Non-urban Sites Research Articles

A CEREMONIAL CENTER FOR THE LIVING AND THE DEAD

Tall al-‘Umayri finds reveal an intact Early Bronze I dolmen, a unique Late Bronze II temple or shrine, and a Late Bronze/Iron Age four-room building packed with collared-rim storage jars. A huge pit filled with animal bones and Late Bronze/Iron Age pottery holds the remains of feasts celebrated at a small nonurban site. People periodically visited this safe and sacred venue near a perennial water source to engage in social and possibly ceremonial events at temples or shrines. Mortuary remains and feasting suggest situations involving the marzea? social institution as known from Ugaritic, biblical, and other written sources.

Plasma Metabolites and Mass Changes of Migratory Landbirds Indicate Adequate Stopover Refueling in a Heavily Urbanized Landscape

Abstract. Large concentrations of migrating landbirds in cities have been well documented, but the refueling conditions urban stopover sites provide are almost entirely unknown. We compared plasma triglyceride (indicator of mass gain) and B-OH-butyrate (indicator of mass loss) concentrations in landbirds in three New York City forests to those of conspecifics in two less disturbed, non-urban forests outside the city to evaluate the quality of urban stopover habitats. We quantified diurnal mass gains with regressions of body mass and capture time and measured arthropod biomass in leaf litter to assess food abundance for ground-foraging insectivores. Metabolite concentrations in Ovenbirds (Seiurus aurocapilla) at urban and non-urban sites did not differ during spring or autumn. In autumn, triglyceride levels of Swainson's Thrushes (Catharus ustulatus) indicated significantly higher refueling rates at the urban sites. In the Yellow-rumped Warbler (Dendroica coronata), butyrate was lowest out-side the city, s...

NMOC, ozone, and organic aerosol in the southeastern United States, 1999–2007: 3. Origins of organic aerosol in Atlanta, Georgia, and surrounding areas

Abstract Carbonaceous compounds constitute a major fraction of the fine particle mass at locations throughout North America; much of the condensed-phase organic carbon (OC) is produced in the atmosphere from NMOC reactions as “secondary” OC (SOC). Ten years of particulate carbon and speciated non-methane organic compound (NMOC) data combined with other measurements from Southeastern Aerosol Research and Characterization (SEARCH) and other sites provide insight into the association between elemental carbon (EC), OC and NMOCs. Data are analyzed to characterize the OC and SOC contrasts between urban Atlanta, Georgia, and nearby non-urban conditions in the Southeast. Analysis of the monitoring record indicates that the mean Atlanta urban excess of total carbon (TC) is 2.1–2.8 μg m −3 . The OC/EC ratio of the Atlanta urban excess is in the range 1.3 to 1.8, consistent with OC/EC ratios observed in motor vehicle emissions and a fossil carbon source of urban excess TC. Carbon isotope analysis of a subset of particle samples demonstrates that the urban excess is mainly fossil in origin, even though the majority of the TC is modern at both urban and non-urban sites. Temperature-dependent partitioning of OC between gas and condensed phases cannot explain the observed diurnal and seasonal variations of OC/CO, EC/CO, and OC/EC ratios. Alternatively, a hypothesis involving vertical mixing of OC-enriched air from aloft is supported by the seasonal and diurnal OC, isopentane, aromatic and isoprene observations at the ground. A statistical model is applied to indicate the relative significance of aerometric factors affecting OC and EC concentrations, including meteorological and pollutant associations. The model results demonstrate strong linkages between fine particle carbon and pollutant indicators of source emissions compared with meteorological factors; the model results show weaker dependence of OC on meteorological factors than is the case for ozone (O 3 ) concentrations.

