Effects of Instrument Precision and Spatial Variability on the Assessment of the Temporal Variation of Ambient Air Pollution in Atlanta,Georgia

Abstract

Data from the U.S. Environmental Protection Agency Air Quality System, the Southeastern Aerosol Research and Characterization database, and the Assessment of Spatial Aerosol Composition in Atlanta database for 1999 through 2002 have been used to characterize error associated with instrument precision and spatial variability on the assessment of the temporal variation of ambient air pollution in Atlanta, GA. These data are being used in time series epidemiologic studies in which associations of acute respiratory and cardiovascular health outcomes and daily ambient air pollutant levels are assessed. Modified semivariograms are used to quantify the effects of instrument precision and spatial variability on the assessment of daily metrics of ambient gaseous pollutants (SO₂, CO, NO_x, and O₃) and fine particulate matter ([PM_2.5] PM_2.5 mass, sulfate, nitrate, ammonium, elemental carbon [EC], and organic carbon [OC]). Variation because of instrument imprecision represented 7–40% of the temporal variation in the daily pollutant measures and was largest for the PM_2.5 EC and OC. Spatial variability was greatest for primary pollutants (SO₂, CO, NO_x, and EC). Population–weighted variation in daily ambient air pollutant levels because of both instrument imprecision and spatial variability ranged from 20% of the temporal variation for O₃ to 70% of the temporal variation for SO₂ and EC. Wind rose plots, corrected for diurnal and seasonal pattern effects, are used to demonstrate the impacts of local sources on monitoring station data. The results presented are being used to quantify the impacts of instrument precision and spatial variability on the assessment of health effects of ambient air pollution in Atlanta and are relevant to the interpretation of results from time series health studies that use data from fixed monitors.     

Large-scale spatial pollution patterns around the North Sea indicated by coastal bird eggs within an EcoQO programme

To categorize the marine environmental health status, the Oslo and Paris commissions have recently formulated Ecological Quality Objectives (EcoQOs) for many ecological features including the contamination of coastal bird eggs with mercury and organochlorines. In this study, we describe spatial and temporal patterns of egg contamination around the North Sea and compared them to the EcoQOs. Concentrations of mercury, polychlorinated biphenyl (??PCB) congeners, dichlorodiphenyltrichloroethane (??DDT) and derivatives, hexachlorobenzene (HCB) and hexachlorocyclohexane (??HCH) isomers were analysed in two tern species (Sterna hirundo and Sterna paradisaea) and Oystercatcher (Haematopus ostralegus) eggs collected between 2008 and 2010 in a total of 21 sites in seven countries surrounding the North Sea. Hg, ??PCB and HCB were highest in the southern sites, while ??DDT and ??HCH concentrations were greatest in eggs from the western North Sea and the Elbe estuary. There were rarely any consistent decreases over time for any compounds. In the terns, Hg, HCB and ??HCH increased at most sites, ??PCB and ??DDT in Sweden and Norway. In the Oystercatcher, HCB and ??HCH increased at more than the half of the sites, ??PCB, ??DDT and Hg at several German sites. In the terns, Hg, ??PCB and ??DDT exceeded the EcoQO in all, HCB in most years and sites. At most sites, ??HCH fulfilled the EcoQO in some study years. In the Oystercatcher, Hg, ??PCB and ??DDT exceeded the EcoQO in all or most years and sites. HCB and ??HCH fulfilled the EcoQO in some or all years at most sites. The EcoQO was exceeded most frequently in estuaries. We conclude that EcoQOs are suitable for drawing contamination patterns of the coastal North Sea in an easily understandable manner, offering the opportunity to harmonize the EcoQOs with coordinated environmental monitoring programmes.     

Temporal variability in dynamic and colloidal metal fractions determined by high resolution in situ measurements in a UK estuary

In recent environmental legislation, such as the Water Framework Directive in the European Union (WFD, 2000/60/EC), the importance of metal speciation and biological availability is acknowledged, although analytical challenges remain. In this study, the Voltammetric In situ Profiler (VIP) was used for high temporal resolution in situ metal speciation measurements in estuarine waters. This instrument simultaneously determines Cd, Cu and Pb species within a size range (ca. <4 nm) that is highly relevant for uptake by organisms. The colloidal metal fraction can be quantified through a combination of VIP measurements and analyses of total dissolved metal concentrations.VIP systems were deployed over tidal cycles in a seasonal study of metal speciation in the Fal Estuary, southwest England. Total dissolved concentrations were 4.97-315 nM Cu, 0.13-8.53 nM Cd and 0.35-5.75 nM Pb. High proportions of Pb (77 ± 17%) and Cu (60 ± 25%) were present as colloids, which constituted a less important fraction for Cd (37 ± 30%). The study elucidated variations in the potentially toxic metal fraction related to river flow, complexation by organic ligands and exchanges between dissolved and colloidal phases and the sediment. Based on published toxicity data, the bioavailable Cu concentrations (1.7-190 nM) in this estuary are likely to severely compromise the ecosystem structure and functioning with respect to species diversity and recruitment of juveniles. The study illustrates the importance of in situ speciation studies at high resolution in pursuit of a better understanding of metal (bio)geochemistry in dynamic coastal systems.     

