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PubMed2007

Evaluation of groundwater contamination beneath an urban environment: the Besòs river basin (Barcelona, Spain).

The urban groundwater of the central Besòs river basin (the La Llagosta aquifer) has become contaminated due to the infiltration of wastewater from septic tanks and sewage networks, and by industrial activities located in urban areas. The groundwater hydrogeochemistry of the La Llagosta aquifer was characterized using isoconcentration maps, hydrogeochemical diagrams (Piper, Schoeller-Berkaloff) and by analyzing hydrogeochemical changes along a flow-path that crosses an urban and peripheral industrial area in the main alluvial aquifer (the La Llagosta unit). The evolution of cations, anions and heavy metals along the flow path and the use of the PHREEQC numerical code indicate a complex set of geochemical processes, which result from the interaction between the sources of pollution, the groundwater flow and the mineral composition of the aquifer materials. The contaminated groundwater below the urban areas shows high contents of NO(3)(-) (90-100 mg/L) and an increase in the concentrations of Ca(2+) and Mg(2+) which coincides with a decrease in pH. The Eh shows greater variation than the pH along the flow line studied, with values ranging between 56 mV in the industrial area and 370 mV in the urban area. The area with the lowest Eh value coincides with the highest concentrations of dissolved Fe (4.7 mg/L) and Mn (0.22 mg/L).

Cities↗
PubMed2006

Multivariate analysis of heavy metal contamination in urban dusts of Xi'an, Central China.

Though there are many studies of heavy metal contaminations of urban dusts in developed countries, little attention has been paid to this kind of study in developing countries, including China. Therefore, a series of investigations were performed to provide heavy metal signatures of urban dusts and to evaluate potential sources in Xi'an, Shaanxi Province. Sixty-five samples of urban dusts were collected in Xi'an. Then Ag, Cr, Cu, Mn, Pb and Zn concentrations were determined by using atomic absorption spectrophotometry, and As, Hg and Sb concentrations by atomic fluorescence spectroscopy. The results indicate that, in comparison with Chinese soil, urban dusts in Xi'an have elevated metal concentrations as a whole, except those of arsenic and manganese. These concentration levels are comparable to those in other studies. Correlation coefficient analysis, principal component analysis (PCA) and cluster analysis (CA) were performed and three main sources with corresponding cluster elements were identified: (1) Ag and Hg have commercial and domestic sources; (2) Cr, Cu, Pb, Sb and Zn are mainly derived from industrial sources, combined with traffic sources as well for Pb and Zn; (3) As and Mn come mainly from soil sources, and As also has an industrial source. Based on PCA and CA analyses, manganese was selected as the reference element, and heavy metal enrichment factors (Efs) were calculated, which in turn further confirms the source identification. Also, Efs give an insight of human influence degree of urban dusts.

Arsenic↗
PubMed2005

Sources of heavy metals and polycyclic aromatic hydrocarbons in urban stormwater runoff.

Polycyclic aromatic hydrocarbons (PAHs) and heavy metals were measured in road debris collecting in urban areas and in the suspended sediment (SS) component of runoff from two stormwater catchments in Dunedin, New Zealand. Levels in the road debris ranged from 119-527 microg/g for lead, 50-464 microg/g for copper, 241-1 325 microg/g for zinc and 1.20-11.6 microg/g for sigma16PAH. The SS from the largely rural catchment (20% urban) had similar concentrations to the road debris, indicating that this urban material was the main source of the contaminants measured in the stormwater. Similar PAH fingerprint profiles and isomer ratios indicative of dominant pyrogenic (combustion) sources were also found in these two groups of materials. The SS from the 100% urban catchment contained 2- to 6-fold higher concentrations of metals and 10-fold greater levels of sigma16PAH. The higher levels of lead and copper were probably a result of industrial land uses in this catchment, while the additional zinc was linked to an abundance of zinc-galvanised roofing iron in the catchment's residential suburbs. The PAH profiles and isomer ratios were different for this urban catchment and suggested that a disused gasworks was contributing PAHs to the stormwater runoff.

Copper↗
PubMed2005

Blood lead level in dogs from urban and rural areas of India and its relation to animal and environmental variables.