NMOC, ozone, and organic aerosol in the southeastern United States, 1999–2007: 1. Spatial and temporal variations of NMOC concentrations and composition in Atlanta, Georgia

Volatile organic compounds (VOCs) are emitted from anthropogenic and natural (biogenic) sources into the atmosphere. Characterizing their ambient mixing ratios or concentrations is a challenge because VOCs comprise hundreds of species, and accurate measurements are difficult. Long-term hourly and daily-resolution data have been collected in the metropolitan area of Atlanta, Georgia, a major city dominated by motor vehicle emissions. A series of observations of daily, speciated C 2–C 10 non-methane organic compounds (NMOC) and oxygenated hydrocarbons (OVOC) in mid-town Atlanta (Jefferson Street, JST) are compared with data from three urban-suburban sites and a nearby non-urban site. Annual-average mixing ratios of NMOC and OVOC at JST declined from 1999 through 2007. Downward trends in NMOC, CO, and NO y corroborate expected emission changes as reflected in emission inventories for Atlanta’s Fulton County. Comparison of the JST NMOC composition with data from roadside and tunnel sampling reveals similarities to motor vehicle dominated samples. The JST annual average VOC-OH reactivities from 1999 to 2007 were relatively constant compared with the decline in annual-average NMOC mixing ratios. Mean reactivity at JST, in terms of concentration*k OH, was approximately 40% alkenes, 22% aromatics, 16% isoprene and 6% other biogenics, 13% C 7–C 10 alkanes and 3% C 2-C 6 alkanes, indicating that biogenic NMOCs are important but not dominant contributors to the urban reactive NMOC mix. In contrast, isoprene constituted ∼50% of the VOC-OH reactivities at two non-urban sites. Ratios of 24-hour average CO/benzene, CO/isopentane, and CO/acetylene concentrations indicate that such species are relatively conserved, consistent with their low reactivity. Ratios of more-reactive to less-reactive species show diurnal variability largely consistent with expected emission patterns, transport and mixing of air, and chemical processing.

Predicted intake of trace elements and minerals via household drinking water by 6-year-old children from Krakow, Poland. Part 5: Zinc

Zinc (Zn) exposure in pre-school children via household drinking water collected by a double sampling method (morning, evening) was evaluated in a sample of the Polish population. Zn concentration was measured by flame atomic absorption spectrometry. Rural and suburban Krakow sites were non-distinguishable in respect of Zn concentrations. However, significantly lower Zn was found in urban as compared with non-urban sites [geometric mean (95% confidence interval) 0.14 (0.01–1.95) mg l−1 versus 0.52 (0.03–10.2) mg l−1, p < 0.001.] Zn levels in water standing overnight in pipelines were higher in all sites by 0.36 mg l−1 on average, but observed really contaminations were higher. The Zn limit based on the taste and colour of drinking water (3 mg l−1) was exceeded in 1% and 10% of households from urban and non-urban sites, respectively. The Zn intake predictions for evening water samples for 6-year-old children averaged between 2% and 9% of the recommended dietary allowance (RDA, 10 mg day−1) for urban and non-urban sites, respectively. Mean Zn intake prediction for the exceedance fraction was 64% of RDA. In conclusion, overnight contamination of drinking water from in-house pipelines was significant and common to all sites investigated. Secondly, drinking water can be considered a significant contributor to dietary Zn intake by children in non-urban sites and may shift the population borderline of deficiency.

Comparison of aerosol optical depths from the Ozone Monitoring Instrument (OMI) on Aura with results from airborne sunphotometry, other space and ground measurements during MILAGRO/INTEX-B

