Atmospheric Environment (v.40, #9)

A review of currently used pesticides (CUPs) in Canadian air and precipitation: Part 1: Lindane and endosulfans by Ludovic Tuduri; Tom Harner; Pierrette Blanchard; Yi-Fan Li; Laurier Poissant; Don T. Waite; Clair Murphy; Wayne Belzer (1563-1578).
This paper, and its companion, review available data on the presence of currently used pesticides (CUPs) in air and precipitation of Canada, since the late 1980s. Pesticides usage/sales are also given when available. Two older CUPs—lindane, which shows a wealth of data, and endosulfan, one of the most abundant and ubiquitous organochlorine pesticides in the North American atmosphere today—are the focus of this first part. Data from local process studies, monitoring work in source and receptor regions, and modelling efforts are compiled to give an overall picture of the atmospheric levels and deposition and how this varies between regions and with time.
Keywords: Pesticides; Atmosphere; Precipitation; Deposition; Canada; Pesticides sales;

A review of currently used pesticides (CUPs) in Canadian air and precipitation. Part 2: Regional information and perspectives by Ludovic Tuduri; Tom Harner; Pierrette Blanchard; Yi-Fan Li; Laurier Poissant; Don T. Waite; Clair Murphy; Wayne Belzer (1579-1589).
This paper, and its companion (that dealt with lindane and endosulfan) review available data on the presence of currently used pesticides (CUPs) in air and precipitation in Canada, since the late 1980s. Pesticides usage/sales are also given when available. Data from local studies/initiatives, region-wide monitoring networks and remote locations are compiled to summarize atmospheric levels of different CUP classes (e.g. acid herbicides, organophosphates, “new” organochlorines, triazines, etc.) and how this varies among regions and with time. Based on this information, and other parameters not specific to Canada, knowledge gaps are identified and ideas for further research work are proposed.
Keywords: Pesticides; Atmosphere; Precipitation; Deposition; Canada; Pesticides sales;

Measurements of relative humidity in a persistent contrail by R.S. Gao; D.W. Fahey; P.J. Popp; T.P. Marcy; R.L. Herman; E.M. Weinstock; J.B. Smith; D.S. Sayres; J.V. Pittman; K.H. Rosenlof; T.L. Thompson; P.T. Bui; D.G. Baumgardner; B.E. Anderson; G. Kok; A.J. Weinheimer (1590-1600).
Persistent contrails are a common feature of the upper troposphere. We describe two methods for intercomparing and evaluating RHi measurements in a persistent contrail with calculated or expected values. The methods were applied to measurements made in the upper troposphere on board an NASA WB-57F aircraft while sampling its own contrail. Included in the analysis are measurements of water vapor pressure, temperature, ice particle number and size, and nitric oxide (NO). The systematic use of these contrail-sampling methods in future studies will improve our understanding of contrail microphysics and the performance of fast-response water and temperature measurements.
Keywords: Contrail; Relative humidity; Water vapor; Microphysics; Ice particles; Aircraft emissions; Nitric oxide;