Lead is a common environmental pollutant with deleterious health effects on human and animal. Industrial and other human activities enhance the lead level in the environment leading to its higher residues in exposed population. The present study was aimed at determining blood lead concentration in dogs from two urban areas and in surrounding rural areas of India and analyzing lead level in dogs in relation to environmental (urban/rural) and animal (age, sex, breed and housing) variables. Blood samples were collected from 305 dogs of either sex from urban (n=277) and unpolluted rural localities (n=28). Irrespective of breed, age and sex, the urban dogs had significantly (P<0.01) higher mean blood lead concentration (0.25+/-0.01 microg/ml) than rural dogs (0.10+/-0.01 microg/ml). The mean blood lead level in stray dogs either from urban or rural locality (0.27+/-0.01 microg/ml) was significantly (P<0.01) higher than that of pets (0.20+/-0.01 microg/ml), and the blood lead concentration was significantly higher in nondescript dogs (0.25+/-0.01 microg/ml) than pedigreed dogs (0.20+/-0.01 microg/ml). The locality (urban/rural) was the major variable affecting blood lead concentration in dogs. Breed and housing of the dogs of urban areas and only housing (pet/stray) in rural areas significantly (P<0.01) influenced the blood lead concentration in dogs.

Animals↗
PubMed2006

Heavy metal and trace element distributions in groundwater in natural slopes and highly urbanized spaces in Mid-Levels area, Hong Kong.

The lower slope of the Mid-Levels area, Hong Kong, is one the most heavily urbanized coastal areas in the world. A comprehensive groundwater heavy metal and trace element study was conducted in the Mid-Levels area aiming to investigate the impacts of urbanization on the aqueous distributions of these chemicals. Groundwater samples were collected in the upper natural slopes and the lower highly urbanized spaces in the area in different seasons, and analyzed for heavy metal and trace element contents. Compared to the results from natural slopes, groundwater samples in the developed spaces did not exhibit significant elevated levels in Zn, Cr, Cu, Cd, Pb and Fe, which are commonly found in stormwater. On the other hand, the samples were found to have elevated contents in Mn, V, Co and Mo, minor stormwater-related heavy metals, suggesting that stormwater drains may be leaking to some extent. However, the results suggested that the vadose zone could remove many of the heavy metals, protecting groundwater from being contaminated seriously. Statistical analysis suggested that a certain amount of Mn and Co was likely to be re-mobilized from natural soils due to the changes in local redox conditions, while Mn, V, Co and Mo may also be derived from steel corrosion as a result of prolonged submergence. Besides, the average B concentration in the developed spaces was about eight times higher than that in the natural slopes, indicating the presence of sewage. The mean Se concentration in the developed spaces was about 100 times higher than that in the natural slopes. About 40% of samples in the developed spaces contained Se level higher than the drinking water guideline value proposed by the World Health Organization. Se was found to be positively correlated with B and SO4(2-) (R = 0.534 and 0.631, respectively), suggesting that Se may also be related to leakage from sewage pipes. Part of the Sr may come from leakage of flushing water and/or sewage as Sr was strongly correlated with Cl- (R = 0.929). According to the measured results, deep groundwater samples collected from piezometers (> 10 m in depth) in the urbanized spaces appeared to be virtually free from any anthropogenic contaminations. This study may shed important light on the identification and evaluation of leakage from service pipes in a particular area based on aqueous distributions of heavy metals and trace elements. Moreover, the above findings may be instructional for other coastal cities with a similar level of urban development to understand the potential threats to their groundwater resources.

Cities↗
PubMed2006

Comparison of MTBE concentrations in groundwater of urban and nonurban areas in Germany.

The occurrence of the gasoline oxygenate methyl tert-butyl ether (MTBE) in groundwater samples from known fuel-contaminated sites (n=29 samples), nonurban (n=74) and urban sites (n=67) in Germany was investigated. The analyses revealed detection frequencies of 58% (contaminated sites), 24% (nonurban sites) and 63% (urban sites) at a detection limit of 0.01 microgL(-1). Median (maximum) MTBE concentrations were calculated for nonurban and urban samples as 0.18 microgL(-1) (2.2 microgL(-1)) and 0.06 microgL(-1) (48 microg L(-1)). The data from nonurban samples revealed MTBE detections mainly at public supply wells with higher pumping rates than monitoring wells. MTBE was more frequently detected in urban samples, most probably due to the higher atmospheric input and direct liquid emissions from motorways or gas stations. Higher concentrations above 1.0 microgL(-1) in urban areas were found in wells located at industrial sites, where also a MTBE plume was accidentally detected during the study. The prevalence of MTBE in shallow aquifers was comparable to those in the USA.