Abstract. Airborne sunphotometer measurements are used to evaluate retrievals of extinction aerosol optical depth (AOD) from spatially coincident and temporally near-coincident measurements by the Ozone Monitoring Instrument (OMI) aboard the Aura satellite during the March 2006 Megacity Initiative-Local And Global Research Observations/Phase B of the Intercontinental Chemical Transport Experiment (MILAGRO/INTEX-B). The 14-channel NASA Ames Airborne Tracking Sunphotometer (AATS) flew on nine missions over the Gulf of Mexico and four in or near the Mexico City area. Retrievals of AOD from near-coincident AATS and OMI measurements are compared for three flights over the Gulf of Mexico for flight segments when the aircraft flew at altitudes 60–70 m above sea level, and for one flight over the Mexico City area where the aircraft was restricted to altitudes ~320–800 m above ground level over the rural area and ~550–750 m over the city. OMI-measured top of atmosphere (TOA) reflectances are routinely inverted to yield aerosol products such as AOD and aerosol absorption optical depth (AAOD) using two different retrieval algorithms: a near-UV (OMAERUV) and a multiwavelength (OMAERO) technique. This study uses the archived Collection 3 data products from both algorithms. In particular, AATS and OMI AOD comparisons are presented for AATS data acquired in 20 OMAERUV retrieval pixels (15 over water) and 19 OMAERO pixels (also 15 over water). At least four pixels for one of the over-water coincidences and all pixels for the over-land case were cloud-free. Coincident AOD retrievals from 17 pixels of the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard Aqua are available for two of the over-water flights and are shown to agree with AATS AODs to within root mean square (RMS) differences of 0.00–0.06, depending on wavelength. Near-coincident ground-based AOD measurements from ground-based sun/sky radiometers operated as part of the Aerosol Robotic Network (AERONET) at three sites in and near Mexico City are also shown and are generally consistent with the AATS AODs (which exclude any AOD below the aircraft) both in magnitude and spectral dependence. The OMAERUV algorithm retrieves AODs corresponding to a non-absorbing aerosol model for all three over-water comparisons whereas the OMAERO algorithm retrieves best-fit AODs corresponding to an absorbing biomass-burning aerosol model for two of the three over-water cases. For the four cloud-free pixels in one over-water coincidence (10 March), the OMAERUV retrievals underestimate the AATS AODs by ~0.20, which exceeds the expected retrieval uncertainty, but retrieved AODs agree with AATS values within uncertainties for the other two over-water events. When OMAERO retrieves AODs corresponding to a biomass-burning aerosol over water, the values significantly overestimate the AATS AODs (by up to 0.55). For the Mexico City coincidence, comparisons are presented for a non-urban region ~50–70 km northeast of the city and for a site near the center of the city. OMAERUV retrievals are consistent with AERONET AOD magnitudes for the non-urban site, but are nearly double the AATS and AERONET AODs (with differences of up to 0.29) in the center of the city. Corresponding OMAERO retrievals exceed the AATS and/or AERONET AODs by factors of 3 to 10.

Predicted intake of trace elements and minerals via household drinking water by 6-year-old children from Krakow (Poland). Part 4: Copper

The aim of this study was to assess exposure of children to copper (Cu) from household drinking water (DW). DW samples were collected between 1997 and 2004 in ∼650 households and pre-schools using a double-sampling method (morning – W1; evening – W2). The study group comprised ∼300 children (5–7 years old) living in Krakow (urban, peripheral) and rural areas in southern Poland. Cu concentrations were determined by flame atomic absorption spectrometry. There was no significant relationship between the sampling period and Cu concentration, but statistically significant differences were found between urban and non-urban (rural, peripheral) sites and between morning and evening samples. Geometric means of Cu concentration in evening DW (95% confidence interval, in μg L−1) were 8 (1–110), 20 (1–274) and 12 (0–364) in urban, peripheral and rural sites, respectively. DW contamination after overnight standing was comparable in all sites (average increase ∼20 μg Cu L−1). The adopted threshold of 100 μg Cu L−1 was exceeded in evening DW by 3.6 and 15% in urban and non-urban households, respectively. Exceedance of the EC limit (2 mg L−1) was not significant. The mean predicted contribution of evening DW to Cu intake by children were 18–37 μg day−1 or 0.8–1.6 μg kg−1 bw day−1 but were 2–3-fold higher for morning DW. The Polish RDA (1 mg Cu day−1) was exceeded for morning (evening) DW in 3.7 (0.2)% of children, with a mean intake of 159 (118)% of RDA. The observed copper levels and predicted intakes can be considered low and should not raise nutritional or toxicological concerns for the age group studied. Nevertheless, due to overnight contamination, the suggestion that the stagnant portion of drinking water should be discarded remains valid.

The anthropogenic influence on carbonaceous aerosol in the European background

To constrain the relatively uncertain anthropogenic impact on the organic aerosol load, radiocarbon analyses were performed on aerosol samples, collected year-round, at six non-urban sites including a maritime background and three remote mountain stations, lying on a west-east transect over Western Europe. From a crude three component model supported by TOC and levoglucosan filter data, the fossil fuel, biomass burning and biogenic TOC fraction are estimated, showing at all stations year-round, a relatively constant fossil fuel fraction of around (26 ± 6)%, a dominant biogenic contribution of on average (73 ± 7)% in summer and the continental as well as the maritime background TOC to be only about 50% biogenic. Assuming biomass burning as completely anthropogenic, the carbonaceous aerosol concentration at the mountain sites was found to have increased by a factor of up to (1.4 ± 0.2) in summer and up to (2.5 ± 1.0) in winter. This figure is significantly lower, however, than the respective TOC change since pre-industrial times seen in an Alpine ice core. Reconciling both observations would require an increase, since pre-industrial times, of the background biogenic aerosol load, which is estimated at a factor of 1.3–1.7.

