Air pollution during pregnancy and lung function in newborns: a birth cohort study

Post-natal exposure to air pollution is associated with diminished lung growth during school age. The current authors aimed to determine whether pre-natal exposure to air pollution is associated with lung function changes in the newborn. In a prospective birth cohort of 241 healthy term-born neonates, tidal breathing, lung volume, ventilation inhomogeneity and exhaled nitric oxide (eNO) were measured during unsedated sleep at age 5 weeks. Maternal exposure to particles with a 50% cut-off aerodynamic diameter of 10 microm (PM(10)), nitrogen dioxide (NO(2)) and ozone (O(3)), and distance to major roads were estimated during pregnancy. The association between these exposures and lung function was assessed using linear regression. Minute ventilation was higher in infants with higher pre-natal PM(10) exposure (24.9 mL x min(-1) per microg x m(-3) PM(10)). The eNO was increased in infants with higher pre-natal NO(2) exposure (0.98 ppb per microg x m(-3) NO(2)). Post-natal exposure to air pollution did not modify these findings. No association was found for pre-natal exposure to O(3) and lung function parameters. The present results suggest that pre-natal exposure to air pollution might be associated with higher respiratory need and airway inflammation in newborns. Such alterations during early lung development may be important regarding long-term respiratory morbidity.

Modeling contaminant behavior in Lake Superior : a comparison of PCBs, PBDEs, and mercury

A mass‐balance model for Lake Superior was applied to polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and mercury to determine the major routes of entry and the major mechanisms of loss from this ecosystem as well as the time required for each contaminant class to approach steady state. A two‐box model (water column, surface sediments) incorporating seasonally adjusted environmental parameters was used. Both numerical (forward Euler) and analytical solutions were employed and compared. For validation, the model was compared with current and historical concentrations and fluxes in the lake and sediments. Results for PCBs were similar to prior work showing that air‐water exchange is the most rapid input and loss process. The model indicates that mercury behaves similarly to a moderately‐chlorinated PCB, with air‐water exchange being a relatively rapid input and loss process. Modeled accumulation fluxes of PBDEs in sediments agreed with measured values reported in the literature. Wet deposition rates were about three times greater than dry particulate deposition rates for PBDEs. Gas deposition was an important process for tri‐ and tetra‐BDEs (BDEs 28 and 47), but not for higher‐brominated BDEs. Sediment burial was the dominant loss mechanism for most of the PBDE congeners while volatilization was still significant for tri‐ and tetra‐BDEs. Because volatilization is a relatively rapid loss process for both mercury and the most abundant PCBs (tri‐ through penta‐), the model predicts that similar times (from 2 ‐ 10 yr) are required for the compounds to approach steady state in the lake. The model predicts that if inputs of Hg(II) to the lake decrease in the future then concentrations of mercury in the lake will decrease at a rate similar to the historical decline in PCB concentrations following the ban on production and most uses in the U.S. In contrast, PBDEs are likely to respond more slowly if atmospheric concentrations are reduced in the future because loss by volatilization is a much slower process for PBDEs, leading to lesser overall loss rates for PBDEs in comparison to PCBs and mercury. Uncertainties in the chemical degradation rates and partitioning constants of PBDEs are the largest source of uncertainty in the modeled times to steady‐state for this class of chemicals. The modeled organic PBT loading rates are sensitive to uncertainties in scavenging efficiencies by rain and snow, dry deposition velocity, watershed runoff concentrations, and uncertainties in air‐water exchange such as the effect of atmospheric stability.

Long-Range Pollution Transport: Trans-Atlantic Mechanisms and Lagrangian Modeling Methods