Cities↗
PubMed2003

Evolution of antibiotic occurrence in a river through pristine, urban and agricultural landscapes.

A river along the semi-arid Front Range of Colorado was monitored for antibiotics including five tetracycline and six sulfonamide compounds. Existing analytical methods were adapted to measure these compounds in a surface water matrix at environmentally relevant concentrations (0.05 microg/L). Natural organic matter present in surface waters was confirmed to significantly impact the low-level analysis of tetracyclines (TCs) necessitating the use of standard addition quantification techniques. Five sites along the Cache la Poudre River were monitored for antibiotics encompassing pristine areas without anthropogenic influence, urban areas impacted by wastewater discharges and agricultural areas susceptible to non-point source contaminant runoff. The only site at which no antibiotics were detected was the pristine site in the mountains before the river had encountered urban or agricultural landscapes. By the time the river had exited the urban area, 6 of the 11 antibiotic compounds that were monitored were found in the samples. At Site 5, which had both urban and agricultural influences all five of the TCs monitored were detected indicating both urban and agricultural influences. The concentration of TCs at Site 5 ranged from 0.08 to 0.30 microg/L.

Agriculture↗
PubMed2004

Chemical properties of urban waste ash produced by open burning on the Jos Plateau: implications for agriculture.

Urban centres produce most of the world's waste and between a third and a half goes uncollected. The answer to the problem of waste disposal lies partly in agriculture, as waste can be extremely nutrient-rich. In the last decade there has been a tremendous increase in the developing world in total city area under informal food production and there are many examples of waste recycling onto the urban or peri-urban plots. Farmers on the Jos Plateau, Nigeria, have developed a successful soil fertility management strategy based on the combination of inorganic fertilisers, manure and urban waste ash. This study sought to provide some preliminary data on urban waste ash produced by open burning and used in farming in a developing country. Ash samples were collected from different locations around Jos and tested for C, N, pH, P, Na, K, Ca, Mg, Fe, Mn, Zn, Cu, Ni, Cd and Pb. It was found that ash is an effective liming material (because of the high pH, and high Ca, Mg and K contents), and has the potential to contribute significant quantities of micro-nutrients such as Mn, Zn and Cu. Ash, however, is far from being a homogenous material and its variability means that its fertilising potential will vary between batches and that, even if mean and median levels are low, there is the risk of the formation of localised areas of soil with excessive heavy metal contents (this is particularly the case with Pb). Further research is required to determine the plant-availability of these elements in the ash and to assess the wider environmental and health implications of uncontrolled, open burning of waste as a means of producing ash for agricultural purposes.

Agriculture↗
PubMed1998

The source and fate of Pb in contaminated soils at the urban area of Falun in central Sweden.

For centuries the city of Falun in central Sweden has been an important industrial region of copper mining, producing sulphuric acid and paint pigment. The mining and chemical industries have generated vast amounts of wastes which have been deposited around the areas. A large part of the city is now built on the wastes. In the last two decades, significant amounts of work on the waste management have been conducted. Previous investigations showed that the soils of the urban areas have been contaminated by the wastes with a rather high level of lead (Pb). What is the speciation of soil-Pb? How does the Pb reach the biosphere? This paper gives answers toward these environmental problems. This study investigates the distribution of Pb in the urban soils by means of chemical and mineralogical methods the quantity and quality of the fallout particles; and traces the potential sources of contamination. The data indicate that in Falun urban soil-Pb speciation, many mainly be associated with some mineral phases, e.g. Fe and Mn oxides, sulphides, Pb-carbonates, as well as retained by organic matters and clay minerals. The concentrations of water soluble Pb are very low. Because of the properties of the Pb-bearing phases, the high concentrations of soil-Pb in the urban area are not likely to have a significant affect on the blood-Pb levels of pre-school children living in the urban areas. Lead and arsenic are found to be associated with iron oxides in the fallout particles collected in the areas. These fine grained particles may have been distributed through wind-related transportation from the industrial wastes dumped in the areas.

Biological Availability↗
PubMed2000

Occurrence of pesticides in rain and air in urban and agricultural areas of Mississippi, April-September 1995.