The relationship between environmental factors and usage behaviors at ‘Hole-in-the-wall’ computers

This paper gathers and analyzes self-reported user behavior data for public computers installed in varied neighborhoods in India to explore the relationship between environmental factors such as urbanicity and reported usage behaviors. There is evidence of large differences in usage behavior between urban and non-urban sites. Children at urban sites fit a profile of dedicated and independent kiosk-goers, while rural children are more likely to use the computers in groups. Total overall computer usage, however, appears similar in both environments. The sites used for the study have other important characteristics, such as proximity to a school complex, which could have large mitigating effects on the measured behaviors. Further study could yield other interesting and more generalizable results. This study provides insight into children's behavior patterns at free-access ‘Hole-in-the-Wall’ computers as well as offers exploratory findings for the designers of free-access computers in developing nations where alternative educational development via technology could be implemented.

Observation of nighttime nitrous acid (HONO) formation at a non-urban site during PRIDE-PRD2004 in China

Though the importance of HONO as an OH precursor has been recognized for years, its chemical formation pathway is still not well understood. This inhibited the simulations of HONO and observation-based formation rates provided an alternative for the air quality models. However, HONO formation rate derived from certain period may be significantly influenced by uncertainties in transport and emission processes. In this study the use of large sample and scaling methods were recommended in the calculation of HONO formation rate. During the Program of Regional Integrated Experiments of Air Quality over Pear River Delta (PRIDE-PRD2004), good correlations between HONO and NO 2 were found supporting the involvement of NO 2 in HONO formation. An average NO 2 -to-HONO nighttime conversion rate C HONO of 1.6 % h - 1 was derived at a non-urban site Xinken. This conversion rate was comparable to other field measurements and could not be explained by gas phase reactions only. If assumed that HONO was formed only on the ground surface, the observed conversion rate could be explained by the reactions of NO 2 on ground surfaces only if three deposited NO 2 lead to one HONO released. The emission factor of HONO and its sampling interferences during the measurements were also evaluated in this article.

Regional Integrated Experiments on Air Quality over Pearl River Delta 2004 (PRIDE-PRD2004): Overview

The aims of the Program of Regional Integrated Experiments on Air Quality over Pearl River Delta of China 2004 (PRIDE-PRD2004) were to characterize in depth the pollution, and to improve the understanding of the chemical and radiative processes in the atmosphere of Pearl River Delta (PRD) in South-Eastern China. This comprehensive program integrated ground-base in situ measurements, vertical observations (including aircraft) and model simulations. The intensive field campaign was conducted from 4 October to 5 November 2004 at two super-sites: an urban site in Guangzhou city (23.13°N, 113.26°E) and a non-urban site at Xinken (22.61°N, 113.59°E). They were coordinated with concurrent meteorological observations as well as measurements at stations of a regional monitoring network. Quality control and quality assurances, application of closure studies and observation-based modeling were the key elements of the research strategies for the PRIDE-PRD2004 campaign. Knowledge and understanding of the important issues, including 3-D distribution of air pollution, ozone formation process and its control strategies, sources of volatile organic compounds, chemical and physical characteristics and radiative properties of aerosols, and the important role of nitrous acid atmospheric chemistry, have been improved substantially by this study.

