-16 hrs for removal by reaction with OH. Reaction products of allyl chloride (formaldehyde, chloroacetaldehyde, peroxychloroacetyl nitrate) and vinylidene chloride (formaldehyde, phosgene, chloroacetyl chloride) are consistent with OH addition-Initiated pathways that include Cl atom elimination. The chlorine atoms produced In the OH reaction sequence react rapidly with all four unsaturated compounds, but these reactions are of negligible Importance for atmospheric removal of the four toxic contaminants studied. Analogous mechanisms are discussed for chloroprene (leading to formaldehyde, CH₂ = CCICHO, and CICOCHO) and for hexachlorocyclopentadlene (leading to oxalyl chloride and CICOCCI₂COCI).     

Gas-Particle Distribution Factors for Organic and Other Pollutants in the Los Angeles Atmosphere

The distribution of organic pollutants between the gas and particu-late phases was measured for 6 days Including one with the highest ozone level observed in Pasadena In 1973 (7/25). Gas phase pollutants were monitored continuously while particulates were sampled over a one hour interval by filtration. The filters were extracted using a polar and a non-polar solvent; particulate organic carbon was determined using a carbon analyzer, and chemical analysis carried out by fractionation, gas chromatography, infrared, and CHON analysis.

The organic carbon fraction (OCF) was always large, up to 43% of the total particulates (TP). Most of the organics were oxygenated compounds of photochemical origin. There was a linear relation between O₃, OCF, and the infrared carbonyl band intensities of the extracts. Hourly variations of OCF and TP are discussed with respect to the gas phase pollutants and conversion processes.

Although secondary pollutant concentrations were found in the order: organics > nitrates > sulfates, nitrates were more efficient than organics in visibility degradation, based on a statistical evaluation of the data. The secondary aerosol contribution varied with O₃, accounting for up to 95% of TP when the O₃ peaked. The unusual nitrate peak observed for 7/25 is discussed with the atmospheric chemistry of other nitrogen compounds.

We define an organic carbon distribution factor: f_c = particulate organic carbon (POC, μg/m³C)/[POC + gas phase reactive hydrocarbons (μg/m³C)]. The gas-particle distribution factors for organics (f_c), nitrates (f_N) and sulfates (f_s) are in inverse order of their aerosol concentrations: f_c < f_N < f_s . The measured f_c are low: average 2–3%, highest value 6% for 7/25, and correspond to a conversion rate ≤2% hour^?1. Ambient f_c are much lower than f_c measured for certain specific hydrocarbon precursors.     

Detecting ozone and demonstrating its phytotoxicity in forested areas of Poland: a pilot study

Ambient concentrations of ozone (O(3)) were measured and O(3) phytotoxicity to tobacco (Nicotiana tabacum L.) was demonstrated in several forest locations in Poland during a pilot study from July-October, 1991. At southern and central locations in Poland, the 24-hour average O(3) concentrations measured with a UV absorption photometer were in the range of 32-55 ppb, and the corresponding 1-hour maxima in the range of 39-83 ppb. At these locations longer period (four to fifteen days) average concentrations were determined using O(3) passive samplers (DGA, Inc.) and were reaching 60 ppb, while at Bialowieza in eastern Poland O(3) concentrations averaged less than 40 ppb. In Szarow, near the Niepolomice Forest in southern Poland, 1-hour O(3) maxima estimated from the data obtained using passive samplers were about 105 ppb in early September. At several locations in southern and central Poland, extensive O(3) injury was determined on O(3)-sensitive Bel W-3 tobacco plants; such injury did not occur in the Bialowieza Forest of eastern Poland. The results of this pilot study indicate that O(3) is present at phytotoxic levels in southern and central Poland.     

Monitoring ambient ozone with a network of passive samplers: a feasibility study

Ambient levels of ozone have been measured at 46 mountain forest, desert, Class I Wilderness areas and other remote locations using a network of passive samplers. Typical values were 40-80 ppb (2 week samples) and exhibited temporal variations (studied for up to 1 year) as well as changes with elevation (studied up to 10 500 ft (3 200 m)). The performance of the passive sampler was evaluated with respect to reproducibility, field controls, data capture (>0.95), precision for co-located samples (av. = 11.9%, n = 103), and the role of other atmospheric oxidants as potential interferents (2 locations). Suggestions for additional sampler performance evaluation and network operation are outlined.     

Occupational exposure in the fluorescent lamp recycling sector in France

The fluorescent lamp recycling sector is growing considerably in Europe due to increasingly strict regulations aimed at inciting the consumption of low energy light bulbs and their end-of-life management. Chemical risks were assessed in fluorescent lamp recycling facilities by field measurement surveys in France, highlighting that occupational exposure and pollutant levels in the working environment were correlated with the main recycling steps and processes.The mean levels of worker exposure are 4.4 mg/m³, 15.4 μg/m³, 14.0 μg/m³, 247.6 μg/m³, respectively, for total inhalable dust, mercury, lead and yttrium. The mean levels of airborne pollutants are 3.1 mg/m³, 9.0 μg/m³, 9.0 μg/m³, 219.2 μg/m³, respectively, for total inhalable dust, mercury, lead and yttrium. The ranges are very wide. Surface samples from employees’ skin and granulometric analysis were also carried out. The overview shows that all the stages and processes involved in lamp recycling are concerned by the risk of hazardous substances penetrating into the bodies of employees, although exposure of the latter varies depending on the processes and tasks they perform. The conclusion of this study strongly recommends the development of a new generation of processes in parallel with more information sharing and regulatory measures.     

An empirical perspective for understanding climate change impacts in Switzerland

Regional Environmental Change - Planning for the future requires a detailed understanding of how climate change affects a wide range of systems at spatial scales that are relevant to humans....     

Photochemical Pollution at Two Southern California Smog Receptor Sites

A one-year survey of air quality has been carried out at two southern California inland locations, Perris and Palm Springs (90 km E-SE and 120 km E of Los Angeles) to evaluate transport of photochemical smog from the Los Angeles area and to assess population exposure to toxic air pollutants in the Coachella Valley and eastern Riverside County. Air pollutants measured included formaldehyde, acetaldehyde, nitric acid, and peroxyacetyl nitrate (PAN). Acetic acid was also measured as part of the time-integrated method employed to measure PAN. In addition, intensive studies were carried out at both locations and included measurements of aldehydes, nitric acid, PAN, peroxypropionyl nitrate (PPN), methylchloroform and tetrachloroethylene.

Maximum concentrations of HCHO, CH₃CHO, HNO₃, PAN, PPN, CH₃COOH and C₂CI₄ were 26, 21, 4.5, 7.6, 0.42, 6.6 and 0.29 ppb in Palm Springs and 15, 30, 6.3, 9.1, 0.73, 7.8 and 0.43 ppb in Perris. Pollutant concentrations measured in Palm Springs and Perris are compared to those measured in the Los Angeles area, and are discussed in terms of formation and removal during transport.