In April 1995, the US Geological Survey began a study to determine the occurrence and temporal distribution of 49 pesticides and pesticide metabolites in air and rain samples from an urban and an agricultural sampling site in Mississippi. The study was a joint effort between the National Water-Quality Assessment and the Toxic Substances Programs and was part of a larger study examining the occurrence and temporal distribution of pesticides in air and rain in the Mississippi River basin. Concurrent high-volume air and wet-only deposition samples were collected weekly. The air samplers consisted of a glass-fiber filter to collect particles and tandem polyurethane foam plugs to collect gas-phase pesticides. Every rain and air sample collected from the urban and agricultural sites had detectable levels of multiple pesticides. The magnitude of the total concentration was 5-10 times higher at the agricultural site as compared to the urban site. The pesticide with the highest concentration in rain at both sites was methyl parathion. The pesticide with the highest concentration in the air samples from the agricultural site was also methyl parathion, but from the urban site the highest concentration was diazinon followed closely by chlorpyrifos. More than two decades since p,p'-DDT was banned from use in the United States, p,p'-DDE, a metabolite of p,p'-DDT, was detected in every air sample collected from the agricultural site and in more than half of the air samples from the urban site.

Agriculture↗
PubMed1997

Stemflow chemistry of urban street trees.

pH and ion concentrations (Na(+), K(+), Mg(2+), Ca(2+), NO(-)(3)) in the stemflow of the evergreen broad-leaved tree, Ilex rotunda, planted in the median strip of a highway and nitrogen oxides concentration in the air in an urban site were compared with a suburban site in Fukuoka city, Japan. The annual average of the nitrogen oxides concentration in the air was higher and NO(-)(3) concentration in the stemflow at the urban site was higher or similar compared with the suburban site. However, the annual average of pH in the stemflow at the urban site was higher than at the suburban. The annual average cation concentrations in the stemflow at the urban site were higher than at the suburban except Na(+). In particular, K(+) and Ca(2+) were higher throughout the measurement period. Therefore, higher pH in the urban stemflow was probably due to neutralization by higher concentrations of K(+), Mg(2+) and Ca(2+).

Journal Article↗
PubMed2000

Urban girls, internet use, and accessing health information

Background: With the burgeoning growth of the Internet, many have raised concerns over whether and how underserved populations might be included in the Information Revolution. This study examines how urban adolescent girls access the Internet and whether it is a viable source for health information.Methods: During Fall 1999 in New York City, 176 girls completed an anonymous survey where half were from a private high school (N = 86) and the other half were patients at a health clinic serving ethnically diverse and disadvantaged youth (N = 90). Data were analyzed to provide information on how urban girls use the Internet.Results: Internet use was widespread; 99% of the high school and 83% of the clinic girls said they used this medium (p <.001). On frequency, 32% of high school girls compared to 13% of the clinic girls used the Internet 6-7 days/wk (p <.001). Among the high school girls, 30% indicated that they used the Internet less than 30 min/wk and another 18% reported using the Internet more than 5 hrs/wk. Among clinic girls, 51% used the Internet less than 30 min/wk while 9% reported more than 5 hrs/wk. Comfort levels differed with 20% of the high school compared to 10% of the clinic girls reporting "extreme" comfort using the Internet (p <.001).Urban girls accessed the Web from multiple locales. Almost all (98%) of the high school girls compared to 45% of the clinic girls reported that they used the Internet from home (p <.001). Most high school girls (82%) used the Internet at school compared to 63% of the clinic girls currently in school (p <.05). More clinic girls used the Internet at another family member's house (28% vs. 14%, p <.05). Similar percentages of high school and clinic girls used the Internet at a friend's house (46%), the library (31%), or a community center (3%).With similar rates among high school and clinic girls, 44% reported that they had tried to get health information from the Web. Of these (N = 74), 50% said that they got information on different diseases, 43% on diet/nutrition, 34% on fitness/exercise, 26% on sex, 24% on alcohol/drug abuse, 20% on mental health, 14% on medicines, 12% on violence among peers, 10% on parenting, 8% on violence among dating partners, 7% on tobacco and smoking, 7% on emotional or physical abuse, 3% on sexual abuse, and 1% on illness support groups. Clinic girls were more likely to have tried to get information on sex (p <. 001) and parenting (p <.001) from the Web. Many girls (59%) indicated that it was "very" or "extremely" worthwhile to have general health information on the Web, with no significant differences between high school and clinic girls. As well, 71% and 62% said it was "very" or "extremely" worthwhile to have access to contraceptive and diet/nutrition information, respectively. Conclusions. High school girls, as anticipated, were technologically savvy. Somewhat surprising, however, were the clinic girls' high levels of Internet use and access. Significant differences revealed that the high school girls were more on-line than clinic girls, but clinic girls were still using the Web frequently. A considerable number or urban girls had tried to get a range of health information from the Internet. This study offers promising statistics on how urban adolescent girls are accessing and using the Internet, especially for health information.