Monitoring plastic ingestion by the northern fulmar Fulmarus glacialis in the North Sea

The abundance of plastics in stomachs of northern fulmars from the North Sea is used in the OSPAR Ecological Quality Objective (EcoQO) for marine litter. The preliminary EcoQO defines acceptable ecological quality as the situation where no more than 10% of fulmars exceed a critical level of 0.1 g of plastic in the stomach. During 2003-2007, 95% of 1295 fulmars sampled in the North Sea had plastic in the stomach (on average 35 pieces weighing 0.31 g) and the critical level of 0.1 g of plastic was exceeded by 58% of birds, with regional variations ranging from 48 to 78%. Long term data for the Netherlands since the 1980s show a decrease of industrial, but an increase of user plastics, with shipping and fisheries as the main sources. The EcoQO is now also used as an indicator for Good Environmental Status in the European Marine Strategy Framework Directive.     

Soil intervention as a strategy for lead exposure prevention: the New Orleans lead-safe childcare playground project

The feasibility of reducing children's exposure to lead (Pb) polluted soil in New Orleans is tested. Childcare centers (median = 48 children) are often located in former residences. The extent of soil Pb was determined by selecting centers in both the core and outlying areas. The initial 558 mg/kg median soil Pb (range 14-3692 mg/kg) decreased to median 4.1 mg/kg (range 2.2-26.1 mg/kg) after intervention with geotextile covered by 15 cm of river alluvium. Pb loading decreased from a median of 4887 μg/m(2) (454 μg/ft(2)) range 603-56650 μg/m(2) (56-5263 μg/ft(2)) to a median of 398 μg/m(2) (37 μg/ft(2)) range 86-980 μg/m(2) (8-91 μg/ft(2)). Multi-Response Permutation Procedures indicate similar (P-values = 0.160-0.231) soil Pb at childcare centers compared to soil Pb of nearby residential communities. At ～$100 per child, soil Pb and surface loading were reduced within hours, advancing an upstream intervention conceptualization about Pb exposure prevention.     

A municipal solid waste incinerator as the single dominant point source of PCDD/Fs in an area of increased non-Hodgkin's lymphoma incidence

Since 1971, a municipal solid waste incinerator (MSWI) with high dioxin emission levels has been in operation in Besan?on, France. We recently found a 2.3-fold risk of non-Hodgkin's lymphoma in the highest exposure zone using a Gaussian-type dispersion model as a proxy for dioxin exposure. However, the sources of PCDD/Fs in this area are a matter of controversy. The aim of this survey was therefore to examine the nature of the PCDD/F soil contamination in the surroundings of the MSWI to characterize whether more than one potential emission source could explain the presence of the PCDD/Fs. PCDD/F congener profiles were determined in 75 soil samples collected in the vicinity of the MSWI. They were compared according to the most environmentally impacted zones and to various spatial contrasts. PCDD/F concentrations ranged from 0.25 to 28.06 pg WHO-TEQ g(-1). Two different clustering algorithms identified the same main cluster (consisting of 73 samples). The remaining two soil samples composed either one, or two clusters. All clusters showed similar congener profiles. Moreover, no contrast was observed for congener distributions between complex and simple topographies, inside and outside the city boundary, the two most and the two least exposed areas, reflecting a common fingerprint. Congener profiles indicate that the area under influence of the MSWI is not subject to other point sources of PCDD/Fs. Since, the most polluting combustion chambers were recently shut down and replaced by a new one with up-to-date pollution control, slowly decreasing dioxin concentrations in the soils are to be expected.     

Water quality indices across Europe--a comparison of the good ecological status of five river basins

The European Water Framework Directive (WFD) requires the definition of near-natural reference conditions to determine the extent of water bodies' deviation from "good ecological status" caused by stress gradients. However, the classification of ecological quality depends on the assessment method applied and the stressor concerned. While assessment methods that are generally applicable would be favourable, many European countries employ the locally developed water quality metrics that assess the impact of organic pollution (including eutrophication) and the associated decrease in dissolved oxygen. These indices do not specifically address stress from organic toxicants, such as pesticides. The aim of this study was to examine the performance of presently used assessment methods to identify reference conditions of non-contaminated streams in five selected European river basins, covering the geographical region from Spain to Finland, as a crucial prerequisite to indicate toxic gradients. The analysis comprised the Belgium biotic index (BBI), the biological monitoring working party (BMWP) scoring system and the revised German saprobic index. For comparison, we included an adaptation of the recently developed SPEAR index. In two previous field studies, this metric highly correlated with measured pesticide gradients. In this study, SPEAR was the only indicator that was generally applicable to all monitoring data and capable of determining "high ecological status" of reference conditions in all basins. Thus, based upon previous and own results, the authors suggest the species at risk (SPEAR) index to be potentially useful as a European-wide index to address deviations from "good ecological status" due to organic toxicants and recommend it for consideration in integrated water-resource evaluations under the WFD.     