Source apportionment of ambient volatile organic compounds in the Pearl River Delta, China: Part II

The chemical mass balance receptor model was applied to the source apportionment of 58 hydrocarbons measured at seven sites in a field campaign that examined regional air quality in the Pearl River Delta (PRD) region in the fall of 2004. A total of 12 volatile organic compound (VOC) emission sources were considered, including gasoline- and diesel-powered vehicle exhausts, headspace vapors of gasoline and diesel fuel, vehicle evaporative emissions, liquid petroleum gas (LPG) leakage, paint vapors, asphalt emissions from paved roads, biomass combustion, coal combustion, the chemical industry, and petroleum refineries. Vehicle exhaust was the largest source of VOCs, contributing to >50% of ambient VOCs at the three urban sites (Guangzhou, Foshan, and Zhongshan). LPG leakage played an important role, representing 8–16% of emissions at most sites in the PRD. Solvent usage was the biggest emitter of VOCs at Dongguan, an industrial site, contributing 33% of ambient VOCs. Similarly, at Xinken, a non-urban site, the evaporation of solvents and coatings was the largest emission source, accounting for 31% of emissions, probably because it was downwind of Dongguan. Local biomass combustion was a noticeable source of VOCs at Xinken; although its contribution was estimated at 14.3%, biomass combustion was the third largest VOC source at this site.

Social Monogamy in Kit Foxes: Formation, Association, Duration, and Dissolution of Mated Pairs

Social monogamy is characterized by long-term pair-bonds, but there is extensive variation among socially monogamous species in the timing of pair formation, the extent to which pair-mates associate throughout the year, the duration of pair-bonds, and the frequency with which pair-bonds are dissolved while both partners are living. We studied these aspects of social monogamy in kit foxes (Vulpes macrotis) at 1 urban and 2 nonurban sites. Behavior was similar across sites despite differences in ecological conditions. Pair formation occurred throughout the year, often within a month after the loss of a mate. Pair-mates associated throughout the year. Some pairs remained associated for more than 1 breeding season. Death of a pair-mate was the most common reason for the dissolution of a pair (14 of 16 cases). Two pairs dissolved while both partners were still living: 1 due to abandonment by a male of his pair-mate and territory and 1 due to displacement of a male by another male. These characteristics of social monogamy in kit foxes may be related to year-round territoriality, and may optimize individual fitness by enhancing survival and ultimately reproductive success.

Analysis of Visible/SWIR surface reflectance ratios for aerosol retrievals from satellite in Mexico City urban area

Abstract. The surface reflectance ratio between the visible (VIS) and shortwave infrared (SWIR) radiation is an important quantity for the retrieval of the aerosol optical depth (τa) from the MODIS sensor data. Based on empirically determined VIS/SWIR ratios, MODIS τa retrieval uses the surface reflectance in the SWIR band (2.1 µm), where the interaction between solar radiation and the aerosol layer is small, to predict the visible reflectances in the blue (0.47 µm) and red (0.66 µm) bands. Therefore, accurate knowledge of the VIS/SWIR ratio is essential for achieving accurate retrieval of aerosol optical depth from MODIS. We analyzed the surface reflectance over some distinct surface covers in and around the Mexico City metropolitan area (MCMA) using MODIS radiances at 0.66 µm and 2.1 µm. The analysis was performed at 1.5 km×1.5 km spatial resolution. Also, ground-based AERONET sun-photometer data acquired in Mexico City from 2002 to 2005 were analyzed for aerosol depth and other aerosol optical properties. In addition, a network of hand-held sun-photometers deployed in Mexico City, as part of the MCMA-2006 Study during the MILAGRO Campaign, provided an unprecedented measurement of τa in 5 different sites well distributed in the city. We found that the average RED/SWIR ratio representative of the urbanized sites analyzed is 0.73±0.06 for scattering angles &lt;140° and goes up to 0.77±0.06 for higher ones. The average ratio for non-urban sites was significantly lower (approximately 0.55). In fact, this ratio strongly depends on differences in urbanization levels (i.e. relative urban to vegetation proportions and types of surface materials). The aerosol optical depth retrieved from MODIS radiances at a spatial resolution of 1.5 km×1.5 km and averaged within 10×10 km boxes were compared with collocated 1-h τa averaged from sun-photometer measurements. The use of the new RED/SWIR ratio of 0.73 in the MODIS retrieval over Mexico City led to a significant improvement in the agreement between the MODIS and sun-photometer AOD results; with the slope, offset, and the correlation coefficient of the linear regression changing from (τaMODIS=0.91τa sun-photometer+0.33, R2=0.66) to (τaMODIS=0.96 τa sun-photometer−0.006, R2=0.87). Indeed, an underestimation of this ratio in urban areas lead to a significant overestimation of the AOD retrieved from satellite. Therefore, we strongly encourage similar analyses in other urban areas to enhance the development of a parameterization of the surface ratios accounting for urban heterogeneities.