Journal Article↗
PubMed1998

Genotoxicity of coke-oven and urban air particulate matter in in vitro acellular assays coupled with 32P-postlabeling and HPLC analysis of DNA adducts.

This study is an in vitro part of the ongoing biomarker studies with population from a polluted region of Northern Bohemia and coke-oven workers from Czech and Slovak Republics. The aim of this study is to compare DNA adduct forming ability of chemical compound classes from both the urban and coke-oven extractable organic mass (EOM) of airborne particles. The crude extracts were fractionated into seven fractions by acid-base partitioning and silica gel column chromatography. In in vitro acellular assays we used calf thymus DNA (CT DNA) with oxidative (+S9) and reductive activation mediated by xanthine oxidase (+XO) under anaerobic conditions. Both the butanol and nuclease P1 versions of 32P-postlabeling for detection of bulky aromatic and/or hydrophobic adducts were used. The results showed that the spectra of major DNA adducts resulting from both the in vitro assays are within the fractions similar for both the urban and coke-oven samples. The highest DNA adduct levels with S9-activation were detected for the neutral aromatic fraction, followed by slightly polar and acidic fractions for both samples. With XO-mediated metabolism, the highest DNA adduct levels were detected for both the acidic fractions. Assuming additivity of compound activities, then the acidic fraction, which in the urban sample comprises a major portion of EOM mass (28%), may contain the greatest activity in both in vitro assays (39 and 69%, +S9 and +XO, respectively). In contrast, the aromatic fraction constituting only 8% of total urban EOM mass may account for comparable activity (34%) with organic acids. The highest DNA adduct forming activity of the coke-oven sample accounts for the aromatic fraction (82 and 63%, +S9 and +XO, respectively) that also contains the greatest portion of the total EOM (48%). To characterize some of the specific DNA adducts formed, we coupled TLC on 20x20 cm plates with HPLC analysis of 32P-postlabeled adducts. In both S9-treated samples of the aromatic fraction, we tentatively identified DNA adducts presumably diolepoxide-derived from: 9-hydroxy-benzo[a]pyrene (9-OH-B[a]P), benzo[a]pyrene-r-7,t-8-dihydrodiol-t-9,10-epoxide[+/-] (anti-BPDE), benzo[b,j,k]fluoranthenes (B[b]F, B[j]F, B[k]F), chrysene (CHRY), benz[a]-anthracene (B[a]A) and indeno[cd]pyrene (I[cd]P). These DNA adducts accounted for about 57% of total DNA adducts detected in both S9-treated samples of the aromatic fraction. DNA adducts of XO-treated samples were sensitive to nuclease P1 and HPLC profiles of the major adducts were markedly different from the major adducts of S9-treated samples. However, the combination of TLC and HPLC did not confirm the presence of DNA adducts derived from 1-nitropyrene (1 NP), 9-nitroanthracene (9 NA) and 3-nitrofluoranthene (3 NF) that were detected by GC-MS in the slightly polar fraction. We concluded that the chemical fractionation procedure facilitates the assessing of DNA adduct forming ability of different chemical compound classes. However, based on the results obtained with the whole extracts, it does not fulfil a task of the actual contribution of individual fractions within the activity of the whole extracts. Our results are the first in detecting of DNA adducts derived from urban air and coke-oven particulate matter.

Air Pollutants↗
PubMed2001

Atmospherically derived organic surface films along an urban-rural gradient.