Temporal trends in polychlorinated dibenzo-p-dioxins and dibenzofurans, dioxin-like PCBs, and polybrominated diphenyl ethers in Niagara river suspended sediments

Archived suspended sediment samples collected over the period 1980-2002 at Niagara-on-the-Lake in the Niagara river were analyzed to assess temporal trends in contaminants associated with historical industrial activities in the watershed (PCDDs/PCDFs, DLPCBs), compared to more modern industrial chemicals (PBDEs). The temporal trends for PCDDs/PCDFs and DLPCBs were generally similar, and showed a general trend toward decreasing concentrations, which was presumably due to implementation of control measures in the Niagara river watershed, including the remediation of hazardous waste facilities. The temporal trend in PBDEs contrasted with those of PCDDs/PCDFs and DLPCBs. Prior to 1988, PBDEs (sum of 16 congeners including deca-BDE) were generally detected at low-ppb concentrations, but showed a trend toward increasing concentrations over the period 1980-1988. After 1988, PBDE concentrations in the Niagara river showed a more rapidly increasing trend to a maximum of approximately 35 ng/g in 1995, with deca-BDE as the predominant congener detected. Samples collected over the period February 2003 to March 2004 at the head and mouth of the Niagara river were also analyzed for PBDEs; in all cases PBDE concentrations were higher at the mouth of the river at the outflow to Lake Ontario, indicating the Niagara river watershed is a source of PBDE contamination to Lake Ontario. However, PBDE concentrations in suspended sediments of the Niagara river were comparable to, or lower than, concentrations in bottom sediments in other industrialized/urbanized areas of the world. Based on these comparisons of global PBDE bottom sediment concentrations, the Niagara river watershed does not appear to be a significant local source of PBDEs to Lake Ontario, and concentrations in suspended sediments appear to be indicative of general PBDE contamination from a contamination of local, regional, and continental sources.     

Multi-residues analysis of pre-emergence herbicides in fluvial sediments: application to the mid-Garonne River

Contamination of man and ecosystems by pesticides has become a major environmental concern. Whereas many studies exist on contamination from agriculture, the effects of urban sources are usually omitted. Fluvial sediment is a complex matrix of pollutants but little is known of its recent herbicide content. This study proposes a method for a fast and reliable analysis of herbicides by employing the accelerated solvent extractor (ASE). The aim of the study is to show the impact of a major town (Toulouse) on the herbicide content in the river. In this study, three herbicide families (i.e.s-triazine, substituted ureas and anilides) were analysed in fluvial sediment fractions at 11 sampling sites along the mid-Garonne River and its tributaries. River water contamination by herbicides is minor, except for at three sites located in urban areas. Among the herbicidal families studied, urban and suburban areas are distinguished from rural areas and were found to be the most contaminated sites during the study period, a winter low-water event. The herbicide content of the coarse sediment fractions is about one third of that found in the fine fractions and usually ignored. The distribution of pesticide concentrations across the whole range of particle sizes was investigated to clarify the role of plant remains on the significant accumulation in the coarse fractions.     

Role of motorcycle type in fatal motorcycle crashes

IntroductionMotorcycles vary in design and performance capability, and motorcyclists may select certain motorcycle types based on driving preferences. Conversely, motorcycle performance capability may influence the likelihood of risky driving behaviors such as speeding. Both mechanisms may affect fatal crash risk when examined by motorcycle type. Although it was not possible to estimate the effect of each mechanism, the current study analyzed fatal crash data for evidence of motorcycle type differences in risky driving behaviors and risk of driver death.MethodsStreet legal motorcycles were classified into 10 types based on design characteristics and then further grouped as cruiser/standard, touring, sport touring, sport/unclad sport, supersport, and all others. For each motorcycle type, driver death rates per 10,000 registered vehicle years and the prevalence of fatal crash characteristics such as speeding were analyzed. Differences among motorcycle types concerning the effect of engine displacement were examined using Poisson regression.ResultsOverall, driver death rates for supersport motorcycles were four times as high as those for cruiser/standard motorcycles. Fatally injured supersport drivers were most likely to have been speeding and most likely to have worn helmets, but least likely to have been impaired by alcohol compared with drivers of other motorcycle types. The patterns in driver factors held after accounting for the effects of age and gender. Increased engine displacement was associated with higher driver death rates for each motorcycle type.ConclusionStrong effects of motorcycle type were observed on driver death rates and on the likelihood of risky driving behaviors such as speeding and alcohol impairment. Although the current study could not completely disentangle the effects of motorcycle type and rider characteristics such as age on driver death rates, the effects of both motorcycle type and rider age on the likelihood of risky driving behaviors were observed among fatally injured motorcycle drivers.Impact on IndustryCertain motorcycle designs, particularly supersport motorcycles, are associated with increases in risky driving behaviors and higher driver death rates. At present, there are no proven countermeasures for this situation. However, existing countermeasures such as helmet laws and automated speed enforcement could have a substantial benefit.