Assessing the role of ammonia in sulfur transformation and deposition in China

Inorganic thermodynamic equilibrium model (ISORROPIA) coupled with the Models-3 Community Multi-scale Air Quality modeling system (CMAQ) was used to understand the role of ammonia (NH 3) in sulfur dioxide (SO 2) transformation and sulfur (S) deposition in China. The simulated S and nitrogen (N) compounds in gas (SO 2, NH 3) and aerosol (sulfate (SO 4 2−), ammonium (NH 4 +)) phases and wet deposition were compared against observations at two non-urban sites: Tie Shan Ping (TSP) and Cai Jia Tang (CJT). Observations showed that SO 4 2− was the predominant anion in aerosol and precipitation at the sites, and there were not enough NH 3 and alkaline dusts (i.e. mineral oxides and carbonates) to neutralize all acidity. Most of the NH 4 + was therefore probably bound to SO 4 2−. The presence of NH 3 significantly altered the regional distributions of S compounds in gas and aerosol phases. Model simulations showed SO 4 2− concentration increased by 10–15% while SO 2 concentration decreased by 10–60% over polluted regions due to NH 3. Furthermore, the presence of NH 3 enhanced long-range S transportation for the longer lifetime of sulfate than of SO 2 in the atmosphere. S deposition thereby decreased by 10–30% over polluted regions.

Seasonal variation of particulate lipophilic organic compounds at nonurban sites in Europe

Atmospheric aerosol samples, collected continuously during a sampling period longer than 1 year at six rural and background sites representing oceanic, rural and continental environments across Europe, were extracted, fractionated and analyzed by gas chromatography/mass spectrometry. The detailed organic speciation of the aerosol samples enabled the choice of some key compounds to assess the contribution of different sources. Lipophilic molecular markers were identified, including vehicle exhaust constituents, meat smoke tracers, phytosterols of higher photosynthetic plants and wood smoke components, especially from coniferous vegetation. The lowest concentrations and a quasi absence of seasonal cycle were observed at the oceanic background site of Azores. The highest values and a greater number of compounds were registered at the two continental lower‐level sites. Aveiro (a rural site close to the small coastal Portuguese city of Aveiro) and K‐puszta (Hungarian plains) both presented a seasonal variation with winter maxima attributable to a sizable contribution of wood‐burning and meat‐cooking sources. At the mountain sites (Puy de Dôme, Schauinsland and the high alpine summit of Sonnblick), concentrations maximized during summer as a result of the decoupling of the lower layers from the midtroposphere with wintry weather and the influence of boundary layer air masses during the warm season.

Climatology of aerosol composition (organic versus inorganic) at nonurban sites on a west‐east transect across Europe

In the framework of the European CARBOSOL project (Present and Retrospective State of Organic versus Inorganic Aerosol over Europe: Implications for Climate), atmospheric aerosol was continuously sampled for 2 years at six sites along a west‐east transect extending from Azores, in the mid‐Atlantic Ocean, to K‐Puszta (Hungary), in central Europe. Aerosols were analyzed for 210Pb, inorganic ions, elemental (EC) and organic (OC) carbon, water soluble organic carbon (WSOC), macromolecular type (humic‐like) organic substances (HULIS), C2–C5 diacids, cellulose, and levoglucosan. Pooled aerosol filters were also used for the identification of different families of organic compounds by gas chromatography/mass spectrometry, GC/MS, as well as 14C determinations. The data resulted in a climatological overview of the aerosol composition over Europe in the various seasons, from west to east, and from the boundary layer to the free troposphere. The paper first summarizes the characteristics of the sites and collected samples and then focuses on the aerosol mass partitioning (mass closure, inorganic versus organic, EC versus OC, water soluble versus insoluble OC), giving an insight on the sources of carbonaceous aerosol present in rural and natural background areas in Europe. It also introduces the main role of other companion papers dealing with CARBOSOL aerosol data that are also presented in this issue.