Atmospherically derived organic films have been found on an impervious surface along an urban-rural gradient in the Toronto, Ontario, Canada area. Film thickness and concentrations, expressed on an aerial basis, of sigman-alkanes, sigmaPCB, sigmaPAH, and sigmaOC (organochlorine) pesticides decrease along this gradient, coincident with lower atmospheric emissions (PCB and PAH) and less accumulation in thinner rural films (OC pesticides). For PCBs and some OC pesticides, patterns of chemical abundance also shift, indicating a "fresh" pattern near emission sources (downtown) versus aged patterns at rural locations that are indicative of atmospheric transport. Plant-derived n-alkane concentrations were greater at urban than rural sites, and we hypothesize greater urban plant wax production and erosion due to air pollution. As expected, along the urban-rural gradient the concentration of particle-phase PAH decreased more rapidly than that of gas-phase compounds, but unexpectedly the contribution of alkylated PAH increased from urban to rural locations. Distances over which concentrations decline by 63% vary from 50 km for persistent gas-phase compounds (e.g., P1,2CB) to 10-20 km for reactive gas-phase compounds (e.g., naphthalene, fluoranthene) to <5-10 km for particle-phase compounds (e.g., P6-10CB, benzo[b]fluoranthene, benzo[e]pyrene).

Air Pollutants↗
PubMed2002

Precipitation scavenging of polychlorinated biphenyls and polycyclic aromatic hydrocarbons along an urban to over-water transect.

Concentrations of semi-volatile organic compounds in dissolved and particulate forms in precipitation are related to those measured concurrently in air measured at multiple locations along the tracks of several storms. In 14 paired (air and precipitation) samples collected at urban, over-water, and downwind stations around southern Lake Michigan, compound-specific total (gas + particle) precipitation scavenging ratios range from 180 to 8.2 x 10(7) (fluorene and benzo[a]pyrene, respectively) for PAHs and from 0.5 to 1.1 x 10(7) for PCBs (PCB26 and PCB194, respectively). Particle scavenging, rather than gas scavenging, is the dominant removal mechanism for both PAHs and PCBs in all samples collected along the urban to over-watertransect. Variations in measured total scavenging ratios within the 14 samples are large (from 69 to 1.00 x 10(6) for sigma-PAHs and from 290 to 88,000 for total sigma-PCBs), with larger variation between samples of differing storms collected at a single location than among samples of the same storm collected along the urban to rural transect. This minimal variance of scavenging ratio during the transport of a storm across multiple locations holds in two of three storms measured at multiple locations along the urban to over-water to rural storm track. This suggests that scavenging mechanisms are largely variable between storms and that the relative importance of each mechanism can occasionally also vary greatly during the progression of the storm from the urban to downwind locations. Furthermore, precipitation scavenging appears to be more variable between storms and generally less variable during progression of a storm down transect, indicating that meteorologic and precipitation characteristics, generally referred to here as storm type, control precipitation scavenging.

Air Pollutants↗
PubMed2005

Multisite study of particle number concentrations in urban air.

Particle number concentration data are reported from a total of eight urban site locations in the United Kingdom. Of these, six are central urban background sites, while one is an urban street canyon (Marylebone Road) and another is influenced by both a motorway and a steelworks (Port Talbot). The concentrations are generally of a similar order to those reported in the literature, although higher than those in some of the other studies. Highest concentrations are at the Marylebone Road site and lowest are at the Port Talbot site. The central urban background locations lie somewhere between with concentrations typically around 20 000 cm(-3). A seasonal pattern affects all sites, with highest concentrations in the winter months and lowest concentrations in the summer. Data from all sites show a diurnal variation with a morning rush hour peak typical of an anthropogenic pollutant. When the dilution effects of windspeed are accounted for, the data show little directionality at the central urban background sites indicating the influence of sources from all directions as might be expected if the major source were road traffic. At the London Marylebone Road site there is high directionality driven by the air circulation in the street canyon, and at the Port Talbot site different diurnal patterns are seen for particle number count and PM10 influenced by emissions from road traffic (particle number count) and the steelworks (PM10) and local meteorological factors. Hourly particle number concentrations are generally only weakly correlated to NO(x) and PM10, with the former showing a slightly closer relationship. Correlations between daily average particle number count and PM10 were also weak. Episodes of high PM10 concentration in summer typically show low particle number concentrations consistent with transport of accumulation mode secondary aerosol, while winter episodes are frequently associated with high PM10 and particle number count arising from poor dispersion of local primary emissions.

Air Pollutants↗
PubMed2005

Using passive air samplers to assess urban-rural trends for persistent organic pollutants and polycyclic aromatic hydrocarbons. 2. Seasonal trends for PAHs, PCBs, and organochlorine pesticides.