Impact of using fishing boat fuel with high poly aromatic content on the emission of polycyclic aromatic hydrocarbons from the diesel engine by Yuan-Chung Lin; Wen-Jhy Lee; Hsing-Wang Li; Chung-Ban Chen; Guor-Cheng Fang; Perng-Jy Tsai (1601-1609).
Because of the fishery subsidy policy, the fishing boat fuel oil (FBFO) exemption from commodity taxes, business taxes and air pollution control fees, resulted in the price of FBFO was ∼50% lower than premium diesel fuel (PDF) in Taiwan. It is estimated that ∼650,000 kL FBFO was illegally used by traveling diesel-vehicles (TDVs) with a heavy-duty diesel engine (HDDE), which accounted for ∼16.3% of the total diesel fuel consumed by TDVs. In this study, sulfur, poly aromatic and total-aromatic contents in both FBFO and PDF were measured and compared. Exhaust emissions of polycyclic aromatic hydrocarbons (PAHs) and their carcinogenic potencies (BaPeq) from a HDDE under transient cycle testing for both FBFO and PDF were compared and discussed. Finally, the impact caused by the illegal use of FBFO on the air quality was examined. Results show that the mean sulfur-, poly aromatic and aromatic-contents in FBFO were 43.0, 3.89 and 1.04 times higher than that of PDF, respectively. Emission factors of total-PAHs and total-BaPeq obtained by utilizing FBFO were 51.5 and 0.235 mg L−1-Fuel, which were 3.41 and 5.82 times in magnitude higher than obtained by PDF, respectively. The estimated annual emissions of total-PAHs and total-BaPeq to the ambient environment due to the illegally used FBFO were 23.6 and 0.126 metric tons, respectively, which resulted in a 17.9% and a 25.0% increment of annual emissions from all mobile sources, respectively. These results indicated that the FBFO used illegally by TDVs had a significant impact on PAH emissions to the ambient environment.
Keywords: Fishery subsidy policy; Fishing boat fuel oil; Diesel fuel; PAH emissions; Carcinogenic potencies;

Ozone concentration gradients and wind conditions in Norway spruce (Picea abies) forests in Sweden by P.E. Karlsson; M. Hansson; H.-O. Höglund; H. Pleijel (1610-1618).
Ozone concentrations and wind conditions were measured at different heights above ground inside two different Norway spruce forest canopies in Sweden and compared to those outside or above the forests. Compared to high above ground outside or above the canopies, the ozone concentrations inside the Norway spruce forests were reduced 3–8% during mid-day and 10–40% during nighttime. Daylight Accumulated exposure Over a Threshold 40 ppb (AOT40) was reduced 15–45% inside as compared to outside the forest. The horizontal concentration differences between inside and outside the forest were in the order of 3–4%, independently of the height above ground. The ozone concentration difference inside and outside the forest depended on the air turbulence as well as the horizontal wind speed inside the forest. It also depended on the distance to the forest edge in relation to the wind direction. The ozone concentration differences inside and outside the Norway spruce forests were explained by the differences in the rate of dry deposition in relation to the rate of replacement of ozone from higher air layers or by the horizontal wind going into the forest.
Keywords: In-canopy ozone concentrations; AOT40; Wind conditions; Forests; Norway spruce;

Long-term atmospheric measurements of C1–C5 alkyl nitrates in the Pearl River Delta region of southeast China by Isobel J. Simpson; Tao Wang; Hai Guo; Y.H. Kwok; Frank Flocke; Elliot Atlas; Simone Meinardi; F. Sherwood Rowland; Donald R. Blake (1619-1632).
Mixing ratios of seven C1–C5 alkyl nitrates (RONO2) were measured during a 16-month study (August 2001–December 2002) at Tai O, a coastal site 30 km west of central Hong Kong in the Pearl River Delta, the fastest-growing industrial region in the world. The C3–C4 (rather than C1–C2) RONO2 were most abundant throughout the study, showing the importance of photochemical (rather than marine) RONO2 production in the sampled air. A lack of methyl nitrate (MeONO2) enhancement during summer, when the prevailing winds are from the ocean, indicates that the South China Sea is not a region of strong RONO2 emissions. By contrast, MeONO2 levels during pollution episodes (up to 25 parts per trillion by volume (pptv)) were the highest that our group has recorded during urban photochemical RONO2 production, as opposed to marine emissions or biomass burning. The highest summed RONO2 level of the study (204 pptv) was measured in the afternoon of 7 November 2002, during an intense pollution episode that captured the highest ozone (O3) level ever recorded in Hong Kong (203 ppbv). During pollution episodes, the average ratio of O3 to summed RONO2 was roughly 1000:1 in freshly polluted air (ethyne/CO∼3–5 pptv/ppbv) and 500:1 in very freshly polluted air (ethyne/CO∼6–8 pptv/ppbv). Ozone and RONO2 share a common photochemical source, and their good correlation in pollution plumes shows that RONO2 can be used as a tracer of photochemical O3 production. Even MeONO2 showed similar diurnal variations as the C2–C5 RONO2, indicating a strong photochemical source despite its very slow photochemical production from methane oxidation. The decomposition of longer-chain alkoxy radicals also does not explain the high MeONO2 levels, and rough calculations show that methoxy radical reaction with NO2 appears to be a viable alternate pathway for MeONO2 production in polluted atmospheres, though further measurements and modeling are required to confirm this mechanism.
Keywords: Alkyl nitrates; Photochemistry; China; Urban pollution; Ozone;