Over the past several decades, it has become apparent that anthropogenic activities have resulted in the large-scale enhancement of the levels of many trace gases throughout the troposphere. More recently, attention has been given to the transport pathway taken by these emissions as they are dispersed throughout the atmosphere. The transport pathway determines the physical characteristics of emissions plumes and therefore plays an important role in the chemical transformations that can occur downwind of source regions. For example, the production of ozone (O3) is strongly dependent upon the transport its precursors undergo. O3 can initially be formed within air masses while still over polluted source regions. These polluted air masses can experience continued O3 production or O3 destruction downwind, depending on the air mass's chemical and transport characteristics. At present, however, there are a number of uncertainties in the relationships between transport and O3 production in the North Atlantic lower free troposphere. The first phase of the study presented here used measurements made at the Pico Mountain observatory and model simulations to determine transport pathways for US emissions to the observatory. The Pico Mountain observatory was established in the summer of 2001 in order to address the need to understand the relationships between transport and O3 production. Measurements from the observatory were analyzed in conjunction with model simulations from the Lagrangian particle dispersion model (LPDM), FLEX-PART, in order to determine the transport pathway for events observed at the Pico Mountain observatory during July 2003. A total of 16 events were observed, 4 of which were analyzed in detail. The transport time for these 16 events varied from 4.5 to 7 days, while the transport altitudes over the ocean ranged from 2-8 km, but were typically less than 3 km. In three of the case studies, eastward advection and transport in a weak warm conveyor belt (WCB) airflow was responsible for the export of North American emissions into the FT, while transport in the FT was governed by easterly winds driven by the Azores/Bermuda High (ABH) and transient northerly lows. In the fourth case study, North American emissions were lofted to 6-8 km in a WCB before being entrained in the same cyclone's dry airstream and transported down to the observatory. The results of this study show that the lower marine FT may provide an important transport environment where O3 production may continue, in contrast to transport in the marine boundary layer, where O3 destruction is believed to dominate. The second phase of the study presented here focused on improving the analysis methods that are available with LPDMs. While LPDMs are popular and useful for the analysis of atmospheric trace gas measurements, identifying the transport pathway of emissions from their source to a receptor (the Pico Mountain observatory in our case) using the standard gridded model output, particularly during complex meteorological scenarios can be difficult can be difficult or impossible. The transport study in phase 1 was limited to only 1 month out of more than 3 years of available data and included only 4 case studies out of the 16 events specifically due to this confounding factor. The second phase of this study addressed this difficulty by presenting a method to clearly and easily identify the pathway taken by only those emissions that arrive at a receptor at a particular time, by combining the standard gridded output from forward (i.e., concentrations) and backward (i.e., residence time) LPDM simulations, greatly simplifying similar analyses. The ability of the method to successfully determine the source-to-receptor pathway, restoring this Lagrangian information that is lost when the data are gridded, is proven by comparing the pathway determined from this method with the particle trajectories from both the forward and backward models. A sample analysis is also presented, demonstrating that this method is more accurate and easier to use than existing methods using standard LPDM products. Finally, we discuss potential future work that would be possible by combining the backward LPDM simulation with gridded data from other sources (e.g., chemical transport models) to obtain a Lagrangian sampling of the air that will eventually arrive at a receptor.

The Determination of Aluminum in the Presence of Manganese and Iron by the Use of a Mercury Cathode

Since 1880, when Wolcott Gibbs made the suggestion that mercury could be used as a cathode in gravimetric electroanalysis, many articles have appeared in literature either criticizing the method or citing successful results which have been obtained by it.

Apparatus and Method for Removing Mercury Vapor from a Gas Stream

A metallic filter effectively removes vapor from gas streams. The filter captures the mercury which then can be released and collected as a product. The metallic filter is a copper mesh sponge plated with a six micrometer thickness of gold. The filter removes up to 90% of mercury vapor from a mercury contaminated gas stream.

Recent environmental change and trace metal pollution in World Heritage Bathurst Harbour, southwest Tasmania, Australia

Bathurst Harbour in World Heritage southwest Tasmania, Australia, is one of the world’s most pristine estuarine systems. At present there is a lack of data on pollution impacts or long-term natural variability in the harbor. A ca. 350-year-old 210Pb-dated sediment core was analysed for trace metals to track pollution impacts from local and long-range sources. Lead and antimony increased from AD 1870 onwards, which likely reflects remote (i.e. mainland Australian and global) atmospheric pollution sources. Variability in the concentrations of copper and zinc closely followed the history of mining activities in western Tasmania, which began in the AD 1880s. Tin was generally low throughout the core, except for a large peak in AD 1989 ± 0.5 years, which may be a consequence of input from a local small-scale alluvial tin mine. Changes in diatom assemblages were also investigated. The diatom flora was composed mostly of planktonic freshwater and benthic brackish-marine species, consistent with stratified estuarine conditions. Since mining began, however, an overall decrease in the proportion of planktonic to benthic taxa occurred, with the exception of two distinct peaks in the twentieth century that coincided with periods of high rainfall. Despite the region’s remoteness, trace metal analyses revealed evidence of atmospheric pollution from Tasmanian and possibly longer-range mining activities. This, together with recent low rainfall, appears to have contributed to altering the diatom assemblages in one of the most pristine temperate estuaries in the world.