This is the second of two papers demonstrating the feasibility of using passive air samplers to investigate persistent organic pollutants along an urban-rural transect in Toronto. The first paper investigated spatial trends for polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs). This second paper investigates the seasonality of air concentrations for polycyclic aromatic hydrocarbons (PAHs), PCBs, and OCPs along this transect. Air samplers, consisting of polyurethane foam (PUF) disks housed in stainless steel domed chambers, were deployed for three 4-month integration periods from June 2000 to July 2001. The seasonal variations of derived air concentrations for PAHs, PCBs, and OCPs reflected the different source characteristics for these compounds. PAHs showed a strong urban-rural gradient with maximum concentrations at urban sites during the summer period (July-October). These high summer values in Toronto were attributed to increases in evaporative emissions from petroleum products such as asphalt. PCBs also exhibited a strong urban-rural gradient with maximum air concentrations (approximately 2-3 times higher) during the spring period (April-June). This was attributed to increased surface-air exchange of PCBs that had accumulated in the surface layer over the winter. alpha-HCH was fairly uniformly distributed, spatially and temporally, as expected. This pattern and the derived air concentration of approximately 35 to approximately 100 pg m(-3) agreed well with high volume air data from this region, adding confidence to the operation of the passive samplers and showing that site-to-site differences in sampling rates was not an issue. For other OCPs, highest concentrations were observed during the spring period. This was associated with either (i) their local and/or regional application (gamma-HCH, endosulfan) and (ii) their revolatilization (chlordanes, DDT isomers, dieldrin, and toxaphene). Principal component analysis resulted in clusters for the different target chemicals according to their chemical class/source type. The results of this study demonstrate how such a simple sampling technique can provide both spatial and seasonal information. These data, integrated over seasons, can be used to evaluate contaminant trends and the potential role of large urban centers as sources of some semivolatile compounds to the regional environment, including the Great Lakes ecosystem.

Air↗
PubMed1997

Mobilization of iron from urban particulates leads to generation of reactive oxygen species in vitro and induction of ferritin synthesis in human lung epithelial cells.

Many of the biochemical effects of asbestos in cultured cells have been shown to be due to iron, which can be as high as 27% by weight. Urban air particulates also contain iron, and some of the pathological effects after inhalation may be due to reactive oxygen species produced by iron-catalyzed reactions. Two standard reference material (SRM) urban air particulate samples were used for the studies described here. SRM 1648 (3.9% iron by weight) was collected in the St. Louis, MO, area, and SRM 1649 (3% iron by weight) was collected in the Washington, DC, area. To determine if iron associated with urban particulates could be mobilized, as it is from asbestos, SRMs 1648 and 1649 were incubated with 1 mM citrate or EDTA, in the presence or absence of ascorbate. Iron was mobilized from both particulates by either chelator, especially in the presence of ascorbate. Citrate, in the presence of ascorbate, mobilized 30.9 nmol of Fe/mg of SRM 1648 and 65.1 nmol of Fe/mg of SRM 1649 in 24 h. EDTA, in the presence of ascorbate, mobilized 53.8 nmol of Fe/mg of SRM 1648 and 98.8 nmol of Fe/mg of SRM 1649 in 24 h. To determine whether reactive oxygen species were being produced by the particulate iron, each particulate was incubated with phi X174 RFI DNA in the presence or absence of ascorbate. Single-strand breaks (SSBs) were produced by either particulate, but only in the presence of ascorbate. Incubation of SRM 1648 or 1649 (0.5 mg/mL) with DNA in the presence of ascorbate and citrate resulted in 20% or 34% DNA with SSBs, respectively. Incubation of SRM 1648 or 1649 (0.1 mg/mL) with DNA in the presence of ascorbate and EDTA resulted in 26% or 45% DNA with SSBs, respectively. To determine if iron associated with urban particulates could be mobilized by human lung epithelial cells (A549), cells were treated with particulates and the amount of the iron storage protein ferritin was determined at the end of treatment. The 6.4- or 8.4-fold increase in ferritin observed in cells treated with SRM 1648 or 1649, respectively, over that of control (untreated) cells strongly suggested that iron was mobilized in the cultured cells. If similar mobilization and reactivity of the iron occurs in the lung, this may explain some of the pathological effects of urban particulates.

Air Pollutants↗