High levels of ozone and related gases over the Bay of Bengal during winter and early spring of 2001 by S. Lal; D. Chand; L.K. Sahu; S. Venkataramani; G. Brasseur; M.G. Schultz (1633-1644).
Measurements of surface ozone and related trace gases were made over a broader region of the Bay of Bengal along with measurements over the Indian Ocean and the Arabian Sea during a Bay of Bengal Experiment (BOBEX) conducted from 18 February to 23 March, 2001. Higher levels of ozone (60–64 ppbv) were observed over the central Bay of Bengal (10–15N, 84–86E) and not near the coastal regions due to different types of wind patterns. Ozone levels in the south of 12N are observed to be higher over the Bay of Bengal than the average levels measured over the Arabian Sea during all the four INDOEX cruises conducted in each winter from 1996 to 1999. The elevated O3 level is consistent with simultaneously measured higher levels of CO, CH4 and SF6 over the Bay of Bengal. These observations together with general wind patterns, 7 days back trajectories and results from a three-dimensional model simulations suggest that higher levels of these trace gases over the Bay of Bengal are due to transport from the continent. These results also suggest that the air over the Bay of Bengal was found to be more polluted than the Arabian Sea during this season.
Keywords: Bay of Bengal; Ozone and trace gases; Pollution; Tropical region; Transport;

Biogenic volatile organic compound emissions from desert vegetation of the southwestern US by Chris Geron; Alex Guenther; Jim Greenberg; Thomas Karl; Rei Rasmussen (1645-1660).
Thirteen common plant species in the Mojave and Sonoran Desert regions of the western US were tested for emissions of biogenic non-methane volatile organic compounds (BVOCs). Only two of the species examined emitted isoprene at rates of 10 μg C g−1  h−1or greater. These species accounted for <10% of the estimated vegetative biomass in these arid regions of low biomass density, indicating that these ecosystems are not likely a strong source of isoprene. However, isoprene emissions from these species continued to increase at much higher leaf temperatures than is observed from species in other ecosystems. Five species, including members of the Ambrosia genus, emitted monoterpenes at rates exceeding 2 μg C g−1  h−1. Emissions of oxygenated compounds, such as methanol, ethanol, acetone/propanal, and hexanol, from cut branches of several species exceeded 10 μg C g−1  h−1, warranting further investigation in these ecosystems. Model extrapolation of isoprene emission measurements verifies recently published observations that desert vegetation is a small source of isoprene relative to forests. Annual and daily total model isoprene emission estimates from an eastern US mixed forest landscape were 10–30 times greater than isoprene emissions estimated from the Mojave site. Monoterpene (and possibly oxygenated terpene and sesquiterpene) emissions may be more comparable, as annual forest terpene emission model estimates were 3–8 times greater than those from the Mojave Desert, and were within a factor of 2 for peak summertime fluxes. Primary productivity and leaf biomass of desert ecosystems are very dependent on annual precipitation, and our model results indicate that there can be at least a three-fold difference in total annual BVOC emissions between dry and wet years. We recommend additional studies of desert plant BVOC emissions, especially those that focus on sesquiterpenes, oxygenated compounds, and the effects of soil moisture, temperature, humidity, and seasonality. Landscape flux studies are needed to test BVOC model estimates and to verify BVOC influences on regional atmospheric chemistry.
Keywords: Isoprene; Monoterpene; Biogenic volatile organic compounds; Leaf temperature; Photosynthetically active radiation; Emission factor; Larrea tridentata; Ephedra nevadensis; Ambrosia dumosa; Ambrosia deltoidea;