Observations of fine and coarse particle nitrate at several rural locations in the United States

Nitrate comprises an important part of aerosol mass at many non-urban locations during some times of the year. Little is known, however, about the chemical form and size distribution of particulate nitrate in these environments. While submicron ammonium nitrate is often assumed to be the dominant species, this assumption is rarely tested. Properties of aerosol nitrate were characterized at several IMPROVE monitoring sites during a series of field studies. Study sites included Bondville, Illinois (February 2003), San Gorgonio Wilderness Area, California (April and July 2003), Grand Canyon National Park, Arizona (May 2003), Brigantine National Wildlife Refuge, New Jersey (November 2003), and Great Smoky Mountains National Park, Tennessee (July/August 2004). Nitrate was found predominantly in submicron ammonium nitrate particles during the Bondville and San Gorgonio (April) campaigns. Coarse mode nitrate particles, resulting from reactions of nitric acid or its precursors with sea salt or soil dust, were more important at Grand Canyon and Great Smoky Mountains. Both fine and coarse mode nitrate were important during the studies at Brigantine and San Gorgonio (July). These results, which complement earlier findings about the importance of coarse particle nitrate at Yosemite and Big Bend National Parks, suggest a need to more closely examine common assumptions regarding the importance of ammonium nitrate at non-urban sites, to include pathways for coarse mode nitrate formation in regional models, and to consider impacts of coarse particle nitrate on visibility. Because coarse particle nitrate modes often extend well below 2.5 μm aerodynamic diameter, measurements of PM 2.5 nitrate in these environments should not automatically be assumed to contain only ammonium nitrate.

Study of water-soluble atmospheric humic matter in urban and marine environments

Recently, atmospheric humic matter or humic-like substances (HULIS) have been found in the water-soluble fraction of atmospheric aerosol sampled at different locations. Most of these locations were continental, non-urban sites. Therefore, in this work HULIS was studied in urban and marine environments. The atmospheric concentration varied over a wide range from 0.40 to 5.44 μg m − 3 , from the clean marine air (Mace Head, Ireland) to the heavily polluted winter urban atmosphere (Christchurch, New Zealand). In terms of carbon, ratio of HULIS was 19–51% of water-soluble organic carbon, and 10–22% of total carbon. Different spectroscopic techniques were applied for the physico-chemical characterisation of HULIS including relative aromaticity and molecular weight. Specific absorbance was observed to be much less variable than specific fluorescence, and consequently UV-VIS spectroscopy at λ > 330 nm was recommended for rapid, semi-quantitative determination of HULIS in the water extracts of atmospheric aerosol. Application of a dual filter sampling system at one of the sampling sites has revealed a significant positive sampling artefact which calls for further systematic studies on this subject, and also supports the idea of a secondary organic aerosol formation mechanism of HULIS.

Concentration and gas/particle partitioning of polychlorinated biphenyls (PCBs) at an industrial site at Bursa, Turkey

Gas and particle phase concentrations of atmospheric polychlorinated biphenyls (PCBs) were measured at an urban/industrial site in the city of Bursa, Turkey. PCB concentration levels were presented between July 2004 and May 2005. Average particle and gas phase concentrations of individual PCB congeners ranged from 0.08 (PCB-183) to 6.86 (PCB-49) pg m − 3 and from 0.01 (PCB-209) to 47.2 (PCB-33) pg m − 3 , respectively. The mean concentration of total (gas + particle) PCBs varied between 24.27 and 666.21 pg m − 3 with an average of 287.27 ± 174.80 pg m − 3 . PCB concentrations at the sampling site were higher than the concentrations reported at non-urban sites. PCBs partitioned between gas and particle phases and the partitioning was examined according to different approaches such as log K p–log P L o, log K p–log K OA and the Junge–Pankow model. In order to present possible interactions, a correlation matrix based on PCB congeners and meteorological parameters was constructed. Application of the Clausius–Clapeyron equation yielded a low slope value indicating possible emissions from local and regional sources originating mainly from urban/industrial areas, landfill and waste incineration plant. Then, likely dry deposition fluxes were estimated depending on reported dry deposition velocity and atmospheric concentration values.