High molecular weight products of the ozonolysis reaction of particle-phase 9-octadecenoic acid (oleic acid) have been studied by photoelectron resonance capture ionization (PERCI) mass spectrometry (MS). Oleic acid particles ( d g = 2 0 2 nm , σ g = 1.9 7 ) were reacted with ozone (1.8×10−4  atm) in a flow reactor at reaction times of 8 and 23 s. Particles were sampled on-line with a differentially pumped particle inlet and chemically analyzed by PERCI-MS. PERCI is a soft ionization method that permits the direct measurement of relatively high molecular weight compounds, facilitating molecular identification. In addition to cyclic oxygenates, such as secondary ozonides and geminal diperoxides that were reported previously, we demonstrate the formation of polymers at the particle surface. Polymer formation is proposed to proceed via addition of a Criegee intermediate to oleic acid forming an α -acyloxyalkyl hydroperoxide, and subsequent additions of Criegee intermediates to this initial addition product and later generations. Ultimately, polyanhydrides are formed through dehydration of these α -acyloxyalkyl hydroperoxide intermediates. The highest molecular weight, unfragmented polyanhydride has been measured at 963 U, resulting from the successive addition of four Criegee intermediates to a parent oleic acid molecule. The low volatility of these products, coupled with their high polarity, may alter particle phase hygroscopicity that can enhance the cloud condensation properties of these particles. Further, the polymer products formed at the particles’ surface may significantly alter diffusion of reactive gases, thereby affecting the reactive uptake of atmospheric trace gases and impacting the oxidizing capacity of the atmosphere.
Keywords: Fatty acid; Aerosol; Hydroperoxide; Polyanhydride; Oligomer;

Assimilative capacity and pollutant dispersion studies for Gangtok city by P. Goyal; Sankalp Anand; B.S. Gera (1671-1682).
The assimilative capacity of Gangtok's atmosphere has been estimated by two different approaches. First approach is based on ventilation coefficient, which is directly proportional to the assimilative capacity of the atmosphere and has been computed through micro-meteorological parameters for two different seasons (winter and summer) of the year 2003–2004 represented by December, 2003 and April, 2004. Similar type of analysis has been done for all the seasons. But winter and summer have only been chosen to limit the presentation to a manageable size. Diurnal variation of ventilation coefficient shows that the assimilative capacity of atmosphere is high during the afternoon hours which get reduced during the evening and morning hours in both the seasons. Among both the season winter has the poorest assimilative capacity throughout the day. Second approach is through pollution potential, which has been estimated through dispersion models in terms of concentration of pollutants, and is inversely proportional to the assimilative capacity of the atmosphere. Dispersion models for line sources have been used to predict the spatial and temporal distribution of three pollutants namely sulphur dioxide (SO2), suspended particulate matter (SPM) and oxides of nitrogen (NO x ). These models have been validated using the observed data. Statistical evaluation of the models indicates satisfactory performance. The model's predictions also indicate that winter is the most critical season having maximum pollution. It has also been observed that the model predicted values are higher in December i.e. in winter than in April i.e., summer. The results of both the approaches show a good correlation and indicate that the assimilative capacity of the study region is not good especially during winter season.
Keywords: Assimilative capacity; Dispersion; Ventilation coefficient; Air pollutants; Mixing height; Wind speed;

Eight organic acids were measured in 111 rain events occurring between September 1996 and May 1998 in Wilmington, North Carolina. Formic and acetic acids were the most abundant comprising approximately 75% of the total molar quantity of organic acids. The annual volume-weighted concentrations of organic acids in order of decreasing abundance in rainwater was formic (9.9 μM), acetic (7.3 μM), oxalic (1.8 μM), lactic (1.3 μM), succinic (1.0 μM), malonic (0.7 μM), pyruvic (0.3 μM), and maleic (0.1 μM), with methanesulfonic and glyoxylic acids usually below their detection limit. Growing season back-trajectory data provided strong evidence that terrestrial organic acid sources dominated over marine sources. Air mass back-trajectory analysis indicated that during the growing season air mass origin had a consistent impact on concentrations of rainwater organic acids. Rain with continental back-trajectories coming from the west had the highest concentrations of organic acids while two predominately marine back-trajectories had the lowest concentrations. Concentrations of organic acids in non-growing season rain did not display a consistent pattern indicating variability in sources. Seasonality of individual organic acids for specific back-trajectories was most pronounced in terrestrial back-trajectories and least in the marine back-trajectories indicating that seasonality in rainwater organic acid concentrations is driven by variations in terrestrial sources. Formic to acetic acid ratios (F:A), previously an indicator of terrestrial versus marine sources of these organic acids, were similar for all back-trajectories reflecting anthropogenic impacts on F:A locally and regionally. The ratios of malonic to succinic acids (M:S), also an indicator of sources for these acids, indicated direct anthropogenic sources for terrestrial back-trajectories and secondary processes for marine back-trajectories.
Keywords: Organic acids; Rainwater; Air mass; Terrestrial; Marine;

Sugars as source indicators of biogenic organic carbon in aerosols collected above the Howland Experimental Forest, Maine by Patricia M. Medeiros; Maureen H. Conte; John C. Weber; Bernd R.T. Simoneit (1694-1705).
Bulk aerosols (>1 μm) were collected continuously above the canopy at the Howland Experimental Forest, Maine, USA from May to October 2002. Each sample integrated over an approximately 2-week period. Mono- and disaccharide sugars were extracted using a microscale technique and were analyzed as their TMS derivatives by gas chromatography–mass spectrometry (GC–MS). Concentrations of total aerosol sugars ranged from 10 to 180 ng m−3. Glucose was the most abundant sugar (40–75% of the total sugars). The monosaccharides arabinose, fructose, galactose, mannose, arabitol and mannitol, and the disaccharides sucrose, maltose and mycose (aka trehalose) were also present in lower concentrations. The sugar composition in the aerosols varied seasonally. Fructose and sucrose were prevalent in early spring and decreased in relative abundance as the growing season progressed. Sugar polyols (arabitol and mannitol) and the disaccharide mycose (a fungal metabolite) were more prevalent in autumn during the period of leaf senescence. The changes in the sugar composition in the aerosol samples appear to reflect the seasonality of sugar production and utilization by the ecosystem. Plant waxes were present as significant components also indicating an input from biogenic background.Smoke plumes from Quebec forest fires passed over the Howland site in early July 2002. Levoglucosan, a biomarker of biomass burning, increased by an order of magnitude in the aerosol samples collected during this time. Glucose, mannose, arabinose, galactose, and also, plant waxes increased in concentration by factors of 2–5 in the smoke-impacted samples, indicating that wildfires enhance atmospheric emissions of uncombusted organic compounds. In contrast, concentrations of fructose, sugar polyols and disaccharides were not significantly higher in the smoke-impacted samples and indicated that biomass burning was not a significant source of these compounds in the aerosols.
Keywords: Sugars; Aerosol; Biomarkers; Smoke; Plant wax; Biogenic; Howland Experimental Forest;

Our objective is to establish the link between energy consumption and technologies, air pollution concentrations, and resulting impacts on public health in eastern China. We use Zaozhuang, a city in eastern China heavily dependent on coal, as a case study to quantify the impacts that air pollution in eastern China had on public health in 2000 and the benefits in improved air quality and health that could be obtained by 2020, relative to business-as-usual (BAU), through the implementation of best available emission control technology (BACT) and advanced coal gasification technologies (ACGT). We use an integrated assessment approach, utilizing state-of-the-science air quality and meteorological models, engineering, epidemiology, and economics, to achieve this objective. We find that total health damages due to year 2000 anthropogenic emissions from Zaozhuang, using the “willingness-to-pay” metric, was equivalent to 10% of Zaozhuang's GDP. If all health damages resulting from coal use were internalized in the market price of coal, the year 2000 price would have more than tripled. With no new air pollution controls implemented between 2000 and 2020 but with projected increases in energy use, we estimate health damages from air pollution exposure to be equivalent to 16% of Zaozhuang's projected 2020 GDP. BACT and ACGT (with only 24% penetration in Zaozhuang and providing 2% of energy needs in three surrounding municipalities) could reduce the potential health damage of air pollution in 2020 to 13% and 8% of projected GDP, respectively. Benefits to public health, of substantial monetary value, can be achieved through the use of BACT; health benefits from the use of ACGT could be even larger. Despite significant uncertainty associated with each element of the integrated assessment approach, we demonstrate that substantial benefits to public health could be achieved in this region of eastern China through the use of additional pollution controls and particularly from the use of advanced coal gasification technology. Without such controls, the impacts of air pollution on public health, presently considerable, will increase substantially by 2020.
Keywords: Air pollution impacts; Public health; China; Energy policy;

Aerosol size distributions of observed mass concentration and number concentration at the Seoul National University (SNU) campus site in Korea during the non-Asian dust and the Asian dust (Hwangsa) periods have been examined using the 8-stage cascade impactor and the 8-channel airborne particle counting system, respectively. The particle size distribution of the observed mass concentration during the Asian dust period at the SNU site is compared with that observed at the Asian dust source site of Duolun in Inner Mongolia, China. The results indicate that the size distribution of both the mass concentration and the number concentration shows a bi-modal distribution that can be regressed optimally with two log-normal distribution functions. It is found that the optimally regressed probability density function of the mass concentration distribution during the non-Asian dust period at the SNU site shows two log-normal distributions with the particle mean diameters of 0.66 and 8.51 μm and the standard deviations of 1.78 and 2.14 μm, respectively. The probability density of the small size mode is slightly smaller than that of the large size mode. During the Asian dust period at the SNU site the estimated probability density function of the mass concentration also composes of two log-normal distributions with the particle mean diameters of 0.89 and 9.12 μm and the standard deviations of 2.40 and 2.14 μm, respectively. However, the high probability density is greatly shifted to the large size mode. The probability density of the small size mode is only 6% of that of the large size mode. A quite similar size distribution pattern is found in the Asian dust source region of Duolun, suggesting the high probability density at the large particle-size mode during the Asian dust period being mainly attributed to long-range transport of particles from the Asian dust source region. It is also found that the estimated probability density function of the number concentration distribution observed at the SNU site during the non-Asian dust period has a bi-modal distribution with the particle mean diameters of 0.36 and 1.12 μm and the mean standard deviations of 1.48 and 1.91 μm, respectively. Much higher probability density is found in the small size mode in contrast to that of the mass concentration distribution where the probability density of both modes is almost the same.
Keywords: Aerosol size distribution; Asian dust particle; Bi-modal distribution; Mass concentration of aerosol; Number concentration of aerosol;

Urban heat island effect analysis for San Juan, Puerto Rico by Alexander Velazquez-Lozada; Jorge E. Gonzalez; Amos Winter (1731-1741).
A climatological analysis of the differences of air temperature between rural and urban areas (dT(U–R)) corroborates the existence of an urban heat island (UHI) in the tropical coastal city of San Juan, Puerto Rico that has been increasing at a rate of 0.06 °C year−1 for the last 40 years with predicted differences as high as 8 °C for the year 2050. The Regional Atmospheric Model System (RAMS) was used to validate the presence of this UHI and to simulate and compare three different land use scenarios consisting of potential natural vegetation, present, and projected future to quantify the impact of the urban development in the regional climate of Puerto Rico. RAMS simulated the UHI conditions at the lower and upper atmosphere revealing significant changes in sensible heat fluxes and sinks, and an increasing low turbulent-kinetic-energy zone (LTKEZ) over the urbanized area of San Juan.
Keywords: Urban heat island; Tropical city; Climatological analysis; Mesoscale modeling; Land use;